Academic literature on the topic 'Anaerobic bacteria Adaptation'
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Journal articles on the topic "Anaerobic bacteria Adaptation"
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Hamad, Mohamad A., Chad R. Austin, Amanda L. Stewart, Mike Higgins, Andrés Vázquez-Torres, and Martin I. Voskuil. "Adaptation and Antibiotic Tolerance of Anaerobic Burkholderia pseudomallei." Antimicrobial Agents and Chemotherapy 55, no. 7 (May 2, 2011): 3313–23. http://dx.doi.org/10.1128/aac.00953-10.
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ABSTRACTThe Gram-negative bacteriumBurkholderia pseudomalleiis the etiological agent of melioidosis and is remarkably resistant to most classes of antibacterials. Even after months of treatment with antibacterials that are relatively effectivein vitro, there is a high rate of treatment failure, indicating that this pathogen alters its patterns of antibacterial susceptibility in response to cues encountered in the host. The pathology of melioidosis indicates thatB. pseudomalleiencounters host microenvironments that limit aerobic respiration, including the lack of oxygen found in abscesses and in the presence of nitric oxide produced by macrophages. We investigated whetherB. pseudomalleicould survive in a nonreplicating, oxygen-deprived state and determined if this physiological state was tolerant of conventional antibacterials.B. pseudomalleisurvived initial anaerobiosis, especially under moderately acidic conditions similar to those found in abscesses. Microarray expression profiling indicated a major shift in the physiological state of hypoxicB. pseudomallei, including induction of a variety of typical anaerobic-environment-responsive genes and genes that appear specific to anaerobicB. pseudomallei. Interestingly, anaerobicB. pseudomalleiwas unaffected by antibacterials typically used in therapy. However, it was exquisitely sensitive to drugs used against anaerobic pathogens. After several weeks of anaerobic culture, a significant loss of viability was observed. However, a stable subpopulation that maintained complete viability for at least 1 year was established. Thus, during the course of human infection, if a minor subpopulation of bacteria inhabited an oxygen-restricted environment, it might be indifferent to traditional therapy but susceptible to antibiotics frequently used to treat anaerobic infections.
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Karasova, Daniela, Marcela Faldynova, Jitka Matiasovicova, Alena Sebkova, Magdalena Crhanova, Tereza Kubasova, Zuzana Seidlerova, et al. "Host Species Adaptation of Obligate Gut Anaerobes Is Dependent on Their Environmental Survival." Microorganisms 10, no. 6 (May 25, 2022): 1085. http://dx.doi.org/10.3390/microorganisms10061085.
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The gut microbiota of warm-blooded vertebrates consists of bacterial species belonging to two main phyla; Firmicutes and Bacteroidetes. However, does it mean that the same bacterial species are found in humans and chickens? Here we show that the ability to survive in an aerobic environment is central for host species adaptation. Known bacterial species commonly found in humans, pigs, chickens and Antarctic gentoo penguins are those capable of extended survival under aerobic conditions, i.e., either spore-forming, aerotolerant or facultatively anaerobic bacteria. Such bacteria are ubiquitously distributed in the environment, which acts as the source of infection with similar probability in humans, pigs, chickens, penguins and likely any other warm-blooded omnivorous hosts. On the other hand, gut anaerobes with no specific adaptation for survival in an aerobic environment exhibit host adaptation. This is associated with their vertical transmission from mothers to offspring and long-term colonisation after administration of a single dose. This knowledge influences the design of next-generation probiotics. The origin of aerotolerant or spore-forming probiotic strains may not be that important. On the other hand, if Bacteroidetes and other host-adapted species are used as future probiotics, host preference should be considered.
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Finn, Thomas J., Sonal Shewaramani, Sinead C. Leahy, Peter H. Janssen, and Christina D. Moon. "Dynamics and genetic diversification ofEscherichia coliduring experimental adaptation to an anaerobic environment." PeerJ 5 (May 3, 2017): e3244. http://dx.doi.org/10.7717/peerj.3244.
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BackgroundMany bacteria are facultative anaerobes, and can proliferate in both anoxic and oxic environments. Under anaerobic conditions, fermentation is the primary means of energy generation in contrast to respiration. Furthermore, the rates and spectra of spontaneous mutations that arise during anaerobic growth differ to those under aerobic growth. A long-term selection experiment was undertaken to investigate the genetic changes that underpin how the facultative anaerobe,Escherichia coli, adapts to anaerobic environments.MethodsTwenty-one populations ofE. coliREL4536, an aerobically evolved 10,000th generation descendent of theE. coliB strain, REL606, were established from a clonal ancestral culture. These were serially sub-cultured for 2,000 generations in a defined minimal glucose medium in strict aerobic and strict anaerobic environments, as well as in a treatment that fluctuated between the two environments. The competitive fitness of the evolving lineages was assessed at approximately 0, 1,000 and 2,000 generations, in both the environment of selection and the alternative environment. Whole genome re-sequencing was performed on random colonies from all lineages after 2,000-generations. Mutations were identified relative to the ancestral genome, and based on the extent of parallelism, traits that were likely to have contributed towards adaptation were inferred.ResultsThere were increases in fitness relative to the ancestor among anaerobically evolved lineages when tested in the anaerobic environment, but no increases were found in the aerobic environment. For lineages that had evolved under the fluctuating regime, relative fitness increased significantly in the anaerobic environment, but did not increase in the aerobic environment. The aerobically-evolved lineages did not increase in fitness when tested in either the aerobic or anaerobic environments. The strictly anaerobic lineages adapted more rapidly to the anaerobic environment than did the fluctuating lineages. Two main strategies appeared to predominate during adaptation to the anaerobic environment: modification of energy generation pathways, and inactivation of non-essential functions. Fermentation pathways appeared to alter through selection for mutations in genes such asnadR, adhE, dcuS/R, andpflB. Mutations were frequently identified in genes for presumably dispensable functions such as toxin-antitoxin systems, prophages, virulence and amino acid transport. Adaptation of the fluctuating lineages to the anaerobic environments involved mutations affecting traits similar to those observed in the anaerobically evolved lineages.DiscussionThere appeared to be strong selective pressure for activities that conferred cell yield advantages during anaerobic growth, which include restoring activities that had previously been inactivated under long-term continuous aerobic evolution of the ancestor.
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Hemsley, Claudia M., Jamie X. Luo, Clio A. Andreae, Clive S. Butler, Orkun S. Soyer, and Richard W. Titball. "Bacterial Drug Tolerance under Clinical Conditions Is Governed by Anaerobic Adaptation but not Anaerobic Respiration." Antimicrobial Agents and Chemotherapy 58, no. 10 (July 21, 2014): 5775–83. http://dx.doi.org/10.1128/aac.02793-14.
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ABSTRACTNoninherited antibiotic resistance is a phenomenon whereby a subpopulation of genetically identical bacteria displays phenotypic tolerance to antibiotics. We show here that compared toEscherichia coli, the clinically relevant genusBurkholderiadisplays much higher levels of cells that tolerate ceftazidime. By measuring the dynamics of the formation of drug-tolerant cells under conditions that mimicin vivoinfections, we show that inBurkholderiabacteria, oxygen levels affect the formation of these cells. The drug-tolerant cells are characterized by an anaerobic metabolic signature and can be eliminated by oxygenating the system or adding nitrate. The transcriptome profile suggests that these cells are not dormant persister cells and are likely to be drug tolerant as a consequence of the upregulation of anaerobic nitrate respiration, efflux pumps, β-lactamases, and stress response proteins. These findings have important implications for the treatment of chronic bacterial infections and the methodologies and conditions that are used to study drug-tolerant and persister cellsin vitro.
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Peng, Meng-Wen, Yong Guan, Jian-Hong Liu, Liang Chen, Han Wang, Zheng-Zhe Xie, Hai-Yan Li, et al. "Quantitative three-dimensional nondestructive imaging of whole anaerobic ammonium-oxidizing bacteria." Journal of Synchrotron Radiation 27, no. 3 (April 17, 2020): 753–61. http://dx.doi.org/10.1107/s1600577520002349.
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Anaerobic ammonium-oxidizing (anammox) bacteria play a key role in the global nitrogen cycle and in nitrogenous wastewater treatment. The anammox bacteria ultrastructure is unique and distinctly different from that of other prokaryotic cells. The morphological structure of an organism is related to its function; however, research on the ultrastructure of intact anammox bacteria is lacking. In this study, in situ three-dimensional nondestructive ultrastructure imaging of a whole anammox cell was performed using synchrotron soft X-ray tomography (SXT) and the total variation-based simultaneous algebraic reconstruction technique (TV-SART). Statistical and quantitative analyses of the intact anammox bacteria were performed. High soft X-ray absorption composition inside anammoxosome was detected and verified to be relevant to iron-binding protein. On this basis, the shape adaptation of the anammox bacteria response to iron was explored.
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Gehrke, Peter, Philip Hartjen, Ralf Smeets, Martin Gosau, Ulrike Peters, Thomas Beikler, Carsten Fischer, et al. "Marginal Adaptation and Microbial Leakage at Conometric Prosthetic Connections for Implant-Supported Single Crowns: An In Vitro Investigation." International Journal of Molecular Sciences 22, no. 2 (January 17, 2021): 881. http://dx.doi.org/10.3390/ijms22020881.
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Encouraging clinical results were reported on a novel cone-in-cone coupling for the fixation of dental implant-supported crowns (Acuris, Dentsply Sirona Implants, Mölndal, Sweden). However, the presence or absence of a microgap and a potential bacterial leakage at the conometric joint has not yet been investigated. A misfit and a resulting gap between the conometric components could potentially serve as a bacterial reservoir that promotes plaque formation, which in turn may lead to inflammation of the peri-implant tissues. Thus, a two-fold study set-up was designed in order to evaluate the bidirectional translocation of bacteria along conometrically seated single crowns. On conometric abutments filled with a culture suspension of anaerobic bacteria, the corresponding titanium nitride-coated (TiN) caps were fixed by friction. Each system was sterilized and immersed in culture medium to provide an optimal environment for microbial growth. Positive and negative controls were prepared. Specimens were stored in an anaerobic workstation, and total and viable bacterial counts were determined. Every 48 h, samples were taken from the reaction tubes to inoculate blood agar plates and to isolate bacterial DNA for quantification using qrt-PCR. In addition, one Acuris test system was subjected to scanning electron microscopy (SEM) to evaluate the precision of fit of the conometric coupling and marginal crown opening. Throughout the observational period of one week, blood agar plates of the specimens showed no viable bacterial growth. qrt-PCR, likewise, yielded a result approaching zero with an amount of about 0.53 × 10−4 µg/mL DNA. While the luting gap/marginal opening between the TiN-cap and the ceramic crown was within the clinically acceptable range, the SEM analysis failed to identify a measurable microgap at the cone-in-cone junction. Within the limits of the in-vitro study it can be concluded that the Acuris conometric interface does not allow for bacterial translocation under non-dynamic loading conditions.
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Boyd, Eric S., Amaya M. Garcia Costas, Trinity L. Hamilton, Florence Mus, and John W. Peters. "Evolution of Molybdenum Nitrogenase during the Transition from Anaerobic to Aerobic Metabolism." Journal of Bacteriology 197, no. 9 (March 2, 2015): 1690–99. http://dx.doi.org/10.1128/jb.02611-14.
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ABSTRACTMolybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Phylogenetic evidence indicates that oxygen (O2)-sensitive Nif emerged in an anaerobic archaeon and later diversified into an aerobic bacterium. Aerobic bacteria that fix N2have adapted a number of strategies to protect Nif from inactivation by O2, including spatial and temporal segregation of Nif from O2and respiratory consumption of O2. Here we report the complement of Nif-encoding genes in 189 diazotrophic genomes. We show that the evolution of Nif during the transition from anaerobic to aerobic metabolism was accompanied by both gene recruitment and loss, resulting in a substantial increase in the number ofnifgenes. While the observed increase in the number ofnifgenes and their phylogenetic distribution are strongly correlated with adaptation to utilize O2in metabolism, the increase is not correlated with any of the known O2protection mechanisms. Rather, gene recruitment appears to have been in response to selective pressure to optimize Nif synthesis to meet fixed N demands associated with aerobic productivity and to more efficiently regulate Nif under oxic conditions that favor protein turnover. Consistent with this hypothesis, the transition of Nif from anoxic to oxic environments is associated with a shift from posttranslational regulation in anaerobes to transcriptional regulation in obligate aerobes and facultative anaerobes. Given that fixed nitrogen typically limits ecosystem productivity, our observations further underscore the dynamic interplay between the evolution of Earth's oxygen, nitrogen, and carbon biogeochemical cycles.IMPORTANCEMolybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Nif emerged in an anaerobe and later diversified into aerobes. Here we show that the transition of Nif from anaerobic to aerobic metabolism was accompanied by both gene recruitment and gene loss, resulting in a substantial increase in the number ofnifgenes. While the observed increase in the number ofnifgenes is strongly correlated with adaptation to utilize O2in metabolism, the increase is not correlated with any of the known O2protective mechanisms. Rather, gene recruitment was likely a response to more efficiently regulate Nif under oxic conditions that favor protein turnover.
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Sierra-Alvarez, R., J. A. Field, S. Kortekaas, and G. Lettinga. "Overview of the Anaerobic Toxicity Caused by Organic Forest Industry Wastewater Pollutants." Water Science and Technology 29, no. 5-6 (March 1, 1994): 353–63. http://dx.doi.org/10.2166/wst.1994.0728.
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Numerous types of organic environmental pollutants are encountered in forest industry effluents which potentially could inhibit consortia of anaerobic bacteria. The purpose of this study was to collect anaerobic bioassay data from the literature to better estimate the impact of these pollutants on anaerobic wastewater treatment systems. The most important methanogenic inhibitors in forest industry wastewaters are wood resin, chlorophenols and tannins. These compounds account for toxicity in alkaline pulping liquors, bleaching effluents and debarking wastewaters, respectively. Adaptation to chlorophenol toxicity can be expected since they are eventually degraded in anaerobic systems. Wood resin compounds, on the other hand, are not biodegraded anaerobically and therefore their toxicity is persistent. Toxicity in forest industry wastewaters does not necessarily preclude anaerobic treatment. A variety of techniques can be employed to diminish inhibition, such as dilution and detoxification treatments.
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Jensen, Dan B., and David W. Ussery. "Bayesian prediction of microbial oxygen requirement." F1000Research 2 (September 13, 2013): 184. http://dx.doi.org/10.12688/f1000research.2-184.v1.
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Background: Prediction of the optimal habitat conditions for a given bacterium, based on genome sequence alone would be of value for scientific as well as industrial purposes. One example of such a habitat adaptation is the requirement for oxygen. In spite of good genome data availability, there have been only a few prediction attempts of bacterial oxygen requirements, using genome sequences. Here, we describe a method for distinguishing aerobic, anaerobic and facultative anaerobic bacteria, based on genome sequence-derived input, using naive Bayesian inference. In contrast, other studies found in literature only demonstrate the ability to distinguish two classes at a time. Results: The results shown in the present study are as good as or better than comparable methods previously described in the scientific literature, with an arguably simpler method, when results are directly compared. This method further compares the performance of a single-step naive Bayesian prediction of the three included classifications, compared to a simple Bayesian network with two steps. A two-step network, distinguishing first respiring from non-respiring organisms, followed by the distinction of aerobe and facultative anaerobe organisms within the respiring group, is found to perform best. Conclusions: A simple naive Bayesian network based on the presence or absence of specific protein domains within a genome is an effective and easy way to predict bacterial habitat preferences, such as oxygen requirement.
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Taotao, Zeng, Li Dong, Zeng Huiping, Xie Shuibo, Qiu Wenxin, Liu Yingjiu, and Zhang Jie. "Nitrogen removal efficiency and microbial community analysis of ANAMMOX biofilter at ambient temperature." Water Science and Technology 71, no. 5 (January 19, 2015): 725–33. http://dx.doi.org/10.2166/wst.2015.019.
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An upflow anaerobic biofilter (AF) was developed to investigate anaerobic ammonium-oxidizing (ANAMMOX) efficiency in treating low-strength wastewater at ambient temperature (15.3–23.2 °C). Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization were used to investigate treatment effects on the microbial community. Stepwise decreases in influent ammonia concentration could help ANAMMOX bacteria selectively acclimate to low-ammonia conditions. With an influent ammonia concentration of 46.5 mg/L, the AF reactor obtained an average nitrogen removal rate of 2.26 kg/(m3 day), and a removal efficiency of 75.9%. polymerase chain reaction-DGGE results showed that microbial diversity in the low matrix was greater than in the high matrix. Microbial community structures changed when the influent ammonia concentration decreased. The genus of functional ANAMMOX bacteria was Candidatus Kuenenia stuttgartiensis, which remained stationary across study phases. Visual observation revealed that the relative proportions of ANAMMOX bacteria decreased from 41.6 to 36.3% across three study phases. The AF bioreactor successfully maintained high activity due to the ANAMMOX bacteria adaptation to low temperature and substrate conditions.
Dissertations / Theses on the topic "Anaerobic bacteria Adaptation"
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Agrawal, Manoj. "Metabolic engineering of Zymomonas mobilis for improved production of ethanol from lignocelluloses." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43618.
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Ethanol from lignocellulosic biomass is a promising alternative to rapidly depleting oil reserves. However, natural recalcitrance of lignocelluloses to biological and chemical treatments presents major engineering challenges in designing an ethanol conversion process. Current methods for pretreatment and hydrolysis of lignocelluloses generate a mixture of pentose (C5) and hexose (C6) sugars, and several microbial growth inhibitors such as acetic acid and phenolic compounds. Hence, an efficient ethanol production process requires a fermenting microorganism not only capable of converting mixed sugars to ethanol with high yield and productivity, but also having high tolerance to inhibitors. Although recombinant bacteria and yeast strains have been developed, ethanol yield and productivity from C5 sugars in the presence of inhibitors remain low and need to be further improved for a commercial ethanol production.
The overarching objective of this work is to transform Zymomonas mobilis into an efficient whole-cell biocatalyst for ethanol production from lignocelluloses. Z. mobilis, a natural ethanologen, is ideal for this application but xylose (a C5 sugar) is not its 'natural' substrate. Back in 1995, researches at National Renewable Energy Laboratory (NREL) had managed to overcome this obstacle by metabolically engineering Z. mobilis to utilize xylose. However, even after more than a decade of research, xylose fermentation by Z. mobilis is still inefficient compared to that of glucose. For example, volumetric productivity of ethanol from xylose fermentation is 3- to 4- fold lower than that from glucose fermentation. Further reduction or complete inhibition of xylose fermentation occurs under adverse conditions. Also, high concentrations of xylose do not get metabolized completely. Thus, improvement in xylose fermentation by Z. mobilis is required.
In this work, xylose fermentation in a metabolically engineered Z. mobilis was markedly improved by applying the technique of adaptive mutation. The adapted strain was able to grow on 10% (w/v) xylose and rapidly ferment xylose to ethanol within 2 days and retained high ethanol yield. Similarly, in mixed glucose-xylose fermentation, the strain produced a total of 9% (w/v) ethanol from two doses of 5% glucose and 5% xylose (or a total of 10% glucose and 10% xylose). Investigation was done to identify the molecular basis for efficient biocatalysis. An altered xylitol metabolism with reduced xylitol formation, increased xylitol tolerance and higher xylose isomerase activity were found to contribute towards improvement in xylose fermentation. Lower xylitol production in adapted strain was due to a single mutation in ZMO0976 gene, which drastically lowered the reductase activity of ZMO0976 protein. ZMO0976 was characterized as a novel aldo-keto reductase capable of reducing xylose, xylulose, benzaldehyde, furfural, 5-hydroxymethyl furfural, and acetaldehyde, but not glucose or fructose. It exhibited nearly 150-times higher affinity with benzaldehyde than xylose. Knockout of ZMO0976 was found to facilitate the establishment of xylose fermentation in Z. mobilis ZM4.
Equipped with molecular level understanding of the biocatalytic process and insight into Z. mobilis central carbon metabolism, further genetic engineering of Z. mobilis was undertaken to improve the fermentation of sugars and lignocellulosic hydrolysates. These efforts culminated in construction of a strain capable of fermenting glucose-xylose mixture in presence of high concentration of acetic acid and another strain with a partially operational EMP pathway.
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Goodwin, Steven D. "Ecophysiological adaptations of anaerobic bacteria to low pH." 1986. http://catalog.hathitrust.org/api/volumes/oclc/14170955.html.
Full textBook chapters on the topic "Anaerobic bacteria Adaptation"
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Pal, Arijit, and Sekhar Pal. "Anaerobes." In Extremophiles: Diversity, Adaptation and Applications, 275–332. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815080353122010015.
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Extremophilicity, or the capability to thrive in environmental conditions considered extreme is generally determined from the human perspective. From that point of view, organisms adapted to scarce, or even the absence of molecular oxygen, can be considered as one of the extremophiles, i.e., anaerobes. In this chapter, various aspects of anaerobic microorganisms are addressed, including their different taxa, their phylogenetic distribution, and the environments from where they have been isolated. Since prokaryotic taxonomy is a dynamic process, here we have emphasized the organisms that are validly placed in taxa and have cultured representatives. In this section, Archaea and Bacteria - the two domains are separately discussed. Similar separation is also maintained while discussing mechanisms of adaptation, as far as possible. Since these two domains share certain properties, the subsequent sections are not separated between these two domains.
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Kumar Tiwary, Bipransh, and Masrure Alam. "Extremophiles: An Overview." In Extremophiles: Diversity, Adaptation and Applications, 1–23. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815080353122010005.
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Earth contains several environmental extremes which are uninhabitable for most of the living beings. But, astonishingly, in the last few decades, several organisms thriving in such extreme environments have been discovered. “Extremophiles”, meaning “Lovers of Extremities” are the entities that are especially adapted to live in such harsh environmental conditions in which other entities cannot live. The discovery of extremophiles has not only boosted the biotech industry to search for new products from them, but also made researchers to think for the existence of extra-terrestrial life. The most inhospitable environments include physical or chemical extremities, like high or low temperatures, radiation, high pressure, water scarcity, high salinity, pH extremes, and limitation of oxygen. Microorganisms have been found to live in all such environmental conditions, like hyperthermophiles and psychrophiles, acidophiles and alkaliphiles. Bacteria like Deinococcus radiodurans, which is able to withstand extreme gamma radiation, and Moritella sp., able to grow at atmospheric pressure of >1000 atm, have been reported. Environments like the Dead Sea, having saturated NaCl concentrations, hold extreme halophiles like Halobacterium salinarum. Highly acidic environments, like the Rio-Tinto River in Spain or Danakil depression in Ethiopia harbour acidophiles with growth optima of pH zero, or close to it. Bacillus alcalophilus, and Microcystis aeruginosa on the other hand inhabit natural alkaline soda lakes where pH can reach about 12.0. A number of anaerobic prokaryotes can live in complete anoxic environments by using terminal electron acceptors other than oxygen. In this chapter, we shall discuss very briefly the diversity of all extremophiles and their mechanism(s) of adaptation.
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Dam, Bomba, Srikanta Pal, Abhijit Sar, and Puja Mukherjee. "Halophilic Microorganisms: Diversity, Adaptation and Application." In Extremophiles: Diversity, Adaptation and Applications, 146–81. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815080353122010010.
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Saline environments are one of the most common extreme habitats prevalent in this universe. They are of two primary types, ‘thalassohaline’ those which arose from seawater, with NaCl as the dominant salt; and ‘athalassohaline’ of non-seawater origin with different ionic compositions. Organisms from all domains of life have adapted themselves to thrive in environments with salinities ranging from normal to the saturation level. In particular, halophilic microorganisms have developed several adaptive mechanisms to cope up with osmotic stress. While halotolerant or moderate halophiles use efflux pumps, or accumulate neutral compatible solutes in the cytoplasm; extreme halophilic microorganisms accumulate potassium ions, a strategy called ‘salting-in’ to match the high ionic composition in the external environment. The later predominantly includes archaeal members, except the bacterium, Salinibacter ruber. The general adaptive features of halophilic microorganisms also help them to thrive under, and overcome other stressed conditions such as resisting antibiotics, heavy metals and ionic liquids. These microorganisms have wide physiological diversities and include members of oxygenic and anoxygenic phototrophs, aerobic heterotrophs, and those capable of diverse anaerobic respiratory metabolisms. Nano.microorganisms are also reported from saline environments. Their great metabolic versatility, low nutritional requirements, and adaptation machineries, make them promising candidates for several biotechnological applications such as production of pigments, biopolymers, compatible solutes, and salt tolerant hydrolytic enzymes. They are also used in bioremediation, food preservation, and preparation of specialized fermented foods. Understanding the halophiles also paves way for astrobiological research. This book chapter summarizes the present understanding of the diversity, adaptation, and application of halophilic microorganisms.