Isolation and identification of lactic acid bacteria inhibiting the proliferation of propionibacterium acnes and staphylococcus epidermidis

Abstract

Propionibacterium acnes is the most common causative agent of acne. Staphylococcus epidermidis is another major bacterial strain to be found in acne lesions. Two strains of lactic acid bacteria (LAB) were isolated from normal inhabitants of humans, which inhibited the proliferation of P. acnes and S. epidermidis. The growth of P. acnes and S. epidermidis was decreased by 4-log scales after incubation for 24 h with LAB isolates, whereas the growth rate of selected LAB isolates were not affected by these pathogenic bacteria. This antibacterial activity of LAB isolates was related to lactic acids, hydrogen peroxide and bacteriocin-like compound production. Two LAB isolates efficiently adhered to human keratinocytes HaCaT and were identified by API 50 CHL medium kit and 16S rDNA partial sequencing analysis. The similarity of 16S rDNA sequences between one isolate and Lactobacillus salivarius subsp. salicinius was 100%, which suggests that they were L. salivarius subsp. salicinius. On the other hand, 16S rDNA sequence similarity between the other isolate and Lactobacillus fermentum was 99.04%, which indicates that it was L. fermentum. In conclusion, these results demonstrate that the two LAB strains isolated from human body were identified as L. salivarius subsp. salicinius and L. fermentum, which inhibit the proliferation of P. acnes and S. epidermidis.