Properties of Polyglutamic Acid Produced by Bacillus subtilis ATCC 6633 in Rehydrated Whey Powder Supplemented with Different Carbon Sources

Abstract

In this study, the use of rehydrated whey powder (RWP) solutions containing different carbon sources (citric acid, ammonium sulfate, or glutamic acid) for γ-poly(glutamic acid) (γ-PGA) by Bacillus subtilis ATCC 6633 was explored. After 72 h of fermentation at 30 o C, cell growth, γ-PGA production, molecular weight by SDS-PAGE, rheological properties and NMR analysis of γ-PGA were determined. The growth of B. subtilis was significantly different during 72 h of fermentation in RWP, medium E, and RWP containing citric acid or glutamic acid. These results showed the dynamic viscosity of the 1% polymer solution was 2.5 Pa•s at 10 1/sec shear rate. The maximum γ-PGA concentration was 1.57 g/100 mL in RWP containing glutamic acid, citric acid and ammonium sulfate. Therefore, RWP as a waste product with being efficient and more economic fermentation medium to produce γ-PGA can be ideal for the industrial production.

Effects of poly-γ-glutamic acid and poly-γ-glutamic acid super absorbent polymer on the sandy loam soil hydro-physical properties

“…γ-PGA is a water-soluble substance because of its single-chain molecular structure and hydrophilic groups. It can increase the viscosity of water and subsequently alter a number of soil properties after dissolving in water [ 39 ]. γ-PGA SAP is a water-insoluble three dimensional network structure modification of γ-PGA ( Fig 1 ).…”