Screening of Poly-Glutamic Acid (PGA)-Producing Bacillus Species from Indian Fermented Soybean Foods and Characterization of PGA

Abstract

This present work is aimed to screen the PGA-producing Bacillus spp. from naturally fermented soybean foods of Arunachal Pradesh in India and to characterize the poly-glutamic acid (PGA) extracted from Bacillus spp. A total of 50 isolates were screened for high stickiness from 165 bacterial isolates isolated from 34 samples viz., grep chhurpi, peha/paeha, peron namsing, and peruñyaan. Based on 16S rRNA gene sequence analysis, 50 isolates were identified as Bacillus spp. Viscosity of 50 species of Bacillus were measured, out of which 7 species of Bacillus showing ≥0.03 Pa.s (30 cP) of viscosity were selected viz., Bacillus velezensis GC1-42, B. siamensis GC4-36, B. subtilis PH3-21, B. subtilis PN1-14, B. subtilis PH6-29, B. tequilensis PN9-22, and B. safensis subsp. safensis PY1-19 for PGA production. Amino acid analysis of PGA extracted from seven species of Bacillus showed high molecular weight (˃600 kDa). B. safensis subsp. safensis PY1-19, isolated from peruñyaan, showed 78.9% of glutamic acid, antagonistic properties against pathogenic bacteria and had the ability to produce phytase with no hemolytic activity. Hence, this strain was selected as a potential starter to prepare peruñyaan at laboratory, and the final product showed high stickiness and viscosity with production of PGA of around 11 g/L.

Molecular weight control of poly-γ-glutamic acid reveals novel insights into extracellular polymeric substance synthesis in Bacillus licheniformis

“…This study illustrates a promising approach for the improvement of extracellular polymeric substances with a low Mw of γ-PGA in one strain through the expression levels of pgdS using manipulation of the endogenous promoters from B. licheniformis CGMCC 2876. The viscosity is an important factor for γ-PGA production, and influenced by γ-PGA Mw [ 42 , 43 ]. The pgdS engineered strain Bl/ pP 2967 -pgdS with the lowest γ-PGA Mw increased extracellular polymeric substance production by 12.8% with low viscosity, which may be the low viscosity favouring oxygen transfer and substrate utilization [ 44 ].…”

Therapeutic and Anti-Thrombotic Properties of Some Naturally Fermented Soybean Foods of the Eastern Himalayas

“…Fermented soybean foods are the sources of bio-peptides with several health benefits, and the availability of amino acids and significant levels of antioxidant activity could also contribute to the anti-inflammatory effects [48,49]. A dominance of Bacillus subtilis in Himalayan fermented soybean foods has been reported [50], which may prevent obesity by improving transport processes and angiogenesis [51]. Interestingly, anti-diabetic properties have also been observed in some Himalayan fermented soybean foods, and probably delay the progression of type-2 diabetes [52].…”

Probiotic Properties of Lactic Acid Bacteria Isolated from the Spontaneously Fermented Soybean Foods of the Eastern Himalayas

“…Bacillus velezensis, B. siamensis, B. tequilensis, B. safensis subsp. safensis, B. inaquosorum, B. halotolerans, B. glycinifermentans, B. cereus, B. licheniformis, B. thermoamylovorans, B. coagulans, B. circulans, and B. paralicheniformis [8][9][10][11][12][13]. Species of Bacillus in the Himalayan fermented soybean foods exhibit several biological functions such as the production of poly-glutamic acid [12,14], the production of untargeted metabolites [11], anti-thrombolytic property [4,7], the production of bio-peptides [15], and the enhancement of antioxidant properties [16,17].…”