TABLE 1.
Some bacteria having capability to degrade feathers.
| Strain | Remarks | References |
| Bacillus amyloliquefaciens | Two extracellular keratinolytic proteases produced by S13 were purified. These two enzymes were with 47 and 28 kDa, respectively | Hamiche et al., 2019 |
| Bacillus cereus | A strain KB043 was shown to be able to produce keratinase | Swetlana and Jain, 2010 |
| This strain producing keratinase was screened from the halophilic environment | Arokiyaraj et al., 2019 | |
| A strain was able to degrade feathers by producing keratinase | Jeevana Lakshmi et al., 2013 | |
| A strain Wu2 was able to produce keratinolytic enzyme using feather as the sole carbon and nitrogen sources | Lo et al., 2012 | |
| Bacillus thuringiensis | This stain is able to degrade heat-treated feather. Additives in the medium affected feather degradation | Sahni et al., 2015 |
| A strain AD-12 was able to produce detergent-stable serine keratinolytic proteinase with a molecular weight of 39 kDa | Gegeckas et al., 2014 | |
| Stenotrophomonas maltophilia | This stain was isolated from the gut of a spider. Three enzymes were purified from this strain | Saravanan and Dhurai, 2012 |
| Strain BBE11-1 secrets two keratinolytic proteases. These two enzymes-KerSMD (48 kDa) and KerSMDF (40 kDa) were overexpressed in E. coli | Fang et al., 2014 | |
| A strain R13 was able to produce keratinolytic enzyme using chicken feathers as the sole carbon and nitrogen sources | Jeong et al., 2010b | |
| A strain BBE11-1 was able to secrete keratinase and degrade wool waste | Fang et al., 2013 | |
| A strain R13 was isolated and able to produce keratinolytic enzyme in the chicken feather medium | Jeong et al., 2010b | |
| Bacillus sp. | Bacillus strains were able to produce keratinase | Lin et al., 1999; Gegeckas et al., 2018 |
| Three strains were used to convert feather into feather hydrolysate | Callegaro et al., 2018 | |
| Quite a few Bacillus sp. strains were screened from marine environment and produced keratinase | Herzog et al., 2016 | |
| A strain was able to degrade feather by producing alkaline keratinase and disulfide reductase | Rahayu et al., 2012 | |
| A metalloprotease with a molecular weight of 134 kDa was purified from the strain | Lee et al., 2002 | |
| Bacillus aerius NSMk2 | Complete degradation of white chicken feather was observed in 3 days | Bhari et al., 2018 |
| Bacillus thuringiensis | This stain is able to degrade heat-treated feather. Additives in the medium affected feather degradation | Sahni et al., 2015 |
| A strain AD-12 was able to produce detergent-stable serine keratinolytic proteinase with a molecular weight of 39 kDa. The enzyme was characterized | Gegeckas et al., 2014 | |
| Bacillus licheniformis | A strain K-508 was isolated having feather degrading activity and its fermentation product exhibited protease activity | Manczinger et al., 2003 |
| A gene of keratinolytic protease was identified in strain PWD-1 that could produce keratinase | Lin et al., 1992, 1995 | |
| A strain K-508 was able to degrade feather with several proteases secreted | Manczinger et al., 2003 | |
| The crude enzyme produced by strain ALW1 was able to degrade native feather up to 63% in redox free system | Abdel-Fattah et al., 2018 | |
| The strain ATCC 21415 was used to treat biostimulants which can affect bioremediation of soil | Rodríguez-Morgado et al., 2015 | |
| Extracellular proteins of this strain were identified when the strain used different feathers as substrates | Parrado et al., 2014 | |
| The keratinase from strain BBE11-1 was mutated based on computational design. The mutant was expressed in B. subtilis and exhibited enhanced thermal stability | Liu et al., 2013 | |
| A strain ER-15 was able to produce a 58 kDa keratinase which could hydrolyze several protein complexes | Tiwary and Gupta, 2010 | |
| The keratinase produced in this stain was expressed in B. subtilis | Wang and Shih, 1999 | |
| Bacillus subtilis | Whole cell mutagenesis was used to improve the enzymatic activity | de Paiva et al., 2018 |
| A strain DP1 was isolated and was able to produce keratinase that was stable range of pH (8–12) and temperature (20–50°C) | Sanghvi et al., 2016 | |
| A strain PF1 was used to simultaneously produce keratinolytic protease and other enzymes using feather containing medium | Bhange et al., 2016b | |
| A strain NRC3 was able to produce thermal stable metallo-keratinase (32 kDa) | Tork et al., 2013 | |
| A strain BF11 was able degrade feather | Jeevana Lakshmi et al., 2013 | |
| A strain RM-01 produced keratinase in solid-state fermentation using chicken feathers as substrate | Rai et al., 2009 | |
| Strain S8 was able to degrade feather and produce indoleacetic acid. This strain also exhibited antifungal activities | Jeong et al., 2010a | |
| A strain was able to degrade feathers and the products could also inhibit bacterial growth | Liu et al., 2017 | |
| Bacillus pumilus | Adding cysteine in feather medium could increase enzyme activity | Kim et al., 2005 |
| A strain was able to produce keratinase using feather as substrate. The produced enzyme was able to remove the blood stains from cloth without affecting its fiber properties | Ramakrishna Reddy et al., 2017 | |
| A strain FH9 was able to produce keratinase which was characterized. KS12 produced a thermal stable enzyme | Rajput et al., 2010; Abdel-Naby et al., 2017 | |
| A strain A1 was able to degrade feathers and the produced feather protein hydrolysate exhibited antioxidant activity | Fakhfakh et al., 2011 | |
| Bacillus sphaericus and Bacillus thuringiensis israelensis | This entomopathogenic bacterial were able to degrade feathers, indicating that this waste can be converted into mosquitocidal biopesticides | Poopathi and Abidha, 2008 |
| Bacillus tequilensis | A 28 kDa protease was overexpressed in E. coli and purified | Zaraî Jaouadi et al., 2015 |
| Bacillus pseudofirmus | A strain FA30-1 was able to degrade feather completely and an enzyme was purified | Kojima et al., 2006 |
| Brevibacillus parabrevis | A surfactant-resistant enzyme was purified from this strain | Zhang et al., 2016 |
| Bacillus megaterium | A strain SN1 was able to degrade feather and produce caesinolytic enzyme in feather medium | Agrahari and Wadhwa, 2012 |
| A strain was found to be able to degrade feathers and other keratin-rich materials | Park and Son, 2009 | |
| Brevibacillus sp. | Production and purification of one 83.2 kDa keratinase from strain AS-S10-II were carried out | Rai and Mukherjee, 2011 |
| Chryseobacterium sediminis | This strain was able to grow using feather as sole carbon and nitrogen sources. It degraded feather and antioxidant and indole-3-acetic acid production were observed | Kshetri et al., 2019 |
| Fusarium sp. | This strain was found to be efficient in keratin degradation | Cǎlin et al., 2017 |
| Fervidobacterium islandicum | A thermophilic anaerobe was able to produce amino acids by degrading feathers. A 97 kDa enzyme could form oligomers | Nam et al., 2002 |
| Stenotrophomonas sp. | Screened strains mostly identified as S. maltophilia and S. rhizophila were able to produce keratinase | Herzog et al., 2016 |
| Geobacillus stearothermophilus | The genome of this strain encodes a keratinolytic protease which was overexpressed in E. coli. The enzyme was purified and characterized | Gegeckas et al., 2015 |
| Chryseobacterium sp. | A bacterium kr6 was able to produce feather hydrolysates which exhibited antioxidant and antihypertensive activities | Lin et al., 1992; Fontoura et al., 2014 |
| Effect of nutritional conditions on enzyme product by kr6 was explored | Riffel et al., 2011 | |
| Micrococcus sp. | A study showed that this strain was able to produce several keratinases with high molecular weights | Laba et al., 2015 |
| Pseudomonas stutzeri | This strain K4 was able to metabolize chicken feather. It could produce five keratinases | Chaturvedi et al., 2014 |
| Pseudomonas aeruginosa | A 33 kDa keratinase was purified from strain C11 which could degrade feathers | Han et al., 2012 |
| Pseudomonas sp. | A 30 kDa keratinase was isolated from a Pseudomonas strain | Tork et al., 2010 |
| Paenibacillus woosongensis | A strain could grow in a feather medium and produce keratinases. The resulting product promoted plant growth | Paul et al., 2013 |
| Xanthomonas sp. | A strain P5 was able to degrade feather through enzymes | Jeong et al., 2010c |
| Nesterenkonia sp. | A strain AL20 produced protease in the presence of chicken feather. The substrate specificity was explored | Bakhtiar et al., 2005 |
| Serratia sp. | A feather hydrolyzing enzyme was obtained from this strain. Feather substrate was able to increase the enzyme production. This enzyme was active at 60°C and pH 10 | Khardenavis et al., 2009 |
| Stenotrophomonas sp. | A strain D-1 was isolated and able to degrade chicken feather at 20°C in 2.5 days | Yamamura et al., 2002a |
| Serratia marcescens | Strain P3 was able to be produce a 53 kDa keratinase belonging to the serralysin family | Bach et al., 2012 |
| Vibrio sp. | A strain was able to degrade feathers | Bockle and Muller, 1997; Grazziotin et al., 2007 |