The solid-state fermentation (SSF) of ammoniated corn straw (ACS) by Pleurotus ostreatus Pl-5 was investigated. The SSF experiments were carried out for 20 d using ACS and corn straw (CS) as the substrates of the experimental group (EP) and control group (CP), respectively. The effects of the ammoniation pretreatment on the CS lignocellulose structure, fungal growth, enzyme production, and components of CS during the SSF process were analyzed. The ammoniation pretreatment effectively degraded the lignin and hemicellulose contents in the CS, by 15.3% and 7.7%, respectively. Thus, the in vitro digestibility (IVD) of the EP was higher than for the CP, and even higher than the ligninase activities (laccase: 661 U/g; MnP: 56.8 U/g) found in the CP. The higher cellulase activities (CMCase: 152.3 U/g; FPA: 224.7 U/g) in the EP improved the cellulose degradation, which also promoted the P. ostreatus Pl-5 growth, and the high total N content significantly increased the EP fungal biomass and amino acid contents. A shorter processing time and a higher level of nutrients were achieved by the SSF of ACS, which showed its potential for use in animal feed production.

Heavy metals polluted soil caused by sewage irrigation, industrial pollution, pesticides and fertilizers, and atmospheric deposition have a harmful effect on the environment, which is difficult to completely eliminate and will threaten the ecological environment, food safety, and human health. The treatment of soil heavy metals and soil safe utilization have become the top priority of the treatment of industrial land and farmland soil. The existing main methods of soil heavy metals remediation include physical remediation, chemical remediation and biological remediation. With changes in governance scenarios and technological innovations, the joint application of interdisciplinary technologies has become an important development direction for soil heavy metals remediation. Especially in the treatment of heavy metals polluted farmland, the combined use of multiple technologies can further improve the safe utilization of farmland. In this paper, the main bioremediation techniques of heavy metals were summarized based on the domestic and foreign literatures in order to provide reference for further research in this field.