Sulfitolytic and keratinolytic potential of Chryseobacterium sp. RBT revealed hydrolysis of melanin containing feathers

Abstract

In black feathers, melanin is embedded in keratin matrix that makes feather more resistance to the microbial degradation. Chryseobacterium sp. RBT previously isolated from the poultry waste disposable site revealed strong sulfitolytic and keratinolytic activities. Maximum keratinase activity was observed at 48 h (89.12 U ml−1) showed 83 % of native black feather degradation. The concentration of free sulfhydryl groups released during degradation was 0.648 × 10−4 M (12 h), 2.144 × 10−4 M (96 h), and however, declined on prolong incubation to 1.752 × 10−4 M (120 h). Melanin was released in the degradation medium after microbial exploitation of black feather. After purification, melanin was dark brown colored powder insoluble in water, 5 M HCL, ethanol, methanol, benzene, chloroform, and acetone; whereas, soluble in KOH and NaOH. On exposure to oxidizing and reducing reagents feather melanin showed decolorization, while formed a brown precipitate when reacted with FeCl3. The spectroscopic characterization of isolated melanin demonstrated absorption at infra-red region. Similarly, UV–visible scan confirmed that increase in the wavelength progressively declined the absorbance of pigment. The crude keratinase enzyme (2 % v/v) produced during degradation showed complete dehairing of goat skin within 20 h.

Biochemical and Molecular Characterization of a Thermostable Alkaline Metallo-Keratinase from Bacillus sp. Nnolim-K1

“…Similarly, Chryseobacterium sp. RBT achieved 83% degradation of melanized feather after 48 h of incubation [ 8 ]. Bacillus altitudinis GVC11 significantly dismembered white and melanized feathers after 48 h and 96 h of cultivation, respectively [ 37 ].…”

“…Some keratinolytic bacteria and their respective feather biodegradation timeline include Chryseobacterium sp. RBT after 48 h [ 8 ], Bacillus subtilis after 72 h [ 9 ], Streptomyces sp. S7 after 96 h [ 10 ], and B. licheniformis PWD-1 after 10 days [ 6 ].…”

Citrobacter diversus-derived keratinases and their potential application as detergent-compatible cloth-cleaning agents

“…In this study, we first determined the ability of the bacterium C. diversus to degrade chicken feathers in a submerged fermentation medium. As a result of microbial growth and metabolism of amino acids derived from protein hydrolysis, increases in turbidity and pH of the medium were observed, demonstrating the ability of this bacterium to efficiently degrade keratin [30]. The keratin degradation ability of C. diversus demonstrated in this study (~85% in 36 h) was higher than that of the bacterium Kocuria rhizophila strain p3-3, which was previously reported to degrade only 52% of chicken feathers in 96 h of fermentation in submerged culture [31].…”

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

“…Globally, 8.5 billion tons of poultry feather waste has been produced annually. In 2018, India produced 4.6 million tons of broiler chicken [3] and approximately 350 million tons of feather waste generated every year [4] and the feathers are indiscriminately dumped into the environment [5]. The accumulation of feathers in the environment leads to a variety of human ailments including chlorosis, fowl cholera, mycoplasmosis, and the outbreaks of H5N1 virus [6,7].…”