Mycostimulator of chitinolytic activity: Thermodynamic studies and its activity against human and food-borne microbial pathogens

Chitinolytic activity and antibiosis are gaining prominence in various biotechnological fields. Dead fungal biomass (DFB) was used as a mycostimulator of chitinase production and antibiosis by Aspergillus fumigatus. The presence of DFB stimulated the synthesis of various secondary metabolites by A. fumigatus that were detected by gas chromatography-mass spectrometry analysis such as 6,8-Di-C-á-glucosylluteolin; bistrimethylsilyl N-acetyl eicosasphinga-4,11-dienine; curan-17-oic acid, 19,20-dihydroxy-, methyl ester, (19S)-; spiro[5à-androstane-3,2′-thiazolidine; retinal; Androsta-1,4-dien-3-one; Panaxydol; Costunolide; Cyclo-(glycyl-L-tyrosyl); and 2-amino ethane thiolsulfuric acid. Chitinase activity was 42.9 Units/mL with the presence DFB, where it was 10.3 Units/mL without DFB. The maximum activity of chitinase was observed at 1.5 g of dead fungal biomass, at 4 h, 50 °C and pH 6. Thermodynamic properties showed ∆H° and ∆S° values of 126 KJ mol-1 and 432 J mol-1 K-1, respectively, indicating an endothermic reaction up to 60 °C. Deviation in ∆G° values confirmed that the reaction at 10 to 20 °C is a nonspontaneous reaction, and at 30 to 60 °C the reaction has a spontaneous nature. DFB encouraged the antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, Aspergillus fumigatus, Mucor circinelloides, and Candida albicans with 2.3, 2.2, 2.8, 0.8, 0.7, and 2.2 mm inhibition zones, respectively.