Screening and identification of an ε-polylysine-producing bacterium

Abstract:

[Objective] The aim of this study was to isolate and identify ε-polylysine-producing (ε-PL) actinomycetes from the environment, followed by determining the structure of ε-PL, and studying its inhibition of microbial growth. [Methods] Strains were isolated based on the transparent zone formed by themethylene blue and ε-PL. Itzhaki method was used to screen the strains. A bacterium strain was identified by morphological and physiological characterization and sequence analyses of 16S rRNA and gyrB gene. The structure of ε-PL was studied by spectrum analysis. Its antimicrobial activity was measured by inhibition zone method. [Results] We isolated 3 actinomycete strains. Strain X-18, with the highest ε-PL yield (0.8 g/L), was identified as Streptomyces albulus. The molecular polymerization degree of ε-PL was 25-30 by the spectral data analysis and the comparison with the ε-PL standard. Its antimicrobial effect was better on bacteria than fungi. [Conclusion] An ε-PL-producing strain S. albulus X-18 was successfully isolated to enrich the resources of ε-PL producers.