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Optimized production of poly (γ‐glutamic acid) (γ‐PGA) using Bacillus licheniformis and its application as cryoprotectant for probiotics
Author(s) -
Xavier Janifer Raj,
Madhan Kumarr Mrithula Mahalakshmi,
Natarajan Gopalan,
Ramana Karna Venkata,
Semwal Anil Dutt
Publication year - 2020
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1002/bab.1879
Subject(s) - cryoprotectant , food science , bran , bacillus licheniformis , casein , freeze drying , chemistry , bacteria , chromatography , biology , organic chemistry , cryopreservation , bacillus subtilis , embryo , genetics , microbiology and biotechnology , raw material
Bacteria produce poly (γ‐glutamic acid) (γ‐PGA), a polymer of l ‐ or d ‐glutamic acid, as a defense response and have gained importance due to their applications in food and pharmaceutical industry. In the present investigation, production of γ‐PGA using cost‐effective carbon substrate, characterization of the produced polymer, and its application as cryoprotectant for selected freeze‐dried probiotic bacteria were investigated. Central composite rotatable design of response surface methodology was used to study the main and the interactive effects of medium components: rice bran and casein peptone concentration. Rice bran at 35% (w/v) and casein peptone at 7.5% (w/v) were found to be optimal at an initial pH of 7.5, and incubation temperature of 37°C for 48 H produced 8.2 g/L γ‐PGA on dry weight basis. The thermal properties such as melting temperature, heat of fusion, and thermal stability were also studied. Ten percent (w/v) of γ‐PGA with 10 percent of sodium alginate (w/v) protected viability of Bifidiobacterium bifidum NCDC 235 and B. adolescentis NCDC 236 during freeze drying at –80 ˚C for 48 H. The γ‐PGA synthesized by the reported bacterium with GRAS status is suitable for food and biomedical applications.