Thermal and non-thermal effects of microwave pretreatment on horse dung microbial communities used as inoculum for acidogenic fermentation.

This research paper assesses how microwave pretreatment influences the microbial community within horse dung, in turn affecting fermentation of xylose and wheat straw. It compares both thermal and non-thermal microwave pretreatment methods and observes notable changes in metabolite production and diversity in microbial fauna.

Research Methods and Pretreatment Comparisons

• The research looks into two types of microwave pretreatments: one heated to 40 degrees celsius (MW40°C) and the other heated to 95 degrees celsius (MW95°C).
• The impact of these microwave pretreatments is compared with conventional thermal pretreatment heated at 95 degrees celsius (Th95°C) and an untreated control condition (Ctrl).
• Both microwave and conventional thermal pretreatments are assessed on their effectiveness in fermenting xylose and wheat straw, specifically looking at the production output.

Fermentation Production and Efficacy of Pretreatments

• The study finds the microwave pretreatment heated to 95 degrees (MW95°C) produces similar results as the conventional thermal pretreatment (Th95°C) in fermenting xylose and wheat straw.
• However, the microwave pretreatment heated at 40 degrees (MW40°C) shows results similar to the untreated control condition, which suggests that higher heat is more effective in this process.
• Notably, the two thermal pretreatments (MW95°C and Th95°C) produced 19% and 45% more respectively than the control and the MW40°C conditions, indicating thermal treatment’s importance.

Impact on Microbial Communities

• The microwave irradiation without heating has a distinct effect on the microbial community within the horse dung, increasing the alpha diversity richness. This suggests that not just thermal effects, but also the non-thermal effects of microwave treatment, can shape the microbial community.
• Specifically, the genus Ruminiclostridium, known for its hydrolytic activity, constituted at least 25% of the total relative abundance following fermentation with thermal shock pretreatment. This could be an explanation for the enhanced metabolite production from straw under these conditions.

Although this study makes some strides in understanding the influence of microwave pretreatment on horse dung microbial communities prior to xylose and wheat straw fermentation, more research is needed to further elucidate this relationship. Observation under different conditions and applied in larger scale could provide further insights.