(160g) Microbial Community Dynamics during the Anaerobic Fermentation of Lignocellulosic Biomass and Wastewater Activated Sludge at Two Temperatures

Lignocellulosic biomass has been considered as an abundant renewable source for the production of biofuels and biochemicals. Robust microbial communities in activated sludges could convert the carbohydrates from lignocellulosic biomass to medium chain carboxylic acids, which can be subsequently utilized as precursors to produce more valuable bioproducts. In this study, wastewater activated sludges were inoculated to pure sugar solutions and sulfite prehydrolysate for anaerobic fermentation, respectively. The fermentation has been conducted under both mesophilic (35 °C) and thermophilic (55 °C) conditions. The result indicated that lactic acid was the major product for pure sugar fermentation at 55 °C, while more medium chain carboxylic acids (such as acetic acid, propionic acid and butyric acid) were generated at 35 °C. Interestingly, it has been found that the addition of peptone could significantly promote the carboxylic acid (especially acetic acid and propionic acid) production rate and affect the acid compositional profiles. For the sulfite prehydrolysate fermentation, similar stimulation effect was observed on acid production at 35 °C, however, the sugars consumption was significantly limited at 55 °C. The reason is that the carbonyl inhibitors in the prehydrolysate showed a strong inhibitory effect at a higher temperature. Additionally, we plan to use the sulfite pretreated aspen as the substrate to investigate anaerobic digestion of woody biomass in our future studies. It is hypothesized that the supplementary of cellulase could accelerate substrate digestion, as well as acid fermentation. To better understand the microbiome-based fermentation process, whole genome sequencing (WGS) analysis will be performed to identify the predominant microbial communities associated with the carboxylic acid productions.