Feather degradation potential of Stenotrophomonas maltophilia KB13 and feather protein hydrolysate (FPH) mediated reduction of hexavalent chromium

Abstract

An efficient keratinolytic strain of Stenorophomonas maltophilia KB13 was isolated from feather disposal site of Bilaspur, Chhattisgarh, India. The strain could metabolize 10 g/l chicken feathers as sole source of carbon and nitrogen. Soluble protein, amino acid, and cysteine content were found to be maximum (690.6 ± 8.7, 688.9 ± 9.12 and 21 ± 0.36 µg/ml, respectively) at late logarithmic phase of growth. Protease and keratinase activity reached its maximum level (103.26 ± 7.09 and 178.5 ± 9.10 U/ml) at the 4th day of incubation. The feather protein hydrolysate (FPH) obtained after degradation of chicken feathers was utilized to reduce hexavalent chromium. About 78.4 ± 2.4 and 63.6 ± 2.2 % reduction of 50 and 100 mg/l Cr(VI), respectively, was observed after 60 min of incubation with FPH. Further, there was no effect of autoclaved FPH on Cr(VI) reduction indicating that any bacterial enzyme was not involved in reduction process. Cr(VI) reduction was significantly inhibited by 10 mm Hg2+ ions indicating the role of sulfur-containing amino acids in reduction process. FTIR analysis confirmed that chromium reduction occurred due to oxidation of amino acids cysteine and cystine. This study shows that FPH arising after feather degradation can be employed as a potential candidate for the reduction of hexavalant chromium.

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

“…Cr(VI) reduction was significantly inhibited by mercury ions (Hg(II)) indicating the role of sulfur-containing amino acids in reduction process. FTIR analysis confirmed that chromium reduction occurred due to oxidation of amino acids such as cysteine and cystine[93].Gram-negative bacteria Acinetobacter belongs to the wider class of Gamma-proteobacteria and has been employed for Cr(VI) reduction. It is a bacterium tolerant to many metals and oxygen demanding pollutants.…”

Microbial Enzymes Used in Bioremediation

“…3.4.21/24/99.11), can degrade keratin proteins and apply in poultry wastes' bioremediation by degrading and recycling keratinous wastes into useful byproducts. e protease enzyme, keratinase produced from Stenotrophomonas maltophilia KB13, has shown significant activity on the biodegradation of chicken feathers [126]. e keratinase enzyme produced by Bacillus sp.…”

“…have shown significant hydrolysis of keratinous wastes from poultry [129]. e products released from the degradation of feathers are rich in amino acids and nutrients and thus can be used as feed additives, fertilizers for plant growth [130], free radical scavengers, ferric ion reducing agent [131], and toxic hexavalent chromium reducing agent [126]. Keratinase is used in enzymatic environment-friendly dehairing processes in the leather industry to replace the traditional chemicals CaO and Na 2 S, which prevent toxic waste release in water bodies to avoid pollution [132].…”

Keratinase Activity of A Newly Keratinolytic Bacteria, Azotobacter chroococcum B4

“…strain kr2 8 , Aeromonas hydrophila strain FB3 8 , Stenotrophomonas spp. [9][10][11] , Chryseobacterium spp [12][13] . A fungal isolate from crocodilian feces was reported to degrade chicken feather waste within 10 days 14 .…”