The Journal of General and Applied Microbiology
Online ISSN : 1349-8037
Print ISSN : 0022-1260
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  • Hiroyuki Komatsu, Junya Yamamoto, Hiromichi Suzuki, Nobuyoshi Nagao, Y ...
    2018 Volume 64 Issue 3 Pages 103-107
    Published: 2018
    Released: July 23, 2018
    [Advance publication] Released: March 12, 2018
    JOURNALS FREE ACCESS

    The marine bacterium Rhodovulum sulfidophilum is a nonsulfur phototrophic bacterium, which is known to produce extracellular nucleic acids in soluble form in culture medium. In the present paper, constructing the response regulator ctrA-deficient mutant of R. sulfidophilum, we found that this mutation causes a significant decrease in the extracellular DNA production. However, by the introduction of a plasmid containing the wild type ctrA gene into the mutant, the amount of extracellular DNA produced was recovered. This is the first and clear evidence that the extracellular DNA production is actively controlled by the CtrA in R. sulfidophilum.

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  • Thi Huyen Do, Ngoc Giang Le, Trong Khoa Dao, Thi Mai Phuong Nguyen, Tu ...
    2018 Volume 64 Issue 3 Pages 108-116
    Published: 2018
    Released: July 23, 2018
    [Advance publication] Released: March 12, 2018
    JOURNALS FREE ACCESS

    The scarcity of enzymes having an optimal activity in lignocellulose deconstruction is an obstacle for industrial-scale conversion of cellulosic biomass into biofuels. With the aim of mining novel lignocellulolytic enzymes, a ~9 Gb metagenome of bacteria in Vietnamese native goats’ rumen was sequenced by Illumina platform. From the data, 821 ORFs encoding carbohydrate esterases (CEs) and polysaccharide lyases (PLs) serving for lignocellulose pre-treatment, 816 ORFs encoding 11 glycoside hydrolase families (GHs) of cellulases, and 2252 ORFs encoding 22 GHs of hemicellulases, were mined. The carbohydrate binding module (CBM) was also abundant with 763 ORFs, of which 480 ORFs are located with lignocellulolytic enzymes. The enzyme modularity analysis showed that CBMs are usually present in endoglucanase, endo 1,3-beta-D-glucosidase, and endoxylanase, whereas fibronectin 3-like module (FN3) mainly represents in GH3 and immunoglobulin-like domain (Ig) was located in GH9 only. Every domain located in each ORF was analyzed in detail to contribute enzymes’ modularity which is valuable for modelling, to study the structure, and for recombinant production. With the aim of confirming the annotated results, a mined ORF encoding CBM63 was highly expressed in E. coli in soluble form. The purified recombinant CBM63 exhibited no cellulase activity, but enhanced a commercial cellulase activity in the destruction of a paper filter.

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  • Koki Nishino, Sawako Takahashi, Hiromi Nishida
    2018 Volume 64 Issue 3 Pages 117-120
    Published: 2018
    Released: July 23, 2018
    [Advance publication] Released: March 31, 2018
    JOURNALS FREE ACCESS

    We compared the gene expression levels of the blue-light-responsive genes, appA (encoding photosynthesis promoting protein AppA), ppsR (encoding photosynthesis suppressing protein PpsR), and EL368 (encoding a blue-light-activated histidine kinase with a light, oxygen, or voltage domain) between aerobic and anaerobic conditions in spheroplasts of the aerobic photosynthetic bacterium Erythrobacter litoralis. The spheroplasts conducted photosynthesis under red light but not under blue light. All three blue-light-responsive genes showed higher expression under aerobic conditions than under anaerobic conditions under blue light. In contrast, under red light, although the expression level of appA was higher in the presence of oxygen than in the absence of oxygen, the expression levels of ppsR and EL368 were similar in the presence and absence of oxygen. Our findings demonstrate that the expression of blue-light-responsive genes is strongly affected by oxygen in E. litoralis spheroplasts.

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  • Hao Ji, Xinyao Lu, Hong Zong, Bin Zhuge
    2018 Volume 64 Issue 3 Pages 121-126
    Published: 2018
    Released: July 23, 2018
    [Advance publication] Released: March 31, 2018
    JOURNALS FREE ACCESS

    Candida glycerinogenes is an osmotolerant yeast used for commercial glycerol production, as well as a glycerol utilization yeast which produces high biomass on glycerol medium. In the present study, two STL1 homologues CgSTL1 and CgSTL2 encoding the putative glycerol transporters were identified, and their products were found to be localized to plasma membranes by tagging GFP protein. The functions of CgSTL1 and CgSTL2 on glycerol transport were confirmed by their expression in S. cerevisiae STL1 null mutant and simultaneous deletion in C. glycerinogenes. The expression of CgSTL1 were osmotic-induced, whereas that of CgSTL2 was constitutive. Over-expression of CgSTL1 and CgSTL2 in C. glycerinogenes resulted in improved glycerol consumption rate and cell growth. Our study provided more details on the glycerol transporter of C. glycerinogenes, the potential cell factory for using glycerol as a carbon source.

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  • Tomoo Ogata, Katsuaki Kuroki, Koki Ito, Akifumi Kondo, Kensuke Nakamur ...
    2018 Volume 64 Issue 3 Pages 127-135
    Published: 2018
    Released: July 23, 2018
    [Advance publication] Released: March 31, 2018
    JOURNALS FREE ACCESS

    Variations of chromosomal structures and nucleotide sequences around mating-type-like (MTL) loci among Zygosaccharomyces species have been reported. We have analyzed these differences in more detail and, on the basis of PCR- and next-generation sequencing data, we describe the MTL loci on chromosomes C and F for Z. rouxii type-strain NBRC1130, Z. rouxii NBRC0740 and Zygosaccharomyces sp. NBRC1876. We developed a mating strategy for Zygosaccharomyces sp. NBRC1876 and Z. rouxii NBRC0740, and found that the mated stains could be identified from parental strains on the basis of nucleotide sequence variations of the MTL loci. We further obtained evidence that Zygosaccharomyces sp. NBRC1876 is a natural interspecies hybrid between Z. rouxii and a related species.

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