Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
2 results
Search Results
Item A marine chitinase from Bacillus aryabhattai with antifungal activity and broad specificity toward crystalline chitin degradation(Taylor and Francis Ltd., 2022) Subramani, A.K.; Raval, R.; Sundareshan, S.; Sivasengh, R.; Raval, K.Chitinases convert chitin into chitin oligomers and are also known antifungal agents. Chitin oligomers have numerous industrial applications. However, chitin’s crystalline nature requires pretreatment before breakdown into oligomers. In the study, a novel marine bacterium Bacillus aryabhattai is isolated from the Arabian Sea. Bacterial growth in different crystalline chitin substrates like chitin powder, chitin flakes, and colloidal chitin confirmed the chitinase presence in bacterium could act upon insoluble crystalline chitin with the fractional release of oligomers. The domain architecture analysis of the chitinase confirmed the presence of two N-terminal LysM domains which help enzyme action on crystalline chitin. Statistical optimization of media and Process parameters revealed glycerol, yeast extract, magnesium chloride, and manganese sulfate as significant media components along with colloidal chitin. The optimum process parameters such as pH 7, temperature 40 °C, inoculum size 12.5% (v/v), and inoculum age 20 hours enhanced the specific enzyme activity to ±146.2 U/mL, ±114.9 U/mL and ±175.4 U/mL against chitin powder, chitin flakes and colloidal chitin respectively, which is five to six times higher than basal level activity. The antifungal activity of chitinase against plant pathogenic fungi like Candida albicans and Fusarium oxysporum revealed a zone of inhibition with 14 mm diameter. © 2022 Taylor & Francis Group, LLC.Item Engineering a recombinant chitinase from the marine bacterium Bacillus aryabhattai with targeted activity on insoluble crystalline chitin for chitin oligomer production(Elsevier B.V., 2024) Subramani, A.K.; Ramachandra, R.; Thote, S.; Govindaraj, V.; Vanzara, P.; Raval, R.; Raval, K.Chitin, an abundant polysaccharide in India, is primary by-product of the seafood industry. Efficiently converting chitin into valuable products is crucial. Chitinase, transforms chitin into chitin oligomers, holds significant industrial potential. However, the crystalline and insoluble nature of chitin makes the conversion process challenging. In this study, a recombinant chitinase from marine bacteria Bacillus aryabhattai was developed. This enzyme exhibits activity against insoluble chitin substrates, chitin powder and flakes. The chitinase gene was cloned into the pET 23a plasmid and transformed into E. coli Rosetta pLysS. IPTG induction was employed to express chitinase, and purification using Ni-NTA affinity chromatography. Optimal chitinase activity against colloidal chitin was observed in Tris buffer at pH 8, temperature 55°C, with the presence of 400 mM sodium chloride. Enzyme kinetics studies revealed a Vmax of 2000 μmole min−1 and a Km of 4.6 mg mL−1. The highest chitinase activity against insoluble chitin powder and flakes reached 875 U mg−1 and 625 U mg−1, respectively. The chitinase demonstrated inhibition of Candida albicans, Fusarium solani, and Penicillium chrysogenum growth. Thin Layer Chromatography (TLC) and LC-MS analysis confirmed the production of chitin oligomers, chitin trimer, tetramer, pentamer, and hexamer, from chitin powder and flakes using recombinant chitinase. © 2024 Elsevier B.V.