Academic literature on the topic 'Yeast strains'
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Journal articles on the topic "Yeast strains"
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Diguță, Camelia Filofteia, Constanța Mihai, Radu Cristian Toma, Carmen Cîmpeanu, and Florentina Matei. "In Vitro Assessment of Yeasts Strains with Probiotic Attributes for Aquaculture Use." Foods 12, no. 1 (December 26, 2022): 124. http://dx.doi.org/10.3390/foods12010124.
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This study aimed to investigate in vitro the probiotic potential of three yeasts strains (BB06, OBT05, and MT07) isolated from agro-food natural sources. Screening was performed, including several functional, technological, and safety aspects of the yeast strains, in comparison to a reference Saccharomyces boulardii, to identify the ones with suitable probiotic attributes in aquaculture. The yeast strains were identified by 5.8S rDNA-ITS region sequencing as Metschnikowia pulcherrima OBT05, Saccharomyces cerevisiae BB06, and Torulaspora delbrueckii MT07. All yeast strains were tolerant to different temperatures, sodium chloride concentrations, and wide pH ranges. S. cerevisiae BB06 showed a strong and broad antagonistic activity. Moreover, the S. cerevisiae strain exhibited a high auto-aggregation ability (92.08 ± 1.49%) and good surface hydrophobicity to hexane as a solvent (53.43%). All of the yeast strains have excellent antioxidant properties (>55%). The high survival rate in the gastrointestinal tract (GIT) can promote yeast isolates as probiotics. All yeast strains presented a resistance pattern to the antibacterial antibiotics. Non-hemolytic activity was detected. Furthermore, freeze-drying with cryoprotective agents maintained a high survival rate of yeast strains, in the range of 74.95–97.85%. According to the results obtained, the S. cerevisiae BB06 strain was found to have valuable probiotic traits.
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Hazra, Fahrizal. "Exploration of Pectin – Utilizing Yeast From Soil of Bogor and Wleri Fruit Orchards." Jurnal Hortikultura Indonesia 2, no. 1 (February 23, 2012): 43. http://dx.doi.org/10.29244/jhi.2.1.43-50.
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<p>There is a high demand on pectin–utilizing yeasts for industrial, agricultural and environmental purposes. Further exploration of yeast from various sources are important to enrich yeast culture collections. Nine yeast strains were isolated from various soil sources sampled based on biological sampling in Bogor and Central Java. Enriched media containing pectin as carbon sources was employed for isolation of the yeast. The isolated yeast were identified according to the methods described in monographs by Kreger – Van Rij (1984), Barnett et.al (2000), Guilliermond and Tanner (2006) . The strains isolated were taxonomically separated into 3 groups. Group I contains 3 strains, and this group is closely related to Candida tropicalis. Group II contains 4 strains, and this group is included in this genus Rhodotorula. Group III contain 2 strains, and this group is closely related to Williopsis saturnus, which is a synonym of Hansenula saturnus. Pectinolytic enzymes (Polygalacturonase) were produced by all of the tested strains. Polygalacturonase was produced as high as 1.7 U.ml-1 by strain no. 111 of group I, 1.7 U.ml-1 by strains no. 123 of group II, and 1.0 U.ml-1 by strain no. 211 of group III.</p><p><br />Key words : yeast, pectin, polygalacturonase</p>
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Alkay, Z., E. Dertli, and M. Z. Durak. "Investigation of probiotic potential of yeasts isolated from sourdoughs from different regions of Turkey." Acta Alimentaria 50, no. 4 (November 15, 2021): 610–19. http://dx.doi.org/10.1556/066.2021.00150.
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Abstract In this study, 14 yeast cultures from 62 isolates from traditional sourdoughs collected from 6 different regions of Turkey were selected by FT-IR identification and characterised to reveal their probiotic properties. Four yeast strains were genotypically identified and compared with FT-IR identification. In all analyses, it was observed that mostly Saccaromyces cerevisiae strain exhibited high hydrophobicity, auto-aggregation feature, and all yeast isolates in this study showed tolerance to 0.3%, even salt concentration. In addition, all yeast strains were susceptible to anti-yeasts agents, although they were resistant to all antibiotics used in the study. All selected yeast isolates exhibited high antimicrobial activity against the Staphylococcus aureus. In conclusion, this study investigated the potential probiotic properties of yeast strains isolated from sourdough.
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Păucean, Man, Chiş, Mureşan, Pop, Socaci, Mureşan, and Muste. "Use of Pseudocereals Preferment Made with Aromatic Yeast Strains for Enhancing Wheat Bread Quality." Foods 8, no. 10 (September 26, 2019): 443. http://dx.doi.org/10.3390/foods8100443.
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Usually, aromatic yeasts are designed to ferment wheat substrates for baking purposes but identification of new substrates for these strains and consequently new formulations for dough could lead to diversified bakery products with improved nutritional qualities and specific sensorial properties. The purpose of our study was to optimize the fermentation of quinoa and amaranth flours with non-conventional yeast strains in order to obtain a preferment with high potential in enhancing nutritional, textural and sensorial features of white wheat bread. Two biotypes of Saccharomyces cerevisiae yeast—a wine yeast strain and a beer yeast strain—commercialized for their aromatic properties were used. Both aromatic yeast strains revealed good performance on fermenting pseudocereal substrates. Utilization of the obtained preferment in white wheat breadmaking led to bread with higher protein, fibres, mineral, total polyphenols content, with specific texture and aroma profile and high consumers’ acceptability.
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Chen, Pei-Hua, and Jui-Yu Chou. "Screening and Identification of Yeasts Antagonistic to Pathogenic Fungi Show a Narrow Optimal pH Range for Antagonistic Activity." Polish Journal of Microbiology 66, no. 1 (March 30, 2017): 101–6. http://dx.doi.org/10.5604/17331331.1234997.
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Microbes have evolved ways of interference competition to gain advantage over their ecological competitors. The use of secreted antagonistic compounds by yeast cells is one of the prominent examples. Although this killer behavior has been thoroughly studied in laboratory yeast strains, our knowledge of the antagonistic specificity of killer effects in nature remains limited. In this study, yeast strains were collected from various niches and screened for antagonistic activity against one toxin-sensitive strain of Saccharomyces cerevisiae and three pathogenic fungi. We demonstrate that some strains with antagonistic activity against these pathogenic fungi can be found in antagonist culture tests. These yeasts were identified as members of Trichosporon asahii, Candida stellimalicola, Wickerhamomyces anomalus, Ustilago esculenta, Aureobasidium pullulans, and Pichia kluyveri. The results indicated that the antagonistic activity of these killer yeasts has a narrow optimal pH range. Furthermore, we found that the antagonistic activity of some species is strain-dependent.
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Gargouri, Boutheina, Najla Mhiri, Fatma Karray, Fathi Aloui, and Sami Sayadi. "Isolation and Characterization of Hydrocarbon-Degrading Yeast Strains from Petroleum Contaminated Industrial Wastewater." BioMed Research International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/929424.
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Two yeast strains are enriched and isolated from industrial refinery wastewater. These strains were observed for their ability to utilize several classes of petroleum hydrocarbons substrates, such asn-alkanes and aromatic hydrocarbons as a sole carbon source. Phylogenetic analysis based on the D1/D2 variable domain and the ITS-region sequences indicated that strains HC1 and HC4 were members of the generaCandidaandTrichosporon, respectively. The mechanism of hydrocarbon uptaking by yeast,Candida,andTrichosporonhas been studied by means of the kinetic analysis of hydrocarbons-degrading yeasts growth and substrate assimilation. Biodegradation capacity and biomass quantity were daily measured during twelve days by gravimetric analysis and gas chromatography coupled with mass spectrometry techniques. Removal ofn-alkanes indicated a strong ability of hydrocarbon biodegradation by the isolated yeast strains. These two strains grew on long-chainn-alkane, diesel oil, and crude oil but failed to grow on short-chainn-alkane and aromatic hydrocarbons. Growth measurement attributes of the isolates, usingn-hexadecane, diesel oil, and crude oil as substrates, showed that strain HC1 had better degradation for hydrocarbon substrates than strain HC4. In conclusion, these yeast strains can be useful for the bioremediation process and decreasing petroleum pollution in wastewater contaminated with petroleum hydrocarbons.
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Castrillo, David, Noemi Neira, and Pilar Blanco. "Saccharomyces cerevisiae Strain Diversity Associated with Spontaneous Fermentations in Organic Wineries from Galicia (NW Spain)." Fermentation 6, no. 3 (September 15, 2020): 89. http://dx.doi.org/10.3390/fermentation6030089.
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Yeast play an essential role in wine quality. The dynamics of yeast strains during fermentation determine the final chemical and sensory characteristics of wines. This study aims to evaluate the Saccharomyces cerevisiae strains diversity in organic wineries from Galicia (NW Spain). Samples from spontaneous fermentations were taken in five wineries over three consecutive years (2013 to 2015). The samples were transported to the laboratory and processed following standard methodology for yeast isolation. S. cerevisiae strains were differentiated by mDNA-RFLPs. A total of 66 different strains were identified. Some of them presented a wide distribution and appeared in several wineries. However, other strains were typical from a specific winery. Similarity analysis using two different statistical tests showed significant differences in strain diversity among wineries. The results also revealed high biodiversity indexes; however, only some strains showed an important incidence in their distribution and frequency. Our findings confirmed that spontaneous fermentation favored the existence of a high S. cerevisiae strain diversity in organic wineries from Galicia. The presence of different yeasts during fermentation, specially winery-specific strains, contribute to increased wine complexity and differentiation.
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Yoshinaga, Masafumi, Stephanie How, Damien Blanco, Ian Murdoch, Matteo Grudny, Samantha Powers, Nelson Molina, Barry Rosen, and Aaron Welch. "Directed Evolution of Saccharomyces cerevisiae for Increased Selenium Accumulation." Microorganisms 6, no. 3 (August 6, 2018): 81. http://dx.doi.org/10.3390/microorganisms6030081.
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Selenium-enriched yeast (selenium yeast) are one of the most popular sources of selenium supplementation used in the agriculture and human nutritional supplements industries. To enhance the production efficiency of selenium yeast, we sought to develop a method to identify, and ultimately select for, strains of yeast with enhanced selenium accumulation capabilities. Selenite resistance of four genetically diverse strains of Saccharomyces cerevisiae was assayed in various conditions, including varying carbon sources, nitrogen sources, and phosphate amounts, and they were correlated with selenium accumulation in a commercially relevant selenium-containing growth medium. Glycerol- and selenite-containing media was used to select for six yeast isolates with enhanced selenite resistance. One isolate was found to accumulate 10-fold greater selenium (0.13 to 1.4 mg Se g−1 yeast) than its parental strain. Glycerol- and selenium-containing medium can be used to select for strains of yeast with enhanced selenium accumulation capability. The methods identified can lead to isolation of industrial yeast strains with enhanced selenium accumulation capabilities that can result in greater cost efficiency of selenium yeast production. Additionally, the selection method does not involve the construction of transgenic yeast, and thus produces yeasts suitable for use in human food and nutrient supplements.
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Doan, Thi Kieu Tien, Thi Tuyet Nhung Do, Tri An Le, Hoang Hiep Tran, Thi Ngoc Mi Huynh, Ngoc Thanh Nguyen, and Xuan Phong Huynh. "Isolation and selection of yeasts from soursop Annona muricata for wine fermentation." Ministry of Science and Technology, Vietnam 63, no. 11 (November 25, 2021): 53–57. http://dx.doi.org/10.31276/vjst.63(11).53-57.
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Wine is a healthy drink and is becoming more diverse thanks to the substances with high biological activity and fully preserved the antioxidant capacity in the fruit after fermentation by yeast. This study aims to isolate yeasts that are capable of soursop fermentation. There were eight yeast strains isolated, in which five strains of yeasts NM1.1, NM1.2, NM2.1, NM3.1, NM3.2 are capable of fermenting soursop wine. Wine product after fermentation using strain NM1.1 with initial conditions of 22ºBrix, pH 4.5, supplemented yeast 1% (w/v) at room temperature (28-30ºC), in twelve-day, produced the ethanol content 10% v/v, methanol 1.304 g/l, and SO2 10.9 mg/l that meet Vietnamese standards (QCVN 6-3:2010/BYT).
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Cheraiti, Naoufel, St�phane Guezenec, and Jean-Michel Salmon. "Redox Interactions between Saccharomyces cerevisiae and Saccharomyces uvarum in Mixed Culture under Enological Conditions." Applied and Environmental Microbiology 71, no. 1 (January 2005): 255–60. http://dx.doi.org/10.1128/aem.71.1.255-260.2005.
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ABSTRACT Wine yeast starters that contain a mixture of different industrial yeasts with various properties may soon be introduced to the market. The mechanisms underlying the interactions between the different strains in the starter during alcoholic fermentation have never been investigated. We identified and investigated some of these interactions in a mixed culture containing two yeast strains grown under enological conditions. The inoculum contained the same amount (each) of a strain of Saccharomyces cerevisiae and a natural hybrid strain of S. cerevisiae and Saccharomyces uvarum. We identified interactions that affected biomass, by-product formation, and fermentation kinetics, and compared the redox ratios of monocultures of each strain with that of the mixed culture. The redox status of the mixed culture differed from that of the two monocultures, showing that the interactions between the yeast strains involved the diffusion of metabolite(s) within the mixed culture. Since acetaldehyde is a potential effector of fermentation, we investigated the kinetics of acetaldehyde production by the different cultures. The S. cerevisiae-S. uvarum hybrid strain produced large amounts of acetaldehyde for which the S. cerevisiae strain acted as a receiving strain in the mixed culture. Since yeast response to acetaldehyde involves the same mechanisms that participate in the response to other forms of stress, the acetaldehyde exchange between the two strains could play an important role in inhibiting some yeast strains and allowing the growth of others. Such interactions could be of particular importance in understanding the ecology of the colonization of complex fermentation media by S. cerevisiae.
Dissertations / Theses on the topic "Yeast strains"
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Reynolds, Nicola C. "Genetic manipulation of yeast strains." Thesis, University of Greenwich, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276133.
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Govender, Patrick. "Industrial yeast strains engineered for controlled flocculation." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1450.
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Thesis (PhD (Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2009.In many industrial fermentation processes, Saccharomyces cerevisiae yeast should ideally meet two partially conflicting demands. During fermentation a high suspended yeast count is of paramount importance to maintain a rapid fermentation rate, whilst efficient flocculation should ideally be initiated only on completion of the primary alcoholic fermentation, so as to enhance product clarification and recovery. Most commercial wine yeast strains are non-flocculent, probably because this trait was counter-selected to avoid fermentation problems. In this study, we assessed molecular strategies to optimise the flocculation behaviour of non-flocculent laboratory and wine yeast strains. For this purpose, the chromosomal copies of three dominant flocculation genes, FLO1, FLO5 and FLO11, of a non-flocculent S. cerevisiae laboratory strain (FY23) and two commercial wine yeast strains (BM45 and VIN13) were placed under the transcriptional control of the stationary phase-inducible promoters of the S. cerevisiae ADH2 or HSP30 genes. Under standard laboratory media and culture conditions, all six promoter-gene combinations resulted in specific flocculation behaviours in terms of timing and intensity. The data show that the strategy resulted in the expected and stable expression patterns of these genes in both laboratory and industrial wine yeast strains. Most importantly, the data confirm that inducible expression of the native FLO1 and FLO5 open reading frames, albeit to varying degrees, are responsible for a quantifiable cell-cell adhesion phenotype that can be characterized as a Flo1 flocculation phenotype. On the other hand, we found that inducible expression of the native FLO11 ORF under these conditions resulted in flor/biofilm formation and invasive growth phenotypes. However, the specific impact of the expression of individual dominant FLO genes with regard to characteristics such as flocculation efficiency, cell wall hydrophobicity, biofilm formation and substrate adhesion properties showed significant differences between the commercial strains as well as between commercial and laboratory strains. These adhesion phenotype differences may at least in part be attributed to wine yeast FLO gene open reading frames containing significantly smaller intragenic repeat regions than laboratory strains. The data show that the ADH2 regulatory sequences employed in this study were unsuitable for the purpose of driving FLO gene expression under wine-making conditions. However, HSP30p-based FLO1 and FLO5 wine yeast transformants displayed similar flocculent phenotypes under both synthetic and authentic red wine-making conditions, and the intensities of these phenotypes were closely aligned to those observed under nutrient-rich YEPD conditions. The fermentation activities of HSP30p-based transgenic yeast strains were indistinguishable from that of their parental host wine yeast strains. The chemical composition of wines obtained using transgenic yeast strains were similar to those produced by parental strains. The BM45-derived HSP30p-FLO5 transformant in particular was capable of generating compacted or ‘caked’ lees fractions, thereby providing a distinct separation of the fermented wine product and lees fractions. Furthermore, in this study we report a novel FLO11 induced flocculation phenotype that seems to exclusively develop under authentic red wine-making conditions. This strong FLO11 flocculation phenotype was not wine yeast strain dependant, possessed both Ca2+-dependant and Ca2+-independent flocculation characteristics and was insensitive to inhibition by both glucose and mannose. A distinct advantage of this unique FLO11 phenotype was highlighted in its ability to dramatically promote faster lees settling rates. Moreover, wines produced by HSP30p-FLO11 wine yeast transformants were significantly less turbid than those produced by their wild type parental strains. The benefit of this attractive property is it facilitates simpler and faster recovery of wines and also promotes greater volume recovery of the wine product.
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Nayyar, Ashima. "Yeast flocculation : understanding cell surface structure-function relationships in industrial yeast strains." Thesis, Abertay University, 2015. https://rke.abertay.ac.uk/en/studentTheses/cec13693-e667-4426-ba6c-6873e5c2b642.
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Adhesion properties of microorganisms are crucial for many essential biological processes such as sexual reproduction, tissue or substrate invasion, biofilm formation and cell-cell aggregation. One of such controlled forms of cellular adhesion in yeast that occurs preferentially in the liquid environments is a process of asexual aggregation of cells which is also referred to as flocculation. The timing during growth and the causes of onset of yeast flocculation are of commercial interest to the brewing industry, as flocculation can determine the degree of attenuation of the wort. Early or premature flocculation is one common causes of ‘hung’ or ‘stuck’ fermentations giving rise to sweeter beer whereas a lack or delay in flocculation can cause filtration difficulties and some problems in obtaining a bright sparkling beer; in addition, the presence of excess yeast in beer during ageing can cause off flavours due to yeast autolysis. Despite this commercial interest, limited information is available about the onset of flocculation and the various factors that may be responsible in the process. In particular, what are the signals that trigger flocculation? Adhesion properties applicable in improving yeast biotechnology are dependent directly or indirectly on characteristics of cellular surfaces, usually the outer layer of the cell wall. Change in the structure and or composition of the cell wall leads to changes in the microbial adhesion properties. Exploring more into the cell wall and studying the nanoscale structure of the yeast cell wall would thus be beneficial to augment our understanding of flocculation.
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Rossouw, Debra. "Comparative 'omic' profiling of industrial wine yeast strains." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1454.
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Thesis (PhD(Agric) Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2009.The main goal of this project was to elucidate the underlying genetic factors responsible for the different fermentation phenotypes and physiological adaptations of industrial wine yeast strains. To address this problem an ‘omic’ approach was pursued: Five industrial wine yeast strains, namely VIN13, EC1118, BM45, 285 and DV10, were subjected to transcriptional, proteomic and exometabolomic profiling during alcoholic fermentation in simulated wine-making conditions. The aim was to evaluate and integrate the various layers of data in order to obtain a clearer picture of the genetic regulation and metabolism of wine yeast strains under anaerobic fermentative conditions. The five strains were also characterized in terms of their adhesion/flocculation phenotypes, tolerance to various stresses and survival under conditions of nutrient starvation. Transcriptional profiles for the entire yeast genome were obtained for three crucial stages during fermentation, namely the exponential growth phase (day 2), early stationary phase (day 5) and late stationary phase (day 14). Analysis of changes in gene expression profiles during the course of fermentation provided valuable insights into the genetic changes that occur as the yeast adapt to changing conditions during fermentation. Comparison of differentially expressed transcripts between strains also enabled the identification of genetic factors responsible for differences in the metabolism of these strains, and paved the way for genetic engineering of strains with directed modifications in key areas. In particular, the integration of exo-metabolite profiles and gene expression data for the strains enabled the construction of statistical models with a strong predictive capability which was validated experimentally. Proteomic analysis enabled correlations to be made between relative transcript abundance and protein levels for approximately 450 gene and protein pairs per analysis. The alignment of transcriptome and proteome data was very accurate for interstrain comparisons. For intrastrain comparisons, there was almost no correlation between trends in protein and transcript levels, except in certain functional categories such as metabolism. The data also provide interesting insights into molecular evolutionary mechanisms that underlie the phenotypic diversity of wine yeast strains. Overall, the systems biology approach to the study of yeast metabolism during alcoholic fermentation opened up new avenues for hypothesis-driven research and targeted engineering strategies for the genetic enhancement/ modification of wine yeast for commercial applications.
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Louw, Campbell (Campbell Trout). "The development of polysaccharide degrading wine yeast strains." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16382.
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Thesis (MSc)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The polysaccharides that are present in wine originate from the grapes, the fungi that grow on the grapes and from other microorganisms that come into contact with the must during winemaking. The grape-derived polysaccharides of most concern in winemaking are pectin, glucan and xylan that can be enzymatically degraded by pectinases, glucanases and xylanases, respectively. These are the main structural polysaccharides of the cell wall of the grape cell. Degradation of the cell walls will result in the separation and rupture of the grape cells, and cell wall-bound compounds will be released into the must. Treating the must with pectinase and macerating enzyme preparations can result in an increase in free-flow juice, an improvement in must clarification and filtration, and an increased extraction of phenols and tannins. The tannins that are extracted polymerise with anthocyanins in red wine during ageing, resulting in increased colour intensity and stability. Wine aroma is also influenced by enzyme treatment. The degradation of the cell wall contributes to the release of glycosidically-bound terpene or alcohol precursors from the berries. The hydrolysis of these precursors during fermentation can result in an improvement in aroma. It can thus be seen that it is possible to improve wine quality and processing by supplementing the endogenous enzymes that are present in the fermentation with commercial enzyme preparations. Commercial enzymes are typically crude fungal preparations. The majority of commercial pectinase and glucanase preparations are derived from Aspergillus and Trichoderma, respectively. Since the endogenous polysaccharase activity of Saccharomyces cerevisiae is very limited, the heterologous expression of specific polysaccharase genes in an industrial yeast strain can improve the winemaking process, resulting in a higher quality wine without the addition of expensive commercial enzyme preparations. Since only the desired enzymes are secreted by the recombinant strain, there will be no undesired sideactivities, which can be detrimental to wine quality. Several pectinase-, glucanaseand xylanase-encoding genes, cloned from a variety of organisms, have been expressed successfully in laboratory strains of S. cerevisiae. Attempts have also been made to construct industrial wine yeast strains that express these polysaccharase genes and secrete the encoded enzymes. Fermentation with some of these strains resulted in a decrease in total phenolics and turbidity, an increase in juice extraction, and alterations in the colour and aromatic profile of the resulting wines. In this study, four polysaccharide-degrading, recombinant wine yeast strains were constructed. The endo-β-1,4-xylanase gene, XYN2, and the endo-β-1,4-glucanase gene, end1, were previously cloned from the soft rot fungus Trichoderma reesei and the rumen bacterium Butyrivibrio fibrisolvens, respectively. These genes were subcloned into different expression cassettes which were used to construct the four integration plasmids. The recombinant plasmids contained the following gene cassettes: TEF1P-XYN2-ADH2T (plasmid pDLG29) ADH1P- MFα1S -end1-TRP5T (plasmid pDLG30) ADH1P-MFα1S-end1-TRP5T and ADH2P-XYN2-ADH2T (plasmid pDLG33), ADH1P-MFα1S-end1-TRP5T and YG100PXYN2- ADH2T (plasmid pDLG39). These four plasmids were then separately integrated into the ILV2 locus of the commercial wine yeast strain S. cerevisiae VIN13. Wine was made with the four strains constructed in this study, a pectolytic strain, VIN13[pPPK], a glucanase- and xylanase-secreting strain, VIN13[pEX], an untransformed VIN13 strain, and an untransformed strain with the addition of the commercial enzyme preparation Rapidase EX Colour. Microvinification experiments were carried out on Pinot noir, Ruby Cabernet and Muscat d’Alexandria wines. Fermentation with the polysaccharide-degrading strains resulted in significant improvements in juice extraction, colour intensity and stability, and in alterations in the aromatic profiles of the wines produced. Subject to the approval by the regulatory authorities and eventual consumer acceptance of the use of genetically modified organisms (GMOs) in fermented foods and beverages, it might be required that the GM status of the yeast that is used appears on the label. Currently, there is no robust technique available with which the use of GM yeast can be revealed in a finished wine because the yeast cells and their DNA are removed from or denatured in the wine during filtration and processing. One way with which the undeclared use of a GM yeast in winemaking could be exposed would be to compare the chemical profile of a suspect wine with that of non-GM wine. In order to explore this concept further, a secondary aim of this study was to investigate whether Fourier Transformation Infra Red (FT-IR) spectroscopy coupled with multivariate data analysis could distinguish between wines fermented with transgenic and non-transgenic yeast strains, or between wines fermented with different transgenic strains. The results showed that this method could be used to classify wines fermented with different yeast strains if fermentation with the strain resulted in a unique chemical profile in the resulting wine. This was a preliminary study and these findings were summarised as an addendum to the thesis.
AFRIKAANSE OPSOMMING: Die polisakkariede wat in wyn teenwoordig is, is afkomstig van die druiwe, die swamme wat op die druiwe groei en vanaf ander mikroörganismes wat tydens die wynmaakproses met die mos in aanraking kom. Die belangrikste druifpolisakkariede in wynbereiding is pektien, glukaan en xilaan, wat onderskeidelik deur pektinases, glukanases en xilanases afgebreek kan word. Hierdie is die vernaamste strukturele polisakkariede van ‘n druifsel se selwand. Die afbreking van die selwande veroorsaak dat die druifselle skei en skeur, met die gevolg dat die selwandgebonde verbindings in die mos vrygelaat word. Die behandeling van die mos met pektinase en versappingsensiempreparate kan tot ʼn toename in vry-afloopsap lei, sowel as ʼn verbetering in mosverheldering en -filtrasie en ʼn verhoogde ekstraksie van fenole en tanniene. Die tanniene wat geëkstraheer word, polimeriseer in rooiwyn tydens veroudering, en dit lei tot verhoogde kleurintensiteit en -stabiliteit. Wynaroma word ook deur ensiembehandeling beïnvloed. Die afbreking van die druifselwand dra by tot die vrylating van glikosidiesgebonde terpeen- en alkoholvoorlopers uit die korrels. Die hidrolise van hierdie voorlopers tydens gisting kan lei tot ʼn verbetering van die aroma. Dit is dus duidelik dat dit moontlik is om wynkwaliteit en wynbereiding te verbeter deur die endogene ensieme wat in die gisting teenwoordig is met kommersiële ensiempreparate te supplementeer. Kommersiële ensiempreparate is tipies ongesuiwerde swampreparate. Die meerderheid kommersiële pektinase- en glukanasepreparate word onderskeidelik vanaf Aspergillus en Trichoderma verkry. Aangesien die endogene polisakkaraseaktiwiteit van Saccharomyces cerevisiae baie beperk is, kan die heteroloë uitdrukking van spesifieke polisakkarase-gene in ʼn industriële gisras die wynbereidingsproses verbeter en lei tot ʼn hoër kwaliteit wyn sonder die byvoeging van duur kommersiële ensiempreparate. Omdat die verkose ensieme deur die rekombinante ras uitgeskei word, sal daar geen ongewenste newe-effekte teenwoordig wees wat ʼn nadelige effek op wynkwaliteit kan hê nie. Verskeie mikrobiese gene wat vir pektinases, glukanases en xilanases kodeer, is reeds voorheen uit ‘n wye verskeidenheid van organismes gekloneer en suksesvol in laboratoriumrasse van S. cerevisiae uitgedruk. Pogings is ook aangewend om industriële wyngisrasse te konstrueer wat hierdie polisakkarasegene uitdruk en hul enkodeerde ensieme uitskei. Gisting met sommige van hierdie rekombinante gisrasse het gelei tot ʼn afname in totale fenoliese verbindings en troebelheid, ʼn verhoging in sapekstraksie, en veranderings in die kleur en aromatiese profiel van die gevolglike wyne. In hierdie studie is vier polisakkaried-afbrekende, rekombinante wyngisrasse gekonstrueer. Die endo-β-1,4-xilanasegeen, XYN2, en die endo-β-1,4- glukanasegeen, end1, is voorheen reeds onderskeidelik vanaf die sagte vrotswam, Trichoderma reesei, en die rumenbakterium, Butyrivibrio fibrisolvens, gekloneer. Hierdie gene is in vier integrasieplasmiede in verskillende ekspressiekassette gesubkloneer. Die plasmiede het die volgende geenkassette bevat: TEF1P-XYN2- ADH2T (plasmied pDLG29) ADH1P- MFα1S -end1-TRP5T (plasmied pDLG30) ADH1PMFα1S- end1-TRP5T and ADH2P-XYN2-ADH2T (plasmied pDLG33), ADH1P-MFα1S end1-TRP5T and YG100P-XYN2-ADH2T (plasmied pDLG39). Hierdie vier plasmiede is toe afsonderlik in die ILV2-lokus van die kommersiële wyngisras, S. cerevisiae VIN 13, geïntegreer. Wyn is met hierdie vier gekonstrueerde gisrasse gemaak, die pektolitiese gisras, VIN13[pPPK], die glukanase- en xilanase-afskeidende gisras, VIN13[pEX], die ongetransformeerde VIN13-ras, en met ʼn ongetransformeerde VIN13 gis waarby die kommersiële ensiempreparaat, Rapidase EX Colour, bygevoeg is. Mikro-wynbereidingseksperimente is op Pinot noir-, Ruby Cabernet- en Muscat D’Alexandria wyne uitgevoer. Gisting met die polisakkaried-afbrekende gisrasse het gelei tot ʼn noemenswaardige verbetering in sapekstraksie, kleurintensiteit en kleurstabiliteit, asook in veranderinge in die aromatiese profiele van die geproduseerde wyne. Indien die gebruik van geneties gemodifiseerde organismes (GMOs) in gefermenteerde voedsel en drank deur die reguleringsowerhede goedgekeur en uiteindelik deur die verbruiker aanvaar sou word, sou dit vereis kon word dat die GMstatus van die wyngisgis op die etiket van die wynbottel aangebring word. Verpligte etikettering van GM-wyn sal metodes vereis waarmee die ‘nalentskap’ van GMgisselle in die finale produk geïdentifiseer en gemoniteer kan word. Tans is daar geen robuuste tegnieke beskikbaar waarmee die gebruik van GM-giste openbaar kan word nie, aangesien die gisselle en hul DNA tydens filtrasie en prosessering verwyder word. Een wyse waarop die onverklaarde gebruik van ‘n GM-gis in wynbereiding blootgestel sou kno word, is om die chemiese profiel van die verdagte wyn met dié van ‘n nie-GM-wyn te vergelyk. Ten einde hierdie konsep verder te ondersoek was ‘n sekondêre doelwit van hierdie studie om te bepaal of FT-IR (Fourier-transformasie-infrarooi) spektroskopie tesame met meervariante dataanalise gebruik kan word om te onderskei tussen wyne wat met transgeniese en nietransgeniese gisrasse gegis is, of tussen wyne wat met verskillende transgeniese rasse gegis is. Die resultate het aangedui dat hierdie metode gebruik kan word om wyne wat met verskillende gisrasse gegis is, te klassifiseer indien die betrokke gisras ʼn unieke chemiese profiel in die uiteindelike wyn veroorsaak het. Dit was egter ʼn voorlopige ondersoek en is as ʼn byvoegsel tot die tesis geskryf.
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Hemmati, Naghmeh. "Engineering yeast strains to enhance bioethanol production efficiency /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674956301&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Mocke, Bernard A. "The breeding of yeast strains for novel oenological outcomes." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1117.
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Zelena, L., S. Nevmyvaka, and I. Hretskyi. "Effect of co-culturing yeast strains on cell density." Thesis, Київський національний університет технологій та дизайну, 2020. https://er.knutd.edu.ua/handle/123456789/15572.
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Trollope, Kim. "Investigation of resveratrol production by genetically engineered Saccharomyces cervisiae strains /." Link to the online version, 2006. http://hdl.handle.net/10019/1247.
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Boeira, Lucia Schuch. "Effects of fusariotoxins on the performance of brewing yeast strains." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/560.
Full textBooks on the topic "Yeast strains"
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Faklaris, D. Effect of drying on growth and stability of brewing yeast strains. Manchester: UMIST, 1998.
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Gough, Suzanne. Production of Ethanol from mollasses using the Thermotolerant Yeast Strain Kluyveromyces marxiamus IMB3. [S.l: The Author], 1998.
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Brady, Damien. Ethanol production by the thermolerant yeast strain kluyveromyces marscianus IMB3 during growth on lactose- containing media. [S.l: The Author], 1996.
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Bakalinsky, Alan Togore. Conversion of wine yeast strains of Saccharomyces cerevisiae to heterothallism and determination of their chromosomal constitution. 1989.
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1949-, Panchal Chandra J., ed. Yeast strain selection. New York: M. Dekker, 1990.
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Panchal, Chandra J. Yeast Strain Selection. Taylor & Francis Group, 2020.
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Panchal, Chandra J. Yeast Strain Selection. Taylor & Francis Group, 2020.
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Panchal, Chandra J. Yeast Strain Selection. Taylor & Francis Group, 2020.
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Panchal, Chandra J. Yeast Strain Selection. Taylor & Francis Group, 2020.
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Panchal. Yeast Strain Selection. Taylor & Francis Group, 2019.
Find full textBook chapters on the topic "Yeast strains"
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Chochinov, Claire A., and Alex N. Nguyen Ba. "Bulk-Fitness Measurements Using Barcode Sequencing Analysis in Yeast." In Methods in Molecular Biology, 399–415. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2257-5_22.
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AbstractThe use of DNA barcodes for determining changes in genotype frequencies has been instrumental to increase the scale at which we can phenotype strain libraries by using next-generation sequencing technologies. Here, we describe the determination of strain fitness for thousands of yeast strains simultaneously in a single assay using recent innovations that increase the precision of these measurements, such as the inclusion of unique-molecular identifiers (UMIs) and purification by solid-phase reverse immobilization (SPRI) beads.
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White, P. A., A. I. Kennedy, and K. A. Smart. "The Osmotic Stress Response of Ale and Lager Brewing Yeast Strains." In Brewing Yeast Fermentation Performance, 46–60. Oxford, UK: Blackwell Science, 2008. http://dx.doi.org/10.1002/9780470696040.ch5.
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Olineka, Tammi L., Apostolos Spiropoulos, Paula A. Mara, and Linda F. Bisson. "Optimization of Proteome Analysis for Wine Yeast Strains." In Microbial Processes and Products, 345–68. Totowa, NJ: Humana Press, 2005. http://dx.doi.org/10.1385/1-59259-847-1:345.
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Smith, David, and Vera Bussas. "Preserving the reference strains." In Trends in the systematics of bacteria and fungi, 55–68. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789244984.0055.
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Abstract It is critical that storage of the living reference strains, on which the names and properties are based and the DNA sequenced to assign a name (the reference genetic resources), are preserved optimally to retain stability. The fact that less than 1% of microbial diversity can be grown sets enormous challenges for repositories (microbial domain biological resource centres or mBRCs). It is most often the case that it is an axenic culture of the reference genetic resource that is preserved but, for those organisms that cannot be grown or where molecular techniques are used to identify the organism, DNA should be stored. This task increases further when the microbiome is being studied, and environmental samples from whole communities are examined; mBRCs need to address how these can be preserved too. This chapter focuses on property retention, selecting the appropriate techniques for longterm survival and stability of characters. It covers the operations of mBRCs and the most appropriate technologies and mechanisms for stability testing and quality assurance. It addresses the preservation of microbial strains of the wide range of archaeal, bacterial (including cyanobacterial), yeast and fungal type and reference strains.
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Dannenmaier, Stefan, Silke Oeljeklaus, and Bettina Warscheid. "2nSILAC for Quantitative of Prototrophic Baker’s Yeast." In Methods in Molecular Biology, 253–70. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1024-4_18.
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AbstractStable isotope labeling by amino acids in cell culture (SILAC) combined with high-resolution mass spectrometry is a quantitative strategy for the comparative analysis of (sub)proteomes. It is based on the metabolicincorporation of stable isotope-coded amino acids during growth of cells or organisms. Here, complete labeling of proteins with the amino acid(s) selected for incorporation needs to be guaranteed to enable accurate quantification on a proteomic scale. Wild-type strains of baker’s yeast (Saccharomyces cerevisiae), which is a widely accepted and well-studied eukaryotic model organism, are generally able to synthesize all amino acids on their own (i.e., prototrophic). To render them amenable to SILAC, auxotrophies are introduced by genetic manipulations. We addressed this limitation by developing a generic strategy for complete “native” labeling of prototrophic S. cerevisiae with isotope-coded arginine and lysine, referred to as “2nSILAC”. It allows for directly using and screening several genome-wide yeast mutant collections that are easily accessible to the scientific community for functional proteomic studies but are based on prototrophic variants of S. cerevisiae.
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Yin, Junwei, Yajun Li, Shujian Li, Xiaofang Wang, Xiao Gong, Yangyang Liu, Lijing Lin, and Jihua Li. "Characteristics of red pitaya wine fermented by different yeast strains." In Advances in Materials Science, Energy Technology and Environmental Engineering, 371–74. P.O. Box 11320, 2301 EH Leiden, The Netherlands, e-mail: Pub.NL@taylorandfrancis.com , www.crcpress.com – www.taylorandfrancis.com: CRC Press/Balkema, 2016. http://dx.doi.org/10.1201/9781315227047-73.
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Shalley Sharma, Sonia Sharma, Surender Singh, Lata, and Anju Arora. "Improving Yeast Strains for Pentose Hexose Co-fermentation: Successes and Hurdles." In Springer Proceedings in Energy, 23–41. New Delhi: Springer India, 2016. http://dx.doi.org/10.1007/978-81-322-2773-1_3.
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Garadi Suresh, Harsha, and Mojca Mattiazzi Usaj. "Systematic High-Content Screening of Fluorescently Tagged Yeast Double Mutant Strains." In Methods in Molecular Biology, 57–78. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1740-3_3.
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Mattiazzi Usaj, Mojca, Dara S. Lo, Ben T. Grys, and Brenda J. Andrews. "High-Throughput Imaging of Arrays of Fluorescently Tagged Yeast Mutant Strains." In Confocal Microscopy, 221–42. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1402-0_12.
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Takagi, Hiroshi. "Construction of Baker’s Yeast Strains with Enhanced Tolerance to Baking-Associated Stresses." In Biotechnology of Yeasts and Filamentous Fungi, 63–85. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-58829-2_3.
Full textConference papers on the topic "Yeast strains"
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de Gee, Maarten, Hilda van Mourik, Arjan de Visser, and Jaap Molenaar. "Modeling competition between yeast strains." In SYMPOSIUM ON BIOMATHEMATICS (SYMOMATH 2015). AIP Publishing LLC, 2016. http://dx.doi.org/10.1063/1.4945057.
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Slanina, Valerina, and Ludmila Batir. "CONSERVATION OF YEAST STRAINS OF BIOTECHNOLOGICAL INTEREST." In XIth International Congress of Geneticists and Breeders from the Republic of Moldova. Scientific Association of Geneticists and Breeders of the Republic of Moldova, Institute of Genetics, Physiology and Plant Protection, Moldova State University, 2021. http://dx.doi.org/10.53040/cga11.2021.134.
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Alasmar, Reem Moath, and Samir Jaoua. "Investigation and Biological Control of Toxigenic Fungi and Mycotoxins in Dairy Cattle Feeds." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0065.
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Mycotoxins, the secondary fungal metabolites are important contaminants of food and feed. Among the other contaminants, aflatoxin B1 (AFB1) and OTA are frequently detected in the animal feed product. In the present study, the mixed dairy cow feed products were collected from the supermarkets in Qatar and analyzed for the presence of AFB1 and OTA. Yeast strains were isolated and tested for their biological control activities against aflatoxigenic and ochratoxin fungi. We demonstrated that local 15 yeasts isolates have important antifungal potential activities through the synthesis of volatile organic compounds (VOC) that are able to act against the mycotoxigenic fungi and their synthesis of the mycotoxins. Two Yeast strains (4&2) isolated from fermented food, have shown a great antifungal inhibition growth in-vitro as well as spores inhibition and mycotoxins synthesis.
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Bardhan, Pritam, and Manabendra Mandal. "Rhodotorula mucilaginosa R2: A potent oleaginous yeast isolated from traditional fermented food, as a promising platform for the production of lipid-based biofuels, bioactive compounds and other value added products." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/qbyp3823.
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Oleaginous yeasts may provide an alternative platform for the sustainable production of microbial lipids-derived biodiesel and other health promoting bioactive metabolites such as natural pigments. In this regard, traditional fermented foods are unique and untapped habitats for the isolation and characterization of oleaginous yeasts with beneficial properties. In this study, we analysed the yeast diversity from selected traditional fermented foods of Manipur and Mizoram, India and studied their oleaginous attributes for biodiesel production. 14 potential oleaginous yeasts were isolated using culture-dependent techniques. The isolates were identified by 5.8S internal transcribed spacer (ITS) rRNA gene sequencing. Intracellular triacylglycerides (TAG) accumulation by yeast cells were confirmed by Nile red fluorescence microscopy. Fatty acid methyl esters (FAME) profile of the yeast strains were analysed by GC-MS. The identified yeast isolates belonged to seven different genera viz. Rhodotorula, Pichia, Candida, Saturnispora, Wickerhamomyces, Zygoascus and Saccharomyces. Rhodotorula mucilaginosa R2 exhibited the maximum lipid content (% lipid/g dry cell weight) of (21.63 %) after 96 h of growth in nitrogen-limited medium. R. mucilaginosa R2 single cell oil (RMSCO) was transesterified into biodiesel with a conversion efficiency of 96.6 % using a heterogeneous potassium hydroxide catalyst (K-RAC) supported on R. mucilaginosa R2 deoiled cake activated carbon. The physico-chemical properties of the biodiesel derived from R. mucilaginosa R2 single cell oil were within the limits of ASTM and EN standards. FAME analysis of the transesterified lipid extract suggested the potential use of yeast derived oil as an alternative to vegetable oil for biodiesel production. Furthermore, carotenoids obtained from the pink yeast R. mucilaginosa R2 was composed of torularhodin, torulene and β-carotene and exhibited strong antioxidant activity. Keywords: Oleaginous yeast, Triacylglycerides, Fermented food, Rhodotorula mucilaginosa
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Satwika, D., V. R. A. Permatasari, and G. E. N. Cahyani. "A Potential Yeast Strains for Biological Control of Mosquitoes." In 10th International Seminar and 12th Congress of Indonesian Society for Microbiology (ISISM 2019). Paris, France: Atlantis Press, 2021. http://dx.doi.org/10.2991/absr.k.210810.023.
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Shydlovska, Olga, and Yevhen Kharchenko. "Review of Green Methods of Synthesis of Silver Nanoparticles." In The 9th International Conference on Advanced Materials and Systems. INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania, 2022. http://dx.doi.org/10.24264/icams-2022.i.8.
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Green synthesis of metal nanoparticles is a very promising area of research. Silver nanoparticles are the most interesting type of nanoparticle in nanotechnology because they have varied properties, such as antibacterial, antioxidant, and antibiofilm forming properties. This review aims to establish which of the most common approaches for the biological synthesis of nanoparticles is the best. In this work, the methods of synthesis of silver nanoparticles using plant extracts, bacteria, and yeast are considered. Each of these methods has its advantages and disadvantages. The most common method of synthesis of silver nanoparticles is the method using plant extracts, however, stabilizing substances from plant extracts have their own direct biological activity, which can be both enhanced and suppressed by silver nanoparticles. Green synthesis of nanoparticles thanks to microorganisms makes it possible to use a wide range of bacterial strains, but it is important to remember of the pathogenicity of the strains and their danger to humans. From this perspective, the use of yeast for the synthesis of silver nanoparticles is the most promising method, as it allows obtaining a large amount of nanomaterial. The synthesis, thanks to yeast method, allows us to control the size and shape of the nanoparticles. Nanoparticles obtained from yeast lysates have effective antibacterial and antifilm-forming activity.
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Yang, Yang, Rahul Mitchell Jairaj, Gaoyan Wang, Tzuen-Rong Tzeng, Xiangchun Xuan, Kama Huang, and Pingshan Wang. "Broadband Dielectric Properties Characterization of Biological Cells." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18508.
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A broadband characterization method for complex permittivity measurements of biological cells is presented. An algorithm for extracting permittivity of biological cells from the measured cell suspension scattering parameters is described. A coplanar wave guide (CPW) based device is fabricated and tested. DI water measurement results show good agreement with theoretical values. Yeast cell suspensions are characterized. Complex permittivity of yeast strains is extracted over the frequency range from 30 kHz to 30 GHz.
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Serba, E. M., M. B. Overchenko, N. I. Ignatova, and L. V. Rimareva. "COMPARATIVE STUDIES OF SACCHAROMYCES CEREVISIAE YEAST STRAINS, PROMOSING FOR CONCENTRATED GRAIN WORT FERMENTATION." In Current issues in the beverage industry. Author-online, 2019. http://dx.doi.org/10.21323/978-5-6043128-4-1-2019-3-201-207.
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Bhatta, H., E. M. Goldys, and J. Ma. "Fluorescence and fluorescence-lifetime imaging microscopy (FLIM) to characterize yeast strains by autofluorescence." In Biomedical Optics 2006, edited by Daniel L. Farkas, Dan V. Nicolau, and Robert C. Leif. SPIE, 2006. http://dx.doi.org/10.1117/12.645354.
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Chou, Fong-In, Chia-Chin Li, Tzung-Yuang Chen, and Hsiao-Wei Wen. "Microbial Occurrence in Bentonite-Based Buffer Materials of a Final Disposal Site for Low Level Radioactive Waste in Taiwan." In ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40284.
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This research addresses the potential of microbial implications in bentonite for use as a buffer and backfill material in final disposal site for low-level radioactive waste (LLRW) in Taiwan, where has a special island-type climate. Microbe activities naturally present in this site were analyzed, and buffer materials (BM) consisted of 100%, 70% or 50% bentonite were prepared for laboratory studies. A total of 39 microbial strains were isolated, and the predominant strains included four bacterial, one yeast and four fungal strains. Growth inhibition was not detected in any tested strain cultured in a radiation field with a dose rate of 0.2 Gy/h. Most of the isolated strains grew under a dose rate of 1.4 Gy/h. The D10 values of the tested strains ranged from 0.16 to 2.05 kGy. The mycelia of tested fungal strains could spread over 5 cm during six months of inoculation in BM. The spreading activity of the tested bacteria was less than that of the fungi. Moreover, biofilms were observed on the surfaces of the BM. Since a large and diverse population of microbes is present in Taiwan, microbes may contribute to the mobilization of radionuclides in the disposal site.
Reports on the topic "Yeast strains"
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Gaugler, Randy, Itamar Glazer, Daniel Segal, and Sarwar Hashmi. Molecular Approach for Improving the Stability of Insecticidal Nematodes. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7580680.bard.
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Our overall goal is to improve insecticidal nematodes by genetically engineering strains capable of entering an enhanced state of dormancy that provides improved stability. Objectives: 1. Clone and sequence tps-l homologue from Steinernema carpocapsae. (Revised: A failure to isolate the tps gene group from Steinernema precipitated a redirection to identifying other genes involved in insecticidal nematode desiccation process.) 2. Incorporate cloned tps-l gene into S. carpocapsae to obtain overexpression, thereby, enhancing desiccation tolerance. (Revised: Other stress genes in addition to tps-l genes were cloned and efforts at expression in S. carpocapsae were conducted) 3. Characterize the transgenic strains. No other biological control agent offers more impressive attributes than insecticidal nematodes. However, their potential is limited by the bane of nearly all biological control agents: poor stability. This leads to inadequate shelf-life and ultimately reduced field efficacy. Nematode storage is based on desiccation, yet insecticidal species are only capable of partial desiccation termed quiescent anhydrobiosis. Overwhelming evidence has shown that when the disaccharide compound trehalose is elevated in anhydrobiotic organisms such as yeast, plants, and nematodes it enables these organisms the ability to survive environmental stresses i.e., desiccation. Armed with this information our goal was to improve insecticidal nematodes stability by engineering trehalose overexpression.
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Lichter, Amnon, Gopi K. Podila, and Maria R. Davis. Identification of Genetic Determinants that Facilitate Development of B. cinerea at Low Temperature and its Postharvest Pathogenicity. United States Department of Agriculture, March 2011. http://dx.doi.org/10.32747/2011.7592641.bard.
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Botrytis cinerea is the postharvest pathogen of many agricultural produce with table grapes, strawberries and tomatoes as major targets. The high efficiency with which B. cinerea causes disease on these produce during storage is attributed in part due to its exceptional ability to develop at very low temperature. Our major goal was to understand the genetic determinants which enable it to develop at low temperature. The specific research objectives were: 1. Identify expression pattern of genes in a coldenriched cDNA library. 2. Identify B. cinerea orthologs of cold-induced genes 3. Profile protein expression and secretion at low temperature on strawberry and grape supplemented media. 4. Test novel methods for the functional analysis of coldresponsive genes. Objective 1 was modified during the research because a microarray platform became available and it allowed us to probe the whole set of candidate genes according to the sequence of 2 strains of the fungus, BO5.10 and T4. The results of this experiment allowed us to validate some of our earlier observations which referred to genes which were the product of a SSH suppression-subtraction library. Before the microarray became available during 2008 we also analyzed the expression of 15 orthologs of cold-induced genes and some of these results were also validated by the microarray experiment. One of our goals was also to perform functional analysis of cold-induced genes. This goal was hampered for 3 years because current methodology for transformation with ‘protoplasts’ failed to deliver knockouts of bacteriordopsin-like (bR) gene which was our primary target for functional analysis. Consequently, we developed 2 alternative transformation platforms, one which involves an air-gun based technique and another which involves DNA injection into sclerotia. Both techniques show great promise and have been validated using different constructs. This contribution is likely to serve the scientific community in the near future. Using these technologies we generated gene knockout constructs of 2 genes and have tested there effect on survival of the fungus at low temperature. With reference to the bR genes our results show that it has a significant effect on mycelial growth of the B. cinerea and the mutants have retarded development at extreme conditions of ionic stress, osmotic stress and low temperature. Another gene of unknown function, HP1 is still under analysis. An ortholog of the yeast cold-induced gene, CCH1 which encodes a calcium tunnel and was shown to be cold-induced in B. cinerea was recently cloned and used to complement yeast mutants and rescue them from cold-sensitivity. One of the significant findings of the microarray study involves a T2 ribonuclease which was validated to be cold-induced by qPCR analysis. This and other genes will serve for future studies. In the frame of the study we also screened a population of 631 natural B. cinerea isolates for development at low temperature and have identified several strains with much higher and lower capacity to develop at low temperature. These strains are likely to be used in the future as candidates for further functional analysis. The major conclusions from the above research point to specific targets of cold-induced genes which are likely to play a role in cold tolerance. One of the most significant observations from the microarray study is that low temperature does not induce ‘general stress response in B. cinerea, which is in agreement to its exceptional capacity to develop at low temperature. Due to the tragic murder of the Co-PI Maria R. Davis and GopiPodila on Feb. 2010 it is impossible to deliver their contribution to the research. The information of the PI is that they failed to deliver objective 4 and none of the information which relates to objective 3 has been delivered to the PI before the murder or in a visit to U. Alabama during June, 2010. Therefore, this report is based solely on the IS data.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
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One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
Full textAbstract:
To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Sessa, Guido, and Gregory Martin. Role of GRAS Transcription Factors in Tomato Disease Resistance and Basal Defense. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696520.bard.
Full textAbstract:
The research problem: Bacterial spot and bacterial speck diseases of tomato are causedby strains of Xanthomonas campestris pv. vesicatoria (Xcv) and Pseudomonas syringae pv.tomato (Pst), respectively. These bacteria colonize aerial parts of the plant and causesignificant losses in tomato production worldwide. Protection against Xcv and Pst bycultural practices or chemical control has been unsuccessful and there are only limitedsources of genetic resistance to these pathogens. In previous research supported in part byBARD IS-3237-01, we extensively characterized changes in tomato gene expression uponthe onset of spot and speck disease resistance. A remarkable finding of these studies wasthe inducibility in tomato leaves by both Xcv and Pst strains of genes encodingtranscriptional activator of the GRAS family, which has not been previously linked todisease resistance. Goals: Central goals of this research were to investigate the role of GRAS genes in tomatoinnate immunity and to assess their potential use for disease control.Specific objectives were to: 1. Identify GRAS genes that are induced in tomato during thedefense response and analyze their role in disease resistance by loss-of-function experiments.2. Overexpress GRAS genes in tomato and characterize plants for possible broad-spectrumresistance. 3. Identify genes whose transcription is regulated by GRAS family. Our main achievements during this research program are in three major areas:1. Identification of tomato GRAS family members induced in defense responses andanalysis of their role in disease resistance. Genes encoding tomato GRAS family memberswere retrieved from databases and analyzed for their inducibility by Pst avirulent bacteria.Real-time RT-PCR analysis revealed that six SlGRAS transcripts are induced during theonset of disease resistance to Pst. Further expression analysis of two selected GRAS genesshowed that they accumulate in tomato plants in response to different avirulent bacteria orto the fungal elicitor EIX. In addition, eight SlGRAS genes, including the Pst-induciblefamily members, were induced by mechanical stress in part in a jasmonic acid-dependentmanner. Remarkably, SlGRAS6 gene was found to be required for tomato resistance to Pstin virus-induced gene silencing (VIGS) experiments.2. Molecular analysis of pathogen-induced GRAS transcriptional activators. In aheterologous yeast system, Pst-inducible GRAS genes were shown to have the ability toactivate transcription in agreement with their putative function of transcription factors. Inaddition, deletion analysis demonstrated that short sequences at the amino-terminus ofSlGRAS2, SlGRAS4 and SlGRAS6 are sufficient for transcriptional activation. Finally,defense-related SlGRAS proteins were found to localize to the cell nucleus. 3. Disease resistance and expression profiles of transgenic plants overexpressing SlGRASgenes. Transgenic plants overexpressing SlGRAS3 or SlGRAS6 were generated. Diseasesusceptibility tests revealed that these plants are not more resistant to Pst than wild-typeplants. Gene expression profiles of the overexpressing plants identified putative direct orindirect target genes regulated by SlGRAS3 and SlGRAS6. Scientific and agricultural significance: Our research activities established a novel linkbetween the GRAS family of transcription factors, plant disease resistance and mechanicalstress response. SlGRAS6 was found to be required for disease resistance to Pstsuggesting that this and possibly other GRAS family members are involved in thetranscriptional reprogramming that takes place during the onset of disease resistance.Their nuclear localization and transcriptional activation ability support their proposed roleas transcription factors or co-activators. However, the potential of utilizing GRAS familymembers for the improvement of plant disease resistance in agriculture has yet to bedemonstrated.
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Xu, Jin-Rong, and Amir Sharon. Comparative studies of fungal pathogeneses in two hemibiotrophs: Magnaporthe grisea and Colletotrichum gloeosporioides. United States Department of Agriculture, May 2008. http://dx.doi.org/10.32747/2008.7695585.bard.
Full textAbstract:
Plant pathogenic fungi have various life styles and different plant infection strategies. Hemibiotrophs like Magnaporthe grisea and Colletotrichum species develop specialized structures during plant infection. The goal of this study was to identify, characterize, and compare genes required for plant infection in M. grisea and C. gloeosporioides. Specific objectives are to: 1) further characterize genes identified in the preliminary studies of C. gloeosporioides and M. grisea;2) identify and characterize additional fungal genes tagged by GFP; and 3) identify in planta growth and appressorium-specific genes by subtractive hybridization and transcript profiling by the LongSAGE method. In this study, the PI and Co-PI collaborated closely on studies in M. grisea and C. gloeosporioides. In M. grisea, REMI and ATMT were used to transform the wildtype with promoter-less EGFP constructs. A total of 28 mutants defective in different plant infection processes or expressing EGFP during plant infection were identified. Genes disrupted in five selected mutants have been identified, including MG03295 that encodes a putative Rho GTPase. In transformant L1320, the transforming vector was inserted in the MIRI gene that encodes a nuclear protein. The expression of MIRI was highly induced during infection. Deletion and site-directed mutagenesis analyses were used to identify the promoter regions and elements that were essential for induced in planta expression of MIRI. This was the first detailed characterization of the promoter of an in planta gene in M. grisea and the MIRI promoter can be used to monitor infectious growth. In addition, the Agilent whole-genome array of M. grisea was used for microarray analyses with RNA samples from appressoria formed by the wild-type shain and the pmkl and mstl2 mutants. Over 200 genes were downregulated in the mst I 2 and pmkl mutants. Some of them are putative transcription factors that may regulate appressorium formation and infectious hyphal growth. In C. gloeosporioides, various REMI mutants showing different pathogenic behavior were identified and characterized. Mutants N3736 had a single insertion and was hyper-virulent. The gene disrupted in mutant3736 (named CgFMOI) encodes a FAD-dependent monooxygenase. Expression analyses linked the expression of the CgFMOI gene with the necrotrophic phase of fungal infection, and also suggest that expression of CgFMOl is unnecessary for the first stages of infection and for biotrophy establishment. All CgFMOl-silenced mutants had reduced virulence. In REMI mutant N159, the tagged gene encodes a putative copper transporter that is homologue of S. cerevisiae CTR2. In yeast, Ctr2 is a vacuolar transporter for moving copper from the vacuole to the cytoplasm. The gene was therefore termed CgCTR2. In addition to characterization of CgCTR2, we also conducted comparative analyses in M. grisea. The M. grisea CgCTR-2 homolog was isolated, knockout strains were generated and characterized and the M. grisea was used to complement the Nl 59 C. gloeosporioides mutant. Overall, we have accomplished most of proposed experiments and are in the process of organizing and publishing other data generated in this project. For objective 3, we used the microarray analysis approach. Several genes identified in this study are novel fungal virulence factors. They have the potential to be used as targets for developing more specific or effective fungicides. In the long run, comparative studies of fungal genes, such as our CgCTR2 work, may lead to better disease control strategies.
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Weil, Clifford F., Anne B. Britt, and Avraham Levy. Nonhomologous DNA End-Joining in Plants: Genes and Mechanisms. United States Department of Agriculture, July 2001. http://dx.doi.org/10.32747/2001.7585194.bard.
Full textAbstract:
Repair of DNA breaks is an essential function in plant cells as well as a crucial step in addition of modified DNA to plant cells. In addition, our inability to introduce modified DNA to its appropriate locus in the plant genome remains an important hurdle in genetically engineering crop species.We have taken a combined forward and reverse genetics approach to examining DNA double strand break repair in plants, focusing primarily on nonhomologous DNA end-joining. The forward approach utilizes a gamma-plantlet assay (miniature plants that are metabolically active but do not undergo cell division, due to cell cycle arrest) and has resulted in identification of five Arabidopsis mutants, including a new one defective in the homolog of the yeast RAD10 gene. The reverse genetics approach has identified knockouts of the Arabidopsis homologs for Ku80, DNA ligase 4 and Rad54 (one gene in what proves to be a gene family involved in DNA repair as well as chromatin remodeling and gene silencing)). All these mutants have phenotypic defects in DNA repair but are otherwise healthy and fertile. Additional PCR based screens are in progress to find knockouts of Ku70, Rad50, and Mre11, among others. Two DNA end-joining assays have been developed to further our screens and our ability to test candidate genes. One of these involves recovering linearized plasmids that have been added to and then rejoined in plant cells; plasmids are either recovered directly or transformed into E. coli and recovered. The products recovered from various mutant lines are then compared. The other assay involves using plant transposon excision to create DNA breaks in yeast cells and then uses the yeast cell as a system to examine those genes involved in the repair and to screen plant genes that might be involved as well. This award supported three graduate students, one in Israel and two in the U.S., as well as a technician in the U.S., and is ultimately expected to result directly in five publications and one Masters thesis.
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Granot, David, Scott Holaday, and Randy D. Allen. Enhancing Cotton Fiber Elongation and Cellulose Synthesis by Manipulating Fructokinase Activity. United States Department of Agriculture, 2008. http://dx.doi.org/10.32747/2008.7613878.bard.
Full textAbstract:
a. Objectives (a) Identification and characterization of the cotton fiber FRKs; (b) Generating transgenic cotton plants overproducing either substrate inhibited tomato FRK or tomato FRK without substrate inhibition; (c) Generating transgenic cotton plants with RNAi suppression of fiber expressed FRKs; (d) Generating Arabidopsis plants that over express FRK1, FRK2, or both genes, as additional means to assess the contribution of FRK to cellulose synthesis and biomass production. b. Background to the topic: Cellulose synthesis and fiber elongation are dependent on sugar metabolism. Previous results suggested that FRKs (fructokinase enzymes that specifically phosphorylate fructose) are major players in sugar metabolism and cellulose synthesis. We therefore hypothesized that increasing fructose phosphorylation may enhance fiber elongation and cellulose synthesis in cotton plants. Accordinlgy, the objectives of this research were: c. Major conclusions and achievements: Two cotton FRKs expressed in fibers, GhFRK2 and GhFRK3, were cloned and characterized. We found that GhFRK2 enzyme is located in the cytosol and GhFRK3 is located within plastids. Both enzymes enable growth on fructose (but not on glucose) of hexose kinase deficient yeast strain, confirming the fructokinase activity of the cloned genes. RNAi constructs with each gene were prepared and sent to the US collaborator to generate cotton plants with RNAi suppression of these genes. To examine the effect of FRKs using Arabidopsis plants we generated transgenic plants expressing either LeFRK1 or LeFRK2 at high level. No visible phenotype has been observed. Yet, plants expressing both genes simultaneously are being created and will be tested. To test our hypothesis that increasing fructose phosphorylation may enhance fiber cellulose synthesis, we generated twenty independent transgenic cotton plant lines overexpressing Lycopersicon (Le) FRK1. Transgene expression was high in leaves and moderate in developing fiber, but enhanced FRK activity in fibers was inconsistent between experiments. Some lines exhibited a 9-11% enhancement of fiber length or strength, but only one line tested had consistent improvement in fiber strength that correlated with elevated FRK activity in the fibers. However, in one experiment, seed cotton mass was improved in all transgenic lines and correlated with enhanced FRK activity in fibers. When greenhouse plants were subjected to severe drought during flowering and boll development, no genotypic differences in fiber quality were noted. Seed cotton mass was improved for two transgenic lines but did not correlate with fiber FRK activity. We conclude that LeFRK1 over-expression in fibers has only a small effect on fiber quality, and any positive effects depend on optimum conditions. The improvement in productivity for greenhouse plants may have been due to better structural development of the water-conducting tissue (xylem) of the stem, since stem diameters were larger for some lines and the activity of FRK in the outer xylem greater than observed for wild-type plants. We are testing this idea and developing other transgenic cotton plants to understand the roles of FRK in fiber and xylem development. We see the potential to develop a cotton plant with improved stem strength and productivity under drought for windy, semi-arid regions where cotton is grown. d. Implications, scientific and agricultural: FRKs are probably bottle neck enzymes for biomass and wood synthesis and their increased expression has the potential to enhance wood and biomass production, not only in cotton plants but also in other feed and energy renewable plants.