Tonnes of feathers generated from slaughterhouses and those that were being used for the removal of heavy metals in wastewaters are often contaminated with high heavy metals and other chemical agents. The toxic nature of these chemicals makes it difficult for feather degrading bacteria to degrade the feathers. An investigation was made on the effect of different concentration of heavy metals on the keratinase activity and feather degrading ability of immobilised cells of Bacillus sp khayat. PH 8, temperature 27�C, gellan gum concentration of 0.8% and 250 beads per 100 ml of heavy metals free media were the optimum conditions to achieve highest keratinase yield and complete feather degradation within 18 h. Immobilised cells were able to secrete higher keratinase enzyme in the presence of 30 ppm Ag, 20 ppm Co and 15 ppm Cu. While feather degradation and keratinase yield were inhibited by above 5 ppm of Hg, Pb and Zn, up to 10 ppm of As and Cd have no effect on the duo. Immobilised cells were successfully used to degrade 5 g/L of feathers in the presence of individual 30 ppm Ag, 20 ppm Co, 15 ppm Cu, and combination of 5 ppm each of Ag, As, Co, Cu and Ni for 10 and 6 consecutive cycles respectively in a semi-continuous mode of cultivation without desorption. The beads used to degrade feather in the presence of a particular heavy metals were successfully used to degrade other feather laden with other metals. Enhanced keratinase activities and 90-100% feather degradations by gellan gum entrapped Bacillus sp. khayat in the presence of various concentrations of chemically known toxic heavy metals showed that the Bacillus has a relatively high tolerance to heavy metals while still maintaining its feather degrading ability. This property makes the Bacillus a potential tool not only in the bioremediation and waste management of heavy metal laden feathers, but also in the production of keratinase protease for industrial usage.

Biodegradation of agricultural wastes, generated annually from poultry farms and slaughterhouses, can solve the pollution problem and at the same time yield valuable degradation products. But these wastes also constitute environmental nuisance, especially in Malaysia where their illegal disposal on heavy metal contaminated soils poses a serious biodegradation issue as feather tends to accumulate heavy metals from the surrounding environment. Further, continuous use of feather wastes as cheap biosorbent material for the removal of heavy metals from effluents has contributed to the rising amount of polluted feathers, which has necessitated the search for heavy metal-tolerant feather degrading strains. Isolation, characterization and application of a novel heavy metal-tolerant feather-degrading bacterium, identified by 16S RNA sequencing as Alcaligenes sp. AQ05-001 in degradation of heavy metal polluted recalcitrant agricultural wastes, have been reported. Physico-cultural conditions influencing its activities were studied using one-factor-at-a-time and a statistical optimisation approach. Complete degradation of 5�g/L feather was achieved with pH 8, 2% inoculum at 27��C and incubation period of 36�h. The medium optimisation after the response surface methodology (RSM) resulted in a 10-fold increase in keratinase production (88.4 U/mL) over the initial 8.85 U/mL when supplemented with 0.5% (w/v) sucrose, 0.15% (w/v) ammonium bicarbonate, 0.3% (w/v) skim milk, and 0.01% (w/v) urea. Under optimum conditions, the bacterium was able to degrade heavy metal polluted feathers completely and produced valuable keratinase and protein-rich hydrolysates. About 83% of the feathers polluted with a mixture of highly toxic metals were degraded with high keratinase activities. The heavy metal tolerance ability of this bacterium can be harnessed not only in keratinase production but also in the bioremediation of heavy metal-polluted feather wastes. � 2016