Rheology, oxygen transfer, and molecular weight characteristics of poly(glutamic acid) fermentation by Bacillus subtilis

Abstract

Poly(glutamic acid) (PGA) is a water-soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that PGA can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. A fundamental understanding of the key fermentation parameters is necessary to optimize the production and molecular weight characteristics of poly(glutamic acid) by Bacillus subtilis for paclitaxel and other applications of pharmaceuticals for controlled release. Because of its high molecular weight, PGA fermentation broths exhibit non-Newtonian rheology. In this article we present experimental results on the batch fermentation kinetics of PGA production, mass transfer of oxygen, specific oxygen uptake rate, broth rheology, and molecular weight characterization of the PGA biopolymer.

Poly-γ-glutamic acid: production, properties and applications

“…When a-PGA is produced synthetically, the product has a molecular mass of ,10 kDa, which limits its application. However, when PGA is produced from bacteria (c-PGA), it has a molecular mass .10 kDa and usually ranges from~100 to .1000 kDa (Richard & Margaritis, 2003;Park et al, 2005;.…”

Contribution of Glycerol on Production of Poly(γ-Glutamic Acid) in Bacillus subtilis NX-2

“…On the other hand, molecular weight is an important feature of microbial γ-PGA for the effect that it has on polymer properties [6]. However, γ-PGA produced by Bacillus genus generally has relatively high molecular weight, and such a high molecular size polymer is too viscous, rheologically unmanageable, and difficult to be modified by chemical reagents [1].…”

Improvement of poly(γ-glutamic acid) biosynthesis and quantitative metabolic flux analysis of a two-stage strategy for agitation speed control in the culture of Bacillus subtilis NX-2

“…The Bacillus species are aerobic microorganisms and oxygen supply is an important factor in their aerobic fermentation, particularly for the production of highly viscous biopolymers [3]. The agitation and aeration rate are associated with the dissolved oxygen level during the fermentation.…”