Ishwar B. Bajaj

Poly (glutamic acid): An emerging biopolymer of commercial interest

Poly (γ-glutamic acid) (PGA) is water-soluble, anionic, biodegradable, and edible biopolymer produced by Bacillus subtilis. It has multifarious potential applications in foods, pharmaceuticals, healthcare, water treatment and other fields. The production of PGA has already been established on the industrial scale. Various studies regarding the fermentative production, downstream processing and characterization of PGA have been reported in the literature. This review provides updated information on fermentative production of PGA by various bacterial strains and effect of fermentation conditions and media component on production of PGA in submerged as well as solid state fermentation. Information on the application of genetic engineering for enhancement of yield of PGA, kinetic studies for production of PGA in submerged fermentation and recovery and purification of PGA is included. An attempt has also been made to review the current and potential applications of PGA. This review may contribute to further development of this commercially and academically interesting biopolymer.

A statistical approach to optimization of fermentative production of poly(γ-glutamic acid) from Bacillus licheniformis NCIM 2324.

This paper reports on the optimization of poly(gamma-glutamic acid) (PGA) production by Bacillus licheniformis NCIM 2324 using a statistical approach. One-factor-at-a-time method was used to investigate the effect of carbon sources, nitrogen sources and pH on PGA production. Plackett-Burman design was adopted to select the most important nutrients influencing the yield of PGA. After identifying effective nutrients, response surface methodology was used to develop a mathematical model to identify the optimum concentrations of the key nutrients for higher PGA production, and confirm its validity experimentally. PGA production increased significantly from 5.27 to 26.12 g/l when the strain was cultivated in the optimal medium developed by using statistical approach, as compared to basal medium.

Media Optimization for the Production of ?- Linolenic Acid by Cunninghamella echinulata var.elegans MTCC 552 Using Response Surface Methodology

?- Linolenic acid (GLA) is an intracellular primary metabolite produced by some plants and fungal species via several distinct biosynthetic pathways. It is an essential fatty acid, and is mainly used in treatment of various diseases such as rheumatoid arthritis, multiple sclerosis, schizophrenia, atopic eczema and premenstrual syndrome. It is also a precursor of a number of biologically active compounds. In present work, strains of Cunninghamella echinulata var.elegans MTCC 552, Mucor rouxii MTCC 386, Mucor hiemallis MTCC 1278 and Rhizopus stolnifer MTCC 2591 were screened for maximum production of GLA. Cunninghamella echinulata var. elegans MTCC 552 produced maximum GLA (13.7 ± 0.31 mg/g of DCW), and hence selected for further work. Many crucial factors that affect GLA production were optimized in two steps. In the first step, one factor at a time method was used to investigate the effects of media constituents. Subsequently, in the second step, concentration of media components was optimized using Response Surface Methodology (RSM). These optimizations increased the GLA production to 19.8 ± 0.35 mg/g of DCW.