科研之友
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摘要
The Philippines, a biodiversity hotspot in the world, is an excellent source of microbes known to produce novel bioactive compounds. Actinomycetes are one of the most efficient groups in producing these bioactive compounds that have valuable medical, veterinary and agricultural applications. In particular, certain bioactive compounds from actinomycetes have been found effective against methicilllin-resistant Staphylococcus sp. (MRS), which is associated with dairy animals suffering from mastitis. From 39 milk samples collected from cows and goats suffering from mastitis from three dairy farms in CALABARZON, three presumptive MRS isolates were chosen for this study. On mannitol salt agar (MSA) with phenol red and 50 ppm oxacillin, the isolates were Gram-positive cocci, exhibited yellow colonies with red coloration and coagulase-negative. Through 16S rRNA sequencing similarity analysis, Isolate C1225 was putatively identified as Staphylococcus lentus, and C1202 and G20 as Staphylococcus sciuri subspecies sciuri. Using these three Staphylococcus species as test organisms, 19 out of 135 actinomycete isolates from Philippine soils were found showing antibacterial activity. The actinomycete isolate (S816), which had the most effective antibacterial property as gauged by cup cylinder method, was putatively identified as Streptomyces sp. but the species was not ascertained by 16S rRNA sequence similarity analysis. This isolate had a minimum inhibitory concentration (MIC) value lower than that of vancomycin, the only commercial antibiotic that has remained effective against MRS. Initial ethyl acetate extraction and bioautography assay detected the presence of active compounds effective against MRS. A subsequent confirmatory test for methicillin resistance of the putative MRS isolates showed that only Staphylococcus G20 had stable resistance.
- 出版日期2017-7
