Abstract

Eighteen bacterial strains were isolated from Sea water collected from different sites of Red Sea, Egypt. They were screened for antagonistic activity against many bacterial pathogens. The most active antimicrobial producer (R6) which isolated from Safaga middle was identified as Bacillus badius strain AAUM using 16S rRNA phylogenetic analysis. The most control variables were selected from Plackett–Burman (PB) factorial design for the production of antimicrobial agent from Bacillus badius strain AAUM. It achieved 1.56-fold fold increase (against S. aureus) when grown in medium composed of g/l: peptone, 2.5; yeast extract, 5.0; sea water, 25ml; size of inoculum (3ml/50ml), adjusted to pH 9 and incubation period 20 hrs at 45oC. Immobilization using entrapment and adsorption techniques were applied to improve the productivity of cells. B. badius strain AAUM adsorbed on polyurethane foam realized 1.4-fold increase than the free cells. Reused of the adsorbed culture caused an increase of antimicrobial agent production by 1.14-fold than the free cells. The predicted crude antimicrobial spectra suggested that the B. badius strain AAUM can produce important and novel antimicrobial drugs.

Key words: Bacillus, Antimicrobial agents, Optimization, Plackett–Burman, immobilization