Production of Poly-γ-Glutamate (PGA) Biopolymer by Batch and Semicontinuous Cultures of Immobilized Bacilluslicheniformis strain-R

Abstract

Production of Polyglutamate (PGA) biopolymer by immobilized Bacillus licheniformis strain-R was intensively investigated. Preliminary experiments were carried out to address the most suitable immobilization methodology. Entrapment of Bacillus cells in alginate–agar led optimal PGA production (36.75 g/l), with 1.32-and 2.18-fold increase in comparison with alginate-or K-carrageenan-immobilized cells, respectively. During semicontinuous cultivation of agar-alginate gel-cell mixture, production of PGA by 10 ml mixture was increased from 2nd to 3rd run whereas, increased till the 4th run using 15ml mixture. Adsorption was the most suitable immobilization technique for production of PGA and the sponge cubes was the preferred matrix recording 43.2 g/l of PGA with the highest cell adsorption. Furthermore, no PGA was detected when B. licheniformis cells were adsorbed on wood and pumice. Although luffa pulp-adsorbed cells recorded the highest PGA production (50.4 g/l), cell adsorption was the lowest. Semicontinuous cultivation of B. licheniformis cells adsorbed on sponge led to increase of PGA production till the 3rd run and reached 55.5 g/l then slightly decreased in the 4th run. The successful use of fixed-bed bioreactor for semicontinuous cultivation of B. licheniformis cells held on sponge cubes (3 runs, 96 hours/run) provides insight for the potential biotechnological production of PGA by immobilized cells.

Flocculation of Real Sewage Sludge Using Poly-γ-glutamic Acid Produced by <i>Bacillus</i> sp. Isolated from Soil

“…In many cases, the preparation of γ-PGA from Bacillus sp. is carried out only by ethanol precipitation (Berekaa et al, 2009;Kongklom et al, 2012;Scoffone et al, 2013;Zhao et al, 2013). Therefore, it was performed in the same way here.…”

Ethanol fermentation of sugarcane molasses by Zymomonas mobilis MTCC 92 immobilized in Luffa cylindrica L. sponge discs and Ca-alginate matrices

“…et al(9) reported the repeated use of immobilized cells in luffa sponge for production of poly-yglutamate (PGA). The application of fed-batch cultivation of Bacillus cells adsorbed on sponge led to increase of production till the 3 rd run and reached 55.5 g/l, then slightly decreased in the 4 th run.Kar et al (18) reported the reusability ofStreptomyces erumpens cells immobilized in luffa sponge disc for production of thermostable alpha-amylase in submerged fermentation.…”

Properties and aerogel applications of a marine algal origin biocellulose produced by the immobilized Gluconacetobacter xylinus ATCC 10245

“…The immobilized G. xylinus cells by different techniques (entrapment and adsorption) were applied for BC synthesis. The production of biopolymers by immobilized bacteria using different materials were studied well (Berekaa et al, 2009). Reusing of microbial cells aimed to enhance the cell population and activity (Chitturi and Lakshmi, 2016).…”