Studies on the keratinolytic enzymes of thermophilic actinomycetes.1-Production of thermostable keratinase enzyme and identification of keratinolytic thermophilic actinomycetes

ABSTRACT

One hundred and ninety thermophilic actinomycetes were isolated from different sources. Screening was carried out according to growth temperatures. Obligate thermophilic actinomycetes were picked up and examined according to their keratinolytic activity. Results indicated that five isolates have keratinase activity. The two most active keratinolytic actinomycete isolates C52 and G114 were selected and subjected to complete identification. The cultural, morphological and physiological characteristics of both isolates indicated that they belong to Theinoactinomyces vulgaris and Microbispora thermodiastatica. The effect of nutritional and environmental conditions on the growth and keratinase activity of Th. vulgaris C52 were studied. Data revealed that Th. vulgaris C52 grew better with good yield of keratinase activity by growing it on the modified Kosmatchev medium [50 ml medium/500 ml clinical bottle], in which the nitrogen and the carbon sources of the Kosmatchev medium were replaced with 1.6% [W/V] sterile chicken feather pieces and 1% [W/V] starch, using tap water with an initial pH of 7.5, inoculated with 2% [v/v] of homogenized spore suspension [containing approximately 7.5 x 10 4 spores ml-1] of one day old culture and incubated at 50§C for 4 days under static condition