New approach for screening of antibacterial compound producing bacteria by colony scraping

Abstract

The present study was aimed to compare the suitability of colony scraping and broth culture methods for screening of antibacterial compound producing bacteria. Eight target marine bacteria species were checked against the four test marine bacteria using colony picking method. Target bacteria which produced clear zones were cultured in marine agar and marine broth media. Antagonistic activity of supernatants which were obtained from the colony scraping (CS) and broth culture (BC) methods was checked using agar disk diffusion assay (CLSI, 2012) against three test bacteria (B. cereus, B. subtilis and H. smyrnensis). Four target bacteria belonged to genus Pseudoalteromonas inhibited the growth of two Bacillus sp. and H. smyrnensis at preliminary screening. But same bacteria did not exhibit any activity against the Vibrio species. P. peptidolytica, P. piscicida and P. rubra showed the antibacterial activity against the H. smyrnensis, B.cereus and B. subtilis respectively when only CS method is used. The antibacterial activity of P. flavipulchra against three test bacteria (B. cereus, B. subtilis and H. smyrnensis) was higher in CS method (14.0±1.4mm, 11.0±0.0mm, 17.5±0.7mm) than BC method (11.5±0.7mm, 10.5±0.7mm, 14.0±0.0mm). Findings of this study indicate that the colony scraping from the solid agar culture of bacteria is more successful for screening of antibacterial producing bacteria.acteria using colony picking method. Target bacteria which produced clear zones were cultured in marine agar and marine broth media. Antagonistic activity of supernatants which were obtained from the colony scraping (CS) and broth culture (BC) methods was checked using agar disk diffusion assay (CLSI, 2012) against three test bacteria (B. cereus, B. subtilis and H. smyrnensis). Four target bacteria belonged to genus Pseudoalteromonas inhibited the growth of two Bacillus sp. and H. smyrnensis at preliminary screening. But same bacteria did not exhibit any activity against the Vibrio species. P. peptidolytica, P. piscicida and P. rubra showed the antibacterial activity against the H. smyrnensis, B.cereus and B. subtilis respectively when only CS method is used. The antibacterial activity of P. flavipulchra against three test bacteria (B. cereus, B. subtilis and H. smyrnensis) was higher in CS method (14.0±1.4mm, 11.0±0.0mm, 17.5±0.7mm) than BC method (11.5±0.7mm, 10.5±0.7mm, 14.0±0.0mm). Findings of this study indicate that the colony scraping from the solid agar culture of bacteria is more successful for screening of antibacterial producing bacteria.