Mycelial colour was also monitored and documented along with the growth parameters. Characterization and identification of actinobacteria Morphological, biochemical, culture and physiological characterization of the actinobacterial isolates of Minnie Bay were performed as recommended by the International Streptomyces Project (ISP) which were described by Shirling and
Gottileb [18]. Microscopic study was performed with cover slip culture and cellophane method [19]. Formation of aerial, substrate mycelium and spore arrangements on mycelium were monitored BIBW2992 chemical structure under a phase contrast microscope (Nikon ECLIPSE E600, USA) at 100× magnification. Culture characteristics such as growth, coloration of aerial and substrate mycelia, formation of soluble pigment were investigated in eight different media including SCA, nutrient agar, yeast malt agar (ISP-2), oat meal agar (ISP-3), inorganic salt agar (ISP-4), glycerol-asparagine agar (ISP-5), peptone yeast extract agar (ISP-6) and tyrosine agar (ISP-7) with the procedures as recommended by ISP. Biochemical characterization, namely, Gram’s reaction, MR-VP, H2S production, nitrate reduction, oxidase,
catalase, urease, starch, casein and gelatin hydrolysis, blood hemolysis, TSI, citrate utilization, esculin and hippurate hydrolysis was also performed as suggested by ISP. Physiological characterization such as, effect of pH (5–11), growth range in NaCl (5-30%) and survival at 50°C CFTRinh-172 was also evaluated. Capability of the isolates to utilize various carbon sources was performed through in ISP-2 agar medium with phenol red as indicator [20]. Carbon sources viz., fructose, lactose, starch, dextrose, rhamnose, mannitol, maltose, adonitol, arabinose and raffinose were used in this study. Identification of the isolates was made with reference to Bergey’s manual of Systematic Bacteriology [21] and Waksman [22]. Screening of marine
actinobacteria for antibacterial potential Isolates collected from Minnie Bay were screened for antibacterial activity by cross streak method [23]. The isolates were cross streaked on SCA medium and incubated at room temperature for 5 days. After observing a good ribbon like growth of actinobacterial cultures, overnight cultures of Proteus mirabilis MTCC1429, Escherichia coli MTCC443, Vibrio cholerae MTCC3904, Klebsiella pneumoniae MTCC109, Streptococcus pneumoniae MTCC1935, Enterococcus faecalis MTCC439, Pseudomonas aeruginosa MTCC424, Bacillus subtilis MTCC441, Staphylococcus aureus MTCC96, Shigella flexineri MTCC1457, Micrococcus luteus MTCC1541 and Salmonella typhi MTCC734 were streaked at the right angle of actionobacterial cultures. Plates were again incubated at 28°C for 48 hrs and the zone of inhibition was documented.