Chryseobacterium cucumeris FHN1 keratinolytic enzyme valorized chicken feathers to amino acids with polar, anionic and non-polar imino side chain characteristics

Screening and genomic evaluation of keratinolytic protease producing Chryseobacterium sp. from tannery waste and its potential application in dehairing of goat skin

Lime and Na2S, used in dehairing in the tannery industry, cause the generation of toxic wastes. Ecological security and financial issues demand a look for innovative approaches to leather dehairing free from pollution. The primary goal of this investigation was to explore keratinolytic protease producing bacteria from tannery waste, their genomic evaluation and to assess their possible use in the dehairing process. A newly isolated Gram-negative bacterium (LRI-TA6) was characterized and checked for its keratinolytic protease producing ability. The strain was identified as Chryseobacterium cucumeris through whole genome sequencing. The genome was 4,541,898 bp in size and contain 4,426 protein coding sequences (CDS) with 36.38 % of GC content. Twenty-five open reading frames (CDS) were found as protease producing genes notably DegQ (serine protease), DegS, and ATP-dependent protease DP (EC 3.4.21.-). The isolate revealed enzyme production throughout an extended pH range of 5.0 to 8.0, and a broad temperature range of 10 °C to 38 °C. The isolate LRI-TA6 was sensitive to all five antibiotics (amoxicillin, tetracycline, gentamicin, ciprofloxacin, and vancomycin) with zone diameter ranges from 17.2 ± 0.8 to 32 ± 0.0 mm. The enzyme was shown to have 29.9 ± 6.7 and 83.6 ± 0.2 U/ml of keratinolytic and proteolytic activity, respectively. By employing crude keratinase, the removal of hair from goat skin was accomplished in 18 h. This study is the first report to isolate and characterize C. cucumeris from tannery waste and also the amazing 18 h dehairing capabilities and thus might be utilized for further studies towards commercial synthesis of keratinase for use in leather processing sectors.

Crop effect and mechanism of amino acid-modified biomass ash in remediation of cadmium-contaminated soil

Lignocellulosic biomass ash (BA) has certain adsorption and passivation effects on heavy metals, but its function is generally weak. Amino acid salt can facilitate the leaching of heavy metals in soil. Therefore, modification of BA with amino acid salt may realize a higher leaching rate and better passivation of heavy metals in soil. In this study, BA was modified by amino acid hydrolysate obtained from the hydrolysis of chicken feathers by sulfuric acid. The physicochemical properties of BA and modified BA (MBA), their effects on Chinese cabbage (CC) yield and nutritional quality, and passivation effects on soil cadmium (Cd) were compared, and the related mechanisms were investigated. SEM-EDS, XRD, and FTIR demonstrated that BA was a CaCO3-type soil amendment, while MBA was a CaSO4-type soil amendment with the loading of amino acid. Compared with BA, MBA significantly increased the fresh weight, soluble sugar, vitamin C (Vc), and protein contents of CC in both non-Cd contaminated soil and Cd contaminated soil, and obviously decreased the nitrate content and Cd uptake of CC in Cd-contaminated soil. After the application of MBA, cadmium species in potted soil were transformed from higher plant availability, representing by exchangeable and carbonate-bound, into lower plant availability, representing by iron-manganese oxide bound, which was identified as the key reason for the significant reduction of Cd content in CC under MBA application.

Thermoactive metallo-keratinase from Bacillus sp. NFH5: Characterization, structural elucidation, and potential application as detergent additive

In recent times, robust green technological developments have advanced the goal of a circular economy by minimizing waste generation. The study was undertaken to explore the keratinolytic activity of chicken feather-degrading bacteria from South African soil. Isolates coded as SSN-01 and HSN-01 were identified as Bacillus sp. NFH5 and Bacillus sp. FHNM and their sequences were deposited in GenBank, with accession numbers MW165830.1 and MW165831.1, respectively. Extracellular enzyme production and thiol group generation by Bacillus sp. NFH5 peaked at 120 h with 1879.09 ± 88.70 U/mL and 9.49 ± 0.78 mM, respectively. Glutamic acid (4.44%), aspartic acid (3.50%), arginine (3.23%), glycine (2.61%), serine (2.08%), and proline (2.08%) were relatively higher in concentration. Keratinase (KerBAN) activity was highest at pH 8.0 and 90 °C but was inhibited by both EDTA and 1,10-phenanthroline. In addition, the keratinase-encoding gene (kerBAN) accessioned OK033360 had 362 amino acid residues, with molecular weight and theoretical isoelectric point of 39 kDa and 8.81, respectively. Findings from this study highlight the significance of Bacillus sp. NFH5 in the bio-recycling of recalcitrant keratinous wastes to protein hydrolysates - potential dietary supplements for livestock feeds. The properties of KerBAN underscore its application potential in green biotechnological processes.

Chryseobacterium aquifrigidense keratinase liberated essential and nonessential amino acids from chicken feather degradation

Keratinous biomass valorization for value-added products presents a high prospect in ecological management and the advancement of the bio-economy. Consequently, soil samples from the poultry dumpsite were collected. The bacteria isolated on the basal salt medium were screened for keratinolytic activity. The potent chicken feathers degrading bacteria were identified through 16S rRNA gene sequencing and phylogenetic analysis. Fermentation process conditions were optimized, and the amino acid compositions of the feather hydrolysate were likewise quantified. Ten (10) proteolytic bacteria evaluated on skimmed milk agar showed intact chicken feather degradation ranging from 33% (WDS-03) to 88% (FPS-09). The extracellular keratinase activity ranged from 224.52 ± 42.46 U/mL (WDS-03) to 834.55 ± 66.86 U/mL (FPS-07). Based on 16S rRNA gene sequencing and phylogenetic analysis, the most potent keratinolytic isolates coded as FPS-07, FPS-09, FPS-01, and WDS-06 were identified as Chryseobacterium aquifrigidense FANN1, Chryseobacterium aquifrigidense FANN2, Stenotrophomonas maltophilia ANNb, and Bacillus sp. ANNa, respectively. C aquifrigidense FANN2 maximally produced keratinase (1460.90 ± 26.99 U/mL) at 72 h of incubation under optimal process conditions of pH (6), inoculum side (5%; v/v), temperature (30°C), and chicken feather (25 g/L). The feather hydrolysate showed a protein value of 67.54%, with a relative abundance of arginine (2.84%), serine (3.14%), aspartic acid (3.33%), glutamic acid (3.73%), and glycine (2.81%). C. aquifrigidense FANN2 yielded high keratinase titre and dismembered chicken feathers into amino acids-rich hydrolysate, highlighting its significance in the beneficiation of recalcitrant keratinous wastes into dietary proteins as potential livestock feed supplements.