Aims:  The objective of this investigation was to evaluate the chitosans produced by several species of fungi. Methods and Results:  Representatives of four species of filamentous fungi, Aspergillus niger , Rhizopus oryzae , Lentinus edodes and Pleurotus sajo‐caju , and two yeast strains, Zygosaccharomyces rouxii TISTR5058 and Candida albicans TISTR5239, were investigated for their ability to produce chitosan in complex media. Fungal chitosan was produced at 10–140 mg g –1 cell dry weight, had a degree of deacetylation of 84–90% and a molecular weight of 2·7 × 10 4 –1·9 × 10 5 Da with a viscosity of 3·1–6·2 centipoises (cP). Conclusions:   Rhizopus oryzae TISTR3189 was found to be the producer of the highest amounts of chitosan. Significance and Impact of the Study:  Commercial chitosan could be obtained from Rhizopus mycelia and would have potential applications for medical and agricultural uses.

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Isolation and identification of a thermotolerant feather-degrading bacterial strain from Thai soil as well as purification and properties of its keratinase were investigated. The thermotolerant bacterium was identified as Bacillus licheniformis. The keratinase was purified to homogeneity by three-step chromatography. The purified enzyme exhibited a high specific activity (218 U mg )1 ) with 86-fold purification and 25% yield. The enzyme was monomeric and had a molecular mass of 35 kDa. The optimum pH and temperature for the enzyme were 8.5 and 60°C, respectively. The enzyme activity was significantly inhibited by PMSF and partly inhibited by EDTA and iodoacetamide, but was stimulated by metal ions. It hydrolysed soluble proteins with a relative activity of 4-100% and insoluble proteins, including keratins, with a relative activity of 3-35%. Therefore, the enzyme could improve the nutritional value of meat-and poultry-processing wastes containing keratins, collagen and gelatin.

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