Table of Contents

ABSTRACT

This study is centered on the isolation and characterization of bacteria producing the keratinase enzyme, crucial for the degradation of keratin-rich substrates. An enrichment technique was employed, utilizing natural sources such as chicken feathers, soil, and compost, to isolate keratinase-producing bacteria. Isolation yielded forty-six bacterial isolates from various sources, comprising 14 isolates from soil, 17 isolates from compost, and 15 isolates from feathers. Screening of efficient isolates was based on their robust production of keratinase, evidenced by clear zones of hydrolysis on agar-based media at 30°C for 72 hours. These isolates were identified through morphological, cultural, biochemical properties, and 16S rRNA gene sequencing, revealing potent keratinolytic strains identified as Stenotrophomonas rhizophilia, Bacillus velezensis, and Psychrobacter pulmonis with sequence similarities of 99.12%, 99.67%, and 88.54%, respectively. Optimal pH and temperature conditions for bacterial growth and enzyme activity were determined to be 7 and 30°C, respectively. Keratinolytic activity was observed during growth in liquid basal medium containing 1% of the feathers as carbon and nitrogen sources, resulting in complete decomposition within eight to nine days. Partial purification of the crude keratinase was achieved using 40% ammonium sulfate precipitation, maintaining pH 7 throughout the process. This study contributes valuable insights into the potential applications of these keratinolytic bacteria in various biotechnological and environmental remediation endeavors.

Keywords: chicken feather, keratinolytic activity, biodegradation, bacterial keratinase; environmental sustainability