Functions of poly-gamma-glutamic acid (γ-PGA) degradation genes in γ-PGA synthesis and cell morphology maintenance.
Poly-γ-glutamic acid (γ-PGA) is an important biopolymer with greatly potential in industrial and medical applications. In the present study, we constructed a metabolically engineered glutamate-independent Bacillus amyloliquefaciens LL3 strain with considerable γ-PGA production, which was carried out by single, double, and triple markerless deletions of three degradation genes pgdS, ggt, and cwlO. The highest γ-PGA production (7.12 g/L) was obtained from the pgdS and cwlO double-deletion strain NK-pc, which was 93 % higher than that of wild-type LL3 strain (3.69 g/L). The triple-gene-deletion strain NK-pgc showed a 28 % decrease in γ-PGA production, leading to a yield of 2.69 g/L. Furthermore, the cell morphologies of the mutant strains were also characterized. The cell length of cwlO deletion strains NK-c and NK-pc was shorter than that of the wild-type strain, while the ggt deletion strains NK-g, NK-pg, NK-gc, and NK-pgc showed longer cell lengths. This is the first report concerning the markerless deletion of γ-PGA degradation genes to improve γ-PGA production in a glutamate-independent strain and the first observation that γ-glutamyltranspeptidase (encoded by ggt) could be involved in the inhibition of cell elongation.
Key Laboratory of Molecular Microbiology and Technology of Ministry of Education, Nankai University, Tianjin, 300071, China.
Jun
J
Feng
Weixia
W
Gao
Yanyan
Y
Gu
Wei
W
Zhang
Mingfeng
M
Cao
Cunjiang
C
Song
Peng
P
Zhang
Min
M
Sun
Chao
C
Yang
Shufang
S
Wang
D001407:Bacillus / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D017353:Gene Deletion; D005798:Genes, Bacterial; D060847:Metabolic Engineering; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000235:genetics / Q000378:metabolism*
C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D005723:gamma-Glutamyltransferase