ABSTRACT
Streptomyces sp. KB1(TISTR 2304), identified by 16S rDNA gene, was collected from the air sample at Ao-nang, Krabi province, Thailand and deposited in the GeneBank database (accession number KF939581.1). It could produce bioactive compounds and excrete into liquid culture medium within 4 days of incubation period at 30 °C, 200 rounds per minute in shaking incubator. Bioactive compounds in culture broth supernatant were extracted with 3-times of ethyl acetate (EA), evaporated by rotary evaporator at 45 °C under reduced pressure, purified by silica gel column chromatography and eluted by gradient solvent system of ethyl acetate: hexane at ratio of 1:9, 3:7, 4:6, 6:4 and 10:0, v/v. Eight pooled fractions were obtained, name PF1 - PF8, from basis of their TLC profile. Only PF4 displayed as purified active compound which showed anti-methicillin resistant Staphylococcus aureus (MRSA) activity. The PF4 was predicted as 2, 4-Di-tert-butylphenol (C14H22O) with molecular weight 206.2.
ABSTRACT
In the present study, we report antibacterial and antioxidant activities of bioactive compounds extracts (ethyl acetate extract, methanolic extract, n-hexane extract) of Streptomyces lydicus A2 isolated from air in Sciencetific and Technological Equipments Building, Walailak University, Thailand. The S. lydicus A2 is potential to produce bioactive compounds showed various biological activities. In previous research, its culture broth or extract shows antimicrobial activity. In this study, extract prepared from S. lydicus A2 stored at -80 oC was reevaluated the antimicrobial activity when grew in various medium and incubation time to find out storage effect towards the antimicrobial activity. The extract (fractions) from S. lydicus A2 still inhibit test bacteria even though it decreases 50% than the extract prepared from S. lydicus A2 without -80 oC storage. Antimicrobial activity against Staphylococcus aureus and Bacillus cereus was only exhibited by the methanolic fraction S. lydicus A2. Only, the ethyl acetate extract was found to possess dose dependent DPPH free radical scavenging. The isolate A2 could be a potential candidate for the development of novel therapeutic agents active against pathogens and free radicals. Further studies on genomic characterization of isolate and structure determination of the bioactive compounds are under progress.