Recently, antibacterial peptides are gaining more attention as an alternative therapeutics and food and other products from spoilage and deterioration. Antibacterial peptide producing strains were isolated from sediments of slaughterhouse sewage wastes. One among them, identified as Bacillus licheniformis inhibited the growth of several gram positive bacteria. Response surface methodology with central composite rotary design was used for optimization of fermentation medium and conditions for antibacterial peptide production. Lactose, NH(4)NO(3), yeast extract and NaCl and environmental factors such as pH, temperature and incubation period were selected as variables. Among ingredients, high concentration of yeast extract and NaCl had a positive effect on antibacterial peptide production and specific activity, respectively. Alkaline pH and high temperature favoured the production of antibacterial peptide by B. licheniformis AnBa9. Under optimized condition, B. licheniformis AnBa9 produced 25-fold higher production of antibacterial peptide than the un-optimized condition. Biochemical characteristics of the antibacterial peptides of B. licheniformis AnBa9 revealed that they are of bacteriocin type. (C) 2008 Elsevier Ltd. All rights reserved.