In order to determine the relatedness of the local isolate to these Streptomyces strains. The phylogenetic tree (as displayed by the Tree View program) revealed that the locally isolated strain is closely related (99.3%) to with 16S rRNA gene sequence of Streptomyces fradiae Selleckchem OTX015 Gene Bank accession number AB184776, score 2866, and characterized as S. fradiae MTCC 11051 ( Fig. 2). The optimum conditions for antifungal metabolite production were observed at pH 8, temperature 28 °C, agitation 180 rpm and glucose concentration 2.5% and the highest activity
was observed equivalent to 40 mm (ZoI) against the C. albicans MTCC 183. The antifungal metabolite production was monitored over a period of 12 days. Antibiotic production was started after 48 h of incubation in culture broth. The rate of antifungal metabolite production correlated
with growth rate of the S. fradiae. The antibiotic compound production was highest at 5th day of incubation in the late log phase with the zone of inhibition 40 mm against C. albicans MTCC 183 and remained constant at 10th day of incubation after then gradually decreases. The pH of the culture broth was within the range 7.2–7.8 throughout fermentation. n-butanol and methanol was found to be best solvent for extracellular and intracellular antifungal activity respectively as they inhibited the growth of all fungal strains. Isolate showed very low intracellular activity as compared to the extracellular activity. After extraction, a brown yellow color active compound most was obtained. The active compound was soluble in methanol, ethanol, acetone, methyl acetate, n-butanol, water but not selleck in benzene, chloroform and diethyl ether. The bioactive crude product of S. fradiae showed potent inhibitory effect as MIC and MFC values against the fungal test pathogens. The MIC and MFC values of the bioactive product were found in the range of
6.25–50 μg/ml of active compound ( Table 1). The supernatant from starch casein nitrate broth of S. fradiae MS02 showed greater potency than the amphotericin B against the yeast, molds and dermatophytes. However, this needs further investigation using purified powdered form of the active component. The antifungal activity of isolate MS02, was seen both on solid as well as in culture broth. 15 Production of antifungal metabolite has been known to be influenced by media components and cultural conditions, such as aeration, agitation, pH, temperature and glucose concentration, which differs from organism to organism. 16 It is well known that variation in pH of the culture medium induces production of new substances that affect antibiotic production. 17 Deviation from optimum temperature for antifungal metabolite production severely affects the yield of antifungal metabolite. 18 Agitation affects aeration and mixing of the nutrients in the fermentation medium.