Journal of Microbiology

Journal Articles

Occurrence of four waterborne viruses at five typical raw water resources in the Republic of Korea during August 2013 to February 2019: Young Yil Bahk , Min-Ho Kim , Tong-Soo Kim , Sang Jung Park , Jeong-Myeong Kim , Ok-Jae Rhee , Sang-Seob Lee; J. Microbiol. 2020;58(11):915-925. Published online October 30, 2020; DOI: https://doi.org/10.1007/s12275-020-0231-0

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Abstract: Waterborne diseases have critical public health issues and socioeconomic relevancy worldwide. Various viral pathogens are ordinarily associated with waterborne diseases. Six-yearsurveillance (a total of 20 times) of norovirus, hepatitis A virus, group C rotavirus, and enterovirus was conducted at five raw water sampling sites including two lakes (Lakes Soyang and Juam), Hyundo region of Geum River in Daejeon City, and Guui region of Han River in Seoul Metropolitan City and Moolgeum region of Nakdong River in Gimhae City which are located near two water intake plants. In this study, we routinely investigated virus contamination in water samples through reverse transcription polymerase chain reaction (RTPCR) and integrated cell culture RT-PCR with high sensitivity and specificity. A total 100 samples were tested. Most of the targeted viruses were found in 32% of the samples and at least one of the indicator bacteria was detected in 65% of these occurrences. Among all the detected viruses, enterovirus was the most prevalent with a detection frequency of 12% and 2.71 MPN/10 L on average, while hepatitis A virus was the least prevalent with a detection frequency of 4%. Nearly all of the analyzed viruses (except for group C rotavirus) were present in samples from Han River (the Guui region), Geum River (the Hyundo region), Lake Juam, and Nakdong River (the Moolgeum region), while group C rotavirus was detected in those from the Guui region. During the six-year sampling period, the targeted waterborne viruses in water samples exhibited seasonal patterns in their occurrence that were different from the indicator bacteria levels in the water samples. The fact that they were detected in the five representative Korean water environments makes it necessary to establish the chemical and biological analysis systems for waterborne viruses and sophisticated management systems.

Biosynthesis of adipic acid in metabolically engineered Saccharomyces cerevisiae: Xi Zhang , Yingli Liu , Jing Wang , Yunying Zhao , Yu Deng; J. Microbiol. 2020;58(12):1065-1075. Published online October 23, 2020; DOI: https://doi.org/10.1007/s12275-020-0261-7

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Abstract: Adipic Acid (AA) is a valued platform chemical compound, which can be used as a precursor of nylon-6,6. Due to the generation of an enormous amount of nitric oxide metabolites and the growing depletion of oil resources as a result of AA production from a mixture of cyclohexanol and cyclohexanone, the microbial methods for synthesizing AA have attracted significant attention. Of the several AA-producing pathways, the reverse adipate degradation pathway in Thermobifida fusca (Tfu RADP) is reported to be the most efficient, which has been confirmed in Escherichia coli. In this study, the heterologous Tfu RADP was constructed for producing AA in S. cerevisiae by co-expressing genes of Tfu_ 0875, Tfu_2399, Tfu_0067, Tfu_1647, Tfu_2576, and Tfu_ 2576. The AA titer combined with biomass, cofactors and other by-products was all determined after fermentation. During batch fermentation in a shake flask, the maximum AA titer was 3.83 mg/L, while the titer increased to 10.09 mg/L during fed-batch fermentation in a 5-L bioreactor after fermentation modification.

Chitosan-chelated zinc modulates cecal microbiota and attenuates inflammatory response in weaned rats challenged with Escherichia coli: Dan Feng , Minyang Zhang , Shiyi Tian , Jing Wang , Weiyun Zhu; J. Microbiol. 2020;58(9):780-792. Published online September 1, 2020; DOI: https://doi.org/10.1007/s12275-020-0056-x

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Abstract: Escherichia coli (E. coli) infection is very common among young growing animals, and zinc supplementation is often used to alleviate inflammation induced by this disease. Therefore, the objective of this study was to evaluate whether chitosan- chelated zinc (CS-Zn) supplementation could attenuate gut injury induced by E. coli challenge and to explore how CSZn modulates cecal microbiota and alleviates intestinal inflammation in weaned rats challenged with E. coli. 36 weaned rats (55.65 ± 2.18 g of BW, n = 12) were divided into three treatment groups consisting of unchallenged rats fed a basal diet (Control) and two groups of rats challenged with E. coli and fed a basal diet or a diet containing 640 mg/kg CS-Zn (E. coli + CS-Zn, containing 50 mg/kg Zn) for a 14-day experiment. On days 10 to 12, each rat was given 4 ml of E. coli solution with a total bacteria count of 1010 CFU by oral gavage daily or normal saline of equal dosage. CS-Zn supplementation mitigated intestinal morphology impairment (e.g. higher crypt depth and lower macroscopic damage index) induced by E. coli challenge (P < 0.05), and alleviated the increase of Myeloperoxidase (MPO) activity after E. coli challenge (P < 0.05). 16S rRNA sequencing analyses revealed that E. coli challenge significantly increased the abundance of Verrucomicrobia and E. coli (P < 0.05). However, CS-Zn supplementation increased the abundance of Lactobacillus and decreased the relative abundance of Proteobacteria, Desulfovibrio and E. coli (P < 0.05). The concentrations of butyrate in the cecal digesta, which decreased due to the challenge, were higher in the E. coli + CS-Zn group (P < 0.05). In addition, CS-Zn supplementation significantly prevented the elevation of pro-inflammatory cytokines IL-6 concentration and upregulated the level of anti-inflammatory cytokines IL-10 in cecal mucosa induced by E. coli infection (P < 0.05). In conclusion, these results indicate that CS-Zn produces beneficial effects in alleviating gut mucosal injury of E. coli challenged rats by enhancing the intestinal morphology and modulating cecal bacterial composition, as well as attenuating inflammatory response.

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

Effects of Crude Oil on Marine Microbial Communities in Short Term Outdoor Microcosms: Seung Won Jung , Joon Sang Park , Oh Youn Kown , Jung-Hoon Kang , Won Joon Shim , Young-Ok Kim; J. Microbiol. 2010;48(5):594-600. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0199-2

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Abstract: To assess the effects of crude oil spills on marine microbial communities, 10 L outdoor microcosms were manipulated over an exposure period of 8 days. The responses of microbial organisms exposed to five crude oil concentrations in 10 to 10,000 ppm (v/v) were monitored in the microcosms. The abundance of microalgae and copepods decreased rapidly upon the addition of crude oil at concentrations over 1,000 ppm, whereas the total density of heterotrophic bacteria increased dramatically at the higher concentrations. Bacterial diversity, determined by denaturing gradient gel electrophoresis, was increased at higher concentrations. In particular, the intensity of the bands representing Jannaschia sp. and Sulfitobacter brevis increased with the addition of oil. These results indicate that crude oil spills with concentrations over 1,000 ppm seriously affected the structure of the microbial communities.

Microbial Community Response to a Simulated Hydrocarbon Spill in Mangrove Sediments: Rodrigo Gouvêa Taketani , Natália Oliveira Franco , Alexandre Soares Rosado , Jan Dirk van Elsas; J. Microbiol. 2010;48(1):7-15. Published online March 11, 2010; DOI: https://doi.org/10.1007/s12275-009-0147-1

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Abstract: In this study, we examined the hypothesis that the microbial communities in mangrove sediments with different chemical and historical characteristics respond differently to the disturbance of a hydrocarbon spill. Two different mangrove sediments were sampled, one close to an oil refinery that had suffered a recent oil spill and another that had not been in contact with oil. Based on the sampled sediment, two sets of mesocosms were built, and oil was added to one of them. They were subjected to mimicked mangrove conditions and monitored for 75 days. Archaeal and bacterial communities were evaluated through PCRDGGE. Both communities showed the emergence of small numbers of novel bands in response to oil pollution. 16S rRNA gene clone libraries were constructed from both mesocosms before the addition of oil and at day 75 after oil addition. LIBSHUFF analysis showed that both mangrove-based mesocosms contained similar communities at the start of the experiment and that they were different from the initial one, as well as from each other, after 75 days. These results hint at a role of environmental history that is not obvious from community diversity indicators, but is apparent from the response to the applied stress.

Comparative Analysis of Cyanobacterial Communities from Polluted Reservoirs in Korea: Jin-Book Kim , Mi-Sook Moon , Dong-Hun Lee , Sung-Taik Lee , Marco Bazzicalupo , Chi-Kyung Kim; J. Microbiol. 2004;42(3):181-187.; DOI: https://doi.org/2092 [pii]

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Abstract: Cyanobacteria are the dominant phototrophic bacteria in water environments. Here, the diversity of cyanobacteria in seven Korean reservoir waters where different levels of algal blooms were observed during the summer of 2002, was examined by T-RFLP analysis. The number of T-RF bands in the HaeIII T-RFLP profiles analyzed from those water samples ranged from 20 to 44. Of these, cyanobacteria accounted for 6.1 to 27.2% of the total bacteria. The water samples could be clustered into 2 groups according to the Dice coefficient of the T-RF profiles. The eutrophic Dunpo and oligotrophic Chungju reservoirs were selected, and several representative clones from both reservoir waters analyzed for the nucleotide sequences of their 16S rDNA. The major clones were found to belong to the Microcystis and Anabaena species in the waters from the Dunpo and Chungju reservoirs, respectively, which was in agreement with the T-RFLP result. That is, the Microcystis and Anabaena species were dominant in the eutrophic and polluted Dunpo and oligotrophic Chungju reservoir waters, respectively. These results indicated that there is a correlation between prevalence of cyanobacterial species and levels of pollution in reservoir waters.

Bacterial Color Response to Hexavalent Chromium, Cr^6+: Ka Hong Cheung , Ji-Dong Gu; J. Microbiol. 2002;40(3):234-236.

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Abstract: A blue pigment-producing bacterium, Vogesella indigofera, was isolated and quantified for the relationship between its synthesis of a blue pigment and exposure concentrations of Cr^6+ . The concentration of Cr^6+ and the percentage of blue colonies on agar plates was negatively correlated (r^2 = -0.8683). Critical concentrations inhibiting bacterial pigment production were found to be between 100-150 ug Cr^6+ /ml on agar plates and 200-300 ug Cr^6+ /ml in liquid culture. As the blue color is characteristic and easily observable, the bacterium Vogesella indigofera may have potential applications in the detection and monitoring of environmental pollution.

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