Feathers, as a waste, are produced in large quantities from poultry processing industry every year. In this paper, feathers were biodegraded by Stenotrophomonas maltophilia DHHJ which was isolated from soil samples. The results show that the optimal conditions for the feather degradation and the keratinase production are 2.5% feather as substrate, the initial pH of 7.8 and cultivation at 40 °C for 5 days. Salts, KCl and NaCl, can increase feather degradation slightly. The proper concentration of Tween 80 can enhance keratinase production significantly. EDTA, as a metalloprotease inhibitor, greatly inhibits keratinolytic activity.

This paper is concerned with the diffusive Leslie–Gower prey–predator model with weak diffusion. Assuming that the diffusion rates of prey and predator are sufficiently small and the natural growth rate of prey is much greater than that of predators, the diffusive Leslie–Gower prey–predator model is a singularly perturbed problem. Using travelling wave transformation, we firstly transform our problem into a multiscale slow-fast system with two small parameters. We prove the existence of heteroclinic orbit, canard explosion phenomenon and relaxation oscillation cycle for the slow-fast system by applying the geometric singular perturbation theory. Thus, we get the existence of travelling waves and periodic solutions of the original reaction–diffusion model. Furthermore, we also give some numerical examples to illustrate our theoretical results.