The gene cluster for the biosynthetic of a nonribosomal peptide, cyanopeptolins and micropeptin (MCN), was identified in Microcystis strains and halogenated MCN-producing Microcystis were found to possess the halogena...The gene cluster for the biosynthetic of a nonribosomal peptide, cyanopeptolins and micropeptin (MCN), was identified in Microcystis strains and halogenated MCN-producing Microcystis were found to possess the halogenase gene, mcnD, between nonribosomal peptide synthetase genes, mcnC and mcnE. A comparative sequence analysis of the mcn gene cluster between halogenated and non-halogenated MCN-producing strains revealed mosaic sequence traces from mcnD in the non-coding region between mcnC and mcnE in the latter strains. A phylogenetic analysis based on a 170-bp non-coding region including the mcnD traces suggests that the recombination events occurred in a particular region of the Microcystis’ mcn gene. This study provides novel insight into the ecological patterning of widespread Microcystis species.展开更多
A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a...A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments（activated sludge） in the 6th segment and sending the sediments beck to the 1st and 2nd segments.Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter（biological oxygen demand [BOD]）, and dissolved oxygen（DO） content. Microbiota from five segments（1st and four successive aerobic segments） in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions（such as DO）, suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.展开更多
文摘The gene cluster for the biosynthetic of a nonribosomal peptide, cyanopeptolins and micropeptin (MCN), was identified in Microcystis strains and halogenated MCN-producing Microcystis were found to possess the halogenase gene, mcnD, between nonribosomal peptide synthetase genes, mcnC and mcnE. A comparative sequence analysis of the mcn gene cluster between halogenated and non-halogenated MCN-producing strains revealed mosaic sequence traces from mcnD in the non-coding region between mcnC and mcnE in the latter strains. A phylogenetic analysis based on a 170-bp non-coding region including the mcnD traces suggests that the recombination events occurred in a particular region of the Microcystis’ mcn gene. This study provides novel insight into the ecological patterning of widespread Microcystis species.
基金supported by a grant for the promotion of desterilizing regional resources funded by the Hokkaido Bureau of Economy,Trade and Industry
文摘A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments（activated sludge） in the 6th segment and sending the sediments beck to the 1st and 2nd segments.Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter（biological oxygen demand [BOD]）, and dissolved oxygen（DO） content. Microbiota from five segments（1st and four successive aerobic segments） in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions（such as DO）, suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.
