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Department of Biological Sciences, Kuwait University, P.O. Box 5969. Safat 13060.Kuwait, sane@ ku01.kuniv.edu.kw, bonif(@kuc01 .kuniv.edu.kw  

ABSTRACT

The isolation of keratin-degrading fungi and actinomycetes from Kuwaiti soils, assessment and improvement of their keratinolytic activities and the characterization of the keratinases were investigated. Soil samples collected from different parts of Kuwait were baited with animal wool inPetri dishes, incubated at 25 ؛C up to 8 weeks and constantly moistened with water containing chloramphenicol to limit excessive bacterial growth. The preponderant fungal species isolated was Chrysosprium, however Fusarium, Aspergillus and Acremonium and three actinomycetes were also isolated. Induction of extracellular keratinase produced by C. zonatum, C. pannicola and a Streptomyces sp. K were selectively carried out in vitro using a keratin-impregnated medium. Considerable improvement in keratinase production was achieved by direct cultivation of the microorganisms in a keratin salt medium. Increased inocula and substrate sizes and mechanical agitation at 200 rpm leading to increased substrate degradation and a shortened fermentation time. The extracellular proteases of the keratinolytic organisms were concentrated from the culture media by ammonium sulfate fractionation at 80% for physio-biochemical characterization. It was concluded that keratin-degrading microorganisms producing multi-component keratinases are widely present in Kuwaiti soils. Due to biotechnological, environmental and industrial applications of keratinases further studies are warranted.

Keywords: fermentation improvement; keratin-degrading microorganisms; keratinase characterization