Journal of Microbiology

Volume 56(9); September 2018

Review

[MINIREVIEW] New perspectives of Lactobacillus plantarum as a probiotic: The gut-heart-brain axis: Yen-Wenn Liu , Min-Tze Liong , Ying-Chieh Tsai; J. Microbiol. 2018;56(9):601-613. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8079-2

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Abstract: Lactobacillus plantarum is a non-gas-producing lactic acid bacterium that is generally regarded as safe (GRAS) with Qualified Presumption of Safety (QPS) status. Although traditionally used for dairy, meat and vegetable fermentation, L. plantarum is gaining increasing significance as a probiotic. With the newly acclaimed gut-heart-brain axis, strains of L. plantarum have proven to be a valuable species for the development of probiotics, with various beneficial effects on gut health, metabolic disorders and brain health. In this review, the classification and taxonomy, and the relation of these with safety aspects are introduced. Characteristics of L. plantarum to fulfill the criteria as a probiotic are discussed. Emphasis are also given to the beneficial functions of L. plantarum in gut disorders such as inflammatory bowel diseases, metabolic syndromes, dyslipidemia, hypercholesteromia, obesity, and diabetes, and brain health aspects involving psychological disorders.

Journal Articles

Aestuariibaculum marinum sp. nov., a marine bacterium isolated from seawater in South Korea: Jiwon Choi , Dongwook Lee , Jun Hyeong Jang , Seho Cha , Taegun Seo; J. Microbiol. 2018;56(9):614-618. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8134-z

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Abstract: A Gram-negative, non-motile, aerobic bacterium, designated strain IP7T, was isolated from seawater at the shore of the Incheon Eulwang-ri beach, South Korea. Cells of strain IP7T are straight or slightly rod-shaped and colonies are round, convex and orange-yellow. Strain IP7T is flexirubin-negative, mild halophile, catalase- and oxidase-positive, and produces a yellow-orange carotenoid pigment. Growth is optimal at 30°C, pH 7–9, and 2.0–4.0% NaCl (w/v). On the basis of 16S rRNA gene sequence similarity, strain IP7T is affiliated with genus Aestuariibaculum in the family Flavobacteriaceae, the closest relative being Aestuariibaculum suncheonense SC17T (98.3% sequence similarity). The DNA G + C content of the novel strain is 37.4 mol%. The only quinone is MK-6 menaquinone. Iso-branched C15:0, iso-branched C15:1 G, and iso-branched C17:0 3-OH are major fatty acids. The major polar lipids are phosphatidylethanolamine, an unidentified aminoglycolipid and two unidentified glycolipids. The DNA-DNA hybridization value of strain IP7T with Aestuariibaculum suncheonense SC17T is 28.87%. Based on the collective DNA-DNA hybridization, biochemical, phylogenetic and physiological data, we report a novel species of the genus Aestuariibaculum for which the name Aestuariibaculum marinum sp. nov. is proposed. The type strain is IP7T (= KCTC 52521T = JCM 31725T).

Bacteroides sedimenti sp. nov., isolated from a chloroethenesdechlorinating consortium enriched from river sediment: Mohamed Ismaeil , Naoko Yoshida , Arata Katayama; J. Microbiol. 2018;56(9):619-627. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8187-z

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23 Citations

Abstract: A Gram-negative, anaerobic, non-motile, non-spore-forming bacterial strain, designated YN3PY1T, was isolated from a chloroethene-dechlorinating consortium originally enriched from river sediment. The strain enhanced the dechlorination of cis-dichloroethene to ethene by Dehalococcoides, especially at the early stages of cultivation. Strain YN3PY1T was the first isolate of the genus Bacteroides, obtained from animal- independent environments, and its 16S rRNA gene had the highest sequence similarity (97.1%) with Bacteroides luti JCM 19020T in the ‘Coprosuis’ clade of the genus Bacteroides. Strain YN3PY1T formed a phylogenetic cluster with other phylotypes detected from sediments and paddy soil, and the cluster was affiliated with a linage of so-called free-living Bacteroides detected from animal-independent environments, suggesting specific adaptations to sediment-like environments. The strain showed typical phenotypes of Bacteroides, i.e., polysaccharolytic anaerobe having anteiso-C15:0 as the most abundant fatty acid and MK-11 as one of the major respiratory quinones. Additionally, the strain uniquely transforms glucose to lactate and malate, has MK-12 as another major respiratory quinone, and grows at comparatively low temperatures, i.e. 10–40°C, with an optimum at 28°C. Based on the presented data, strain YN3PY1T (= KCTC 15656T = NBRC 113168T) can be proposed as a novel species of the genus Bacteroides and named as Bacteroides sedimenti sp. nov.

Fluorescence change of Fusobacterium nucleatum due to Porphyromonas gingivalis: Min-Ah Lee , Si-Mook Kang , Se-Yeon Kim , Ji-Soo Kim , Jin-Bom Kim , Seung-Hwa Jeong; J. Microbiol. 2018;56(9):628-633. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-7515-7

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Abstract: The aim of this study was to measure changes in the fluorescence of Fusobacterium nucleatum interacting with Porphyromonas gingivalis for excitation with blue light at 405-nm. P. gingivalis was mono- and co-cultivated in close proximity with F. nucleatum. The fluorescence of the bacterial colonies was photographed using a QLF-D (Quantitative Light-induced Fluorescence-Digital) Biluminator camera system with a 405 nm light source and a specific filter. The red, green and blue intensities of fluorescence images were analyzed using the image analysis software. A fluorescence spectrometer was used to detect porphyrin synthesized by each bacterium. F. nucleatum, which emitted green fluorescence in single cultures, showed intense red fluorescence when it was grown in close proximity with P. gingivalis. F. nucleatum co-cultivated with P. gingivalis showed the same pattern of fluorescence peaks as for protoporphyrin IX in the red part of the spectrum. We conclude that the green fluorescence of F. nucleatum can change to red fluorescence in the presence of adjacent co-cultured with P. gingivalis, indicating that the fluorescence character of each bacterium might depend on the presence of other bacteria.

Variation of cassiicolin genes among Chinese isolates of Corynespora cassiicola: Jun Wu , Xuewen Xie , Yanxia Shi , Ali Chai , Qi Wang , Baoju Li; J. Microbiol. 2018;56(9):634-647. Published online July 27, 2018; DOI: https://doi.org/10.1007/s12275-018-7497-5

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15 Citations

Abstract: Corynespora cassiicola is a species of fungus that is a plant pathogen of many agricultural crop plants, including severe target spot disease on cucumber. Cassiicolin is an important effector of pathogenicity of this fungus. In this study, we collected 141 Corynespora isolates from eighteen hosts, and the casscolin gene was detected in 82 C. cassiicola strains. The deduced protein sequences revealed that 72 isolates contained the Cas2 gene, two strains from Gynura bicolor harboured the Cas2.2 gene, and 59 isolates without a cassiicolin gene were classified as Cas0. Phylogenetic analyses was performed for the 141 isolates using four loci (ITS, ga4, caa5, and act1) and revealed two genetic clusters. Cluster A is composed of four subclades: subcluster A1 includes all Cas2 isolates plus 18 Cas0 strains, subcluster A2 includes the eight Cas5 isolates and one Cas0 isolate, and subclusters A3 and A4 contain Cas0 strains. Cluster B consists of 21 Cas0 isolates. Twenty-two C. cassiicola strains from different toxin classes showed varying degrees of virulence against cucumber. Cas0 or Cas2 strains induced diverse responses on cucumber, from no symptoms to symptoms of moderate or severe infection, but all Cas5 isolates exhibited avirulence on cucumber.

SucA-dependent uptake of sucrose across the outer membrane of Caulobacter crescentus: Samantha K. Modrak , Martha E. Melin , Lisa M. Bowers; J. Microbiol. 2018;56(9):648-655. Published online July 27, 2018; DOI: https://doi.org/10.1007/s12275-018-8225-x

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Abstract: Caulobacter crescentus is an aquatic Gram-negative bacterium that lives in nutrient-poor environments. Like several other aquatic and phytopathogenic bacteria, Caulobacter cells have a relatively large number of genes predicted to encode TonB-dependent receptors (TBDRs). TBDRs transport nutrients across the outer membrane using energy from the proton motive force. We identified one TBDR gene, sucA, which is situated within a cluster of genes predicted to encode a lacIfamily transcription factor (sucR), amylosucrase (sucB), fructokinase (sucC), and an inner membrane transporter (sucD). Given its genomic neighborhood, we proposed that sucA encodes a transporter for sucrose. Using RT-qPCR, we determined that expression of sucABCD is strongly induced by sucrose in the media and repressed by the transcription factor, SucR. Furthermore, cells with a deletion of sucA have a reduced uptake of sucrose. Although cells with a non-polar deletion of sucA can grow with sucrose as the sole carbon source, cells with a polar deletion that eliminates expression of sucABCD cannot grow with sucrose as the sole carbon source. These results show that the suc locus is essential for sucrose utilization while SucA functions as one method of sucrose uptake in Caulobacter crescentus. This work sheds light on a new carbohydrate utilization locus in Caulobacter crescentus.

Overexpression and characterization of a novel cold-adapted and salt-tolerant GH1 β-glucosidase from the marine bacterium Alteromonas sp. L82: Jingjing Sun , Wei Wang , Congyu Yao , Fangqun Dai , Xiangjie Zhu , Junzhong Liu , Jianhua Hao; J. Microbiol. 2018;56(9):656-664. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8018-2

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Abstract: A novel gene (bgl) encoding a cold-adapted β-glucosidase was cloned from the marine bacterium Alteromonas sp. L82. Based on sequence analysis and its putative catalytic conserved region, Bgl belonged to the glycoside hydrolase family 1. Bgl was overexpressed in E. coli and purified by Ni2+ affinity chromatography. The purified recombinant β- glucosidase showed maximum activity at temperatures between 25°C to 45°C and over the pH range 6 to 8. The enzyme lost activity quickly after incubation at 40°C. Therefore, recombinant β-glucosidase appears to be a cold-adapted enzyme. The addition of reducing agent doubled its activity and 2 M NaCl did not influence its activity. Recombinant β-glucosidase was also tolerant of 700 mM glucose and some organic solvents. Bgl had a Km of 0.55 mM, a Vmax of 83.6 U/mg, a kcat of 74.3 s-1 and kcat/Km of 135.1 at 40°C, pH 7 with 4-nitrophenyl-β-D-glucopyranoside as a substrate. These properties indicate Bgl may be an interesting candidate for biotechnological and industrial applications.

Comparison of virulence between matt and mucoid colonies of Klebsiella pneumoniae coproducing NDM-1 and OXA-232 isolated from a single patient: Haejeong Lee , Jin Yang Baek , So Yeon Kim , HyunJi Jo , KyeongJin Kang , Jae-Hoon Ko , Sun Young Cho , Doo Ryeon Chung , Kyong Ran Peck , Jae-Hoon Song , Kwan Soo Ko; J. Microbiol. 2018;56(9):665-672. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8130-3

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21 Citations

Abstract: Nine Klebsiella pneumoniae isolates coproducing NDM-1 and OXA-232 carbapenemases were successively isolated from a single patient. Although they were isolated simultaneously and were isogenic, they presented different colony phenotypes (matt and mucoid). All nine isolates were resistant to most antibiotics except colistin and fosfomycin. In addition, matt-type isolates were resistant to tigecycline. No differences were detected in the cps cluster sequences, except for the insertion of IS5 in the wzb gene of two matt-type isolates. In vitro virulence assays based on production of capsular polysaccharide, biofilm formation, and resistance to human serum indicated that the mucoid-type isolates were significantly more virulent than the matt-type. In addition, mucoid-type isolates showed higher survival rates than the matt-type ones in infection experiments in the fruit fly, suggesting a higher virulence of K. pneumoniae isolates with a mucoid phenotype. To our knowledge, this is the first report of K. pneumoniae colonies with different phenotypes being isolated from the same sample. In addition, we show that virulence varies with colony phenotype. Dissemination of K. pneumoniae isolates expressing both antibiotic resistance and high virulence would constitute a great threat.

Diet-induced obese mice exhibit altered immune responses to early Salmonella Typhimurium oral infection: Ricardo Ernesto Ramírez-Orozco , Elena Franco Robles , Victoriano Pérez Vázquez , Joel Ramírez Emiliano , Marco Antonio Hernández Luna , Sergio López Briones; J. Microbiol. 2018;56(9):673-682. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8083-6

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9 Citations

Abstract: Obesity is a chronic disease associated with different metabolic diseases as well as alterations in immune cell function. It is characterized by a chronic systemic low grade inflammation. There are several studies demonstrating the influence of obesity on the impaired immune response to infection. However, it is not completely clear whether the obese environment influences the development or maintenance of the immune response against infections. The aim of this study was to determine how obesity induced by a high-fat diet affects the immune response to an early oral Salmonella infection. Four groups of mice were kept in separate cages. Two of these designated as controls, fed with a normal diet; whereas other two groups were fed with a high fat diet for 10 weeks. Some mice were used for Salmonella oral infection. After 7 days of oral infection with S. Thypimurium the proportions of spleen cell subsets expressing activation markers in normal diet and HFD obese mice were stained with monoclonal antibodies and analyzed by flow cytometry. Also, mRNA levels of different cytokines were quantified by RT-PCR. It was found that obesity affects the function of the immune system against an early oral Salmonella infection, decreasing NK cells, altering the expression of activation molecules as well as cytokines mRNA levels. Interestingly, the expression some activation molecules on T lymphocytes was reestablished after Salmonella infection, but not the CD25 expression. Immune alterations could lead to immunosuppression or increased susceptibility to infections in HFD obese mice.

Antiviral activity of Schizonepeta tenuifolia Briquet against noroviruses via induction of antiviral interferons: Yee Ching Ng , Ye Won Kim , Jeong-Su Lee , Sung Joon Lee , Moon Jung Song; J. Microbiol. 2018;56(9):683-689. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8228-7

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Abstract: Human noroviruses are the causative agents of non-bacterial gastroenteritis worldwide. The rapid onset and resolution of disease symptoms suggest that innate immune responses are critical for controlling norovirus infection; however, no effective antivirals are yet available. The present study was conducted to examine the antiviral activities of Schizonepeta tenuifolia Briquet extract (STE) against noroviruses. Treatment of human norovirus replicon-bearing HG23 cells with STE at 5 and 10 mg/ml concentrations resulted in the reduction in the viral RNA levels by 77.2% and 85.9%, respectively. STE had no cytotoxic effects on HG23 cells. Treatment of RAW 264.7 cells infected with murine norovirus 1 (MNV-1), a surrogate virus of human noroviruses, with STE at 10 and 20 μg/ml concentrations resulted in the reduction of viral replication by 58.5% and 84.9%, respectively. STE treatment induced the expression of mRNAs for type I and type II interferons in HG23 cells and upregulated the transcription of interferon-β in infected RAW 264.7 cells via increased phosphorylation of interferon regulatory factor 3, a critical transcription regulator for type I interferon production. These
results
suggest that STE inhibits norovirus replication through the induction of antiviral interferon production during virus replication and may serve as a candidate antiviral substance for treatment against noroviruses.

Retraction of Publication

[Retraction Note] Interferon-mediated antiviral activities of Angelica tenuissima Nakai and its active components: Prasanna Weeratunga , Md Bashir Uddin , Myun Soo Kim , Byeong-Hoon Lee , Tae-Hwan Kim , Ji-Eun Yoon , Jin Yeul Ma , Hongik Kim , Jong-Soo Lee; J. Microbiol. 2018;56(9):690-690.; DOI: https://doi.org/10.1007/s12275-018-0579-6

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Abstract: The above article by Weeratunga et al. has been retracted from Journal of Microbiology at the request of the corresponding author. The authors found that they were unable to reproduce Figure 1, Figure 3(A), Figure 4(A) and Figure 7(D) presented in this paper. All of the authors agreed to this retraction. The authors regret any inconvenience that this may cause and apologize sincerely to the readers, reviewers, and editors of Journal of Microbiology.

Published Erratum

Erratum] Variation of cassiicolin genes among Chinese isolates of Corynespora cassiicola: Jun Wu , Xuewen Xie , Yanxia Shi , Ali Chai , Qi Wang , Baoju Li; J. Microbiol. 2018;56(9):691-691.; DOI: https://doi.org/10.1007/s12275-018-8580-7

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Abstract: In the online published article by Wu et al. since 30 July 2018, the figure 4 is unfortunately incorrect. The figure 4 should be corrected as below.

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