Improvement of Bacillus subtilis for poly-?-glutamic acid production by genome shuffling.

ABSTRACT: Poly-?-glutamic acid (?-PGA) is a promising microbial polymer with potential applications in industry, agriculture and medicine. The use of high ?-PGA-producing strains is an effective approach to improve productivity of ?-PGA. In this study, we developed a mutant, F3-178, from Bacillus subtilis GXA-28 using genome shuffling. The morphological characteristics of F3-178 and GXA-28 were not identical. Compared with GXA-28 (18.4 ± 0.8 g l-1 ), the yield of ?-PGA was 1.9-fold higher in F3-178 (34.3 ± 1.2 g l-1 ). Results from batch fermentation in 3.7 l fermenter showed that F3-178 was satisfactory for industrial production of ?-PGA. Metabolic studies suggested that the higher ?-PGA yield in F3-178 could be attributed to increased intracellular flux and uptake of extracellular glutamate. Real-time PCR indicated that mRNA level of pgsB in F3-178 was 18.8-fold higher than in GXA-28, suggesting the higher yield might be related to the overexpression of genes involved in ?-PGA production. This study demonstrated that genome shuffling can be used for rapid improvement of ?-PGA strains, and the possible mechanism for the improved phenotype was also explored at the metabolic and transcriptional levels.

SUBMITTER: Zeng W 

PROVIDER: S-EPMC5072198 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature