Screening and Functional Properties of a Complex Microbial System RSS-4 for Effective Decomposition of Rice Straws

Abstract:

A complex microbial system (CMS) RSS-4 with high ability of rice straw degradation was screened and constructed from the soils sampled from fields cultivated with straw-returning techniques for a long term in Sichuan Province by using the restricted cultivation and gradient-temperature induction methods. When RSS-4-induced rice straws degrading experiment was performed at 22°C, the pH value of the system increased at the initial stage and then slightly decreased until to 7.20. The CMC activity and xylan activity also showed an increase at the beginning and followed by an obvious decrease, with the peak values being 0.91 U and 3.40 U, respectively. At the end of fermentation (16 d), the weight of rice straws and the component cellulose and hemicellulose reduced to 45.0%, 55.5% and 44.0%, respectively, while no obvious change happened in the lignin content. It was also found that the RSS-4 by the unsterilized method has better degradation effect than that of the RSS-4￠ by the sterilized method.

Key words:Rice straw, Composite microbial system, Screening, Degradation property