The influences of illite/smectite clay on lignocellulose decomposition and maturation process revealed by metagenomics analysis during cattle manure composting.

The purpose of this study was to analyze the effects of illite/smectite clay (I/S) on lignocellulosic degradation and humification process via metagenomics analysis during cattle manure composting. The test group (TG) with 10% I/S and the reference group (RG) were established. The results indicated that the addition of I/S made the degradation rate of cellulose, hemicellulose and lignin in TG (1.56%, 29.01%, 19.95%) was higher than that in RG (1.16%, 17.24%, 13.14%). Compared with RG, the abundance values of AA2, AA10, GH1 and GH10 in TG increased by 15.18%, 29.28%, 31.08%, 21.65%, respectively. Meanwhile, humic substance (HS) content was increased by 3.49% and 7.16% during RG and TG composting. Furthermore, the microbial community in TG changed, in which the relative abundance of Actinobacteria increased and Proteobacteria decreased. Redundancy analysis (RDA) showed that the temperature was positively correlated with the abundance of AA2, AA10, GH1 and GH10, whereas the organic matter content was negatively correlated. Overall, adding I/S to the composting could stimulate microbial activity, promote the degradation of lignocellulose and humification process.