RESUMO
Aims: The present investigation describes the utilization of Aspergillus oryzae var. effusus NRC14 biomass producing kojic acid in the production of fine chemicals that have valuable applications such as chitin, chitosan, β-1, 3 glucan and /or their derivatives. Methodology: Experiments of cell growth and substrate utilization were conducted in static cultures with identified medium composition. The technology involved in the extraction of their biopolymers is quite simple and the size scale is compatible with those currently used. This work was performed in Department of Microbial Chemistry, NRC. Results and Conclusion: The utilization of A. oryzae var. effusus NRC14 biomass waste actually will cover a part of the cost production of kojic acid; therefore, clean cell walls preparations were isolated from the fungus biomass at different stages during kojic acid fermentation in a glucose salts medium. The major chitin constituent was extracted from the prepared cell walls from six days cultured A. oryzae var. effusus NRC14 biomass by cold conc. HCl or by 5% of LiCl/ DMAA solvent in yields 4.78% and 2.44%, respectively. Among the chitin family, chitosan has received special attention since it has several applications. Chitosan was extracted from alkali insoluble material (cell wall) obtained from 12 days cultured biomass by using different concentrations of acetic acid (0.5-2.5%) the results showed that the highest yield of chitosan was 4.65% at a concentration of 2% acetic acid. The isolated product was characterized by infrared spectrum. Chitosanglucan complex was isolated in 17.94% yield by treating the A. oryzae var. effusus NRC14 biomass produced from kojic acid production for 12 days with 40% aqueous NaOH for 6h. at 95°C. Chitosan-glucan complex was fractionated into its components. The amount of extracted chitosan was 3.5%; the residue obtained after solubilization of chitosan by acid treatment was characterized as being mostly insoluble glucan (94%). Chitin-glucan complex was isolated from 6 days cultured A. oryzae var. effusus NRC14 biomass in yield 17.034%. The lyophilized product was fractionated into its components (chitin and glucan) in yields 16.36% chitin, 82.72% β, 1-3 glucan. The infrared spectra of the isolated products as well as of standard samples proved the identity of the isolated materials as chitosan, chitin and glucan.
RESUMO
An alkaline protease was purified from a halophilic and thermotolerant potent alkaline protease-producing strain Streptomyces pseudogrisiolus NRC-15 using ammonium sulphate precipitation and Sephadex G-100 column chromatography. The enzyme was purified to 77.24-folds with a yield of 91.8% and the specific activity was 112 U/mg of protein. The protease showed a single band on SDS-PAGE with its molecular mass at 20 kDa and exhibited a maximum relative activity of 100% using casein as a substrate and. The enzyme had an optimum pH of 9.5 and displayed optimum activity at 50°C. The enzyme activity was completely inhibited by the serine protease inhibitor PMSF, suggesting the presence of serine residue in the active site. The enzyme activity was increased by the metal ions Ca2+, Co2+, K+ and Mg2+. The enzyme significantly enhanced the removal of stains when used with wheel detergent, indicating the potential of the enzyme for using as a laundry detergent additive to improve the performance of heavy-duty laundry detergent.