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Literatura académica sobre el tema "Psychrotrophy"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 20 de febrero de 2023

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Artículos de revistas sobre el tema "Psychrotrophy"

D'Aoust, Jean-Yves. "Psychrotrophy and foodborne Salmonella". International Journal of Food Microbiology 13, n.º 3 (julio de 1991): 207–15. http://dx.doi.org/10.1016/0168-1605(91)90004-9.

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GARCÍA-ARMESTO, M. ROSARIO y ALASTAIR D. SUTHERLAND. "Temperature characterization of psychrotrophic and mesophilic Bacillus species from milk". Journal of Dairy Research 64, n.º 2 (mayo de 1997): 261–70. http://dx.doi.org/10.1017/s002202999600204x.

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A total of 50 isolates of Bacillus spp. and one reference strain were investigated for their growth at 6·5°C for 10 d, 30°C for 3 d and 40°C for 2 d. The results obtained differentiated three physiological groups: one clearly psychrotrophic (able to grow at 6·5°C in 10 d, but not at 40°C in 2 d), one intermediate in psychrotrophy (it grew at both 40 and 6·5°C) and one mesophilic (capable of growth at 30 and 40°C, but not at 6·5°C). The proportion of strains in the second group was higher among isolates of B. cereus than for other Bacillus spp. However, the proportion of real mesophilic strains was lower for B. cereus isolates. Psychrotrophic B. cereus grew better at both 6·5 and 30°C than other psychrotrophic Bacillus spp. Using eight strains, a correlation between differential growth at mesophilic temperatures (count at 30°C minus count at 40°C) and a standard psychrotrophic count at 6·5°C for 10 d (r=0·95) was obtained in mixed cultures when the psychrotrophic flora count was [les ]1 log (cfu/ml) lower than the mesophilic count.

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Malimon, Z., M. Kukhtyn, N. Grynevych y N. Mekh. "Analysis of the insemination of the mesophilic and psychrotrophic microflora of frozen fish". Naukovij vìsnik veterinarnoï medicini, n.º 1(149) (30 de mayo de 2019): 22–29. http://dx.doi.org/10.33245/2310-4902-2019-149-1-22-29.

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The article presents the results of research on the dehiscence of frozen fish with mesophilic and psychrotrophic microflora. Physico-chemical and organoleptic changes which appear in fish during refrigeration are connected with the life of the psychotropic group of microflora, which is more active than mesophilic. Fish are a nutrient medium for the development of microorganisms of all groups, due to its high nutritional and biological value, so the fish are perishable food products, the conditions and terms of their storage require appropriate temperature regimes to stop the development of microorganisms. The aim of the work was carrying out a comparative analysis of insemination of frozen fish with mesophilic and psychrotrophic microflora to make an amend to standards according to microbiological criteria. The microbial number in frozen fish samples was estimated with the temperature of (30 ± 1) ºC incubation of crops for 72 hours (mesophilic microflora) and incubation for 10 days (psychrotrophic microflora) with the temperature (6.5 ± 0.5) ºC. It was identified that there were taken the samples from frozen fish with a quantity of mesophilic bacteria to 102 CFU/g, 1.4-1.8 times (p <0.05) more psychotropic microorganisms. The researched samples with the number of mesophilic microorganisms from 103 to 104 CFU/g were contaminated with psychotropic microflora, which in 1.7-6.8 times (p <0.05) exceeded the content of the mesophilic microflora. With such amount of mesophilic microorganisms, on average of up to 25% of samples, this had a content of psychotrophs of more than 105 CFU/g of fish. According to the content of mesophilic bacteria the samples of frozen fish, which were mathed to a certain norm of 5 × 104 CFU/g, basically in the number of psychrotrophic microflora did not correspond to this indicator, and exceeded it 2 times or more. In the cold period of the year, 63.6 ± 2.1% of frozen fish samples were mesophilic bacteria containing less than 101 CFU/g. At the same time, samples with such content mesophilic bacteria in the warm period of the year was 9.0%, or 7.0 times (p <0.05) less. In addition, in the cold period of the year, only 9.0% of samples were detected, which, according to the content of mesophilic bacteria exceeded the maximum allowable level. At the same time, during the warm period, the number of samples with an excess of mesophilic bacteria content was 27.3 ± 0.3%. Practically the same pattern was observed regarding the insemination of the psychrotrophic microflora in these periods of the year, which was characterized by the fact that in the warm period of the year, frozen fish contains a large number of psychrotrophic microorganisms. Consequently, the results of studies on the amount of microflora in the warm period of the year established 3,0 times (p <0,05) more samples of frozen fish, which, according to the content of mesophilic bacteria, exceeded the maximum permissible level compared with the cold period of the year. It was established that samples of frozen fish containing mesophilic microorganisms less than 101 CFU/g were most unevenly contaminated with psychrotrophic microflora. Among these samples, only 30.1 ± 1.4% were with the number of psychrotrophic microflora less than 101 CFU/g, at the same time, 60.0 ± 0.5% of the samples were contaminated with a psychrotrophic microflora of 101 to 105 CFU/g and 10, 0 ± 0.2% over 105 CFU/g. In the study of frozen fish samples with the number of mesophilic bacteria from 101 to 102 CFU/g revealed a coincidence in the content of psychrotrophs in only 16,7 ± 0,3% of samples, and 33,3 ± 0,3% of fish samples were with the content of psychrotrophic microflora from 102 to 103 CFU/g and 103 to 104 CFU/g and 16.7 ± 0.3% were contaminated with psychrotrophy more than 104 CFU/g. It was established that samples of frozen fish containing mesophilic microorganisms less than 101 CFU/g were most unevenly contaminated with psychrotrophic microflora. Among these samples, only 30.1 ± 1.4% were with the number of psychrotrophic microflora less than 101 CFU/g, at the same time, 60.0 ± 0.5% of the samples were contaminated with a psychrotrophic microflora of 101 to 105 CFU/g and 10, 0 ± 0.2% over 105 CFU/g. In the study of frozen fish samples with the number of mesophilic bacteria from 101 to 102 CFU/g revealed a coincidence in the content of psychrotrophs in only 16,7 ± 0,3% of samples, and 33,3 ± 0,3% of fish samples were with the content of psychrotrophic microflora from 102 to 103 CFU/g and 103 to 104 CFU/g and 16.7 ± 0.3% were contaminated with psychrotrophy more than 104 CFU/g. It was found that that the psychrotrophic microflora of frozen fish is quantitatively predominantly content of mesophilic bacteria several orders of magnitude. During the warm period of the year, more samples of frozen fish were detected in 3,0 times (p <0,05), which, according to the content of mesophilic bacteria, exceeded the maximum permissible level in comparison in the cold period of the year. It was found that 92,6 ± 2,5% of frozen fish samples were in compliance with the requirements of DSTU 4868: 2007. The fish is frozen. At the same time, during the fish evaluation, the contents of the psychrotrophic microflora showed that samples exceeding 5 × 104 CFU/g was in 2.6 times (p <0.05) more than the mesophilic bacteria content. In future the generic and species composition of the psychrotrophic microflora of frozen fish will be studied and the fish evaluating criteria according to the psychrotrophs in order to make corrections according to the microbiological criteria. Key words: frozen fish, psychrotrophic microflora, mesophilic bacteria, contamination, microbial number.

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CHAMPAGNE, C. P., F. GIRARD y N. MORIN. "Inhibition of the Psychrotrophic Bacteria of Raw Milk by Addition of Lactic Acid Bacteria". Journal of Food Protection 53, n.º 5 (1 de mayo de 1990): 400–403. http://dx.doi.org/10.4315/0362-028x-53.5.400.

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Two commercial cultures of lactic acid bacteria (LAB) were added to raw milk in order to inhibit the development of psychrotrophic bacteria. The effects of inoculation level, pH development, media for culture preparation, and milk heat treatment on the inhibitory activity of LAB were studied. Inoculation levels of 2.5 × 106/mL and less of LAB did not significantly reduce psychrotrophic growth. Maximum inoculation level of LAB studied was 25 × 106/mL and this reduced psychrotrophic development by a factor of 10; however, milk pH was reduced to 6.54 over 48 h of incubation at 7°C with this inoculation level. This acidification was not responsible for the inhibitory activity of LAB on psychrotrophs. The LAB were more effective when psychrotroph populations had high multiplication rates. Initial populations of Pseudomonas putida in pasteurized milk did not influence the activity of the LAB. Pseudomonas putida grew faster in sterile milk than in pasteurized milk, but average inhibition rates of LAB were similar in both media.

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NORTJÉ, G. L., L. NEL, E. JORDAAN, K. BADENHORST, G. GOEDHART, W. H. HOLZAPFEL y R. J. GRIMBEEK. "A Quantitative Survey of a Meat Production Chain to Determine the Microbial Profile of the Final Product". Journal of Food Protection 53, n.º 5 (1 de mayo de 1990): 411–17. http://dx.doi.org/10.4315/0362-028x-53.5.411.

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Samples from carcasses, personnel surfaces, equipment, and minced meat, packaged and displayed in cabinets were taken at a city abattoir, a wholesaler, and 10 different supermarkets. Bacteria enumerated were 1) psychrotrophs; 2) Enterobacteriaceae; 3) enterococci; 4) micrococci; 5) Pseudomonas spp; and 6) Brochothrix thermosphacta. The non integrated production system of abattoirs, wholesalers, and retailers yielded psychrotrophic and enterococci counts at retail which compared fairly well with those reported in literature, while the Enterobacteriaceae and micrococci counts were higher. Besides the psychrotrophs the pseudomonads were the most numerous group in the final product. Different surfaces were not sanitized with the same efficacy, while a general tendency towards lower counts at one supermarket group was monitored. The counts described 96% of the variation in the psychrotrophic count at the abattoir, while the success in using these counts in estimating the psychrotrophic count at the wholesaler and retailers was not as significant. At the abattoir the Enterobacteriaceae and psuedomonads were the biggest contributors to the psychrotrophic count, at the wholesaler the Enterobacteriaceae and micrococci counts, and at the retailers the micrococci and pseudomonads respectively. This indicates that Enterobacteriaceae might be common psychrotrophs in the meat production chain, maybe originating from the abattoir and wholesale environments.

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Vigentini, I., A. Praz, D. Domeneghetti, S. Zenato, C. Picozzi, A. Barmaz y R. Foschino. "Characterization of malolactic bacteria isolated from Aosta Valley wines and evidence of psychrotrophy in some strains". Journal of Applied Microbiology 120, n.º 4 (17 de marzo de 2016): 934–45. http://dx.doi.org/10.1111/jam.13080.

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Munsch-Alatossava, Patricia, Jean-Pierre Gauchi, Bhawani Chamlagain y Tapani Alatossava. "Trends of Antibiotic Resistance in Mesophilic and Psychrotrophic Bacterial Populations during Cold Storage of Raw Milk". ISRN Microbiology 2012 (12 de marzo de 2012): 1–13. http://dx.doi.org/10.5402/2012/918208.

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Psychrotrophic bacteria in raw milk are most well known for their spoilage potential and cause significant economic losses in the dairy industry. Despite their ability to produce several exoenzyme types at low temperatures, psychrotrophs that dominate the microflora at the time of spoilage are generally considered benign bacteria. It was recently reported that raw milk-spoiling Gram-negative-psychrotrophs frequently carried antibiotic resistance (AR) features. The present study evaluated AR to four antibiotics (ABs) (gentamicin, ceftazidime, levofloxacin, and trimethoprim-sulfamethoxazole) in mesophilic and psychrotrophic bacterial populations recovered from 18 raw milk samples, after four days storage at C or C. Robust analysis of variance and non parametric statistics (e.g., REGW and NPS) revealed that AR prevalence among psychrotrophs, for milk samples stored at C, often equalled the initial levels and equalled or increased during the cold storage at C, depending on the AB. The study performed at C with an intermediate sampling point at day 2 suggested that (1) different psychrotrophic communities with varying AR levels dominate over time and (2) that AR (determined from relative amounts) was most prevalent, transiently, after 2-day storage in psychrotrophic or mesophilic populations, most importantly at a stage where total counts were below or around CFU/mL, at levels at which the milk is acceptable for industrial dairy industrial processes.

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Shtenikov, M. D., O. Y. Zinchenko y V. V. Boldyreva. "ANTAGONISTIC ACTIVITY OF MARINE BACTERIA OF BACILLUS, PRIESTIA AND PAENIBACILLUS GENERA OF DIFFERENT THERMOTYPES". Microbiology&Biotechnology, n.º 2(55) (20 de septiembre de 2022): 50–65. http://dx.doi.org/10.18524/2307-4663.2022.2(55).261778.

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SummaryAim. To study the antagonistic activity of bacteria of genera Bacillus, Priestia and Paenibacillus at different conditions of cultivation. Methods. Antagonistically active spore-forming bacteria isolated from deep-sea bottom sediments of the Black Sea were used for the study. Determination of thermotypes was performed using the results of analysis of fatty acid profile parameters. Antagonistic activity to test strains of bacterial opportunistic pathogens was detected by the method of agar blocks on Gauze № 1 and Nutrient Agar media at different cultivation temperatures. Results. Aerobic bacilli of genera Bacillus, Priestia and Paenibacillus of all three thermotypes – thermotolerants, mesophiles and psychrotrophes, in general show lower antagonistic activity when cultured at 37 °C on both media, except for a marked increase in psychrotrophe antagonistic activity at 37 °С on Gauze № 1. Conclusions. It was established that belonging to a certain thermotype affects the character of the antagonistic activity of sporeforming bacteria. The antagonistic activity of mesophilic and thermotolerant bacteria at a higher temperature of cultivation is lower, and that of psychrotrophic bacteria at a higher temperature and on Gauze № 1 medium is higher.

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Teider Junior, Pedro I., José C. Ribeiro Júnior, Eric H. Ossugui, Ronaldo Tamanini, Juliane Ribeiro, Gislaine A. Santos, Amauri A. Alfieri y Vanerli Beloti. "Pseudomonas spp. and other psychrotrophic microorganisms in inspected and non-inspected Brazilian Minas Frescal cheese: proteolytic, lipolytic and AprX production potential". Pesquisa Veterinária Brasileira 39, n.º 10 (octubre de 2019): 807–15. http://dx.doi.org/10.1590/1678-5150-pvb-6037.

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ABSTRACT: The most consumed cheese in Brazil, Minas Frescal cheese (MFC) is highly susceptible to microbial contamination and clandestine production and commercialization can pose a risk to consumer health. The storage of this fresh product under refrigeration, although more appropriate, may favor the growth of spoilage psychrotrophic bacteria. The objective of this study was to quantify and compare Pseudomonas spp. and other psychrotrophic bacteria in inspected and non-inspected MFC samples, evaluate their lipolytic and proteolytic activities and their metalloprotease production potentials. Twenty MFC samples were evaluated: 10 inspected and 10 non-inspected. Counts of psychrotrophic bacteria and Pseudomonas spp., evaluation of the proteolytic and lipolytic potential of the isolates, and identification of potential producers of alkaline metalloprotease (AprX) were assessed. The mean total psychrotrophic counts were 1.07 (±2.18) × 109CFU/g in the inspected samples and 4.5 (±5.86) × 108CFU/g in the non-inspected, with no significant difference (p=0.37). The average score of Pseudomonas spp. was 6.86 (±18.6) × 105 and 2.08 (±3.65) × 106 CFU/g for the inspected and non-inspected MFC samples, respectively, with no significant difference (p=0.1). Pseudomonas spp. represented 0.06% and 0.004% of psychrotrophic bacteria found in inspected and non-inspected MFC samples, respectively. Collectively, 694 psychrotrophic strains and 47Pseudomonas spp. were isolated, of which 59.9% and 68.1% were simultaneously proteolytic and lipolytic, respectively. Of the 470 psychrotrophs isolated from inspected and 224 from non-inspected cheese samples, 5.74% and 2.23% contained aprX, respectively, while 100 and 86.96% of the Pseudomonas spp. isolates in inspected and non-inspected cheese samples contained the gene. The production potential of AprX did not, however, determine the proteolytic activity on plates of these isolates under the conditions evaluated in this study. Of total, 65.63% of the psychrotrophs that contained aprX gene were confirmed as Pseudomonas spp., using genus-specific PCR. Phylogenetic analysis of the 16S rRNA gene of the other psychrotrophs that were potential producers of AprX identified them as Serratia spp. (n=7), Raoultella ornithinolytica (n=1), and Acinetobacter schindleri (n=1) in the inspected samples and Psychrobacter sanguinis (n=1) and Leuconostoc mesenteroides (n=1) in the non-inspected samples. The production conditions of Brazilian MFC of these samples, while meeting the legal determinations, are not sufficient to control Pseudomonas and other spoilage-related psychrotrophs. Thus, stricter hygienic measures are required during the formal production of this type of cheese.

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Nurlinawati, Kristof Vanoirbeek, Abram Aertsen y Chris W. Michiels. "Role of 1-acyl-sn-glycerol-3-phosphate acyltransferase in psychrotrophy and stress tolerance of Serratia plymuthica RVH1". Research in Microbiology 166, n.º 1 (enero de 2015): 28–37. http://dx.doi.org/10.1016/j.resmic.2014.11.001.

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Más fuentes

Tesis sobre el tema "Psychrotrophy"

McCarthy, Conor Neil y n/a. "Regulatory Elements Controlling Lipase and Metalloprotease Production in Pseudomonas fluorescens B52". Griffith University. School of Health Science, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20031015.124744.

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Psychrotrophic bacteria, such as Pseudomonas fluorescens B52, are a major cause of milk spoilage at refrigeration temperature due to the production of lipolytic and proteolytic enzymes. Regulatory mechanisms controlling the production of lipase and protease by the B52 lipA and aprX genes were investigated. Transposon mutagenesis identified the possible involvement of a poly-A polymerase enzyme which destabilises mRNA by 3' polyadenylation. A homologue of the E. coli EnvZ/OmpR two-component sensor/regulator system was identified by transposon mutagenesis and shown to repress lipase and protease production. This system responds to Na+ and K+ concentration in E. coli and these ions were also shown to repress lipase and protease expression in B52, however the EnvZ/OmpR system is not solely responsible for this. Assays of translational lacZ fusions with aprX and lipA were used to speculate on the mechanism by which Na+ and EnvZ/OmpR repress the aprX-lipA operon. A membrane-bound sensor, MspA, which regulates protease production in P. fluorescens LS107d₂, was shown to exist in B52 but mutagenesis of the B52 mspA gene had no effect on lipase and protease expression. A homologue of the P. fluorescens CHA0 rsmA gene, encoding an RNA-binding translation repressor, was found in B52. Although aprX and possibly lipA contain consensus sequences for RsmA, mutagenesis of rsmA had no significant effect on lipase and protease expression. Repression of lipase and protease expression by Na+ was increased by expression of the P. fluorescens M114 pbrA sigma-factor gene in B52.

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McCarthy, Conor Neil. "Regulatory Elements Controlling Lipase and Metalloprotein Production in Pseudomonas fluorescens B52". Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367432.

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Psychrotrophic bacteria, such as Pseudomonas fluorescens B52, are a major cause of milk spoilage at refrigeration temperature due to the production of lipolytic and proteolytic enzymes. Regulatory mechanisms controlling the production of lipase and protease by the B52 lipA and aprX genes were investigated. Transposon mutagenesis identified the possible involvement of a poly-A polymerase enzyme which destabilises mRNA by 3' polyadenylation. A homologue of the E. coli EnvZ/OmpR two-component sensor/regulator system was identified by transposon mutagenesis and shown to repress lipase and protease production. This system responds to Na+ and K+ concentration in E. coli and these ions were also shown to repress lipase and protease expression in B52, however the EnvZ/OmpR system is not solely responsible for this. Assays of translational lacZ fusions with aprX and lipA were used to speculate on the mechanism by which Na+ and EnvZ/OmpR repress the aprX-lipA operon. A membrane-bound sensor, MspA, which regulates protease production in P. fluorescens LS107d2, was shown to exist in B52 but mutagenesis of the B52 mspA gene had no effect on lipase and protease expression. A homologue of the P. fluorescens CHA0 rsmA gene, encoding an RNA-binding translation repressor, was found in B52. Although aprX and possibly lipA contain consensus sequences for RsmA, mutagenesis of rsmA had no significant effect on lipase and protease expression. Repression of lipase and protease expression by Na+ was increased by expression of the P. fluorescens M114 pbrA sigma-factor gene in B52.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Health Sciences
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Stevenson, Robert Gregory. "Psychrotrophic spoilage of pasteurised milk". Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342983.

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Drevet, Pascal. "Etude du système protéolytique intracellulaire d'une bactérie psychrotrophe du genre Arthrobacter". Lyon 1, 1987. http://www.theses.fr/1987LYO10144.

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Drevet, Pascal. "Etude du système protéolytique intracellulaire d'une bactérie psychrotrophe du genre Arthrobacter". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376046391.

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Suzuki, Takeshi. "Enzymological Studies of Cold-active Esterases from Psychrotrophic Bacteria". Kyoto University, 2003. http://hdl.handle.net/2433/149012.

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Guillou, Catherine. "Mise en évidence d'une température critique chez la bactérie psychrotrophe Pseudomonas fluorescens". Compiègne, 1994. http://www.theses.fr/1994COMPD762.

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Pseudomonas fluorescens MFO est une souche psychrotrophe isolée du lait cru, qui produit des enzymes exocellulaires (protéase et lipase). Une famille d'enzymes comprenant la protéase et la lipase, mais aussi trois phosphatases endocellulaires, a été caractérisée par une température optimale de production commune (17°C), inferieure à la température optimale de croissance (30°C). Une étude en chémostat des effets respectifs de la température et du taux de croissance nous a permis de montrer que la production de ces enzymes est effectivement régulée par la température. Cependant le mécanisme de régulation de la production des enzymes exocellulaires apparait beaucoup plus complexe que celui des phosphatases cellulaires acides constitutives. Il met en jeu une induction et une répression exercée soit par le substrat énergétique (répression catabolique), soit par le taux (ou la phase) de croissance. C'est à ce dernier niveau qu'intervient la régulation par la température : l'effet de la répression n'est complètement levé à faible taux de croissance qu'a la température intermédiaire de 17°C. D'un point de vue plus général, les effets de la température et du taux de croissance sur la composition macromoléculaire (protéines, ARN) et la taille cellulaire de P. Fluorescens MFO ont été analysés en cultures discontinues et continues, et comparés à ceux observés chez les bactéries mésophiles et psychrophiles. Il apparait que le comportement de P. Fluorescens MFO vis à vis de la température diffère fondamentalement de celui de bactéries mésophiles et psychrophiles. Il est caractérisé par l'existence d'une zone de température critique intermédiaire (17°C-20°C), qui marque la limite entre deux domaines thermiques (domaine inférieur froid et domaine supérieur chaud) différant dans leurs implications cinétiques et physiologiques. Ainsi le comportement de cette souche psychrotrophe apparait comme intermédiaire entre celui de bactéries mésophiles et de bactéries psychrophiles.

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Abdelrahim, Khalid Ali. "Production and characterization of b-galactosidase from psychrotrophic Bacillus subtilis". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59294.

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$ beta$-Galactosidase (E.C. 3.2.1.23) or lactase was produced by the growth of a selected Bacillus subtilis strain (KL88) which was adapted to grow at 10$ sp circ$C. The growth and enzyme production were maximal at 2% (w/v) lactose supplemented with 0.2% (w/v) yeast extract. A Fast Protein Liquid Chromatography system (FPLC) was used for $ beta$-galactosidase purification. The enzyme was purified to 44-fold over the crude extract with a recovery of $ sim$54%. Native-PAGE and SDS-PAGE using "PhastSystem" showed the presence of two isoenzymes having molecular weights of 88 and 170 kD. The purified enzyme showed high activity at low temperatures (10$ sp circ$C) and recorded an optimum pH of 7.0. The K$ sb{ rm m}$ values were found to be 2.21 mM and 28.08 mM for o-nitrophenyl-$ beta$-D-galactopyranoside (ONPG) and lactose, respectively.
$ beta$-Galactosidase from psychrotrophic Bacillus subtilis was specific to the $ beta$-D-glycosidic linkage normally present in lactose.
To investigate the possibility of producing proteinase-free $ beta$-galactosidase from this psychrotrophic microorganism, FPLC was used for the rapid separation of $ beta$-galactosidase.

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Michel, Valérie. "Caracterisation de la reponse aux chocs thermiques d'une bacterie psychrotrophe d'alteration, pseudomonas fragi". Clermont-Ferrand 2, 1996. http://www.theses.fr/1996CLF21813.

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Les effets de chocs thermiques sur la croissance et la synthese proteique ont ete etudies chez pseudomonas fragi, bacterie psychotrophe d'alteration des aliments. Les cinetiques de synthese proteique ont ete caracterisees par autoradiographies des proteines intracellulaires marquees a la methionine-#3#5s et separees en electrophorese bidimensionnelle (e-2d). La croissance se poursuivait avec un taux caracteristique de la temperature finale du choc de facon immediate apres les chocs chauds de 5 a 20 ou 30c et de 28 a 34c, et apres 3 et 5 h de latence a la suite d'un transfert de 20 a 5c et de 30 a 5c. Les profils obtenus en e-2d apres les differents chocs ont revele des variations dans le niveau relatif de synthese de 20 a 37 proteines. Ces proteines ont ete repertoriees en fonction de leur poids moleculaire, point isoelectrique et de leur cinetique de variations en reponse a un choc thermique. Les principales proteines impliquees dans la reponse adaptative de p. Fragi a la temperature, ont ainsi ete caracterisees. Les genes de 3 d'entre elles, designees c7. 0, c8. 0, e7. 0, ont ete amplifies pas pcr et sequences. Ces proteines appartiennent a une famille d'activateur de faible masse moleculaire capables de se lier aux acides nucleiques dont le representant type est cspa, la proteine majeure de choc froid d'e. Coli, caracterisee comme un activateur transcriptionnel

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Gauthier, Elisabeth. "Utilization of low molecular weight substrates by psychrotrophic meat spoilage organisms". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59274.

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Four meat spoilage organisms were grown at 4$ sp circ$C for 7 d, in an aqueous extract of meat (Meat Juice Medium), and the levels of various nutrients in the extracts were measured. At an agitation rate of 50 rev$ cdot$min$ sp{-1},$ the four species reached viable counts of 10$ sp8$ Colony Forming Units (CFU)$ cdot$ml$ sp{-1},$ and the order of nutrient utilization was as follows: (1) glucose, (2) gluconate and urea, (3) glycerol, (4) glucose-6-phosphate. Several substrates were still present in the growth medium at the end of the growth period, namely lactate, glucose-6-phosphate and the two unknowns. At a higher agitation rate (100 rev$ cdot$min$ sp{-1}),$ the non-fluorescent pseudomonad reached final counts of ca. 10$ sp{10}$ CFU$ cdot$ml$ sp{-1},$ 2 logs higher than those of the other three organisms present in the mixed culture. The order of nutrient utilization was: (1) glucose, (2) gluconate, urea and glycerol, (3) lactate and glucose-6-phosphate, (4) unknowns 1 and 2. At day 7, none of the nine substrates studied remained in the growth medium.

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Libros sobre el tema "Psychrotrophy"

Psychrotrophic bacteria in foods: Disease and spoilage. Boca Raton: CRC Press, 1992.

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Brown, Steven A. Screening for plasmid DNA in an exopolymer-producing psychrotrophic bacterium. Sudbury, Ont: Laurentian University, 1987.

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Andrews, Shelley Ann. Purification and initial chemical characterization of an exopolymer produced by a psychrotrophic bacterium. Sudbury, Ont: Laurentian University, 1991.

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Mondal, Abdul Alim. Studies on the identity of the stimulatory material for exopolymer production, in a psychrotrophic bacterium. [s.l: s.n.], 1992.

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Enzymes of psychrotrophs in raw food. Boca Raton, Fla: CRC Press, 1989.

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McKellar, Robin C. Enzymes of Psychrotrophs in Raw Food. Taylor & Francis Group, 2020.

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McKellar, Robin C. Enzymes of Psychrotrophs in Raw Food. Taylor & Francis Group, 2020.

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McKellar, Robin C. Enzymes of Psychrotrophs in Raw Food. Taylor & Francis Group, 2020.

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McKellar, Robin C. Enzymes of Psychrotrophs in Raw Food. Taylor & Francis Group, 2020.

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Meer, Ralph R. Identification and characterization of some psychrotrophic heat resistant/sporeforming bacteria in the Grade A raw milk supply of Oregon. 1987.

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Capítulos de libros sobre el tema "Psychrotrophy"

Kraft, A. A. "Psychrotrophic Organisms". En Advances in Meat Research, 191–208. London: Macmillan Education UK, 1986. http://dx.doi.org/10.1007/978-1-349-09145-4_6.

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Brasca, Milena, Marilù Decimo, Stefano Morandi, Solimar Gonçalves Machado, François Bagliniére y Maria Cristina Dantas Vanetti. "Psychrotrophic bacteria". En Microbiology in Dairy Processing, 37–61. Chichester, UK: John Wiley & Sons Ltd and the Institute of Food Technologists, 2017. http://dx.doi.org/10.1002/9781119115007.ch3.

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Kanekar, Pradnya Pralhad y Sagar Pralhad Kanekar. "Psychrophilic, Psychrotrophic, and Psychrotolerant Microorganisms". En Diversity and Biotechnology of Extremophilic Microorganisms from India, 215–49. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1573-4_7.

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Kumari, Anita, Jyoti Upadhyay y Rohit Joshi. "Psychrotrophic Microbes: Biodiversity, Adaptation, and Implications". En Microbial Metatranscriptomics Belowground, 273–93. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9758-9_13.

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Sindhu, Meena, Kamla Malik, Seema Sangwan, Anuj Rana, Nayan Tara y Sushil Ahlawat. "Alleviation of Cold Stress by Psychrotrophic Microbes". En Advances in Plant Microbiome and Sustainable Agriculture, 179–98. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3204-7_8.

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Choudhary, Kanak, Najeeb Hussain Wani, Farooq Ahmad Ahanger, Suhaib Mohamad Malik, Vinod Chourse, Abdul Majid Khan y Sanjay Sahay. "Psychrotrophic Microfungi: Major Habitats, Diversity and Living Strategies". En Extremophilic Fungi, 111–27. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-4907-3_6.

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Jay, James M. "Low-Temperature Food Preservation and Characteristics of Psychrotrophic Microorganisms". En Modern Food Microbiology, 323–39. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-4427-2_16.

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Murano, Peter S. y Elsa A. Murano. "Low-Temperature Food Preservation and Characteristics of Psychrotrophic Microorganisms". En Food Science Text Series, 41–42. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-4543-9_16.

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Jay, James M. "Low-Temperature Food Preservation and Characteristics of Psychrotrophic Microorganisms". En Modern Food Microbiology, 314–34. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-6480-1_13.

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Das, Tuyelee, Samapika Nandy, Devendra Kumar Pandey, Abdel Rahman Al-Tawaha, Potshangbam Nongdam, Ercan Bursal, Mahipal S. Shekhawat y Abhijit Dey. "Physiology and Molecular Biology of Psychrotrophic Fungi: An Insight". En Extremophilic Fungi, 129–39. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-4907-3_7.

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Actas de conferencias sobre el tema "Psychrotrophy"

Maziero, João Pedro, Carolina Toledo Santos, Pricila Veiga dos Santos y Juliano Gonçalves Pereira. "Avaliação do uso de ozônio em temperaturas de leite cru refrigerado na contagem de psicrotróficos". En Semana Online Científica de Veterinária. CONGRESSE.ME, 2021. http://dx.doi.org/10.54265/gsri7118.

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A qualidade do leite cru está associada às boas práticas de ordenha proveniente de rebanhos sadios e com refrigeração obrigatória do leite cru na granja leiteira entre 4 e 7° C, podendo chegar até, no máximo, 9° C durante a coleta final (BRASIL 2018). Embora a refrigeração seja eficaz para aumentar a vida útil do leite cru, a manutenção das baixas temperaturas favorece a multiplicação de bactérias psicrotróficas, que produzem proteases e lipases termorresistentes, que permanecendo ativas mesmo após a pasteurização, podem afetar negativamente, tanto o próprio leite, quanto seus derivados (RIBEIRO et al., 2018). Visando reduzir a contagem de microrganismos psicrotróficos no leite cru, o presente trabalho avaliou a eficácia da aplicação de ozônio, considerado um bactericida verde por não ser poluente e não deixar resíduos no alimento, diretamente no tanque de resfriamento. As amostras de leite cru foram obtidas de um rebanho saudável e recolhidas diretamente do tanque de resfriamento da propriedade e armazenadas em frascos estéreis com volume de 6 litros sob refrigeração (4 e 9° C). A aplicação do ozônio seguiu delineamento fatorial com variáveis independentes sendo as temperaturas do leite (4 e 9° C) e os tempos de exposição ao ozônio (5 e 15 minutos) utilizando Gerador de Ozônio N202F Bivolt 500mg/h O³ Disinfector - Diluka Power. Foram retiradas amostras antes e após a ozonização. As amostras foram então armazenadas por 48 horas sob refrigeração (4° C) para permitir a proliferação da flora psicrotrófica. O teor de psicrotróficos e a contagem bacteriana total das amostras e do grupo controle foram avaliados em meio ágar bacteriológico PCA por 10 dias a 7° C e a 36° C por 24 horas, respectivamente. A aplicação de ozônio foi eficaz em reduzir a contagem de microrganismos psicrotróficos no tempo de 5 minutos a 4° C, esse resultado é extremamente satisfatório, visto que, a temperatura de aplicação é a mesma aplicada aos tanques de refrigeração nas propriedades, o que permitiria, facilmente, a aplicação nas próprias fazendas. Agradecimentos Agradecemos à equipe do Serviço de Orientação à Alimentação Pública da FMVZ-Unesp e ao proprietário da fazenda por disponilibizar o material utilizado na pesquisa. Referências BRASIL. Ministério da Agricultura, Pecuária e Abastecimento. Instrução normativa nº 76, de 26 de novembro de 2018. Regulamentos Técnicos que fixam a identidade e as características de qualidade que devem apresentar o leite cru refrigerado, o leite pasteurizado e o leite pasteurizado tipo A. Diário Oficial da União, Brasília, 2018. RIBEIRO JÚNIOR, J. C.et al. The main spoilage1 related psychrotrophic bacteria in refrigerated raw milk. Journal of dairy science, v. 101, n. 1, p. 75-83, 2018. PALAVRAS-CHAVE: Microbiologia dos alimentos, Qualidade do leite, Tecnologia verde

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