Journal of Microbiology

Journal Articles

Genetic and Functional Characterization of a Salicylate 1‑monooxygenase Located on an Integrative and Conjugative Element (ICE) in Pseudomonas stutzeri AJR13: Igor Ivanovski , Gerben J. Zylstra; J. Microbiol. 2023;61(12):1025-1032. Published online December 15, 2023; DOI: https://doi.org/10.1007/s12275-023-00093-x

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Abstract: Pseudomonas stutzeri strain AJR13 was isolated for growth on the related compounds biphenyl (BPH) and diphenylmethane (DPM). The BPH and DPM degradative pathway genes are present on an integrative and conjugative element (ICE) in the chromosome. Examination of the genome sequence of AJR13 revealed a gene encoding a salicylate 1-monooxygenase (salA) associated with the ICE even though AJR13 did not grow on salicylate. Transfer of the ICE to the well-studied Pseudomonas putida KT2440 resulted in a KT2440 strain that could grow on salicylate. Knockout mutagenesis of the salA gene on the ICE in KT2440 eliminated the ability to grow on salicylate. Complementation of the knockout with the cloned salA gene restored growth on salicylate. Transfer of the cloned salA gene under control of the lac promoter to KT2440 resulted in a strain that could grow on salicylate. Heterologous expression of the salA gene in E. coli BL21 DE3 resulted in the production of catechol from salicylate, confirming that it is indeed a salicylate 1-monooxygenase. Interestingly, transfer of the cloned salA gene under control of the lac promoter to AJR13 resulted in a strain that could now grow on salicylate, suggesting that gene expression for the downstream catechol pathway is intact.

Rasiella rasia gen. nov. sp. nov. within the family Flavobacteriaceae isolated from seawater recirculating aquaculture system: Seong-Jin Kim , Young-Sam Kim , Sang-Eon Kim , Hyun-Kyoung Jung , Jeeeun Park , Min-Ju Yu , Kyoung-Ho Kim; J. Microbiol. 2022;60(11):1070-1076. Published online October 17, 2022; DOI: https://doi.org/10.1007/s12275-022-2099-7

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A novel bacterium designated RR4-40T was isolated from a biofilter of seawater recirculating aquaculture system in Busan, South Korea. Cells are strictly aerobic, Gram-negative, irregular short rod, non-motile, and oxidase- and catalase-negative. Growth was observed at 15–30°C, 0.5–6% NaCl (w/v), and pH 5.0–9.5. The strain grew optimally at 28°C, 3% salinity (w/v), and pH 8.5. The phylogenetic analysis based on 16S rRNA gene sequences showed that strain RR4-40T was most closely related to Marinirhabdus gelatinilytica NH83T (94.16% of 16S rRNA gene similarity) and formed a cluster with genera within the family Flavobacteriaceae. The values of the average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), and average amino acid identity (AAI) between genomes of strain RR4-40T and M. gelatinilytica NH83T were 72.91, 18.2, and 76.84%, respectively, and the values against the strains in the other genera were lower than those. The major fatty acids were iso-C15:0 (31.34%), iso-C17:0 3-OH (13.65%), iso-C16:0 3-OH (10.61%), and iso-C15:1 G (10.38%). The polar lipids comprised phosphatidylglycerol, diphosphatidylglycerol, aminophospholipid, aminolipid, glycolipid, and sphingolipid. The major respiratory quinone was menaquinone-6 (MK-6) and the DNA G + C content of strain RR4-40T was 37.4 mol%. According to the polyphasic analysis, strain RR4-40T is considered to represent a novel genus within the family Flavobacteriaceae, for which the name Rasiella rasia gen. nov, sp. nov. is proposed. The type strain is RR4-40T (= KCTC 52650T = MCCC 1K04210T).

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Rhodobacteraceae are Prevalent and Ecologically Crucial Bacterial Members in Marine Biofloc Aquaculture
Meora Rajeev, Jang-Cheon Cho
Journal of Microbiology.2024; 62(11): 985. CrossRef
Validation List no. 215. Valid publication of new names and new combinations effectively published outside the IJSEM
Aharon Oren, Markus Göker
International Journal of Systematic and Evolutionary Microbiology .2024;[Epub] CrossRef

Contrasting patterns of the bacterial and archaeal communities in a high-elevation river in northwestern China: Yang Hu , Jian Cai , Chengrong Bai , Keqiang Shao , Xiangming Tang , Guang Gao; J. Microbiol. 2018;56(2):104-112. Published online February 2, 2018; DOI: https://doi.org/10.1007/s12275-018-7244-y

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Abstract

The patterns of macrobiota in lotic ecosystems have been extensively explored, however, the dynamics of microbiota remain poorly investigated, especially in the high-elevation region. To address this deficit, we collected eight samples to unveil the bacterial and archaeal community in the Kaidu river, located at the arid region of northwestern China (an average of 2,500 m a.s.l.). For the bacterial community, phylogenetically Betaproteobacteria prevailed, followed by Alphaproteobacteria and Actinobacteria; at the finer genus level, Limnohabitans and Variovorax were prominent. Along the river, the bacterial community showed a continuous succession. Specifically, their α- and β-diversity gradually increased, suggesting a distance-decay pattern. Additionally, there was an ecological transition between the dominant and the rare sub-community along the river: the relative abundance of the dominant members gradually decreased as the rare members increased. We report that temperature and spatial distance were significantly related to the variation of bacterial community. Variance partitioning analysis showed that the environmental factors contributed more to the bacterial community than did the spatial distance. In the case of the archaeal community, the methanogenic groups, mainly Methanosaeta and Methanosarcina, were prominent within the Kaidu river. Unlike the continuous change in the patterns of the bacterial community, the archaeal community showed a constant pattern along the river. Our results showed that the archaeal community was independent of the environmental and spatial factors. We propose that the inoculation of soil-derived archaea is responsible for the archaeal community in the Kaidu river. Together, our study demonstrated that the bacterial community in the high-elevation Kaidu river is a continuum, whereas the archaeal community is not.

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Planktonic archaea reveal stronger dispersal limitation and more network connectivity than planktonic bacteria in the Jinsha River of southwestern China
Ge Cui, Juan Chen, Chao Wang, Peifang Wang, Bo Zhang, Han Gao, Rui Fu
Freshwater Biology.2023; 68(11): 1995. CrossRef
Insights on the particle-attached riverine archaeal community shifts linked to seasons and to multipollution during a Mediterranean extreme storm event
Mégane Noyer, Maria Bernard, Olivier Verneau, Carmen Palacios
Environmental Science and Pollution Research.2023; 30(17): 49685. CrossRef
Using the health index of the environmental microbiota to predict the health status of aquatic wildlife
Haile Yang, Qiong Zhou, Xia Guo, Zhigang Liu, Hui Zhang, Hao Du
Ecological Indicators.2023; 151: 110346. CrossRef
Phytoplankton dynamics and implications for eutrophication management in an urban river with a series of rubber dams
Linlin Bao, Jie Chen, Hongjin Tong, Jun Qian, Xuyong Li
Journal of Environmental Management.2022; 311: 114865. CrossRef
Effect of Water Chemistry, Land Use Patterns, and Geographic Distances on the Spatial Distribution of Bacterioplankton Communities in an Anthropogenically Disturbed Riverine Ecosystem
Jun Zhao, Wang Peng, Mingjun Ding, Minghua Nie, Gaoxiang Huang
Frontiers in Microbiology.2021;[Epub] CrossRef
Bacterial community composition shaped by water chemistry and geographic distance in an anthropogenically disturbed river
Peng Wang, Jun Zhao, Hanyu Xiao, Wenjing Yang, Xiaofang Yu
Science of The Total Environment.2019; 655: 61. CrossRef
Structure of bacterial and eukaryote communities reflect in situ controls on community assembly in a high-alpine lake
Eli Michael S. Gendron, John L. Darcy, Katherinia Hell, Steven K. Schmidt
Journal of Microbiology.2019; 57(10): 852. CrossRef

Dynamic variation of toxic and non-toxic Microcystis proportion in the eutrophic Daechung Reservoir in Korea: Seung-Hyun Joung , Hee-Mock Oh , Kyung-A You; J. Microbiol. 2016;54(8):543-550. Published online August 2, 2016; DOI: https://doi.org/10.1007/s12275-016-6141-5

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Abstract

This study was conducted to determine the environmental factors affecting the level of potentially toxic Microcystis. The long-term tendencies of temperature, precipitation, and water quality factors were analyzed to determine the environmental characteristics of the Daechung Reservoir in Korea, and water samples were directly collected to analyze the dynamics of toxic and non-toxic Microcystis at weekly intervals from May to October 2012. Microcystis was the dominant genus during the study period, and it was composed of potentially toxic and non-toxic Microcystis. The fraction of potentially toxic Microcystis ranged from 6.0% to 61.1%. The amount of toxic Microcystis was highly related to the intracellular microcystin concentration (r = 0.760, P < 0.01). Therefore, the fraction of potentially toxic Microcystis is an important concern in Microcystis blooming because the intracellular microcystin concentration may reflect microcystin levels in the water. The prevalence of potentially toxic Microcystis was highly related to water temperature in Daechung Reservoir (r = 0.585, P < 0.01). Thus, temperature increase during Microcystis blooming may lead to more frequent toxic Microcystis blooms in eutrophic water bodies.

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Combined effects of spinetoram and Microcystis aeruginosa on Daphnia pulex offspring: Maternal effects and multigenerational implications
Xuexia Zhu, Yihe Zhan, Xuanhe Jia, Meng Li, Tianchi Yin, Jun Wang
Chemosphere.2024; 352: 141376. CrossRef
Research on the Analysis of and Countermeasures for the Eutrophication of Water Bodies: Waihu Reservoir as a Case Study
Yiting Qi, Xin Cao, Ruisi Cao, Mingjie Cao, Ailan Yan, Erpeng Li, Dong Xu
Processes.2024; 12(4): 796. CrossRef
Water Quality Assessment and Genetic Insights into Cyanobacterial Toxin Presence in Gyeonggi Province Reservoirs
Soon-Mi Go, Yong-Jun Kim, Yeong-Yeon Kim, Kyeong-Hui Kang, Kyu-Seung Shim, Hee-Cheon Moon, Ju-Yong Jeong
Journal of Environmental Analysis, Health and Toxicology.2024; 27(3): 132. CrossRef
Nitrogen availability controls response of microcystin concentration to phosphorus reduction: Evidence from model application to multiple lakes
Charlotte Schampera, Ferdi L. Hellweger
Harmful Algae.2024; 139: 102711. CrossRef
Toxicity Reduction of Microcystis Aeruginosa Using Microbubble Ozonation
Gwiwoong Nam, Min-Seo Jeon, Yoon-E Choi, Jinho Jung
Ozone: Science & Engineering.2023; 45(2): 182. CrossRef
Chemodiversity of Cyanobacterial Toxins Driven by Future Scenarios of Climate Warming and Eutrophication
Yalan Yang, Huan Wang, Shuwen Yan, Tao Wang, Peiyu Zhang, Huan Zhang, Hongxia Wang, Lars-Anders Hansson, Jun Xu
Environmental Science & Technology.2023; 57(32): 11767. CrossRef
Autonomous calibration of EFDC for predicting chlorophyll-a using reinforcement learning and a real-time monitoring system
Seok Min Hong, Ather Abbas, Soobin Kim, Do Hyuck Kwon, Nakyung Yoon, Daeun Yun, Sanguk Lee, Yakov Pachepsky, JongCheol Pyo, Kyung Hwa Cho
Environmental Modelling & Software.2023; 168: 105805. CrossRef
Relationship between freshwater harmful algal blooms and neurodegenerative disease incidence rates in South Korea
Seungjun Lee, Boseung Choi, Sung Jae Kim, Jinnam Kim, Dayun Kang, Jiyoung Lee
Environmental Health.2022;[Epub] CrossRef
Environmental factors associated with cyanobacterial assemblages in a mesotrophic subtropical plateau lake: A focus on bloom toxicity
Lili Hu, Kun Shan, Licheng Huang, Yuanrui Li, Lei Zhao, Qichao Zhou, Lirong Song
Science of The Total Environment.2021; 777: 146052. CrossRef
High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys
Emma Johansson, Catherine Legrand, Caroline Björnerås, Anna Godhe, Hanna Mazur-Marzec, Torbjörn Säll, Karin Rengefors
Toxins.2019; 11(12): 698. CrossRef
Harmful algal blooms and liver diseases: focusing on the areas near the four major rivers in South Korea
Seungjun Lee, Jinnam Kim, Boseung Choi, Gijung Kim, Jiyoung Lee
Journal of Environmental Science and Health, Part C.2019; 37(4): 356. CrossRef
Development of Algal Bloom Removal System Using Unmanned Aerial Vehicle and Surface Vehicle
Sungwook Jung, Hoon Cho, Donghoon Kim, Kyukwang Kim, Jong-In Han, Hyun Myung
IEEE Access.2017; 5: 22166. CrossRef

Research Support, Non-U.S. Gov'ts

The effects of fluctuating culture temperature on stress tolerance and antioxidase expression in Esteya vermicola: Yun-bo Wang , Wen-xing Pang , Xiao-na Yv , Jing-jie Li , Yong-an Zhang , Chang-keun Sung; J. Microbiol. 2015;53(2):122-126. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4529-2

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Abstract

The endoparasitic nematophagous fungus, Esteya vermicola, has shown great potential as a biological control agent against the pine wood nematode, Bursaphelenchus xylophilus. Fluctuating culture temperatures can affect fungal yields and fungal tolerance to desiccation, UV radiation, H2O2, and heat stress, as well as antioxidase expression. To explore these effects, E. vermicola cultured under five temperature ranges, 26oC, 15-26oC, 26-35oC, 20-30oC, and 15-35oC, were compared. The cultures grown at lower temperatures showed better growth, stronger tolerance to desiccation, UV, and H2O2 stresses, and increased catalase expression, However, these cultures also showed weaker heat stress tolerance and lower superoxide dismutase expression than the higher-temperature cultures. In particular, the E. vermicola cultured at 20-30oC, i.e., fluctuating in a narrow range around the optimal temperature, showed the best performance. Therefore, for production in practical applications, this narrowly fluctuating, moderate temperature appears to be optimal for yield and stress tolerance in E. vermicola.

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Establishing Gene Expression and Knockout Methods in Esteya vermicola CBS115803
Zhijuan Hu, Chi Chen, Xinyao Zheng, Jingjie Yuan, Run Zou, Chengjian Xie
Molecular Biotechnology.2024; 66(10): 2872. CrossRef
Research Progress on Biocontrol of Pine Wilt Disease by Microorganisms
Guiming Dou, Dong-Hui Yan
Forests.2022; 13(7): 1047. CrossRef
Effect of culture conditions on conidia production and enhancement of environmental stress resistance of Esteya vermicola in solid‐state fermentation
Y. Zhu, Y. Mao, T. Ma, X. Wen
Journal of Applied Microbiology.2021; 131(1): 404. CrossRef
In vivo infection of Bursaphelenchus xylophilus by the fungus Esteya vermicola
Hai‐Hua Wang, Yun‐Bo Wang, Can Yin, Jie Gao, Ran Tao, Yu‐Lou Sun, Chun‐Yan Wang, Zhen Wang, Yong‐Xia Li, Chang‐Keun Sung
Pest Management Science.2020; 76(8): 2854. CrossRef
Research advance on Esteya vermicola, a high potential biocontrol agent of pine wilt disease
Wen Hui Chu, Qing Dou, Hong Long Chu, Hai Hua Wang, Chang Keun Sung, Chun Yan Wang
Mycological Progress.2015;[Epub] CrossRef

σB Affects Biofilm Formation under the Dual Stress Conditions Imposed by Adding Salt and Low Temperatur in Listeria monocytogenes: Jin-Ju Lee , Gilho Lee , Ji-Hyun Shin; J. Microbiol. 2014;52(10):849-855. Published online October 1, 2014; DOI: https://doi.org/10.1007/s12275-014-4369-5

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Abstract

The food-borne pathogenic bacteria Listeria monocytogenes can form biofilms on various surfaces including food-processing equipment. Biofilms offer survival benefits to the organisms entrapped against environmental insults. Moreover, the σB transcription factor of L. monocytogenes plays an important role in its survival under various stress conditions. In this study, we evaluated whether σB contributes to biofilm formation when L. monocytogenes is grown under various temperatures and media. When the wild-type strain was grown under static biofilm culture below ambient temperature (15°C) for 72 h, the difference in viable cell number (in both planktonic and biofilm cells) between the wild-type and ΔsigB mutant increased by adding NaCl to BHI broth (9% salt BHI > 6% salt BHI > BHI, w/v), and the specific activity of β-galactosidase was highly induced in the wild-type strain grown in 6% salt containing BHI broth. Furthermore, we measured surface-adhered biofilm forming ability using the crystal violet staining method. The wild-type strain formed a four times larger biofilm than that of the ΔsigB mutant in 6% salt-BHI medium at 15°C over a 72 h incubation and also showed the highest level of β-galactosidase specific activity. However, both the wild-type and ΔsigB mutant L. monocytogenes were defective for forming a biofilm in 9% salt-BHI medium at 15°C. Our results suggest that σB plays an enhanced role in surface-adhered biofilm formation when L. monocytogenes encounters dual stress conditions, such as 6% NaCl and low temperature.

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Characteristics of Clinical Isolates of Listeria monocytogenes in Sichuan, China, in 2022 Based on Whole Genome Sequencing Analysis
Qian Liang, Weifeng Huang, Tao Xiao, Lin Zhang, Gaopeng Lei, Hong Lv, Xiaorong Yang
Foodborne Pathogens and Disease.2024; 21(7): 424. CrossRef
The influence of stress factors on selected phenotypic and genotypic features of Listeria monocytogenes – a pilot study
Natalia Wiktorczyk-Kapischke, Ewa Wałecka-Zacharska, Jakub Korkus, Katarzyna Grudlewska-Buda, Anna Budzyńska, Kacper Wnuk, Eugenia Gospodarek-Komkowska, Krzysztof Skowron
BMC Microbiology.2023;[Epub] CrossRef
Marked inter-strain heterogeneity in the differential expression of some key stress response and virulence-related genes between planktonic and biofilm cells in Listeria monocytogenes
Christos Toliopoulos, Efstathios Giaouris
International Journal of Food Microbiology.2023; 390: 110136. CrossRef
Proteomic analysis reveals the temperature-dependent presence of extracytoplasmic peptidases in the biofilm exoproteome of Listeria monocytogenes EGD-e
Yue-Jia Lee, Chinling Wang
Journal of Microbiology.2020; 58(9): 761. CrossRef
Genomic Differences between Listeria monocytogenes EGDe Isolates Reveal Crucial Roles for SigB and Wall Rhamnosylation in Biofilm Formation
Chih-Yu Hsu, Lynne Cairns, Laura Hobley, James Abbott, Conor O’Byrne, Nicola R. Stanley-Wall, Tina M. Henkin
Journal of Bacteriology.2020;[Epub] CrossRef
Listeria monocytogenes Biofilm Adaptation to Different Temperatures Seen Through Shotgun Proteomics
Tiago Santos, Didier Viala, Christophe Chambon, Julia Esbelin, Michel Hébraud
Frontiers in Nutrition.2019;[Epub] CrossRef
Cross Talk between SigB and PrfA in Listeria monocytogenes Facilitates Transitions between Extra- and Intracellular Environments
Ahmed Gaballa, Veronica Guariglia-Oropeza, Martin Wiedmann, Kathryn J. Boor
Microbiology and Molecular Biology Reviews.2019;[Epub] CrossRef
Salt stress affects global protein expression profiles of extracellular membrane-derived vesicles of Listeria monocytogenes
Taewon Lee, So Hyun Jun, Chi Won Choi, Seung Il Kim, Je Chul Lee, Ji Hyun Shin
Microbial Pathogenesis.2018; 115: 272. CrossRef
Genomic and transcriptomic analyses reveal distinct biological functions for cold shock proteins (VpaCspA and VpaCspD) in Vibrio parahaemolyticus CHN25 during low-temperature survival
Chunhua Zhu, Boyi Sun, Taigang Liu, Huajun Zheng, Wenyi Gu, Wei He, Fengjiao Sun, Yaping Wang, Meicheng Yang, Weicheng Bei, Xu Peng, Qunxin She, Lu Xie, Lanming Chen
BMC Genomics.2017;[Epub] CrossRef
Regulation of Escherichia coli RNase III activity
Boram Lim, Minji Sim, Howoon Lee, Seogang Hyun, Younghoon Lee, Yoonsoo Hahn, Eunkyoung Shin, Kangseok Lee
Journal of Microbiology.2015; 53(8): 487. CrossRef

Cel8H, a Novel Endoglucanase from the Halophilic Bacterium Halomonas sp. S66-4: Molecular Cloning, Heterogonous Expression, and Biochemical Characterization: Xiaoluo Huang , Zongze Shao , Yuzhi Hong , Ling Lin , Chanjuan Li , Fei Huang , Hui Wang , Ziduo Liu; J. Microbiol. 2010;48(3):318-324. Published online June 23, 2010; DOI: https://doi.org/10.1007/s12275-009-0188-5

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Abstract: A recombinant Escherichia coli clone expressing an endoglucanase was identified from a genomic library of the halophilic bacterium Halomonas sp. S66-4, and the enzyme was designated Cel8H. The cel8H gene consisted of 1,053 bp and encoded 350 amino acids sharing the highest identity of 48% to other known endoglucanases. The protein was expressed in E. coli BL21 (DE3) and purified to homogeneity. The purified recombinant enzyme had an optimal activity of 4.9 U/mg at pH 5 and 45°C toward the substrate carboxymethylcellulose. It exhibited extraordinary properties which differed from endoglucanases reported previously at the point of high salt tolerance above 5 M, simultaneously with high pH stability at pH 4-12 and high temperature stability at 40-60°C. Various substrate tests indicated that the enzyme hydrolyzes β-1,4-glucosidic bonds specifically.

Journal Article

Gene Expression Profile of Helicobacter pylori in Response to Growth Temperature Variation: Yue-hua Han , Wen-zhong Liu , Yao-zhou Shi , Li-qiong Lu , Shu-dong Xiao , Qing-hua Zhang; J. Microbiol. 2009;47(4):455-465. Published online September 9, 2009; DOI: https://doi.org/10.1007/s12275-009-0003-3

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Abstract: A Helicobacter pylori whole-genome DNA microarray was constructed to study expression profiles of H. pylori in response to a sudden temperature transfer from 37°C to 20°C. The expression level of the genome at each of four time points (15, 30, 60, and 120 min) after temperature downshift was compared with that just before cold treatment. Globally, 10.2% (n=167) of the total predicted H. pylori genes (n=1636) represented on the microarray were significantly differentially expressed (p<0.05) over a 120 min period after shift to low temperature. The expression profiles of the differentially expressed genes were grouped, and their expression patterns were validated by quantitative real-time PCR. Up-regulated genes mainly included genes involved in energy metabolism and substance metabolism, cellular processes, protein fate, ribosomal protein genes, and hypothetical protein genes, which indicate the compensational responses of H. pylori to temperature downshift. Those genes play important roles in adaption to temperature downshift of H. pylori. Down-regulation of DNA metabolism genes and cell envelope genes and cellular processes genes may reflect damaged functions under low temperature, which is unfavorable to bacterial infection and propagation. Overall, this time-course study provides new insights into the primary response of H. pylori to a sudden temperature downshift, which allow the bacteria to survive and adapt to the new host environment.

Research Support, Non-U.S. Gov'ts

Impact of Some Environmental Factors on Growth and Production of Ochratoxin A of/by Aspergillus tubingensis, A. niger, and A. carbonarius Isolated from Moroccan Grapes: Atar Selouane , Driss Bouya , Ahmed Lebrihi , C. Decock , Amina Bouseta; J. Microbiol. 2009;47(4):411-419. Published online September 9, 2009; DOI: https://doi.org/10.1007/s12275-008-0236-6

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Abstract: The effects of temperature, water activity (aw), incubation time, and their combinations on radial growth and ochratoxin A (OTA) production of/by eight Aspergillus niger aggregate strains (six A. tubingensis and two A. niger) and four A. carbonarius isolated from Moroccan grapes were studied. Optimal conditions for the growth of most studied strains were shown to be at 25°C and 0.95 aw. No growth was observed at 10°C regardless of the water activity and isolates. The optimal temperature for OTA production was in the range of 25°C~30°C for A. carbonarius and 30°C~37°C for A. niger aggregate. The optimal aw for toxin production was 0.95~0.99 for A. carbonarius and 0.90~0.95 for A. niger aggregate. Mean OTA concentration produced by all the isolates of A. niger aggregate tested at all sampling times shows that maximum amount of OTA (0.24 µg/g) was produced at 37°C and 0.90 aw. However, for A. carbonarius, mean maximum amounts of OTA (0.22 µg/g) were observed at 25°C and 0.99 aw. Analysis of variance showed that the effects of all single factors (aw, isolate, temperature and incubation time) and their interactions on growth and OTA production were highly significant.

Analysis of Vaginal Lactic Acid Producing Bacteria in Healthy Women: Hyeran Nam , Kyunghee Whang , Yeonhee Lee; J. Microbiol. 2007;45(6):515-520.; DOI: https://doi.org/2642 [pii]

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Abstract: Vaginal lactic acid-producing bacteria of 80 pre-menopausal women were studied by isolation on Blood and DeMan-Rogosa-Sharpe agar, PCR with group-specific primers for Lactobacillus-denaturing gradient gel electrophoresis (DGGE), and PCR with specific primers for V3 region in 16S rRNA-temporal temperature gel electrophoresis (TTGE). Conventional isolation method on media detected only one lactobacillus (Lactobacillus brevis) while TTGE detected only Lactobacillus sp. DGGE detected seven Lactobacillus species; L. coleohominis, L. crispatus, L. iners, L. reuteri, L. rhamnosus, L. vaginalis, and Leuconostoc lactis. L. acidophilus and L. gasseri, which are prevalent in Western women, were not detected in Korean women. Furthermore, L. rhamnosus, Leuc. lactis, L. coleohominis, and Weissella cibaria, which were not previously reported in the vaginal microbiota of Korean women, were detected. The five most prevalent LABs in vaginal microbiota in Korean women were L. iners, Enterococcus faecalis, L. crispatus, Leuc. lactis, and W. cibaria.

Effect of Temperature on Persistence of Recombinant Plasmid pCU103 in Different Waters: Kwak, Myong Ja , Kim, Chi Kyung , Kim, Young Chang , Lim, Jae Yun , Kim, Young Soo , Lee, Ki Sung , Min, Kyung Hee; J. Microbiol. 1995;33(3):178-183.

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Abstract: The recombinant plasmid of pCU103 constructed by cloning pcbCD genes in pBluescript SK(+) was studied for the effect of temperature on its persistence in different waters by the methods of electrophoresis, Southern hybridization, quantification, and transformation. The plasmid was very rapidly degraded out in non-sterile FW water without regards to water temperature, probably due to the effect of biochemical factor such as nucleases. The pCU103 was most persistent at 4℃ in any water environments, moderately persistant at 15℃, but least stable at 30℃ such results could be explained by the facts that hydrogen bonds in double-stranded plasmid DNAs become unstable and that nucleases are activated by increasing temperature. The intact structure of pCU1-3 was generally observed by gel electrophoresis under the conditions which the plasmid should be 2.0 ng/㎕ or higher in concentration and that about 10² CFU/ml or more transformant cells should be recovered.

A conditional lethal mutation of a nucleoporin gene, NUP49 in saccharomyces cerevisiae: Lee, Youn Soo , Song, Young Ja , Hwang, Mi Kyung , Lee, Woo Bok , Kim, Jin Mi; J. Microbiol. 1997;35(3):234-238.

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Abstract: Conditional lethal mutation nup49-1 of a nuclear pore complex component gene was constructed in Saccharomyces cerevisiae. This mutation deleted one third of the essential NUP49 gene at the carboxy-terminal, but retained 13 repeats of the highly conserved GLFG domain. The nup49-1 mutant strain was viable with a slow-growth phenotype, indicating that the C-terminal is dispensable at normal growth temperature. This strain exhibited both temperature-sensitivity at 37℃ and cold-sensitivity at 16℃. Temperature shift experiments revealed that the arrest phenotype at 37℃ was random in the cell division cycle. The nup49-1 mutation was tested to be recessive and is expected to be useful for the functional analysis of nuclear pore complex proteins as well as for studies of nuclear transport systems.

Isolation and characterization of pre-tRNA^Val splicing Mutants of Schizosaccharomyces pombe: Hwang, Ku Chan , Kim, Dae Myung; J. Microbiol. 1997;35(4):334-340.

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Abstract: A collection of 132 temperature sensitive (ts) mutants was generated by the chemical mutagenesis of Schizosaccharomyces pombe wild type strain and screened for tRNA splicing defects on Northern blots by hybridization with an oligonucleotide that recognizes the exon of the S. pombe tRNA^Val as a probe. We identidied 6 mutants which accumulate precursor tRNA^Val. Among them, 2 mutants exhibited remarkable morphological differences compared to wild type cells. One tRNA splicing mutant showed elongated cell shape in permissive as well as non-permissive cultures. The other mutant exhibited shortened cell morphology only in nonpermissive culture. The total RNA pattern in the splicing mutants appeared to be normal. Genetic analysis of four tRNA^Val splicing mutants demonstrated that the mutation reside in different genes.

Factors affecting pheromone induction of schizosaccharomyces pomba and isolation of pheromone induction mutants: Jun, Jai Hyun , Kim, Young Min , Lee, Joo Hun , Chung, In Kwon , Kim, Dae Myung; J. Microbiol. 1998;36(3):196-202.

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Abstract: The mating pheromones of Schizosaccharomyces pombe are induced by nutritional starvation. However, this nutritional signaling pathway is largely unknown. For a complete understanding of pheromone induction, we examined the environmental factors affecting the induction afer cells were transferred to a nitrogen-starved medium. It appeared that the induction of mfm2 transcription was affected by the general environmental stress including incubation time, incubation temperature, and the growth phase of the cells. We identified 7 pheromone induction mutants by screening temperature sensitive mutant bank. Three of these mutants showed elongated cell shapes and one mutant exhibited swollen cell morphology in permissive culture, suggesting that their cell cycles were also impaired. Characterization of the pheromone induction mutants may elucidate the components required in nutritional signaling pathway leading to pheromone induction.

Genetic DNA Marker for A2 mating type in Phytophthora infestans: Kwon Jong Kim , Youn Su Lee; J. Microbiol. 2002;40(4):254-259.

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Abstract: The Phytophthora infestans requires two mating types for sexual reproduction. Amplified fragment length polymorphism (AFLP) was used to specifically detect different mating types of P. infestans . The AFLP primers E+AA (5'-GACTGCGTACCAATTCAA-3') and M+CAA (5'-GATGAGTCCTGAGTAACAA-3') detected a fragment that is specific in the A2 mating type of P. infestans . This fragment was cloned and sequenced. Based on the sequence data, PHYB-1 and PHYB-2 primer were designed to detect the A2 mating type of P. infestans. A single 347 bp segment was observed in the A2 mating type of P. infestans, but not in the A1 mating type of P. infestans or other Phytophthora spp. Identification of mating type was performed with phenotype (sexual reproduction) and genotype (CAPs marker) methods. Two factors, the annealing temperature and template DNA quantity, were investigated to determine the optimal conditions. Using mating type-specific primers, a unique band was obtained within annealing temperatures of 57 ℃-62℃ and DNA levels of 10pg-100 ng (data not shown).

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