Effect of pgsE expression on the molecular weight of poly(γ-glutamic acid) in fermentative production

Poly(gamma-glutamic acid) (PGA) is a biopolymer produced byBacillusspp. via the gamma-amide linkages ofd- and/orl-glutamate. Although high-molecular-weight (HMW) PGA possesses many attractive properties, such as flocculating, wound healing, and immune-stimulating effects, no studies have reported factors useful for increasing the molecular weight of PGA during microbial production. PgsB, PgsC, and PgsA are the minimum protein sets required for PGA production inB. subtilis, and PgsE improves PGA productivity. Analysis by size-exclusion chromatography combined with multiangle laser light scattering revealed that the molecular weight of PGA was M-w = 2,900,000 g mol(-1)and predominantly M-w = 47,000 g mol(-1)in preparations derived fromB. subtiliscells with and withoutpgsE, respectively. PgsE may be required to increase the molecular weight of PGA.

Automated summary

The study identified the role of different proteins in the production of PGA by Bacillus subtilis, with PgsE shown to be essential in increasing PGA productivity and molecular weight.