The Journal of General and Applied Microbiology
Online ISSN : 1349-8037
Print ISSN : 0022-1260
ISSN-L : 0022-1260
早期公開論文
早期公開論文の26件中1~26を表示しています
  • Yoshinori Tsuji, Akari Kinoshita, Mizuho Tsukahara, Takumi Ishikawa, H ...
    原稿種別: research-article
    論文ID: 2022.08.001
    発行日: 2022年
    [早期公開] 公開日: 2022/08/24
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    電子付録

    Yet another kinase (YAK) 1 is a conserved eukaryotic protein kinase coordinating growth and development. We previously isolated a mutant of Chlamydomonas reinhardtii defective in the YAK1 ortholog triacylglycerol (TAG) accumulation regulator 1 (TAR1). The mutant tar1-1 displayed higher levels of chlorophyll, starch, TAG, and biomass than the parental strain C9 (renamed as C9-3) in photoautotrophic nitrogen (N)-deficient conditions. However, we found that the parental C9-3 showed faster chlorosis upon N-deficiency than the original C9 (C9-1) freshly recovered from cryopreservation, suggesting that C9-3 had acquired particular characteristics during long-term subculturing. To exclude phenotypes dependent on a particular parental strain, we newly created tar1 mutants from two wild-types, C9-1 and CC 125. Like tar1-1, the new tar1 mutants showed higher levels of chlorophyll and TAG/starch than the parental strain. Upon removal of N, Chlamydomonas cells divide once before ceasing further division. Previously, the single division after N-removal was arrested in tar1-1 in photomixotrophic conditions, but this phenotype was not observed in photoautotrophic conditions because of the particular characteristics of the parental C9-3. However, using C9- 1 and CC-125 as parental strains, we showed that cell division after N-removal was impaired in new tar1 mutants in photoautotrophic conditions. Consistent with the view that the division under N-deficiency is necessary for gametic differentiation, new tar1 mutants showed lower mating efficiency than the parental strains. Taken together, TAR1 was suggested to promote differentiation into gametes through the regulation of cell division in response to N-deficiency.

  • Naoya Kataoka, Mienosuke Matsutani, Kazunobu Matsushita, Toshiharu Y ...
    原稿種別: research-article
    論文ID: 2022.08.002
    発行日: 2022年
    [早期公開] 公開日: 2022/08/22
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    Corynebacterium glutamicum was metabolically engineered to produce phenylalanine, a valuable aromatic amino acid that can be used as a raw material in the food and pharmaceutical industries. First, a starting phenylalanine-producer was constructed by overexpressing tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase and phenylalanine- and tyrosine-insensitive bifunctional enzyme chorismate mutase prephenate dehydratase from Escherichia coli, followed by the inactivation of enzymes responsible for the formation of dihydroxyacetone and the consumption of shikimate pathway-related compounds. Second, redirection of the carbon flow from tyrosine to phenylalanine was attempted by deleting of the tyrA gene encoding prephenate dehydrogenase, which catalyzes the committed step for tyrosine biosynthesis from prephenate. However, suppressor mutants were generated, and two mutants were isolated and examined for phenylalanine production and genome sequencing. The suppressor mutant harboring an amino acid exchange (L180R) on RNase J, which was experimentally proven to lead to a loss of function of the enzyme, showed significantly enhanced production of phenylalanine. Finally, modifications of phosphoenolpyruvate-pyruvate metabolism were investigated, revealing that the inactivation of either phosphoenolpyruvate carboxylase or pyruvate carboxylase, which are enzymes of the anaplerotic pathway, is an effective means for improving phenylalanine production. The resultant strain, harboring a phosphoenolpyruvate carboxylase deficiency, synthesized 50.7 mM phenylalanine from 444 mM glucose. These results not only provided new insights into the practical mutations in constructing a phenylalanine-producing C. glutamicum but also demonstrated the creation of a potential strain for the biosynthesis of phenylalanine-derived compounds represented by plant secondary metabolites.

  • Yanjie Tian, Jia Xu, Jianing Shi, Mengyuan Kong, Changjiang Guo, Caix ...
    原稿種別: research-article
    論文ID: 2021.10.003
    発行日: 2022年
    [早期公開] 公開日: 2022/08/15
    ジャーナル フリー 早期公開

    A xylanase gene xynZT-1 from Alteromonas macleodii HY35 was cloned and expressed in Escherichia coli (E. coli). The sequencing results showed that the ORF of xynZT-1 was 831 bp. The xylanase DNA sequence encoded a 29 amino acids (aa) signal peptide and a 247-aa mature peptide. The XynZT-1 has been a calculated molecular weight (MW) of 27.93 kDa, isoelectric point (pI) of 5.11 and the formula C1266H1829N327O384S5. The amino acid sequence of the xynZT-1 had a high similarity with that of glycosyl hydrolase family 11 (GHF11) reported from other microorganisms. The DNA sequence encoding mature peptide was subcloned into pET-28a(+) expression vector. The resulted plasmid pET-28a-xynZT-1 was transformed into E. coli BL21(DE3), and the recombinant strain BL21(DE3)/xynZT-1 was obtained. The optimum temperature and pH of the recombinant XynZT-1 were 45 ℃ and 5.0, respectively.

  • Tomoko Fujiwara, Atsuko Matsura, Momoka Fukuda, Katsuaki Kuroki, Tomoo ...
    原稿種別: research-article
    論文ID: 2022.07.002
    発行日: 2022年
    [早期公開] 公開日: 2022/08/08
    ジャーナル フリー 早期公開
    電子付録

    There is currently great interest in the salt-tolerant yeast strains used to produce miso and soy sauce. Since the isolation of Zygosaccharomyces sp. strain from Japanese miso more than 60 years, several hybrid strains have been identified in fermented foods. Studies have shown that the active mating-type locus of the original Zygosaccharomyces sp. yeast strain is located between the T-subgenome sequence and the P-subgenome sequence. In this study, 32 salt-tolerant Zygosaccharomyces sp. yeast strains were isolated from five miso factories in Hiroshima Prefecture, Japan. Analysis by flow cytometry revealed that 27 strains were diploid and five strains were haploid. PCR analysis indicated that the 27 diploid strains had the same chromosomal structure of the active mating-type (MAT) locus as the original yeast strain isolated from miso 60 years ago. In addition, the 27 diploid strains were allodiploid, namely, natural hybrids of Z. rouxii and a related species, while the five haploid strains were all Z. rouxii. We found that cells of yeast strains isolated from miso changed morphologically when co-cultured with a yeast strain of opposite mating-type under nitrogen starvation conditions. The DNA sequence of the active mating-type locus and the results of cell morphology changes by co-culture were consistent with the mating type of each strain shown in the mating experiments. These findings will be useful for the future production of miso and soy sauce.

  • Sarunpron Khruengsai, Teerapong Sripahco, Patcharee Pripdeevech
    原稿種別: research-article
    論文ID: 2022.07.001
    発行日: 2022年
    [早期公開] 公開日: 2022/08/04
    ジャーナル フリー 早期公開

    Low-density polyethylene (LDPE) has been commercially used and accumulated as plastic solid waste. LDPE has also been found to be a non-degradable waste for decades and found as a pollution source in the environment. In this study, 65 fungi were screened for their biodegradation of LDPE. The fungi Neopestalotiopsis phangngaensis, Alternaria burnsii, Alternaria pseudoeichhorniae, and Arthrinium sacchari showed significant potential in LDPE biodegradation. These fungi were individually cultured with an LDPE sheet as a carbon source for 90 days. A maximum weight loss of the LDPE sheet was detected by the fungus N. phangngaensis (54.34%). This fungus also revealed the highest reduction rate of tensile strength of the LDPE sheet (0.33 MPa). The morphological surface of LDPE culturing with N. phangngaensis was crack, pit, and rough analyzed by scanning electron microscopy. The biodegradation of the LDPE sheet by N. phangngaensis was also confirmed by the Sturm test and analysis of enzymatic activities. The Sturm test showed the highest decomposition of the LDPE sheet by N. phangngaensis into CO2 with 2.14 g/L after incubation. Enzymatic activities of laccase, manganese peroxidase, and lignin peroxidase enzymes were found by N. phangngaensis during the LDPE degradation. The volatile organic compounds in culture supernatant of N. phangngaensis were also investigated. The major compounds were 3Z-diethyl acetal hexenal, 2E,4E-decadienol, and 2Z-diethyl acetal hexenal. This study reveals the utilization of the fungus N. phangngaensis as the carbon source at a considerable biodegradation rate without any prior treatment. Therefore, the fungus N. phangngaensis may be applied as an alternative degrader for LDPE degradation in the environment.

  • Suma Devivilla, Manjusha Lekshmi, Fathima Salam, Sanath Kumar H, Ra ...
    原稿種別: research-article
    論文ID: 2022.04.001
    発行日: 2022年
    [早期公開] 公開日: 2022/07/21
    ジャーナル フリー 早期公開

    Consumption of temperature-abused marine fish containing elevated levels of histamine results in histamine poisoning. Histamine is a biogenic amine produced in fish by the action of certain groups of bacteria which are capable of producing an exogenous enzyme called histidine decarboxylase (HDC). Morganella morganii is one of the major causative organisms of histamine poisoning. In this study, the histamine forming potential of M. morganii (BSS142) is evaluated when it is co-incubated with proteolytic and polyamine forming bacteria. This experiment was designed to examine whether biotic factors such as proteolysis and the presence of other amines influenced histamine forming ability of BSS142. The study showed that the proteolytic activity of Aeromonas hydrophila as well as Pseudomonas aeruginosa greatly enhanced the histamine forming ability of M. morganii. Psychrobacter sangunis, a non proteolytic polyamine producer, negatively influenced histamine production by M. morganii.

  • Ruijie Wang, Manabu Arioka
    原稿種別: research-article
    論文ID: 2022.06.002
    発行日: 2022年
    [早期公開] 公開日: 2022/07/21
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    電子付録

    Glucuronoyl esterase (GE) is a promising agent for the delignification of plant biomass since it has been shown to cleave the linkage between xylan and lignin in vitro. In this study, we demonstrate that NcGE, a GE from Neurospora crassa, stimulates plant biomass degradation. In vitro, NcGE synergistically increased the release of reducing sugars from plant biomass when added together with cellulase or xylanase. In vivo, overexpression of NcGE in N. crassa resulted in an increase in xylanolytic activity. Consistently, elevated transcription of genes encoding the major plant biomass degrading-enzymes (PBDEs) was observed in the NcGE overexpression strain. Increased xylanolytic activity and transcription of PDBE genes were largely abolished when the transcription factors clr-1, clr-2, or xlr-1 were deleted. Interestingly, the expression of some PBDE genes was increased when the hydrolysate of plant biomass by NcGE was added to the culture medium. We propose that NcGE boosts the production of PBDEs through the activation of key transcription factors, which is presumably caused by NcGE-mediated generation of hypothetical inducer(s) from plant biomass.

  • Qiong Deng, Zhu Wang, Pengmei Wu, Hui Liang, Haixia Wu, Lirong Zhang, ...
    原稿種別: research-article
    論文ID: 2022.05.004
    発行日: 2022年
    [早期公開] 公開日: 2022/07/09
    ジャーナル フリー 早期公開
    電子付録

    Mycoplasma pneumoniae is one of the most important pathogens causing community acquired pneumonia in children, and the pathogenic mechanism of M. pneumoniae infection is complex. Azithromycin is an effective agent for treating the acquired lower respiratory tract infection and urogenital tract infection with slight adverse reactions. This study aimed to compare the intestinal microflora before (PP1) and after azithromycin intervention (PP2) in children with pneumonia caused by M. pneumoniae, combined with body fluid biochemical analysis to determine the intestinal flora affecting the progress of the disease. Fifteen children diagnosed with M. pneumoniae pneumonia were recruited. The fecal samples and clinical biochemical data were collected. 16S rRNA gene amplicon sequencing and bioinformatics analysis were conducted by the Beijing Genomics Institute. The operational taxonomic unit abundance analysis showed significant differences between the two groups. The species richness analysis showed differences in class, family, genus, order, species, and phylum. The abundance of Haemophilus, Pasteurellales, and Pasteurellaceae was found to be significantly higher in the PP1 group. The Pearson correlation analysis showed that the microbes strongly correlated with the clinical features. 16S rRNA gene sequencing data revealed altered composition of gut microbiota in children with M. pneumoniae pneumonia treated with azithromycin. The altered expression of microbes correlated with clinical features, which might help diagnose and treat the disease.

  • Tomohiro Inaba, Mami Yamaguchi, Akira Taniguchi, Yuya Sato, Tomo Aoy ...
    原稿種別: research-article
    論文ID: 2022.04.003
    発行日: 2022年
    [早期公開] 公開日: 2022/06/13
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    The decolorization of 11 dyes by granular sludge from an anaerobic expanded granular sludge bed (EGSB) reactor was evaluated. Biological decolorization of Reactive Red 21, 23, and 180, and Reactive Yellow 15, 17, and 23 in model textile wastewater was observed for the first time after a 7-day incubation (over 94% decolorization). According to the sequencing analysis of 16S rRNA gene amplicons from EGSB granular sludge, the operational taxonomic unit related to Paludibacter propionicigenes showed the highest increase in relative abundance ratios in the presence of dyes (7.12 times on average over 11 dyes) compared to those without dyes.

  • Vu Dinh Giap, Hoang Thanh Duc, Pham Thi Mai Huong, Do Thi Hanh, Do H ...
    原稿種別: research-article
    論文ID: 2022.05.005
    発行日: 2022年
    [早期公開] 公開日: 2022/07/02
    ジャーナル フリー 早期公開

    From the biotechnological point of view, enzymes are powerful tools that help sustain a clean environment in several ways. The enzymatic biodegradation of synthetic dyes is a promising goal since it reduces pollution caused by textile dyeing factory wastewater. Lignin peroxidase (EC 1.11.1.14, LiP) has high redox potential; thus, it is great for application in various industrial fields (e.g., paper- waste treatment and textile dyeing wastewater treatment). In the present study, a LiP from an isolated strain Pleurotus pulmonarius CPG6 (PpuLiP) was successfully purified with a specific activity of 6.59 U mg -1. The enzyme was purified by using three-step column chromatography procedures including DEAE, Sephadex G-75, and HiTrapTM Q FF columns with 17.8-fold purity. The enzyme with a molecular weight of 40 kDa exhibited enhanced pH stability in the acidic range. The activity retention was over 75% at a pH of 3.0 for more than 6 hours. Purified PpuLiP was able to oxidize a variety of substrates including veratryl alcohol, 2,4-DCP, n propanol, and guaiacol. The effect of metal ions on PpuLiP activity was analyzed. The study will provide a ground to decolorize dyes from various groups of PpuLiP. Purified PpuLiP could decolorize 35% Acid blue 25 (AB25), 50% Acid red 129 (AB129), 72% Acid blue 62 (NY3), 85% Acid blue 113 (AB113), 55% Remazol Brilliant blue R (RBBR), and 100% Reactive red 120 (RR120) for 12 hours. Most of the dyes were decolorized, but the heat-denatured enzyme used as negative control obviously did not decolorize the tested dyes. These results indicate that the PpuLiP has potential application in enzyme-based decolorization of synthetic dyes. Keywords: Decolorization; lignin peroxidase; Pleurotus pulmonarius; textile dyes.

  • Teppei Maruyama, Kanako Hayashi, Kotaro Matsui, Yasukichi Maekawa, Tak ...
    原稿種別: research-article
    論文ID: 2022.05.006
    発行日: 2022年
    [早期公開] 公開日: 2022/07/02
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    電子付録

    Fission yeast, Schizosaccharomyces pombe, possesses eight hexose transporters, Ght1~8. In order to clarify the role of each hexose transporter on glucose uptake, a glucose uptake assay system was established and the actual glucose uptake activity of each hexose transporter-deletion mutant was measured. Under normal growth condition containing 2% glucose, ∆ght5 and ∆ght2 mutants showed large and small decrease in glucose uptake activity, respectively. On the other hand, the other deletion mutants did not show any decrease in glucose uptake activity indicating that, in the presence of Ght5 and Ght2, the other hexose transporters do not play a significant role in glucose uptake. To understand the relevance between glucose uptake and lifespan regulation, we measured the chronological lifespan of each hexose transporter deletion mutant, and found that only ∆ght5 mutant showed a significant lifespan extension. Based on these results we showed that Ght5 is mainly involved in the glucose uptake in Schizosaccharomyces pombe, and suggested that the ∆ght5 mutant has prolonged lifespan due to physiological changes similar to calorie restriction.

  • Yanxiang Yao, Naren Xi, E Hai, Xiaomin Zhang, Jiayi Guo, Zhi Lin, Wei ...
    原稿種別: research-article
    論文ID: 2022.05.003
    発行日: 2022年
    [早期公開] 公開日: 2022/06/21
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    As a central signaling molecule, c-di-GMP (bis-(3,5)-cyclic diguanosine monophosphate) is becoming the focus for research in bacteria physiology. Pseudomonas aeruginosa PAO1 genome contains highly complicated c-di-GMP metabolizing genes and a number of these proteins have been identified and investigated. Especially, a sophisticated network of these proteins is emerging. In current study, mainly through Bacteria-2-Hybrid assay, we found PA0575 (RmcA), a GGDEF-EAL dual protein, to interact with two other dual proteins of PA4601 (MorA) and PA4959 (FimX). These observations imply the intricacy of c-di-GMP metabolizing protein interactions. Our work thus provides one piece of data to increase the understandings to c-di-GMP signaling.

  • Orn anong Chaiyachet, Ketsara Wongtham, Komsan Sangkasame
    原稿種別: research-article
    論文ID: 2022.05.002
    発行日: 2022年
    [早期公開] 公開日: 2022/06/10
    ジャーナル フリー 早期公開

    The present study investigated the efficacy of bacterial cellulose production by K. xylinus TISTR 1011 and K. nataicola TISTR 975 using yam bean juice as a nutrient source, and the physicochemical and sensory characteristics of bacterial cellulose were examined. Bacterial cellulose content, production yield, and production rate were significantly higher when K. xylinus TISTR 1011 rather than K. nataicola TISTR 975 was used as the bacterial strain. The analysis of physicochemical characteristics revealed that bacterial cellulose produced by K. xylinus TISTR 1011 using yam bean juice medium had higher scores for CIE L*, a*, and b* values, wet weight, moisture content, firmness, and gel strength than bacterial cellulose produced by K. nataicola TISTR 975. In contrast, sensory evaluation showed that the acceptability scores and preference of all attributes of bacterial cellulose produced by K. nataicola TISTR 975 using yam bean juice medium were higher than those of bacterial cellulose produced by K. xylinus TISTR 1011. The results of this study indicate that yam bean juice from yam bean tubers, an alternative raw material agricultural product, can be used as a nutrient source for producing bacterial cellulose or nata by Komagataeibacter strains.

  • Kasumi Shimodate, Hiroyuki Honda
    原稿種別: research-article
    論文ID: 2022.04.002
    発行日: 2022年
    [早期公開] 公開日: 2022/06/08
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    Godo is a traditional fermented soy food made in Aomori prefecture, Japan. It is mainly made of soybeans, rice koji, and salt. Since godo ripens during the long and severe winter in northeast Japan, it is assumed that lactic acid bacteria inhabiting godo have cold tolerance. We aimed to investigate the presence or absence of psychrotrophic lactic acid bacteria in godo. The viable counts of estimated lactic acid bacteria ranged from 106 to 108 cfu/g. In addition, aerobic and anaerobic microorganisms were detected in four godo products though the microbial population differed from sample to sample. Twenty-two bacterial strains were able to be isolated from godo, and all of the isolated strains were Gram-positive and catalase-negative. Some of the isolates grew well at 10°C. The carbohydrate fermentation profile of the selected three strains was determined by API50 CHL analysis. These strains were identified as Leuconostoc mesenteroides, and Latilactobacillus sakei by 16S rRNA gene sequence analysis. Leuconostoc mesenteroides strains HIT231 and HIT252, and Latilactobacillus sakei strain HIT273 could grow at 5°C in MRS broth, but their optimum growth temperature was 20°C-30°C. These results suggest that psychrotrophic lactic acid bacteria presumed to be derived from rice koji are present in godo, which is one of the factors in the low temperature ripening of godo in winter.

  • Takashi Kuribayashi, Toshiki Sakurai, Akira Hatakeyama, Toshio Joh, Mi ...
    原稿種別: research-article
    論文ID: 2022.05.001
    発行日: 2022年
    [早期公開] 公開日: 2022/06/08
    ジャーナル フリー 早期公開

    In Saccharomyces cerevisiae, ethyl caprylate is produced by the esterification of caprylic acid, which is synthesized through the action of fatty acid synthase. A recent study reported a yeast mutant with a single nucleotide substitution in the alpha subunit of fatty acid synthase (FAS2) gene (F1279Y; 3836T>A) that produced large amounts of ethyl caprylate. Here, we designed two primer sets (P1/P2 and P3/P4) with mismatches that incorporate restriction sites for the enzymes NdeI and SspI, respectively and developed an easy and rapid polymerase chain reaction-restriction fragment length polymorphism assay to identify yeasts harboring the FAS2-F1279Y mutation associated with high ethyl caprylate productivity.

  • Zhi Tao, Shiqi Zheng, Shuangyue Liu, Jing Wang, Di Geng, Rufeng Wang
    原稿種別: research-article
    論文ID: 2021.10.002
    発行日: 2022年
    [早期公開] 公開日: 2022/05/31
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    Flavone C-glycosides are not easily degraded because of their strong C-C bond between sugar moieties and aglycones. However, some bacteria such as intestinal species can produce specific enzymes to degrade them. In this study, a bacterial strain P581a, which is capable of deglycosylating flavone C-glycosides, was isolated from human intestinal bacteria and was identified as Enterococcus gallinarum by morphological examination, physiological and biochemical analysis and 16S rRNA gene sequencing. This strain may produce a specific flavonoside glycosidase. The activity of the enzyme in the culture medium containing different quantity of carbon sources was also studied, and it was found that the content of carbon sources is negatively correlated with the deglycosylation efficiency of this strain.

  • Hidetoshi Inoue, Kumiko Tajima, Cristina Mitsumori, Natsuko Inoue-Kash ...
    原稿種別: research-article
    論文ID: 2021.11.001
    発行日: 2022年
    [早期公開] 公開日: 2022/05/31
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    A genetically modified (GM) strain of the diatom Chaetoceros gracilis expressing the phosphite dehydrogenase gene (ptxD), which is a useful gene both for the biological containment and the avoidance of microbial contamination, was characterized to estimate the risk against the biodiversity by laboratory experiments. GM strain could grow in the medium containing phosphite as a sole source of phosphorus, while its general characteristics such as growth, salt tolerance, heat and dehydration resistance in the normal phosphate-containing medium were equivalent to those of wild type (WT) strain. The increase in potential toxicity of GM strain against plant, crustacean, fish and mammal was also disproved. The dispersal ability of WT strain cultured in an outdoor raceway pond was investigated for 28 days by detecting the psb31 gene in vessels, settled at variable distances (between 5 and 60 m) from the pond. The diatom was detected only in one vessel placed 5 m apart. To estimate the influence on the environment, WT and GM strains were inoculated into freshwater, seawater and soil. The influence on the microbiome in those samples was assessed by 16S rRNA gene amplicon sequencing, in addition to the analysis of the survivability of those strains in the freshwater and the seawater. The results indicated that the effect to the microbiome and the survivability were comparable between WT and GM strains. All results showed that the introduction of the ptxD gene into the diatom had a low risk on biodiversity.

  • Takuma Suzuki, Kenji Morimoto
    原稿種別: research-article
    論文ID: 2022.01.004
    発行日: 2022年
    [早期公開] 公開日: 2022/05/31
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    電子付録

    Researchers continue to search for efficient processes to reduce the production costs of rare sugars. In this paper, we report a novel D-xylose isomerase from Shinella zoogloeoides NN6 (SzXI) and its application for efficient rare sugar production. Purified SzXI did not show remarkable properties when compared with those of a previously reported D-xylose isomerase. However, NN6 was found to express inducible SzXI and constitutive D-allulose 3-epimerase (SzAE) when cultivated with D-xylose as the sole carbon source. These two enzymes were partially purified and immobilized onto HPA25L, an anion exchange resin. The co-immobilized SzXI and SzAE (i-XA) showed optimal activity at 65°C in sodium phosphate buffer (pH 7.5) and 90°C in sodium phosphate buffer (pH 6.5), respectively. i-XA produced D-ribulose via D-xylulose from D-xylose at a conversion ratio of D-xylose:D-xylulose:D-ribulose of 72:18:10. Furthermore, D-allulose was also produced via D-fructose using D-glucose as the substrate, with a D-allulose yield of 11.2%. This is the first report describing a bacterium expressing D-xylose isomerase and D-allulose 3-epimerase that converts readily available sugars such as D-glucose and D-xylose to rare sugars.

  • Yuko Yoshimura, Yuri Kobayashi, Takashi Kawaguchi, Shuji Tani
    原稿種別: research-article
    論文ID: 2021.10.005
    発行日: 2022年
    [早期公開] 公開日: 2022/05/23
    ジャーナル フリー 早期公開
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    We investigated the effects of deleting major extracellular protease-encoding genes on cellulolytic and xylanolytic enzyme production in Aspergillus aculeatus. We first investigated the effect of prtT deletion, a positive transcription factor for extracellular protease-encoding genes in Aspergillus, on extracellular protease production in A. aculeatus. Genetic analysis indicated that among the major extracellular proteases, pepIIa and pepIIb are controlled by PrtT, but pepI is not. Thus, we generated a mutant with deletion of the two genes prtT and pepIprtTΔpepI) and one with deletion of the three genes pepI, pepIIa, and pepIIbpepIΔIIaΔIIb). Extracellular protease activities decreased in both ΔprtTΔpepI and ΔpepIΔIIaΔIIb to 3% of that in the control strain (MR12). Comparative time-course analyses indicated that endoglucanase activity in ΔprtTΔpepI increased to double that in MR12. Xylanase activities increased in both ΔprtTΔpepI and ΔpepIΔIIaΔIIb to fourfold higher than that in MR12 at maximum. β-Glucosidase activities were increased in ΔprtTΔpepI and ΔpepIΔIIaΔIIb 1.3- and 1.4-fold higher than that in MR12 at maximum, respectively. Residual activities of endoglucanase, xylanase, and β-glucosidase after 7 days of incubation at 37°C in the culture supernatant were 63%, 36%, and 48% of the original in MR12. Residual endoglucanase activities were more than 80% of the original in ΔprtT, ΔprtTΔpepI, and ΔpepIΔIIaΔIIb. Residual xylanase activities were not improved in all test strains. β-Glucosidase remained almost 97% of the original in ΔprtTΔpepI. These findings indicated that the reduction of extracellular proteases effectively improved cellulolytic and xylanolytic enzyme production and stability in A. aculeatus.

  • Ayan Mahanty, Subhrajyoti Giri, Akas Kar, Shilpi Ghosh
    原稿種別: research-article
    論文ID: 2022.01.005
    発行日: 2022年
    [早期公開] 公開日: 2022/05/23
    ジャーナル フリー 早期公開

    Rice (Oryza sativa L.) straw is an agricultural byproduct of high yield, and its disposal by burning has detrimental effect on ecosystem. It has potential as source of fermentable sugars for industrial use; however, it requires effective pretreatment to remove lignin. Bacterial enzymes based pretreatment is advantageous due to their extracellular nature, and tolerance to higher temperature, pH and oxygen limitation. We herein report screening of lignocellulose degradation environment of vermicompost for ligninolytic bacteria, and studying role of Micrococcus unnanensis strain B4 in delignification of rice straw. The bacterium was capable to degrade acid soluble and insoluble lignin; and produced lignin degrading laccase and peroxidase having maximum activity at pH 6.5 and 72 h incubation. Both enzymes exhibited alkaline pH stability, and thermal stability with retention of 100 % activity on pre-incubation at 60 oC. The enzymes were used for pretreatment of rice straw using chemicals (acetic acid:hydrogen peroxide) pretreatment as reference. Scanning electron microscopy of pretreated rice straw samples showed alteration in morphology with exposure of cellulosic components. Enzymatically pretreated rice straw on saccharification by a commercial cellulase yielded about 400 mg of reducing sugar per gram, comparable to that released on chemical pretreatment. Hence, pretreatment based on M.unnanensis strain B4 and its ligninolytic enzymes can be an alternative to chemical pretreatment for saccharification of rice straw to fermentable sugars.

  • Toshio Sakamoto, Yang Wei, Koki Yuasa, Yoshitaka Nishiyama
    原稿種別: research-article
    論文ID: 2022.01.003
    発行日: 2022年
    [早期公開] 公開日: 2022/05/20
    ジャーナル フリー 早期公開
    電子付録

    The terrestrial cyanobacterium Nostoc commune is an anhydrobiotic organism with extreme longevity. Recovery of photosynthesis by rehydration was examined using our laboratory stocks of dry N. commune thalli after long-term storage in a desiccated state. In the samples stored at room temperature for over 8 years, photosynthetic oxygen evolution was barely detectable, whereas oxygen consumption was recovered. There was an exceptional case in which photosynthetic oxygen evolution recovered after 8 years of storage at room temperature. Both photosynthetic oxygen evolution and respiratory oxygen consumption were recovered in dry thalli stored at -20°C for over 15 years. Consistent with the recovery of photosynthetic oxygen evolution, Fv/Fm was detected in the samples stored at -20°C at levels similar to those of freshly collected N. commune colonies. Carotenoids, scytonemin and chlorophyll a appeared to be intact in the dry thalli stored at -20°C, but β-carotene was not detected in the samples stored at room temperature. α-Tocopherol was intact in the samples stored at -20°C but was degraded in the samples stored at room temperature. These results suggest that dry thalli of N. commune are capable of sustaining biological activities for a long time, although they are gradually damaged when stored at room temperature.

  • Toshikazu Komoda, Yoshitaka Koseki
    原稿種別: research-article
    論文ID: 2022.03.001
    発行日: 2022年
    [早期公開] 公開日: 2022/05/20
    ジャーナル フリー 早期公開

    In this study, we successfully isolated two compounds, 17T223A (1, C22 H22 O10 ) and 17T223B (2, C22 H20 O9 ), from a culture of Streptomyces sp. 17T223. Spectroscopic analyses revealed that these two compounds belong to the spiroximicin family. The chemical structure of 2 was consistent with that of the established antibiotic spiroximicin, whereas 1 was previously unknown. Furthermore, 1 exhibited moderate radical -scavenging activity, with an ED 50 of 1000 μM, whereas 2 showed no radical -scavenging activity, even at an ED50 of 2000 μM. Significant antimicrobial activity was exhibited by 2 whereas 1 exhibited no antimicrobial activity, suggesting that the epoxide portion of 2 influences its antimicrobial activity.

  • Yoshihiro Watanabe, Yurika Yoshida, Toshiyuki Tokiwa, Mayuka Higo, Say ...
    原稿種別: research-article
    論文ID: 2022.03.002
    発行日: 2022年
    [早期公開] 公開日: 2022/05/20
    ジャーナル フリー 早期公開
    電子付録

    A new antifungal polyketide, named hakuhybotric acid (1), was isolated from a cultured broth of a mycoparasitic fungus Hypomyces pseudocorticiicola FKI-9008, together with two known analogs, F2928-1 (2) and Cladobotric acid E (3). Their structures were elucidated by MS and NMR analyses. The structure of hakuhybotric acid was the two epoxy groups of F2928-1 converted to olefins. All compounds showed antifungal activity against four different species of Aspergillus spp., the causative agents of aspergillosis. It was suggested that mycoparasitic fungi are a useful source to search antifungal drug lead compounds.

  • Qian Lin, Jieni Li, Xinru Ling, Xinmei Zhang
    原稿種別: research-article
    論文ID: 2021.10.001
    発行日: 2022年
    [早期公開] 公開日: 2022/04/18
    ジャーナル フリー 早期公開

    trans-Anethole oxygenase (TAO) is the key enzyme responsible for the oxidation of trans-anethole to p-anisaldehyde. A strain, Paraburkholderia sp. MR185, was isolated from soil in Yulin star anise-planting regions using trans-anethole as a sole carbon source and a gene which encodes a protein with high similarities to a hypothetical protein of Paraburkholderia sp. MM5384-R2 which shows 61.27% identies with TAO from Pseudomonas putida JYR-1 was cloned and sequenced. The gene, tao, was expressed in E. coli cells and its protein product was purified by affinity chromatography through regenerated amorphous cellulose (RAC). SDS-PAGE analysis indicated a clear band of recombinant protein TAO, and its molecular weight, 38.3 kDa, was consistent with the theoretical value. Its enzyme activity of producing p-anisaldehyde from trans-anethole was detected by DNPH (2,4-dinitrophenylhydrazine) chromogenic reaction and HPLC, and the specific activity of TAO reached 3.93 U/mg protein. Immobilized TAO on RAC was used to catalyze the production of p-anisaldehyde from trans-anethole, and the enzyme retained more than 60% of its initial activity after 10 uses. This is the first report on Paraburkholderia TAO.

  • Akira Matsumoto, Sung-Jin Kawai, Miwa Yamada
    原稿種別: research-article
    論文ID: 2021.11.002
    発行日: 2022年
    [早期公開] 公開日: 2022/04/13
    ジャーナル フリー 早期公開

    The marine bacterium Cobetia sp. IU180733JP01 (5-11-6-3) can accumulate poly(3- hydroxybutyrate) [P(3HB)] during cultivation on alginate or waste Laminaria sp. Here, we examined this strain’s ability to utilize various carbon sources for P(3HB) production. When cultured in mineral salt medium containing 1% (w/v) glucose, fructose, glycerol, or gluconic acid, the strain showed better growth and higher P(3HB) production than on alginate, with fructose enabling the highest P(3HB) yield (0.8 ± 0.06 g/L). We also predicted metabolic pathways for P(3HB) synthesis based on draft genome sequence analysis, in which carbon sources are assimilated through Entner–Doudoroff and Embden–Meyerhof pathways, and the resultant acetyl-CoA is converted into P(3HB). Our findings reveal the potential of the 5-11-6-3 strain for application in bioplastic production from not only marine biomass but also other biomass and industrial wastes.

  • Muhammad Imran Firdaus Kamardan, Ezzah Atikah Binti Marsid, Fazrena Na ...
    原稿種別: research-article
    論文ID: 2021.09.004
    発行日: 2022年
    [早期公開] 公開日: 2022/04/08
    ジャーナル フリー 早期公開
    電子付録

    Tropical peatlands account for one of the largest carbon stores in the form of organic matter due to the accumulation of plant litter and waterlogged conditions. Recent anthropogenic disturbances, such as forest fires, agricultural conversion and drainage, in tropical peatlands have caused a vast amount of carbon to be released into the atmosphere, and microbial activities are impacted by these changes. A recent study showed that many phenol- and lignin-degrading bacteria prefer alkaline and neutral pH conditions, while tropical peatland conditions are acidic, possibly changing the mechanisms of the utilization of organic matter from peat soil. The purpose of this study was to isolate and characterize phenolic compound-degrading bacteria from tropical peatlands under acidic conditions due to the lack of information on how the biological processes of microorganisms occur in this unique habitat. Two isolates show the capability to utilize phenolic aldehydes based on building blocks of lignin that are abundant in tropical peatlands, including hydroxyphenyl, guaiacyl and syringyl units. The identification of these isolates by 16S rRNA gene sequence shows that strain S38 is similar to Stenotrophomonas sp., while strain S46 is similar to Burkholderia sp. Further characterization of these isolates shows their ability to degrade 4-hydroxybenzaldehyde and vanillin into phenolic acids within 24 hours of incubation and syringaldehyde within 7 days of incubation. In conclusion, these isolated bacteria show the ability to withstand the acidic environment of tropical peatlands and utilize lignin monomers through unknown metabolic pathways.

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