The sodium caseinate fermentated by Lactobacillus fermentum NCDC 141 showed antimicrobial activity against pathogenic strain Escherichia coli O157:H7 and against some spoilage causing microbial species Bacillus subtilis NCDC 70, Saccharomyces cerevisiae NCDC 47 and Rhizopus oryzae NCDC 52. This property of Lactobacillus fermentum NCDC 141 may have bioprotective applicability in milk based formula, which needs further exploration to confirm its potentility.