Distribution of Epsilon-Polylysine Synthetases in Coryneform Bacteria Isolated from Cheese and Human Skin

Abstract

Epsilon-polylysine (ε-PL) is an antimicrobial commercially produced by Streptomyces fermentation and widely used in Asian countries for food preservation. Here we discovered a gene from cheese bacterium Corynebacterium variabile that showed high similarity to the ε-PL synthetase from Streptomyces in terms of enzymatic domain architecture and gene context. By cloning it into Streptomyces coelicolor with a Streptomyces albulus ε-PL synthetase promoter, we confirmed that its product is indeed ε-PL. A comprehensive sequence analysis suggests that ε-PL synthetases are widely spread among coryneform bacteria isolated from cheese and human skin; 14 out of 15 Brevibacterium isolates and 10 out of 12 Corynebacterium isolates contain Pls gene. This discovery raises the possibility that ε-PL as a bioactive secondary metabolite might be produced and play a role in the cheese and skin ecosystems.IMPORTANCEEvery year, microbial contamination causes billions of tons of food wasted and millions of cases of foodborne illness. ε-PL is an excellent food preservative as it is potent, wide spectrum and is heat stable and biodegradable. It has not been accepted by all countries (e.g those in the EU) partially because it was not a natural composition of food but rather originated from the soil bacteria Streptomyces, a famous producer of various antibiotic drugs and toxins. The unexpected finding of ε-PL synthetases in cheese and skin bacteria suggests that ε-PL may naturally exist in cheese and on our skin.