Journal of Microbiology

Volume 55(9); September 2017

Journal Articles

Spirosoma metallicus sp. nov., isolated from an automobile air conditioning system: Hyosun Lee , Dong-Uk Kim , Suyeon Lee , Sooyeon Park , Jung-Hoon Yoon , So Yoon Park , Jong-Ok Ka; J. Microbiol. 2017;55(9):673-677. Published online August 5, 2017; DOI: https://doi.org/10.1007/s12275-017-7162-4

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Abstract: A Gram-stain-negative and orangish yellow-pigmented bacterial strain, designated PR1014KT, was isolated from an automobile evaporator core collected in Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PR1014KT was related with the members of the genus Spirosoma (94.7–90.2%) and closely related with Spirosoma lacussanchae CPCC 100624T (94.7%), Spirosoma knui 15J8- 12T (94.3%), and Spirosoma soli MIMBbqt12T (93.3%). The strain grew at 15–40°C (optimum, 25°C), pH 6.5–7.0 (optimum, 6.5) and 0–1% (w/v) NaCl (optimum, 0%). The predominant fatty acids were summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0, iso-C15:0, C16:1 ω5c, and iso-C17:0 3-OH. The major menaquinone was MK-7. The polar lipid profile of the strain indicated that the presence of one phosphatidylethanolamine, one unidentified aminolipid, two unidentified aminophospholipids, and three unidentified lipids. The DNA G+C content of the strain was 47.4 mol%. On the basis of the phenotypic, genotypic and chemotaxonomic characteristics, strain PR1014KT represents a novel species in the genus Spirosoma, for which the name Spirosoma metallicus sp. nov. (=KACC 17940T =NBRC 110792T) is proposed.

Spirosoma daeguensis sp. nov., isolated from beach soil: Nabil Elderiny , Leonid N. Ten , Jae-Jin Lee , Seung-Yeol Lee , Sangkyu Park , Young-Je Cho , Myung Kyum Kim , Hee-Young Jung; J. Microbiol. 2017;55(9):678-683. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-7211-z

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Abstract: A Gram-stain-negative, non-motile, non-spore-forming, rodshaped, aerobic bacterium, designated 15J9-6T, was isolated from beach soil on Jeju Island, South Korea. Strain 15J9-6T, grew at 10–30°C (optimum growth at 25°C) and pH 7–8 (optimum growth at pH 7) on R2A, NA, and TSA agar. Phylogenetically, the strain was closely related to members of the genus Spirosoma (92.3–90.1% 16S rRNA gene sequence similarities) and showed highest sequence similarity to Spirosoma panaciterrae DSM 21099T (92.3%). The G+C content of the genomic DNA of strain 15J9-6T was 45.7 mol%. The strain contained phosphatidylethanolamine, two unidentified aminophospholipids, an unidentified phospholipid, and an unidentified lipid as the major polar lipids; menaquinone MK-7 as the predominant respiratory quinone and summed feature 3 (C16:1 ω6c/C16:1 ω7c; 30.1%), C16:1 ω5c (23.1%), iso C15:0 (13.3%), and C16:0 (8.4%) as the major fatty acids which supported the affiliation of strain 15J9-6T to the genus Spirosoma. The results of physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain 15J9-6T from recognized Spirosoma species. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain 15J9-6T represents a novel species of the genus Spirosoma, for which the name Spirosoma daeguensis sp. nov. is proposed. The type strain is 15J9-6T (=KCTC 52036T =JCM 31995T)

Variations in bacterial and fungal communities through soil depth profiles in a Betula albosinensis forest: Can Du , Zengchao Geng , Qiang Wang , Tongtong Zhang , Wenxiang He , Lin Hou , Yueling Wang; J. Microbiol. 2017;55(9):684-693. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-6466-8

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Abstract: Microbial communities in subsurface soil are specialized for their environment, which is distinct from that of the surface communities. However, little is known about the microbial communities (bacteria and fungi) that exist in the deeper soil horizons. Vertical changes in microbial alpha-diversity (Chao1 and Shannon indices) and community composition were investigated at four soil depths (0–10, 10–20, 20–40, and 40–60 cm) in a natural secondary forest of Betula albosinensis by high-throughput sequencing of the 16S and internal transcribed spacer rDNA regions. The numbers of operational taxonomic units (OTUs), and the Chao1 and Shannon indices decreased in the deeper soil layers. Each soil layer contained both mutual and specific OTUs. In the 40–60 cm soil layer, 175 and 235 specific bacterial and fungal OTUs were identified, respectively. Acidobacteria was the most dominant bacterial group in all four soil layers, but reached its maximum at 40–60 cm (62.88%). In particular, the 40–60 cm soil layer typically showed the highest abundance of the fungal genus Inocybe (47.46%). The Chao1 and Shannon indices were significantly correlated with the soil organic carbon content. Redundancy analysis indicated that the bacterial communities were closely correlated with soil organic carbon content (P = 0.001). Collectively, these results indicate that soil nutrients alter the microbial diversity and relative abundance and affect the microbial composition.

Effect of dietary copper level on the gut microbiota and its correlation with serum inflammatory cytokines in Sprague-Dawley rats: Feng Zhang , Weijiang Zheng , Rong Guo , Wen Yao; J. Microbiol. 2017;55(9):694-702. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-6627-9

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Abstract: In China’s swine industry, copper is generally supplemented above the National Research Council (NRC) requirement (2012) because of its antimicrobial properties and the potential for growth promotion. Yet few are concerned about whether this excess supplementation is necessary. In this study, the 16S rRNA pyrosequencing was designed and used to investigate the effect of dietary copper level on the diversity of the fecal microbial community and the correlation of copper level with the serum level of inflammatory cytokines in Sprague-Dawley rat models. The results showed that the diet containing a high level of Cu (120 and 240 mg/kg) changed the microbial richness and diversity of rat feces associated with the increased copper content in the rat ileac and colonic digesta. Furthermore, a Pearson’s correlation analysis indicated that an accumulation of unabsorbed copper in the chyme was correlated with the microbial composition of the rat feces, which was linked with TNF-α in serum. The results suggest that dietary copper level may have a direct impact on circulating inflammatory cytokines in the serum, perhaps inducing an inflammatory response by altering the microbial composition of rat feces. Serum TNF-α could be the chief responder to excessive copper exposure.

Comparison of antibiotic resistance and copper tolerance of Enterococcus spp. and Lactobacillus spp. isolated from piglets before and after weaning: Xueting Zou , Mengwei Weng , Xu Ji , Rong Guo , Weijiang Zheng , Wen Yao; J. Microbiol. 2017;55(9):703-710. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-6241-x

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Abstract: In China, antimicrobials and copper are used extensively as growth-promoting agents for piglets. This study aimed to characterize the role of in-feed copper in the emergence of copper-tolerant and antibiotic-resistant Enterococcus and Lactobacillus isolates in Chinese pig farms. Feces of the same eight piglets from four litters at 7 and 55 days old and their mothers were traced in order to isolate Enterococcus spp. and Lactobacillus spp.. The minimum inhibitory concentrations of 10 antimicrobials and copper sulfate were determined using an agar dilution method. The feed levels of Cu2+ for lactating sows, suckling piglets, and weaned piglets were 6, 177, and 18 mg/kg, respectively. All the 136 Enterococcus isolates were sensitive to vancomycin; and the resistance rates to penicillin, enrofloxacin, and high level streptomycin resistance increased significantly after weaning. For the 155 Lactobacillus isolates, the resistance rates to ampicillin, chloramphenicol, tetracycline, and enrofloxacin were significantly higher in weaned piglets. The ratios of copper tolerant Enterococcus and Lactobacillus isolates both increased significantly after weaning (P < 0.05). A phenotypic correlation was observed after classifying the isolates into two groups (CuSO4 MIC50 < 16 or 􎃶􀁇16 for enterococci; CuSO4 MIC50 < 12 or 􎃶􀁇12 for lactobacilli) and comparing the antimicrobial-resistant percentage of two groups. On species level, a significant increase of E. faecalis to enrofloxacin was observed in line with the increase of copper MIC (P < 0.05). The findings revealed the changes of the antibiotic resistance and copper tolerance level of enterococci and lactobacilli between suckling and weaned piglets and demonstrated that there might be a strong association between in-feed copper and increased antibiotic resistance in enterococci and lactobacilli in Chinese intensive swine farms.

Promising cellulolytic fungi isolates for rice straw degradation: Diana Catalina Pedraza-Zapata , Andrea Melissa Sánchez-Garibello , Balkys Quevedo-Hidalgo , Nubia Moreno-Sarmiento , Ivonne Gutiérrez-Rojas; J. Microbiol. 2017;55(9):711-719. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-6282-1

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Abstract: The objective of this study was to evaluate the potential of eight fungal isolates obtained from soils in rice crops for straw degradation in situ. From the initial eight isolates, Pleurotus ostreatus T1.1 and Penicillium sp. HC1 were selected for further characterization based on qualitative cellulolytic enzyme production and capacity to use rice straw as a sole carbon source. Subsequently, cellulolytic, xylanolytic, and lignolytic (Pleurotus ostreatus) activity on carboxymethyl cellulose, oat xylan, and rice straw with different nitrogen sources was evaluated. From the results obtained it was concluded both isolates are capable to produce enzymes necessary for rice straw degradation. However, their production is dependent upon carbon and nitrogen source. Last, it was established that Pleurotus ostreatus T1.1 and Penicillium sp. HC1 capability to colonize and mineralize rice straw, in mono-and co-culture, without affecting nitrogen soil content.

Diversity of lactic acid bacteria from Miang, a traditional fermented tea leaf in northern Thailand and their tannin-tolerant ability in tea extract: Siriporn Chaikaew , Sasitorn Baipong , Teruo Sone , Apinun Kanpiengjai , Naradorn Chui-chai , Kozo Asano , Chartchai Khanongnuch; J. Microbiol. 2017;55(9):720-729. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-7195-8

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Abstract: The microbiota of lactic acid bacteria (LAB) in thirty-five samples of Miang, a traditional fermented tea leaf product, collected from twenty-two different regions of eight provinces in upper northern Thailand was revealed through the culture-dependent technique. A total of 311 presumptive LAB strains were isolated and subjected to clustering analysis based on repetitive genomic element-PCR (rep-PCR) fingerprinting profiles. The majority of the strains belonged to the Lactobacillus genera with an overwhelming predominance of the Lb. plantarum group. Further studies of species-specific PCR showed that 201 of 252 isolates in the Lb. plantarum group were Lb. plantarum which were thus considered as the predominant LAB in Miang, while the other 51 isolates belonged to Lb. pentosus. In contrast to Lb. plantarum, there is a lack of information on the tannase gene and the tea tannin-tolerant ability of Lb. pentosus. Of the 51 Lb. pentosus isolates, 33 were found to harbor the genes encoding tannase and shared 93-99% amino acid identity with tannase obtained from Lb. pentosus ATCC 8041T. Among 33 tannase gene-positive isolates, 23 isolates exhibited high tannin- tolerant capabilities when cultivated on de Man Rogosa and Sharpe agar-containing bromocresol purple (0.02 g/L, MRS-BCP) supplemented with 20% (v/v) crude tea extract, which corresponded to 2.5% (w/v) tannins. These Lb. pentosus isolates with high tannin-tolerant capacity are expected to be the high potential strains for functional tannase production involved in Miang fermentation as they will bring about certain benefits and could be used to improve the fermentation of tea products.

Loss of FrmB results in increased size of developmental structures during the multicellular development of Dictyostelium cells: Hyeseon Kim , Mi-Rae Lee , Taeck Joong Jeon; J. Microbiol. 2017;55(9):730-736. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-7221-x

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Abstract: FERM domain-containing proteins are involved in diverse biological and pathological processes, including cell-substrate adhesion, cell-cell adhesion, multicellular development, and cancer metastasis. In this study, we determined the functions of FrmB, a FERM domain-containing protein, in the cell morphology, cell adhesion, and multicellular development of Dictyostelium cells. Our results show that FrmB appears to play an important role in regulating the size of developmental structures. frmB null cells showed prolonged aggregation during development, resulting in increased size of developmental structures, such as mounds and fruiting bodies, compared to those of wild-type cells, whereas FrmB overexpressing cells exhibited decreased size of developmental structures. These results suggest that FrmB may be necessary for limiting the sizes of developmental structures. Loss of FrmB also resulted in decreased cell-substrate adhesion and slightly increased cell area, suggesting that FrmB had important roles in the regulation of cell adhesion and cell morphology. These studies would contribute to our understanding of the intertwined and overlapped functions of FERM domain-containing proteins.

Potential of 2, 2'-dipyridyl diselane as an adjunct to antibiotics to manage cadmium-induced antibiotic resistance in Salmonella enterica serovar Typhi Ty2 strain: Praveen Rishi , Reena Thakur , Ujjwal Jit Kaur , Harjit Singh , Kuldip K. Bhasin; J. Microbiol. 2017;55(9):737-744. Published online August 5, 2017; DOI: https://doi.org/10.1007/s12275-017-7040-0

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Abstract: One of the reasons for increased antibiotic resistance in Salmonella enterica serovar Typhi Ty2 is the influx of heavy metal ions in the sewage, from where the infection is transmitted. Therefore, curbing these selective agents could be one of the strategies to manage the emergence of multidrug resistance in the pathogen. As observed in our earlier study, the present study also confirmed the links between cadmium accumulation and antibiotic resistance in Salmonella. Therefore, the potential of a chemically-synthesised compound 2, 2􍿁-dipyridyl diselane (DPDS) was explored to combat the metal-induced antibiotic resistance. Its metal chelating and antimicrobial properties were evidenced by fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and microbroth dilution
method
. Owing to these properties of DPDS, further, this compound was evaluated for its potential to be used in combination with conventional antibiotics. The data revealed effective synergism at much lower concentrations of both the agents. Thus, it is indicated from the study that the combination of these two agents at their lower effective doses might reduce the chances of emergence of antibiotic resistance, which can be ascribed to the multi-pronged action of the agents.

Gallibacterium elongation factor-Tu possesses amyloid-like protein characteristics, participates in cell adhesion, and is present in biofilms: Jaqueline López-Ochoa , J. Fernando Montes-García , Candelario Vázquez , Patricia Sánchez-Alonso , Victor M. Pérez-Márquez , Patrick J. Blackall , Sergio Vaca , Erasmo Negrete-Abascal; J. Microbiol. 2017;55(9):745-752. Published online September 2, 2017; DOI: https://doi.org/10.1007/s12275-017-7077-0

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Abstract: Gallibacterium, which is a bacterial pathogen in chickens, can form biofilms. Amyloid proteins present in biofilms bind Congo red dye. The aim of this study was to characterize the cell-surface amyloid-like protein expressed in biofilms formed by Gallibacterium strains and determine the relationship between this protein and curli, which is an amyloid protein that is commonly expressed by members of the Enterobacteriaceae family. The presence of amyloid-like proteins in outer membrane protein samples from three strains of G. anatis and one strain of Gallibacterium genomospecies 2 was evaluated. A protein identified as elongation factor-Tu (EF-Tu) by mass spectrometric analysis and in silico analysis was obtained from the G. anatis strain F149T. This protein bound Congo red dye, cross-reacted with anti-curli polyclonal serum, exhibited polymerizing properties and was present in biofilms. This protein also reacted with pooled serum from chickens that were experimentally infected with G. anatis, indicating the in vivo immunogenicity of this protein. The recombinant EF-Tu purified protein, which was prepared from G. anatis 12656-12, polymerizes under in vitro conditions, forms filaments and interacts with fibronectin and fibrinogen, all of which suggest that this protein functions as an adhesin. In summary, EF-Tu from G. anatis presents amyloid characteristics, is present in biofilms and could be relevant for the pathogenesis of G. anatis.

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