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Hassan S, Mushtaq M, Ganiee SA, Zaman M, Yaseen A, Shah AJ, Ganai BA. Microbial oases in the ice: A state-of-the-art review on cryoconite holes as diversity hotspots and their scientific connotations. ENVIRONMENTAL RESEARCH 2024; 252:118963. [PMID: 38640991 DOI: 10.1016/j.envres.2024.118963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 04/13/2024] [Accepted: 04/16/2024] [Indexed: 04/21/2024]
Abstract
Cryoconite holes, small meltwater pools on the surface of glaciers and ice sheets, represent extremely cold ecosystems teeming with diverse microbial life. Cryoconite holes exhibit greater susceptibility to the impacts of climate change, underlining the imperative nature of investigating microbial communities as an essential module of polar and alpine ecosystem monitoring efforts. Microbes in cryoconite holes play a critical role in nutrient cycling and can produce bioactive compounds, holding promise for industrial and pharmaceutical innovation. Understanding microbial diversity in these delicate ecosystems is essential for effective conservation strategies. Therefore, this review discusses the microbial diversity in these extreme environments, aiming to unveil the complexity of their microbial communities. The current study envisages that cryoconite holes as distinctive ecosystems encompass a multitude of taxonomically diverse and functionally adaptable microorganisms that exhibit a rich microbial diversity and possess intricate ecological functions. By investigating microbial diversity and ecological functions of cryoconite holes, this study aims to contribute valuable insights into the broader field of environmental microbiology and enhance further understanding of these ecosystems. This review seeks to provide a holistic overview regarding the formation, evolution, characterization, and molecular adaptations of cryoconite holes. Furthermore, future research directions and challenges underlining the need for long-term monitoring, and ethical considerations in preserving these pristine environments are also provided. Addressing these challenges and resolutely pursuing future research directions promises to enrich our comprehension of microbial diversity within cryoconite holes, revealing the broader ecological and biogeochemical implications. The inferences derived from the present study will provide researchers, ecologists, and policymakers with a profound understanding of the significance and utility of cryoconite holes in unveiling the microbial diversity and its potential applications.
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Affiliation(s)
- Shahnawaz Hassan
- Department of Environmental Science, University of Kashmir, Srinagar, 190006, India.
| | - Misba Mushtaq
- Centre of Research for Development, University of Kashmir, Srinagar, 190006, India
| | - Shahid Ahmad Ganiee
- Department of Environmental Science, University of Kashmir, Srinagar, 190006, India
| | - Muzafar Zaman
- Department of Environmental Science, University of Kashmir, Srinagar, 190006, India
| | - Aarif Yaseen
- Department of Environmental Science, University of Kashmir, Srinagar, 190006, India
| | - Abdul Jalil Shah
- Department of Pharmaceutical Sciences, University of Kashmir, Srinagar, 190006, India
| | - Bashir Ahmad Ganai
- Centre of Research for Development, University of Kashmir, Srinagar, 190006, India.
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2
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Dopson M, González-Rosales C, Holmes DS, Mykytczuk N. Eurypsychrophilic acidophiles: From (meta)genomes to low-temperature biotechnologies. Front Microbiol 2023; 14:1149903. [PMID: 37007468 PMCID: PMC10050440 DOI: 10.3389/fmicb.2023.1149903] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/16/2023] [Indexed: 03/17/2023] Open
Abstract
Low temperature and acidic environments encompass natural milieus such as acid rock drainage in Antarctica and anthropogenic sites including drained sulfidic sediments in Scandinavia. The microorganisms inhabiting these environments include polyextremophiles that are both extreme acidophiles (defined as having an optimum growth pH < 3), and eurypsychrophiles that grow at low temperatures down to approximately 4°C but have an optimum temperature for growth above 15°C. Eurypsychrophilic acidophiles have important roles in natural biogeochemical cycling on earth and potentially on other planetary bodies and moons along with biotechnological applications in, for instance, low-temperature metal dissolution from metal sulfides. Five low-temperature acidophiles are characterized, namely, Acidithiobacillus ferriphilus, Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, “Ferrovum myxofaciens,” and Alicyclobacillus disulfidooxidans, and their characteristics are reviewed. Our understanding of characterized and environmental eurypsychrophilic acidophiles has been accelerated by the application of “omics” techniques that have aided in revealing adaptations to low pH and temperature that can be synergistic, while other adaptations are potentially antagonistic. The lack of known acidophiles that exclusively grow below 15°C may be due to the antagonistic nature of adaptations in this polyextremophile. In conclusion, this review summarizes the knowledge of eurypsychrophilic acidophiles and places the information in evolutionary, environmental, biotechnological, and exobiology perspectives.
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Affiliation(s)
- Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
- *Correspondence: Mark Dopson
| | - Carolina González-Rosales
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - David S. Holmes
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastian, Santiago, Chile
| | - Nadia Mykytczuk
- Goodman School of Mines, Laurentian University, Sudbury, ON, Canada
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The MAP-Kinase HOG1 Controls Cold Adaptation in Rhodosporidium kratochvilovae by Promoting Biosynthesis of Polyunsaturated Fatty Acids and Glycerol. Curr Microbiol 2022; 79:253. [PMID: 35834133 DOI: 10.1007/s00284-022-02957-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2022] [Indexed: 11/03/2022]
Abstract
The aim of this study was to investigate the role of RKHog1 in the cold adaptation of Rhodosporidium kratochvilovae strain YM25235 and elucidate the correlation of biosynthesis of polyunsaturated fatty acids (PUFAs) and glycerol with its cold adaptation. The YM25235 strain was subjected to salt, osmotic, and cold stress tolerance analyses. mRNA levels of RKhog1, Δ12/15-fatty acid desaturase gene (RKD12), RKMsn4, HisK2301, and RKGPD1 in YM25235 were detected by reverse transcription quantitative real-time PCR. The contents of PUFAs, such as linoleic acid (LA) and linolenic acid (ALA) was measured using a gas chromatography-mass spectrometer, followed by determination of the growth rate of YM25235 and its glycerol content at low temperature. The RKHog1 overexpression, knockout, and remediation strains were constructed. Stress resistance analysis showed that overexpression of RKHog1 gene increased the biosynthesis of glycerol and enhanced the tolerance of YM25235 to cold, salt, and osmotic stresses, respectively. Inversely, the knockout of RKHog1 gene decreased the biosynthesis of glycerol and inhibited the tolerance of YM25235 to different stresses. Fatty acid analysis showed that the overexpression of RKHog1 gene in YM25235 significantly increased the content of LA and ALA, but RKHog1 gene knockout YM25235 strain had decreased content of LA and ALA. In addition, the mRNA expression level of RKD12, RKMsn4, RKHisK2301, and RKGPD1 showed an increase at 15 °C after RKHog1 gene overexpression but were unchanged at 30 °C. RKHog1 could regulate the growth adaptability and PUFA content of YM25235 at low temperature and this could be helpful for the cold adaptation of YM25235.
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Zhang Y, Shi H, Gu J, Jiao Y, Han S, Akindolie MS, Wang Y, Zhang L, Tao Y. Anthraquinone-2,6-disulfonate enhanced biodegradation of dibutyl phthalate: Reducing membrane damage and oxidative stress in bacterial degradation. BIORESOURCE TECHNOLOGY 2020; 302:122845. [PMID: 32000129 DOI: 10.1016/j.biortech.2020.122845] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
Plasticizer dibutyl phthalate (DBP) pollution has received more and more attention. In this study, a DBP degrading bacteria Enterobacter sp. DNB-S2 was found to suffer membrane damage and oxidative stress during DBP degradation. Physiological and transcriptome analysis showed that 100 μmol L-1 anthraquinone-2,6-disulfonate (AQDS) could enhance the ability of strain DNB-S2 for biodegradation of DBP. AQDS adjusted the cell surface structure, including increase levels of hydrophobic and unsaturated fatty acids. These changes increased the chemotactic ability of the strain DNB-S2 to the hydrophobic pollutant DBP and the fluidity of the cell membrane. The expression of methyl chemotactic protein and genes associated with cell membrane-fixed components were up-regulated. AQDS also improved the scavenging ability of ·OH and H2O2 of DNB-S2 by promoting expression genes related to glutathione metabolism, thereby reducing oxidative stress. These results will provide new insights into the biodegradation of DBP.
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Affiliation(s)
- Ying Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Hongtao Shi
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Jidong Gu
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Yaqi Jiao
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Siyue Han
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Modupe Sarah Akindolie
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Yifan Wang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Lin Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China
| | - Yue Tao
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China.
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Characterization of the glycerol-3-phosphate acyltransferase gene and its real-time expression under cold stress in Paeonia lactiflora Pall. PLoS One 2018; 13:e0202168. [PMID: 30096187 PMCID: PMC6086452 DOI: 10.1371/journal.pone.0202168] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 07/30/2018] [Indexed: 11/25/2022] Open
Abstract
Elucidating the cold tolerance mechanism of Paeonia lactiflora, which is one of the most valuable ornamental and medicinal plants in Asia, fundamentally impacts its breeding and production. The glycerol-3-phosphate acyltransferase (GPAT) gene plays a pivotal role in cold resistance in a variety of plant species. Here, we cloned the P. lactiflora GPAT gene, determined its expression pattern, and tested its role in cold resistance. We obtained the full-length P. lactiflora GPAT gene using tissue-cultured seedlings and real-time polymerase chain reaction and rapid amplification of cDNA ends analyses. We named this gene PlGPAT in P. lactiflora. Phylogenetic analysis indicates that the PlGPAT gene is closely related with the GPAT genes in core eudicots. The phylogenetic tree containing 31 angiosperm species based on GPAT protein sequences is largely consistent with the known phylogeny in flowering plants. We conducted a time-course PlGPAT expression analysis and demonstrated that PlGPAT expression is correlated with low-temperature stress. Our results suggest that the PlGPAT gene plays an important role in regulating cold resistance in P. lactiflora.
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Lu Q, Li J, Wang J, Li K, Li J, Han P, Chen P, Zhou W. Exploration of a mechanism for the production of highly unsaturated fatty acids in Scenedesmus sp. at low temperature grown on oil crop residue based medium. BIORESOURCE TECHNOLOGY 2017; 244:542-551. [PMID: 28803104 DOI: 10.1016/j.biortech.2017.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
The ability of algae to produce lipids comprising of unsaturated fatty acids varies with strains and culture conditions. This study investigates the effect of temperature on the production of unsaturated fatty acids in Scenedesmus sp. grown on oil crop residue based medium. At low temperature (10°C), synthesis of lipids compromising of high contents of unsaturated fatty acids took place primarily in the early stage while protein accumulation mainly occurred in the late stage. This stepwise lipid-protein synthesis process was found to be associated with the contents of acetyl-CoA and α-KG in the algal cells. A mechanism was proposed and tested through simulation experiments which quantified the carbon flux allocation in algal cells at different cultivation stages. It is concluded that low culture temperature such as 10°C is suitable for the production of lipids comprising of unsaturated fatty acids.
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Affiliation(s)
- Qian Lu
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China
| | - Jun Li
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China
| | - Jinghan Wang
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, China
| | - Kun Li
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China
| | - Jingjing Li
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China
| | - Pei Han
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China
| | - Paul Chen
- Center for Biorefining, Bioproducts and Biosystems Engineering Department, University of Minnesota, Saint Paul, United States
| | - Wenguang Zhou
- School of Resources, Environmental & Chemical Engineering and Key Laboratory of Poyang Lake Environment and Resource Utilization, Nanchang University, Nanchang, China.
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Wang J, Chen W, Nian H, Ji X, Lin L, Wei Y, Zhang Q. Inhibition of Polyunsaturated Fatty Acids Synthesis Decreases Growth Rate and Membrane Fluidity of Rhodosporidium kratochvilovae at Low Temperature. Lipids 2017; 52:729-735. [DOI: 10.1007/s11745-017-4273-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 06/08/2017] [Indexed: 12/01/2022]
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Auld RR, Mykytczuk NC, Leduc LG, Merritt TJ. Seasonal variation in an acid mine drainage microbial community. Can J Microbiol 2017; 63:137-152. [DOI: 10.1139/cjm-2016-0215] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Environmental oxidation and microbial metabolism drive production of acid mine drainage (AMD). Understanding changes in the microbial community, due to geochemical and seasonal characteristics, is fundamental to AMD monitoring and remediation. Using direct sequencing of the 16S and 18S rRNA genes to identify bacterial, archaeal, and eukaryotic members of the microbial community at an AMD site in Northern Ontario, Canada, we found a dynamic community varying significantly across winter and summer sampling times. Community composition was correlated with physical and chemical properties, including water temperature, pH, conductivity, winter ice thickness, and metal concentrations. Within Bacteria, Acidithiobacillus was the dominant genus during winter (11%–57% of sequences) but Acidiphilium was dominant during summer (47%–87%). Within Eukarya, Chrysophyceae (1.5%–94%) and Microbotrymycetes (8%–92%) dominated the winter community, and LKM11 (4%–62%) and Chrysophyceae (25%–87%) the summer. There was less diversity and variability within the Archaea, with similar summer and winter communities mainly comprising Thermoplasmata (33%–64%) and Thermoprotei (5%–20%) classes but also including a large portion of unclassified reads (∼40%). Overall, the active AMD community varied significantly between winter and summer, with changing community profiles closely correlated to specific differences in AMD geochemical and physical properties, including pH, water temperature, ice thickness, and sulfate and metal concentrations.
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Affiliation(s)
- Ryan R. Auld
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON P3E 2C6, Canada
| | | | - Leo G. Leduc
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
| | - Thomas J.S. Merritt
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON P3E 2C6, Canada
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9
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He S, Ding LL, Xu K, Geng JJ, Ren HQ. Effect of low temperature on highly unsaturated fatty acid biosynthesis in activated sludge. BIORESOURCE TECHNOLOGY 2016; 211:494-501. [PMID: 27035483 DOI: 10.1016/j.biortech.2016.03.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/09/2016] [Accepted: 03/13/2016] [Indexed: 06/05/2023]
Abstract
Low temperature is a limiting factor for the microbial activity of activated sludge for sewage treatment plant in winter. Highly unsaturated fatty acid (UFA) biosynthesis, phospholipid fatty acid (PLFA) constituents and microbial structure in activated sludge at low temperature were investigated. Over 12 gigabases of metagenomic sequence data were generated with the Illumina HiSeq 2000 platform. The result showed 43.11% of phospholipid fatty acid (PLFA) in the activated sludge participated in UFA biosynthesis, and γ-Linolenic could be converted to Arachidonic acid at low temperature. The highly UFA biosynthesis in activated sludge was n-6 highly UFA biosynthesis, rather than n-3 highly UFA biosynthesis. The microbial community structures of activated sludge were analyzed by PLFA and high-throughput sequencing (HiSeq) simultaneously. Acidovorax, Pseudomonas, Flavobacterium and Polaromonas occupied higher percentage at 5°C, and genetic changes of highly UFA biosynthesis derived from microbial community structures change.
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Affiliation(s)
- Su He
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Li-Li Ding
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Ke Xu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Jin-Ju Geng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China
| | - Hong-Qiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
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10
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Wan C, Chen S, Wen L, Liu X, Lee DJ, Yang X. Biosynthesis, characterization and potentiality of lipopeptides produced by Bacillus flexus S1 without inductive carbon sources. RSC Adv 2016. [DOI: 10.1039/c6ra17510d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This study newly isolated a bacterial stain ofBacillus flexusS1 which had abilities of synthesizing lipopeptides without any inductive operations, and thus it could effectively save operational procedures or cost.
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Affiliation(s)
- Chunli Wan
- Department of Environmental Science and Engineering
- Fudan University
- Shanghai 200433
- China
| | - Si Chen
- Department of Environmental Science and Engineering
- Fudan University
- Shanghai 200433
- China
| | - Lei Wen
- Department of Environmental Science and Engineering
- Fudan University
- Shanghai 200433
- China
| | - Xiang Liu
- Department of Environmental Science and Engineering
- Fudan University
- Shanghai 200433
- China
| | - Duu-Jong Lee
- Department of Chemical Engineering
- National Taiwan University of Science and Technology
- Taipei 106
- Taiwan
| | - Xue Yang
- State Key Laboratory of Pollution Control and Resources Reuse
- College of Environmental Science and Engineering
- Tongji University
- Shanghai 200092
- China
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11
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He J, Yang Z, Hu B, Ji X, Wei Y, Lin L, Zhang Q. Correlation of polyunsaturated fatty acids with the cold adaptation of Rhodotorula glutinis. Yeast 2015; 32:683-90. [PMID: 26284451 DOI: 10.1002/yea.3095] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/28/2015] [Accepted: 08/05/2015] [Indexed: 11/11/2022] Open
Abstract
This study aimed to investigate the correlation between the cold adaptation of Rhodotorula glutinis YM25079 and the membrane fluidity, content of polyunsaturated fatty acids and mRNA expression level of the Δ(12)-desaturase gene. The optimum temperature for YM25079 growth was analysed first, then the composition changes of membrane lipid in YM25079 were detected by GC-MS and membrane fluidity was evaluated by 1-anilinonaphthalene-8-sulphonate (ANS) fluorescence. Meanwhile, the encoding sequence of Δ(12)-fatty acid desaturase in YM25079 was cloned and further transformed into Saccharomyces cerevisiae INVScl for functional analysis. The mRNA expression levels of Δ(12)-fatty acid desaturase at 15°C and 25°C were analysed by real-time PCR. YM25079 could grow at 5-30°C, with the optimum temperature of 15°C. The membrane fluidity of YM25079 was not significantly reduced when the culture temperature decreased from 25°C to 15°C, but the content of polyunsaturated fatty acids (PUFAs), including linoleic acid and α-Linolenic acid increased significantly from 29.4% to 55.39%. Furthermore, a novel Δ(12)-fatty acid desaturase gene YM25079RGD12 from YM25079 was successfully identified and characterized, and the mRNA transcription level of the Δ(12)-desaturase gene was about five-fold higher in YM25079 cells grown at 15°C than that at 25°C. These results suggests that the cold adaptation of Rhodotorula glutinis YM25079 might result from higher expression of genes, especially the Δ(12)-fatty acid desaturase gene, during polyunsaturated fatty acids biosynthesis, which increased the content of PUFAs in the cell membrane and maintained the membrane fluidity at low temperature.
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Affiliation(s)
- Jing He
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China.,Genetic Diagnosis Centre, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, First People's Hospital of Yunnan Province, Kunming, People's Republic of China
| | - Zhaojie Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
| | - Binbin Hu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
| | - Xiuling Ji
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
| | - Yunlin Wei
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
| | - Lianbing Lin
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
| | - Qi Zhang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, People's Republic of China
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12
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Taylor GJ, Sarles SA. Heating-enabled formation of droplet interface bilayers using Escherichia coli total lipid extract. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:325-37. [PMID: 25514167 DOI: 10.1021/la503471m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Droplet interface bilayers (DIBs) serve as a convenient platform to study interactions between synthetic lipid membranes and proteins. However, a majority of DIBs have been assembled using a single lipid type, diphytanoylphosphatidylcholine (DPhPC). The work described herein establishes a new method to assemble DIBs using total lipid extract from Escherichia coli (eTLE); it is found that incubating oil-submerged aqueous droplets containing eTLE liposomes at a temperature above the gel-fluid phase transition temperature (Tg) promotes monolayer self-assembly that does not occur below Tg. Once monolayers are properly assembled via heating, droplets can be directly connected or cooled below Tg and then connected to initiate bilayer formation. This outcome contrasts immediate droplet coalescence observed upon contact between nonheated eTLE-infused droplets. Specific capacitance measurements confirm that the interface between droplets containing eTLE lipids is a lipid bilayer with thickness of 29.6 Å at 25 °C in hexadecane. We observe that bilayers formed from eTLE or DPhPC survive cooling and heating between 25 and 50 °C and demonstrate gigaohm (GΩ) membrane resistances at all temperatures tested. Additionally, we study the insertion of alamethicin peptides into both eTLE and DPhPC membranes to understand how lipid composition, temperature, and membrane phase influence ion channel formation. Like in DPhPC bilayers, alamethicin peptides in eTLE exhibit discrete, voltage-dependent gating characterized by multiple open channel conductance levels, though at significantly lower applied voltages. Cyclic voltammetry measurements of macroscopic channel currents confirm that the voltage-dependent conductance of alamethicin channels in eTLE bilayers occurs at lower voltages than in DPhPC bilayers at equivalent peptide concentrations. This result suggests that eTLE membranes, via composition, fluidity, or the presence of subdomains, offer an environment that enhances alamethicin insertion. For both membrane compositions, increasing temperature reduces the lifetimes of single channel gating events and increases the voltage required to cause an exponential increase in channel current. However, the fact that alamethicin insertion in eTLE exhibits significantly greater sensitivity to temperature changes through its Tg suggests that membrane phase plays an important role in channel formation. These effects are much less severe in DPhPC, where heating from 25 to 50 °C does not induce a phase change. The described technique for heating-assisted monolayer formation permits the use of other high transition temperature lipids in aqueous droplets for DIB formation, thereby increasing the types of lipids that can be considered for assembling model membranes.
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Affiliation(s)
- Graham J Taylor
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
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13
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Poerschmann J, Schultze-Nobre L. Structural characterization of organic intermediates arising from xylenol degradation by laboratory-scale constructed wetlands. CHEMOSPHERE 2014; 109:120-127. [PMID: 24393564 DOI: 10.1016/j.chemosphere.2013.12.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 12/09/2013] [Accepted: 12/11/2013] [Indexed: 06/03/2023]
Abstract
A mixture of xylenols (2,6-, 3,4-, 3,5-) was subjected to laboratory-scale constructed wetland treatment using helophytes. Conversion efficiencies under aerobic conditions ranged from 89% to 94%; the corresponding numbers under anaerobic conditions were lower. The studies were focused on the identification of stable organic intermediates. Identification was performed by a combination of GC/MS analysis and pre-chromatographic derivatization of the lyophilizates. In addition to common intermediates including citraconate, succinate and dimethyl benzenediols, an array of α- and β-ketoadipic acid carboxylates could be identified. The ketoadipic acid carboxylates have not been known to be formed in bioremediation of phenols including xylenols so far. Mechanisms for the formation of ketoadipic acid carboxylates are proposed. Chemotaxonomic considerations using diagnostic fatty acids provided mounting evidence that organic matter originating from plants prevailed over bacterial organic matter. Biomarkers indicated a virtual absence of fungi and algae.
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Affiliation(s)
- J Poerschmann
- UFZ - Helmholtz Center for Environmental Research, Department of Environmental Engineering, Permoserstr. 15, D-04318 Leipzig, Germany.
| | - L Schultze-Nobre
- UFZ - Helmholtz Center for Environmental Research, Department of Environmental Biotechnology, Germany
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14
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Zhu B, Xia X, Xia N, Zhang S, Guo X. Modification of Fatty acids in membranes of bacteria: implication for an adaptive mechanism to the toxicity of carbon nanotubes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:4086-4095. [PMID: 24579825 DOI: 10.1021/es404359v] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We explored whether bacteria could respond adaptively to the presence of carbon nanotubes (CNTs) by investigating the influence of CNTs on the viability, composition of fatty acids, and cytoplasmic membrane fluidity of bacteria in aqueous medium for 24 h exposure. The CNTs included long single-walled carbon nanotubes (L-SWCNTs), short single-walled carbon nanotubes (S-SWCNTs), short carboxyl single-walled carbon nanotubes (S-SWCNT-COOH), and aligned multiwalled carbon nanotubes (A-MWCNTs). The bacteria included three common model bacteria, Staphyloccocus aureus (Gram-positive), Bacillus subtilis (Gram-positive), and Escherichia coli (Gram-negative), and one polybrominated diphenyl ether degrading strain, Ochrobactrum sp. (Gram-negative). Generally, L-SWCNTs were the most toxic to bacteria, whereas S-SWCNT-COOH showed the mildest bacterial toxicity. Ochrobactrum sp. was more susceptible to the toxic effect of CNTs than E. coli. Compared to the control in the absence of CNTs, the viability of Ochrobactrum sp. decreased from 71.6-81.4% to 41.8-70.2%, and E. coli from 93.7-104.0% to 67.7-91.0% when CNT concentration increased from 10 to 50 mg L(-1). The cytoplasmic membrane fluidity of bacteria increased with CNT concentration, and a significant negative correlation existed between the bacterial viabilities and membrane fluidity for E. coli and Ochrobactrum sp. (p < 0.05), indicating that the increase in membrane fluidity induced by CNTs was an important factor causing the inactivation of bacteria. In the presence of CNTs, E. coli and Ochrobactrum sp. showed elevation in the level of saturated fatty acids accompanied with reduction in unsaturated fatty acids, compensating for the fluidizing effect of CNTs. This demonstrated that bacteria could modify their composition of fatty acids to adapt to the toxicity of CNTs. In contrast, S. aureus and B. subtilis exposed to CNTs increased the proportion of branched-chain fatty acids and decreased the level of straight-chain fatty acids, which was also favorable to counteract the toxic effect of CNTs. This study suggests that the bacterial tolerances to CNTs are associated with both the adaptive modification of fatty acids in the membrane and the physicochemical properties of CNTs. This is the first report about the physiologically adaptive response of bacteria to CNTs, and may help to further understand the ecotoxicological effects of CNTs.
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Affiliation(s)
- Baotong Zhu
- School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation/Key Laboratory of Water and Sediment Sciences of Ministry of Education , Beijing 100875, People's Republic of China
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Shapiro RS, Cowen LE. Thermal control of microbial development and virulence: molecular mechanisms of microbial temperature sensing. mBio 2012; 3:e00238-12. [PMID: 23033469 PMCID: PMC3518907 DOI: 10.1128/mbio.00238-12] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Temperature is a critical and ubiquitous environmental signal that governs the development and virulence of diverse microbial species, including viruses, archaea, bacteria, fungi, and parasites. Microbial survival is contingent upon initiating appropriate responses to the cellular stress induced by severe environmental temperature change. In the case of microbial pathogens, development and virulence are often coupled to sensing host physiological temperatures. As such, microbes have developed diverse molecular strategies to sense fluctuations in temperature, and nearly all cellular molecules, including proteins, lipids, RNA, and DNA, can act as thermosensors that detect changes in environmental temperature and initiate relevant cellular responses. The myriad of molecular mechanisms by which microbes sense and respond to temperature reveals an elegant repertoire of strategies to orchestrate cellular signaling, developmental programs, and virulence with spatial and temporal environmental cues.
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Affiliation(s)
- Rebecca S Shapiro
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Poerschmann J, Koschorreck M, Górecki T. Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: fatty acids. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 414:614-623. [PMID: 22119026 DOI: 10.1016/j.scitotenv.2011.10.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 09/28/2011] [Accepted: 10/03/2011] [Indexed: 05/31/2023]
Abstract
Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5 cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far. Combined FA concentrations in the surface sediment were higher compared to those in the deep sediment (497 vs. 127 μg g(-1)d.w., respectively). This was related to deposition of autochthonous biomass and higher terrestrial plants onto the surface sediment, as well as--to lesser extent--with higher bacterial activity on the sediment-water interface. The FA distribution in both sediments was characterized by a strong even-over-odd preference and was bimodal in nature: there was a cluster at nC(14)-nC(18) characteristic of chiefly autochthonous (algal and bacterial) SOM production, and another cluster at nC(22-28) related to input from higher plants. The FA distribution in the surface sediment pointed to higher terrestrial input compared to autochthonous contribution to SOM (67%:33%) as an estimate. Fingerprinting of viable bacteria was accomplished through signature FA markers including branched C(15) and C(17) surrogates, cyclopropanoic acids, 3-hydroxy (OH) acids and monounsaturated surrogates with unusual double bond localization. The abundance of Gram-negative bacteria was higher in the surface sediment as evidenced by total diagnostic 3-OH-fatty acids (37 μg g(-1) versus 25 μg g(-1)). Potential source taxa in both sediment layers included acidophilic iron- and sulfur-oxidizing bacteria including Acidithiobacillus ferrooxidans. High abundances of terminally branched C(15) and C(17) surrogates in both sediments pointed to sulfate- and iron-reducing bacteria. Signature FAs characteristic of methanotrophs were virtually lacking in both sediments.
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Affiliation(s)
- Juergen Poerschmann
- UFZ-Helmholtz Center for Environmental Research, Department of Environmental Engineering, Permoserstr 15, 04318 Leipzig, Germany.
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Metagenomic analysis of stress genes in microbial mat communities from Antarctica and the High Arctic. Appl Environ Microbiol 2011; 78:549-59. [PMID: 22081564 DOI: 10.1128/aem.06354-11] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Polar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived from Proteobacteria and Cyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation of Actinobacteria and Alphaproteobacteria in the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.
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Role of alcohols in growth, lipid composition, and membrane fluidity of yeasts, bacteria, and archaea. Appl Environ Microbiol 2011; 77:6400-8. [PMID: 21784917 DOI: 10.1128/aem.00694-11] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Increased membrane fluidity, which causes cofactor leakage and loss of membrane potential, has long been documented as a cause for decreased cell growth during exposure to ethanol, butanol, and other alcohols. Reinforcement of the membrane with more complex lipid components is thus thought to be beneficial for the generation of more tolerant organisms. In this study, organisms with more complex membranes, namely, archaea, did not maintain high growth rates upon exposure to alcohols, indicating that more complex lipids do not necessarily fortify the membrane against the fluidizing effects of alcohols. In the presence of alcohols, shifts in lipid composition to more saturated and unbranched lipids were observed in most of the organisms tested, including archaea, yeasts, and bacteria. However, these shifts did not always result in a decrease in membrane fluidity or in greater tolerance of the organism to alcohol exposure. In general, organisms tolerating the highest concentrations of alcohols maintained membrane fluidity after alcohol exposure, whereas organisms that increased membrane rigidity were less tolerant. Altered lipid composition was a common response to alcohol exposure, with the most tolerant organisms maintaining a modestly fluid membrane. Our results demonstrate that increased membrane fluidity is not the sole cause of growth inhibition and that alcohols may also denature proteins within the membrane and cytosol, adversely affecting metabolism and decreasing cell growth.
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Mykytczuk NCS, Trevors JT, Foote SJ, Leduc LG, Ferroni GD, Twine SM. Proteomic insights into cold adaptation of psychrotrophic and mesophilic Acidithiobacillus ferrooxidans strains. Antonie Van Leeuwenhoek 2011; 100:259-77. [DOI: 10.1007/s10482-011-9584-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 04/29/2011] [Indexed: 11/29/2022]
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Mykytczuk NCS, Trevors JT, Ferroni GD, Leduc LG. Cytoplasmic membrane fluidity and fatty acid composition of Acidithiobacillus ferrooxidans in response to pH stress. Extremophiles 2010; 14:427-41. [PMID: 20582711 DOI: 10.1007/s00792-010-0319-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 05/26/2010] [Indexed: 11/25/2022]
Abstract
Strain variation in the acidophile Acidithiobacillus ferrooxidans was examined as a product of membrane adaptation in response to pH stress. We tested the effects of sub and supra-optimal pH in two type strains and four strains isolated from acid mine drainage water around Sudbury, Ontario, Canada. Growth rate, membrane fluidity and phase, determined from the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene, and fatty acid profiles were compared. The effect of pH 1.5 was the most pronounced compared to the other pH values of 1.8, 3.1, and 3.5. Three different types of response to lower pH were observed, the first of which appeared to maintain cellular homeostasis more effectively. This adaptive mode included a decrease in membrane fluidity and concomitant depression of the phase transition in two distinct membrane lipid components. This was explained through the increase in saturated fatty acids (predominantly 16:0 and cyclopropane 19:0 w8c) with a concomitant decrease in 18:1 w7c fatty acid. The other strains also showed common adaptive mechanisms of specific fatty acid remodeling increasing the abundance of short-chain fatty acids. However, we suspect membrane permeability was compromised due to potential phase separation, which may interfere with energy transduction and viability at pH 1.5. We demonstrate that membrane physiology permits differentiating pH tolerance in strains of this extreme acidophile.
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Affiliation(s)
- N C S Mykytczuk
- Department of Biology, Laurentian University, Sudbury, ON, P3E 2C6, Canada.
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