Members of the genus Micromonospora show a complex life cycle which normally involves the presence of substrate or vegetative mycelia and sporulation with single spores born on the vegetative hyphae followed by the sy...Members of the genus Micromonospora show a complex life cycle which normally involves the presence of substrate or vegetative mycelia and sporulation with single spores born on the vegetative hyphae followed by the synthesis of a dark extracellular polysaccharide. Bergey’s Manual states that micromonosporae rarely produces aerial mycelia (AM) and if so, is considered “sterile”. During the characterisation of novel micromonosporae from the Sea of Cortes, it was observed that AM is produced reproducibly in the presence of certain carbon and/or nitrogen sources. Micromanipulation of the AM subcultured onto fresh media produced colonies;hence, this structure should not be called “sterile”. TEM of the AM producing isolates suggests that the spores also show activity as reported for bacilli of marine origin. This would be the first report of the presence of “inducible” AM in micromonosporae of marine sources and that the spores of this genus have a role other than just dispersal.展开更多
To research the potential ability of marine-derived actinomycetes to act as biocatalysts, 8 Micromonospora strains and 5 Streptomyces strains were screened. Two recommended media (227 and 1076 media) and 2 modified me...To research the potential ability of marine-derived actinomycetes to act as biocatalysts, 8 Micromonospora strains and 5 Streptomyces strains were screened. Two recommended media (227 and 1076 media) and 2 modified media (1076-25% and P-1076-25% media) for liquid culture of these marine-derived actinomycetes were tested. As a result, 2 Micromonospora strains (Micromonospora sp. NBRC107096 and 107097) cultured with the 1076-25% medium and 2 Streptomyces strains (Streptomyces tateyamensis NBRC105048 and Streptomyces sp. NBRC105896) cultured with P-1076-25% medium showed a good growth. The stereoselective reduction of α-keto esters using these 4 actinomycetes was tested. As a result, it was found that these strains had a reducing activity toward various α-keto esters. The introduction of L-glutamate or sucrose as an additive remarkably increased the conversion ratios in the reduction of substrates by the Micromonospora strain. Furthermore, in the presence of L-alanine, Streptomyces tateyamensis NBRC105048 reduced ethyl pyruvate, ethyl 2-oxobutanoate, ethyl 2-oxopentanoate, ethyl 2-oxohexanoate, and ethyl 3-methyl-2-oxobutyrate to the corresponding α-hydroxy ester with a high conversion ratio and with excellent enantiomeric excess. Thus, we found that these marine-derived actinomycetes have great potential to be used as biocatalysts for stereoselective reduction of carbonyl compounds.展开更多
文摘Members of the genus Micromonospora show a complex life cycle which normally involves the presence of substrate or vegetative mycelia and sporulation with single spores born on the vegetative hyphae followed by the synthesis of a dark extracellular polysaccharide. Bergey’s Manual states that micromonosporae rarely produces aerial mycelia (AM) and if so, is considered “sterile”. During the characterisation of novel micromonosporae from the Sea of Cortes, it was observed that AM is produced reproducibly in the presence of certain carbon and/or nitrogen sources. Micromanipulation of the AM subcultured onto fresh media produced colonies;hence, this structure should not be called “sterile”. TEM of the AM producing isolates suggests that the spores also show activity as reported for bacilli of marine origin. This would be the first report of the presence of “inducible” AM in micromonosporae of marine sources and that the spores of this genus have a role other than just dispersal.
文摘To research the potential ability of marine-derived actinomycetes to act as biocatalysts, 8 Micromonospora strains and 5 Streptomyces strains were screened. Two recommended media (227 and 1076 media) and 2 modified media (1076-25% and P-1076-25% media) for liquid culture of these marine-derived actinomycetes were tested. As a result, 2 Micromonospora strains (Micromonospora sp. NBRC107096 and 107097) cultured with the 1076-25% medium and 2 Streptomyces strains (Streptomyces tateyamensis NBRC105048 and Streptomyces sp. NBRC105896) cultured with P-1076-25% medium showed a good growth. The stereoselective reduction of α-keto esters using these 4 actinomycetes was tested. As a result, it was found that these strains had a reducing activity toward various α-keto esters. The introduction of L-glutamate or sucrose as an additive remarkably increased the conversion ratios in the reduction of substrates by the Micromonospora strain. Furthermore, in the presence of L-alanine, Streptomyces tateyamensis NBRC105048 reduced ethyl pyruvate, ethyl 2-oxobutanoate, ethyl 2-oxopentanoate, ethyl 2-oxohexanoate, and ethyl 3-methyl-2-oxobutyrate to the corresponding α-hydroxy ester with a high conversion ratio and with excellent enantiomeric excess. Thus, we found that these marine-derived actinomycetes have great potential to be used as biocatalysts for stereoselective reduction of carbonyl compounds.
