Enhanced ε-poly-L-lysine production by inducing double antibiotic-resistant mutations in Streptomyces albulus.
ε-Poly-L-lysine (ε-PL), as a food additive, has been widely used in many countries. However, its production still needs to be improved. We successfully enhanced ε-PL production of Streptomyces albulus FEEL-1 by introducing mutations related to antibiotics, such as streptomycin, gentamicin, and rifampin. Single- and double-resistant mutants (S-88 and SG-31) were finally screened with the improved ε-PL productions of 2.81 and 3.83 g/L, 1.75- to 2.39-fold compared with that of initial strain FEEL-1. Then, the performances of mutants S-88 and SG-31 were compared with the parent strain FEEL-1 in a 5-L bioreactor under the optimal condition for ε-PL production. After 174-h fed-batch fermentation, the ε-PL production and productivity of hyper-strain SG-31 reached the maximum of 59.50 g/L and 8.21 g/L/day, respectively, which was 138 and 105% higher than that of FEEL-1. Analysis of streptomycin-resistant mutants demonstrated that a point mutation occurred in rpsL gene (encoding the ribosomal protein S12). These single and double mutants displayed remarkable increases of the activities and transcriptional levels of key enzymes in ε-PL biosynthesis pathway, which may be responsible for the enhanced mycelia viability, respiratory activity, and ε-PL productions of SG-31. These results showed that the new breeding method, called ribosome engineering, could be a novel and effective breeding strategy for the evolution of ε-PL-producing strains.
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Liang
L
Wang
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China. chenxs@jiangnan.edu.cn.
Xusheng
X
Chen
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Guangyao
G
Wu
Xiwang Group Company Limited, Zouping, 256209, China.
Shu
S
Li
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Xin
X
Zeng
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Xidong
X
Ren
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Lei
L
Tang
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China. maozg@jiangnan.edu.cn.
Zhonggui
Z
Mao
D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005839:Gentamicins; D009154:Mutation; D011107:Polylysine / Q000096:biosynthesis*; D012293:Rifampin; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism; D013307:Streptomycin
D005839:Gentamicins; D011107:Polylysine; D012293:Rifampin; D013307:Streptomycin
Double drug-resistant mutation; Key enzyme activities; Ribosome engineering; Streptomyces albulus FEEL-1; qRT-PCR