一株ε-多聚赖氨酸产生菌的筛选与鉴定

Screening and identification of an ε-polylysine-producing bacterium

摘要:

[目的]筛选和鉴定产ε-多聚赖氨酸（ε-polylysine，ε-PL）的放线菌菌株，测定所产ε-PL的结构和聚合度，研究其抑制微生物生长的效果。[方法]利用亚甲基蓝和ε-PL因静电排斥而形成透明圈原理筛选ε-PL产生菌，采用Itzhaki方法复筛。考察分离菌株的形态、生理生化特征和16S rRNA基因、gyrB基因序列的同源性鉴定菌种。结合其波谱特征对其所产ε-PL进行结构和聚合度鉴定。采用抑菌圈法考察所产ε-PL对7株指示菌的抑菌活性。[结果]获得3株能够产生ε-PL的放线菌，其中X-18的ε-PL产量最高，达到0.8 g/L，综合形态、生理和分子生物学分析结果，鉴定为白色链霉菌（Streptomyces albulus）。根据波谱学特征，并与标准品比对，证实该ε-PL分子聚合度为25-30，抑菌实验结果显示，它对细菌的抑菌效果明显好于真菌。[结论]从土壤中分离到1株抑菌效果较好的ε-PL产生菌S.albulus X-18，丰富了ε-PL产生菌资源。

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.