Keratinolytic activity of Cladosporium and Trichoderma species isolated from barbers’ landfill

Abstract

Studies were carried out on the ability of filamentous fungi to degrade keratin based substrates (human hair and chicken feather) using their keratinase. Soil samples were collected at random from barbers’ landfills in Jos city, Nigeria and were screened using the hair baiting technique. Proteolytic ability of the fungal isolates was carried out using skim milk agar. Fungal strains that showed the highest activity following the diameter zones of clearance were further tested for keratinase activity in submerged fermentation (SmF) using basal mineral medium supplemented with human hair and chicken feather as sole sources of carbon and nitrogen. A total of 17 fungal species belonging to 10 genera were isolated with Aspergillus species the most dominant. Cladosporium cladosporioides and Trichoderma viride had the highest potential to hydrolyze skim milk casein with the peak period of 72h (77.1U/ml and 50.1U/ml) for C. cladosporioides and T. viride, respectively, after which there was a decline in enzyme production. The keratinase activity of the two species on both human hair and chicken feather were highly variable. C. cladosporioides and T. viride had keratinase activity of 6.3 U/ml and 37.5 U/ml after 72h and 96h, respectively, on human hair while for chicken feather medium, C. cladosporioides had keratinase activity of 35.5 U/ml after 96h and T. viride 37.5 U/ml after 72h. The spent medium containing chicken feather showed higher specific activity for keratinase as compared to the spent human hair medium. It is deduced that these fungi may have an important role in the degradation of keratin containing wastes in a natural environment.