Journal of Microbiology

Journal Articles

Saxibacter everestensis gen. nov., sp. nov., A Novel Member of the Family Brevibacteriaceae, Isolated from the North Slope of Mount Everest.: Mao Tian, Shiyu Wu, Wei Zhang, Gaosen Zhang, Xue Yu, Yujie Wu, Puchao Jia, Binglin Zhang, Tuo Chen, Guangxiu Liu; J. Microbiol. 2024;62(4):277-284. Published online March 6, 2024; DOI: https://doi.org/10.1007/s12275-024-00108-1

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Abstract: We isolated and analyzed a novel, Gram-stain-positive, aerobic, rod-shaped, non-motile actinobacterium, designated as strain ZFBP1038(T), from rock sampled on the north slope of Mount Everest. The growth requirements of this strain were 10-37 °C, pH 4-10, and 0-6% (w/v) NaCl. The sole respiratory quinone was MK-9, and the major fatty acids were anteiso-C(15:0) and iso-C(17:0). Peptidoglycan containing meso-diaminopimelic acid, ribose, and glucose were the major cell wall sugars, while polar lipids included diphosphatidyl glycerol, phosphatidyl glycerol, an unidentified phospholipid, and an unidentified glycolipid. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZFBP1038(T) has the highest similarity with Spelaeicoccus albus DSM 26341( T) (96.02%). ZFBP1038(T) formed a distinct monophyletic clade within the family Brevibacteriaceae and was distantly related to the genus Spelaeicoccus. The G + C content of strain ZFBP1038(T) was 63.65 mol% and the genome size was 4.05 Mb. Digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between the genomes of strain ZFBP1038(T) and representative reference strains were 19.3-25.2, 68.0-71.0, and 52.8-60.1%, respectively. Phylogenetic, phenotypic, and chemotaxonomic characteristics as well as comparative genome analyses suggested that strain ZFBP1038(T) represents a novel species of a new genus, for which the name Saxibacter gen. nov., sp. nov. was assigned with the type strain Saxibacter everestensis ZFBP1038(T) (= EE 014( T) = GDMCC 1.3024( T) = JCM 35335( T)).

Impact of Elevational Gradients and Chemical Parameters on Changes in Soil Bacterial Diversity Under Semiarid Mountain Region: Salman Khan , Chun Han , Awais Iqbal , Chao Guan , Changming Zhao; J. Microbiol. 2023;61(10):903-915. Published online November 23, 2023; DOI: https://doi.org/10.1007/s12275-023-00085-x

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Abstract: Elevation gradients, often regarded as “natural experiments or laboratories”, can be used to study changes in the distribution of microbial diversity related to changes in environmental conditions that typically occur over small geographical scales. We obtained bacterial sequences using MiSeq sequencing and clustered them into operational taxonomic units (OTUs). The total number of reads obtained by the bacterial 16S rRNA sequencing analysis was 1,090,555, with an average of approximately 45,439 reads per sample collected from various elevations. The current study observed inconsistent bacterial diversity patterns in samples from the lowest to highest elevations. 983 OTUs were found common among all the elevations. The most unique OTUs were found in the soil sample from elevation_2, followed by elevation_1. Soil sample collected at elevation_6 had the least unique OTUs. Actinobacteria, Protobacteria, Chloroflexi were found most abundant bacterial phyla in current study. Ammonium nitrogen ( NH4 +-N), and total phosphate (TP) are the main factors influencing bacterial diversity at elevations_ 1. pH was the main factor influencing the bacterial diversity at elevations_2, elevation_3 and elevation_4. Our results provide new visions on forming and maintaining soil microbial diversity along an elevational gradient and have implications for microbial responses to environmental change in semiarid mountain ecosystems.

Description of Polaribacter batillariae sp. nov., Polaribacter cellanae sp. nov., and Polaribacter pectinis sp. nov., novel bacteria isolated from the gut of three types of South Korean shellfish: Su-Won Jeong , Jeong Eun Han , June-Young Lee , Ji-Ho Yoo , Do-Yeon Kim , In Chul Jeong , Jee-Won Choi , Yun-Seok Jeong , Jae-Yun Lee , So-Yeon Lee , Euon Jung Tak , Hojun Sung , Hyun Sik Kim , Pil Soo Kim , Dong-Wook Hyun , Jin-Woo Bae; J. Microbiol. 2022;60(6):576-584. Published online April 18, 2022; DOI: https://doi.org/10.1007/s12275-022-1604-3

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Abstract: Three aerobic, Gram-negative, and rod-shaped bacterial strains, designated strains G4M1T, SM13T, and L12M9T, were isolated from the gut of Batillaria multiformis, Cellana toreuma, and Patinopecten yessoensis collected from the Yellow Sea in South Korea. All the strains grew optimally at 25°C, in the presence of 2% (w/v) NaCl, and at pH 7. These three strains, which belonged to the genus Polaribacter in the family Flavobacteriaceae, shared < 98.8% in 16S rRNA gene sequence and < 86.68% in whole-genome sequence with each other. Compared with the type strains of Polaribacter, isolates showed the highest sequence similarity to P. haliotis KCTC 52418T (< 98.68%), followed by P. litorisediminis KCTC 52500T (< 98.13%). All the strains contained MK-6 as their predominant menaquinone and iso-C15:0 as their major fatty acid. Moreover, all the strains had phosphatidylethanolamine as their polar lipid component. In addition, strain G4M1T had two unidentified lipids and three unidentified aminolipids, strain SM13T had three unidentified lipids and three unidentified aminolipids, and strain L12M9T had three unidentified lipids and one unidentified aminolipid. The DNA G + C contents of strains G4M1T, SM13T, and L12M9T were 31.0, 30.4, and 29.7 mol%, respectively. Based on phenotypic, phylogenetic, chemotaxonomic, and genotypic findings, strains G4M1T (= KCTC 82388T = DSM 112372T), SM13T (= KCTC 82389T = DSM 112373T), and L12M9T (= KCTC 62751T = DSM 112374T) were classified into the genus Polaribacter as the type strains of novel species, for which the names Polaribacter batillariae sp. nov., Polaribacter cellanae sp. nov., and Polaribacter pectinis sp. nov., respectively, have been proposed.

Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov., two novel species of the family Bacillaceae isolated from kimchi: Young Joon Oh , Joon Yong Kim , Seul Ki Lim , Min-Sung Kwon , Hak-Jong Choi; J. Microbiol. 2021;59(5):460-466. Published online April 28, 2021; DOI: https://doi.org/10.1007/s12275-021-0513-1

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Abstract: To date, all species in the genus Salicibibacter have been isolated in Korean commercial kimchi. We aimed to describe the taxonomic characteristics of two strains, NKC5-3T and NKC21-4T, isolated from commercial kimchi collected from various regions in the Republic of Korea. Cells of these strains were rod-shaped, Gram-positive, aerobic, oxidase- and catalase- positive, non-motile, halophilic, and alkalitolerant. Both strains, unlike other species of the genus Salicibibacter, could not grow without NaCl. Strains NKC5-3T and NKC21-4T could tolerate up to 25.0% (w/v) NaCl (optimum 10%) and grow at pH 7.0–10.0 (optimum 8.5) and 8.0–9.0 (optimum 8.5), respectively; they showed 97.1% 16S rRNA gene sequence similarity to each other and were most closely related to S. kimchii NKC1-1T (97.0% and 96.8% similarity, respectively). The genome of strain NKC5-3T was nearly 4.6 Mb in size, with 4,456 protein-coding sequences (CDSs), whereas NKC21-4T genome was nearly 3.9 Mb in size, with 3,717 CDSs. OrthoANI values between the novel strains and S. kimchii NKC1-1T were far lower than the species demarcation threshold. NKC5-3T and NKC21-4T clustered together to form branches that were distinct from the other Salicibibacter species. The major fatty acids in these strains were anteiso-C15:0 and anteiso-C17:0, and the predominant menaquinone was menaquinone-7. The polar lipids of NKC5-3T included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), and five unidentified phospholipids (PL), and those of NKC21-4T included DPG, PG, seven unidentified PLs, and an unidentified lipid. Both isolates had DPG, which is the first case in the genus Salicibibacter. The genomic G + C content of strains NKC5-3T and NKC21-4T was 44.7 and 44.9 mol%, respectively. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic analyses, strains NKC5-3T (= KACC 22040T = DSM 111417T) and NKC21-4T (= KACC 22041T = DSM 111418T) represent two novel species of the genus Salicibibacter, for which the names Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov. are proposed.

Role of melatonin in murine “restraint stress”-induced dysfunction of colonic microbiota: Rutao Lin , Zixu Wang , Jing Cao , Ting Gao , Yulan Dong , Yaoxing Chen; J. Microbiol. 2021;59(5):500-512. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0305-7

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Abstract: Intestinal diseases caused by physiological stress have become a severe public health threat worldwide. Disturbances in the gut microbiota-host relationship have been associated with irritable bowel disease (IBD), while melatonin (MT) has antiinflammatory and antioxidant effects. The objective of this study was to investigate the mechanisms by which MT-mediated protection mitigated stress-induced intestinal microbiota dysbiosis and inflammation. We successfully established a murine restraint stress model with and without MT supplementation. Mice subjected to restraint stress had significantly elevated corticosterone (CORT) levels, decreased MT levels in their plasma, elevated colonic ROS levels and increased bacterial abundance, including Bacteroides and Tyzzerella, in their colon tract, which led to elevated expression of Toll-like receptor (TLR) 2/4, p-P65 and p-IκB. In contrast, supplementation with 20 mg/kg MT reversed the elevation of the plasma CORT levels, downregulated the colon ROS levels and inhibited the changes in the intestinal microbiota induced by restraint stress. These effects, in turn, inhibited the activities of TLR2 and TLR4, p-P65 and p-IκB, and decreased the inflammatory reaction induced by restraint stress. Our results suggested that MT may mitigate “restraint stress”-induced colonic microbiota dysbiosis and intestinal inflammation by inhibiting the activation of the NF-κB pathway.

Monthly distribution of ammonia-oxidizing microbes in a tropical bay: Tie-Qiang Mao , Yan-Qun Li , Hong-Po Dong , Wen-Na Yang , Li-Jun Hou; J. Microbiol. 2021;59(1):10-19. Published online November 17, 2020; DOI: https://doi.org/10.1007/s12275-021-0287-5

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Abstract: Ammonia oxidation, performed by ammonia-oxidizing archaea (AOA) and bacteria (AOB), plays a critical role in the cycle of nitrogen in the ocean. For now, environmental variables controlling distribution of ammonia-oxidizing microbes are still largely unknown in oceanic environments. In this study, we used real-time quantitative PCR and high-throughput sequencing
methods
to investigate the abundance and diversity of AOA and AOB from sediment and water in Zhanjiang Bay. Phylogenic analysis revealed that the majority of AOA amoA sequences in water and sediment were affiliated with the genus Nitrosopumilus, whereas the Nitrosotalea cluster was only detected with low abundance in water. Nitrosomonas and Nitrosospira dominated AOB amoA sequences in water and sediment, respectively. The amoA copy numbers of both AOA and AOB varied significantly with month for both sediment and water. When water and sediment temperature dropped to 17– 20°C in December and February, respectively, the copy number of AOB amoA genes increased markedly and was much higher than for AOA amoA genes. Also, AOA abundance in water peaked in December when water temperature was lowest (17–20°C). Stepwise multiple regression analyses revealed that temperature was the most key factor driving monthly changes of AOA or AOB abundance. It is inferred that low water temperature may inhibit growth of phytoplankton and other microbes and so reduce competition for a common substrate, ammonium.

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