Evaluation of bacteriocin resistance in Staphylococcus aureus against the bacteriocin complex secreted by Bacillus subtilis LFB112

Abstract

In order to pre-evaluate the possibility of bacteriocin resistance when utilizing a bacteriocin complex against pathogenic bacteria, Staphylococcus aureus was used to develop a resistant variant by stepwise method. The spontaneous frequency of S. aureus resistance to bacteriocin complex was about 10-5. The stability of resistant variant was confirmed by hundred successive transfers without bacteriocin complex stress. The growth rate of resistant variant was similar as that of its original strain. Interestingly in co-culture system, even inoculated with 90% of resistant variant, the resistant variant was cleared out by wild strain in eight consecutive transfers. When treated with either antibiotics or msm, the resistant variant was more susceptible than the wild strain to all tested antimicrobial agents except chloramphenicol. However, only the tetracycline and chloramphenicol tested groups showed statistically significant increase and decrease of antibacterial potency (p<0.05), respectively. The cellular membrane fatty acid composition of resistant variant was similar to that of wild strain when cultured without bacteriocin complex suggested that the alterations of membrane fatty acid composition in resistant variants might not be the primary defense against bacteriocin. It is proposed that the bacteriocin complex can be used in animal disease preventions and therapeutics as an alternative or complement to traditional antibiotics. © 2011 Medwell Journals.