Use of Nonspecific, Glutamic Acid-Free, Media and High Glycerol or High Amylase as Inducing Parameters for ScreeningBacillusIsolates Having High Yield of Polyglutamic Acid

Abstract

Out of fifty-five Bacillus isolates obtained from ten different regional locations and sources, seven showed the ability to consistently produce specific extracellular polymeric substance (EPS) on rich as well as synthetic but nonspecific media which did not contain glutamic acid. The isolates were identified as either Bacillus licheniformis or Bacillus subtilis. The EPS from all isolates was resistant to alpha protease, proteinase K, and was thus of high molecular weight. Further it was detected after SDS-PAGE by methylene blue but not by coomassie blue R staining as in case of proteins with high proportion of acidic amino acids. Cell-free EPS, after acid hydrolysis, showed absence of carbohydrates and presence of only glutamic acid. Thus the native the EPS from all seven isolates was confirmed to be gamma polyglutamic acid (PGA) and not exopolysaccharide. The Bacillus isolate T which produced maximum polymer on all media tested had higher amylase: protease activity as compared to other strains. If inoculum was developed in rich medium as compared to synthetic medium, the PGA produced increased by twofold in the subsequent synthetic production medium. Similarly, use of inoculum consisting of young and vegetative cells also increased the PGA production by twofold though amount of inoculum did not affect yield of PGA. Though PGA was produced in even in the absence of glutamic acid supplementation in the production medium by all isolates, the yield of PGA increased by fourfold in the presence glutamic acid and the maximum yield was 30 g/l for isolate K. The supplementation of glutamine instead of glutamic acid into the medium caused an increase in the viscosity of the non-Newtonian solution of PGA.

Isolation, Identification and Evaluation of Egyptian Bacillus sp. Isolates for Producing Poly-γ-glutamic Acid

“…Increasing the inoculum over 3% had a negative impact on PGA production. Our results were in the same line with Baxi, [37] investigation who assessed 5A). Similar results were also reported by [44,45,37] who found that the production of PGA dry weight incremented 2-fold when the media inoculated by young outgrowth vegetative cells at the age of 24 h when compared to another inoculum contained a mixture of outgrowth vegetative cells and spores.…”

“…Our results were in the same line with Baxi, [37] investigation who assessed 5A). Similar results were also reported by [44,45,37] who found that the production of PGA dry weight incremented 2-fold when the media inoculated by young outgrowth vegetative cells at the age of 24 h when compared to another inoculum contained a mixture of outgrowth vegetative cells and spores. In addition, PGA productivity, yield, and conversion coefficient were the most efficient at the same inoculum state (outgrowth vegetative cells) revealing (0.16 gl , 772.5%) for Bacillus and (0.14 gl -1 h -1 , 4.5 gg -1 , 738.6%) for strain, respectively (Fig.…”

“…Increasing the inoculum over 3% had a negative impact on PGA production. Our results were in the same line with Baxi, [37] investigation who assessed inoculums from 4 to 20% (v/v).…”

“…On the microscopic level, the isolates were grampositive, rod-shaped and forming endospores. Several studies reported the importance of Bacillus found in the soil, rhizosphere and fermented food that generate exopolysaccharides such as levan, gellan, and curdlan, and Poly-ɣ-glutamic acid [20,35,36,37,38]. Here, we attempted to isolate and purify Bacillus sp.…”

<p>Enhancing ZnO-NP Antibacterial and Osteogenesis Properties in Orthopedic Applications: A Review</p>

“…Microorganisms including bacteria, fungi, and algae can also participate in ZnO-NP biosynthesis, 47,48 as these microorganisms have a self-defense mechanism for heavy metal ion exposure. 49 The preparation process can be divided into microorganism cultivation, biochemical activities of microorganisms, intra-and extracellular transport of metal ions, intracellular nucleation, and finally NP formation. 35,49 Shamsuzzaman et al 50 used a Candida albicans suspension as a reducing and capping agent, and successfully prepared quasi-spherical ZnO-NPs with a diameter of ~15-20 nm.…”