Efficient molasses utilization for low-molecular-weight poly-γ-glutamic acid production using a novel Bacillus subtilis stain

Microb Cell Fact. 2022 Jul 16;21(1):140. doi: 10.1186/s12934-022-01867-5.

Abstract

Background: Poly-γ-glutamic acid (γ-PGA) is a biopolymer and has various applications based on its biocompatibility, non-toxicity, and edibility. Low-molecular-weight (Mw)-γ-PGA has promising applications in agriculture and pharmaceuticals. It is traditionally produced by enzymatic hydrolysis. Cost-effective bioproduction of low-Mw-γ-PGA is essential for commercial application of γ-PGA.

Results: Bacillus subtilis 242 is a newly isolated low-Mw-γ-PGA-producing strain. To develop cost-effective production of γ-PGA using this newly isolated strain, cane molasses and corn steep liquor were used to produce γ-PGA. The concentration of cane molasses was optimized and 100 g/L cane molasses resulted in high γ-PGA production. The effects of yeast extract and corn steep liquor on γ-PGA yield were investigated. High concentration of γ-PGA was obtained in the medium with corn steep liquor. A concentration of 32.14 g/L γ-PGA was achieved in fed-batch fermentation, with a productivity of 0.67 g/L/h and a percentage yield (gγ-PGA/gglutamate) of 106.39%. The Mw of γ-PGA was 27.99 kDa.

Conclusion: This study demonstrated the potential application of B. subtilis 242 for cost-effective production of low-Mw-γ-PGA from cane molasses.

Keywords: Bacillus subtilis; Cane molasses; Low molecular weight; Poly-γ-glutamic acid.

MeSH terms

  • Bacillus subtilis*
  • Coloring Agents
  • Fermentation
  • Glutamic Acid
  • Molasses*
  • Polyglutamic Acid / analogs & derivatives

Substances

  • Coloring Agents
  • poly(gamma-glutamic acid)
  • Polyglutamic Acid
  • Glutamic Acid