Isolation, characterization and optimization of keratinolytic bacteria from chicken feather waste dumping site

Abstract

Chicken feathers are considered to be the waste products of poultry industry and can create a solid waste problem in the environment. Keratinases have the potential to degrade insoluble keratin predominantly present in feathers, hair, horns, and hooves. The aim of present study is to isolate, screen, and identify keratinolytic bacteria from feather waste dumping site and to optimize the culture conditions for maximum keratinase production and subsequent degradation of feathers. Fourteen bacteria were isolated from the feather waste dumping site at Virudhunagar, Tamil Nadu, India, and were screened for their keratinolytic property. Comparatively, three bacteria displayed better keratinolytic activity. Based on morphological and biochemical characteristics and 16S rRNA gene sequence analysis, they were identified as Bacillus licheniformis, Glutamicibacter arilaitensis, and Serratia marcescens, respectively. The effect of temperature, pH, feather concentration, and various substrates on the growth parameters of those bacteria was studied. The growth and protein production was high at 40°C for all bacteria. B. licheniformis and S. marcescens produced more protein at pH 8.5, whereas G. arilaitensis produced more protein and grown well at pH 8. Hence, three bacteria were subjected to submerged fermentation using chicken feather powder (1%) as Carbon and Nitrogen sources. Among them, G. arilaitensis is the superior in degrading feathers producing more protein (2.15 ± 0.04 mg/ ml) and amino acids (0.498 ± 0.019 µg/ml). The microscopically observed smears of feather hydrolysates revealed that G. arilaitensis degraded the chicken feathers more efficient comparatively other two bacteria.