Determination Of The Effects of Salt and Oil on Substance Transformation, Microbial Community, and Transcriptional Activity During Anaerobic Digestion of Food Waste Through Integrated 16s Rrna Sequencing Technology and Metatranscriptomic Analysis

Abstract

Salt and oil are two inherent components of food waste (FW) and they significantly affect the stability of anaerobic digestion (AD). Based on the quantitative detection of key substances and enzyme activities, an integrated 16S rRNA sequencing and metatranscriptomic analysis revealed the mechanisms through which salt and oil influence the biotransformation process during AD. The results demonstrated that salt = 6 g/L promoted lipid metabolism and hydrogenotrophic methanogenesis, whereas the acetoclastic pathway was inhibited. Oil = 5 g/L promoted the expression of key enzyme-encoding genes involved in the β-oxidation of long-chain fatty acids, transcription, and acetoclastic methanogenesis, promoted the enrichment of syntrophic propionate/butyrate oxidation bacteria (Syntrophomonas and DMER64). The expression of genes related to glucose metabolism, amino acid metabolism, organic acid synthesis, and quorum sensing was enhanced by salt/oil co-addition. Furthermore, salt/oil co-addition hindered the secretion of key enzymes related to methanogens by inhibiting the process of transcription.

Keywords: Salt, oil, Food waste, microbial community, Transcriptional activity.