Both enzymatic pathway (degradation by keratinase) and non-enzymatic pathway that is sulfitolysis occurred in the degradation process by streptomycete sp.B221.

链霉菌B221降解角蛋白的过程中不但存在角蛋白酶降解途径，而且存在非酶降解途径—亚硫酸分解作用。