Improving the Anaerobic Digestion of Switchgrass via Cofermentation of Rumen Microorganisms (Rumen Bacteria, Protozoa, and Fungi) and a Biogas Slurry

Abstract

Rumen microorganisms can effectively digest lignocellulosic biomass. Various rumen microbial groups (bacteria (B), fungi (F), and protozoa (P)) make different contributions to the fermentation of the biomass material. In this study, physical, chemical, and antibiotic methods were used to treat rumen fluid to obtain the following groups: whole rumen fluid (WRF), protozoa + bacteria (PB), fungi + bacteria (FB), fungi + protozoa (FP), bacteria (B), protozoa (P), fungi (F), and negative control (CON). Subsequently, a biogas slurry was added to each rumen microbial group (at ratios of 1:1, 3:1, 1:3, 5:1, and 1:5 v/v) and the mixtures were used to ferment switchgrass. These mixtures were labeled on the basis of their inoculum and ratio; for example, the WRF and biogas slurry at ratios of 1:1, 3:1, 1:3, 5:1, and 1:5 (v/v) were labeled as WRF1, WRF2, WRF3, WRF4, and WRF5, respectively. The efficiencies of digestion by all mixtures were compared to that of monodigestion with the biogas slurry (CK). The results sho...