Journal of Microbiology

Volume 54(7); July 2016

Review

MINIREVIEW] Clinical relevance of infections with zoonotic and human oral species of Campylobacter: Soomin Lee , Jeeyeon Lee , Jimyeong Ha , Yukyung Choi , Sejeong Kim , Heeyoung Lee , Yohan Yoon , Kyoung-Hee Choi; J. Microbiol. 2016;54(7):459-467. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6254-x

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35 Citations

Abstract: Genus Campylobacter has been recognized as a causative bacterial agent of animal and human diseases. Human Campylobacter infections have caused more concern. Campylobacters can be classified into two groups in terms of their original host: zoonotic and human oral species. The major zoonotic species are Campylobacter jejuni and Campylobacter coli, which mostly reside in the intestines of avian species and are transmitted to humans via consumption of contaminated poultry products, thus causing human gastroenteritis and other diseases as sequelae. The other campylobacters, human oral species, include C. concisus, C. showae, C. gracilis, C. ureolyticus, C. curvus, and C. rectus. These species are isolated from the oral cavity, natural colonization site, but have potential clinical relevance in the periodontal region to varying extent. Two species, C. jejuni and C. coli, are believed to be mainly associated with intestinal diseases, but recent studies suggested that oral Campylobacter species also play a significant role in intestinal diseases. This review offers an outline of the two Campylobacter groups (zoonotic and human oral), their virulence traits, and the associated illnesses including gastroenteritis.

Journal Articles

Dominant genera of cyanobacteria in Lake Taihu and their relationships with environmental factors: Lijun Feng , Shiyou Liu , Wenxian Wu , Jiawen Ma , Pei Li , Hailing Xu , Na Li , Yaoyu Feng; J. Microbiol. 2016;54(7):468-476. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6037-4

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18 Citations

Abstract: Cyanobacterial blooms in freshwaters have become one of the most widespread of environmental problems and threaten water resources worldwide. Previous studies on cyanobacteria in Lake Taihu often collected samples from one site (like Meiliang Bay or Zhushan Bay) and focused on the variation in patterns or abundance of Microcystis during the blooming season. However, the distribution of cyanobacteria in Lake Taihu shows differing pattern in various seasons. In this study, water samples were collected monthly for one year at five sites in Lake Taihu with different trophic status and a physicochemical analysis and denaturing gradient gel electrophoresis (DGGE) were conducted. DGGE fingerprint analysis showed that Microcystis (7/35 bands) and Synechococcus (12/35 bands) were the two most dominant genera present during the study period at all five sites. Cyanobium (3/35 bands) was the third most common genus which has seldom been previously reported in Lake Taihu. Redundancy analysis (RDA) indicated that the cyanobacterial community structure was significantly correlated with NO3 --N, CODMn, and NH4 +-N in the winter and spring, whereas it was correlated with water temperature in the summer and autumn. Limiting the nutrient input (especially of N and C loading) in Lake Taihu would be a key factor in controlling the growth of different genera of cyanobacteria.

Gamete-associated flavobacteria of the oviparous Chinook salmon (Oncorhynchus tshawytscha) in lakes Michigan and Huron, North America: Thomas P. Loch , Mohamed Faisal; J. Microbiol. 2016;54(7):477-486. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-5629-3

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Abstract: Flavobacterial diseases, caused by multiple members of the Family Flavobacteriaceae, elicit serious losses in wild and farmed fish around the world. Flavobacteria are known to be transmitted horizontally; however, vertical transmission has been suspected but proven only for one fish-pathogenic flavobacterial species (e.g., Flavobacterium psychrophilum). Herein, we report on the isolation and molecular identification of multiple Flavobacterium and Chryseobacterium taxa from the ovarian fluid and eggs of feral Great Lakes Chinook salmon (Oncorhynchus tshawytscha). Identified egg- and ovarian fluid-associated flavobacteria were either well-known flavobacterial fish pathogens (e.g., F. psychrophilum and F. columnare), most similar to emerging fish-associated flavobacteria (e.g., F. spartansii, F. tructae, F. piscis, C. piscium, C. scophthalmum), or were distinct from all other described Chryseobacterium and Flavobacterium spp., as determined by phylogenetic analyses using neighbor-joining, Bayesian, and Maximum Likelihood methodologies. The gamete-associated flavobacteria fell into three groups (e.g., those that were recovered from the ovarian fluid but not eggs; those that were recovered from the ovarian fluid and eggs; and those that were recovered from eggs but not ovarian fluid), a portion of which were recovered from eggs that were surface disinfected with iodophor at the commonly used dose and duration for egg disinfection. Some gamete-associated flavobacteria were also found in renal, splenic, and neurological tissues. Systemic polymicrobial infections comprised of F. psychrophilum and F. columnare were also detected at nearly an 11% prevalence. This study highlights the potential role that sexual products of female Great Lakes Chinook salmon may play in the transmission of fish-associated flavobacteria.

Requirement of the isocitrate lyase gene ICL1 for VPS41-mediated starvation response in Cryptococcus neoformans: Zhe Xu , Yafei Zhi , Jianzhang Dong , Benfeng Lin , Di Ye , Xiaoguang Liu; J. Microbiol. 2016;54(7):487-491. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6177-6

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Abstract: Cryptococcus neoformans is a major cause of fungal meningitis in individuals with impaired immunity. Our previous studies have shown that the VPS41 gene plays a critical role in the survival of Cryptococcus neoformans under nitrogen starvation; however, the molecular mechanisms underlying VPS41-mediated starvation response remain to be elucidated. In the present study, we show that, under nitrogen starvation, VPS41 strongly enhanced ICL1 expression in C. neoformans and that overexpression of ICL1 in the vps41 mutant dramatically suppressed its defects in starvation response due to the loss of VPS41 function. Moreover, targeted deletion of ICL1 resulted in a dramatic decline in viability of C. neoformans cells under nitrogen deprivation. Taken together, our data suggest a model in which VPS41 up-regulates ICL1 expression, directly or indirectly, to promote survival of C. neoformans under nitrogen starvation.

Autoinducer-2 detection among commensal oral streptococci is dependent on pH and boric acid: Giancarlo A. Cuadra , Ashley J. Frantellizzi , Kimberly M. Gaesser , Steven P. Tammariello , Anika Ahmed; J. Microbiol. 2016;54(7):492-502. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-5507-z

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Abstract: Autoinducer-2, considered a universal signaling molecule, is produced by many species of bacteria; including oral strains. Structurally, autoinducer-2 can exist bound to boron (borated autoinducer-2). Functionally, autoinducer-2 has been linked to important bacterial processes such as virulence and biofilm formation. In order to test production of autoinducer-2 by a given bacterial strain, a bioassay using marine bioluminescent bacteria Vibrio harveyi as a reporter for autoinducer-2 has been designed. We hypothesize that pH adjustment and addition of boron are required for optimal bioluminescence and accurate autoinducer-2 detection. Using this reporter strain we tested autoinducer-2 activity from two oral commensal species, Streptococcus gordonii DL1 and Streptococcus oralis 34. Spent broth was collected and adjusted to pH 7.5 and supplemented with boric acid prior to measuring autoinducer- 2 activity. Results show that low pH inhibits bioluminescence of the reporter strain, but pH 7.5 allows for bioluminescence induction and proper readings of autoinducer-2 activity. Addition of boric acid also has a positive effect on bioluminescence allowing for a more sensitive detection of autoinducer-2 activity. Our data suggests that although autoinducer- 2 is present in spent broth, low pH and/or low levels of boric acid become an obstacle for proper autoinducer-2 detection. For proper autoinducer-2 detection, we propose a protocol using this bioassay to include pH adjustment and boric acid addition to spent broth. Studies on autoinducer-2 activity in several bacteria species represent an important area of study as this universal signaling molecule is involved in critical bacterial phenotypes such as virulence and biofilm formation.

Lactobacillus curvatus WiKim38 isolated from kimchi induces IL-10 production in dendritic cells and alleviates DSS-induced colitis in mice: Sung-Gang Jo , Eui-Jeong Noh , Jun-Young Lee , Green Kim , Joo-Hee Choi , Mo-Eun Lee , Jung-Hee Song , Ji-Yoon Chang , Jong-Hwan Park; J. Microbiol. 2016;54(7):503-509. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6160-2

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58 Citations

Abstract: Probiotics such as lactobacilli and bifidobacteria have healthpromoting effects by immune modulation. In the present study, we examined the immunomodulatory properties of Lactobacillus curvatus WiKim38, which was newly isolated from baechu (Chinese cabbage) kimchi. The ability of L. curvatus WiKim38 to induce cytokine production in bone marrow-derived dendritic cells (BMDCs) was determined by enzyme-linked immunosorbent assay. To evaluate the molecular mechanisms underlying L. curvatus Wikim38-mediated IL-10 production, Western blot analyses and inhibitor assays were performed. Moreover, the in vivo anti-inflammatory effects of L. curvatus WiKim38 were examined in a dextran sodium sulfate (DSS)-induced colitis mouse model. L. curvatus WiKim38 induced significantly higher levels of IL- 10 in BMDCs compared with that induced by LPS. NF-κB and ERK were activated by L. curvatus WiKim38, and an inhibitor assay revealed that these pathways were required for L. curvatus WiKim38-induced production of IL-10 in BMDCs. An in vivo experiment showed that oral administration of L. curvatus WiKim38 increased the survival rate of mice with DSS-induced colitis and improved clinical signs and histopathological severity in colon tissues. Taken together, these results indicate that L. curvatus Wikim38 may have health-promoting effects via immune modulation, and may thus be applicable for therapy of various inflammatory diseases.

Carbohydrate-binding specificities of potential probiotic Lactobacillus strains in porcine jejunal (IPEC-J2) cells and porcine mucin: Valerie Diane Valeriano , Bernadette B. Bagon , Marilen P. Balolong , Dae-Kyung Kang; J. Microbiol. 2016;54(7):510-519. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6168-7

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Abstract: Bacterial lectins are carbohydrate-binding adhesins that recognize glycoreceptors in the gut mucus and epithelium of hosts. In this study, the contribution of lectin-like activities to adhesion of Lactobacillus mucosae LM1 and Lactobacillus johnsonii PF01, which were isolated from swine intestine, were compared to those of the commercial probiotic Lactobacillus rhamnosus GG. Both LM1 and PF01 strains have been reported to have good adhesion ability to crude intestinal mucus of pigs. To confirm this, we quantified their adhesion to porcine gastric mucin and intestinal porcine enterocytes isolated from the jejunum of piglets (IPEC-J2). In addition, we examined their carbohydrate-binding specificities by suspending bacterial cells in carbohydrate solutions prior to adhesion assays. We found that the selected carbohydrates affected the adherences of LM1 to IPEC-J2 cells and of LGG to mucin. In addition, compared to adhesion to IPEC-J2 cells, adhesion to mucin by both LM1 and LGG was characterized by enhanced specific recognition of glycoreceptor components such as galactose, mannose, and N-acetylglucosamine. Hydrophobic interactions might make a greater contribution to adhesion of PF01. A similar adhesin profile between a probiotic and a pathogen, suggest a correlation between shared pathogen–probiotic glycoreceptor recognition and the ability to exclude enteropathogens such as Escherichia coli K88 and Salmonella Typhimurium KCCM 40253. These findings extend our understanding of the mechanisms of the intestinal adhesion and pathogen-inhibition abilities of probiotic Lactobacillus strains.

Hepatitis C virus infection stimulates transforming growth factor-β1 expression through up-regulating miR-192: Ji Hyun Kim , Chang Ho Lee , Seong-Wook Lee; J. Microbiol. 2016;54(7):520-526. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6240-3

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Abstract: The objective of this study was to determine the molecular mechanisms underlying chronic liver injury and fibrosis caused by hepatitis C virus (HCV). This study revealed that miR-192 expression was induced by HCV infection without affecting viral replication. However, viral-induced miR-192 up-regulated transforming growth factor-β1 (TGF-β1) expression in liver cells at transcriptional level. TGF-β1 stimulation by HCV-induced miR-192 was caused through ZEB1 down-regulation and TGF-β1 increased miR-192 level via positive feedback pathway. Increase in miR-192 expression by HCV infection was due to HCV core protein released and/or expressed by viral infection. TGF-β1 promoter activity was also increased by HCV core protein in liver cells. Taken together, HCV infection resulted in increased TGF-β1 transcription in hepatocytes through ZEB1 down-regulation by HCV core-mediated miR-192 stimulation. Importantly, miR-192 inhibition with anti-miR-192 rescued ZEB1 expression down-regulated by HCV infection, thus reducing the level of TGF-β1 expression increased by HCV infection in hepatocytes. These results suggest a novel mechanism of HCV-mediated liver fibrogenesis with miR-192 being a potential molecular target to ameliorate viral pathogenesis.

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