Effect of m_C/m_N on Acidification Characteristic of a New Complex Microbial Community LZF-12 with High Cellulose-Degradation Ability

Abstract

The key rate-limiting step of methane production by dry anaerobic fermentation with straw as main materials is acidication phase, and carbon nitrogen ratio (mC/mN) is major factor in affecting microbial fermentation performance. In this study, a batch test was carried out to investigate the effect of different mC/mN ratio on acidogenic fermentation performance by means of a new medium-temperature complex microbial community LZF-12 with high efficent lignocellulosic degration, which straw and peptone were sole carbon and nitrogen respectively in reaction system. The results showed that flora growth of LZF-12 increased graduately along with the dicrease of mC/mN ratio, especially that the mC/mN ratio reached 5.0, the growth rate of microbial flora was obviously better than that of other mC/mN ratio, and pH revealed similar change trend that finial pH was between 6-7 along with different mC/mN ratio. Analysis of straw weightlessness revealed that substrate degradation rate achieved above 70% at the condition of diffenent mC/mN ratio, and fermentation was typically acetate-type, which main liquid end production were volatile fatty acid (VFA) comprising 90% acetate, butyate and a small amount of ethanol and propionate. This work presents important analysis of fermentation property together with carbon nitrogen scale applicable for biodegradation process of cellulose by complex microbial community LZF-12, and is benefical to technological optimization of dry anaerobic straw fermentation.