Metagenomic insights into microbial mechanism of pH shifts enhancing short-chain carboxylic acid production from fruit waste anaerobic fermentation

• Published in: Industrial crops and products 2024-12, Vol.222, p.119520, Article 119520
• Main Authors: Cui, Hao-Wen, Chen, Ya-Ting, Chen, Yu-Wei, Dolfing, Jan, Li, Ben-Yan, Sun, Zhao-Yong, Tang, Yue-Qin, Huang, Yu-Lian, Dai, Wen-Ying, Cui, Qi-Jia, Cheng, Xun, Jiao, Shuo-Bo
• Format: Article
• Language: English
• Subjects: acetates; Bifidobacterium; butyrates; chemical industry; chemical oxygen demand; Clostridium; Corynebacterium; fermentation; fermenters; fruits; lactic acid; Lactobacillus; metabolites; Metagenome assembled genomes; metagenomics; Microbial community; Pathway reconstruction; propionic acid; SCCA production; Stepwise pH change; supply balance; wastes
• ISSN: 0926-6690
• DOI: 10.1016/j.indcrop.2024.119520

Short-chain carboxylic acids (SCCAs) production from waste-streams is attractive due to the increasing market demand and wide range of applications. This study investigated the influence of pH on the performance of anaerobic SCCA-producing reactors treating fruit waste and employed metagenomics to unveil the shifts and metabolic pathways of functional acidogens. Results showed that high SCCA concentrations of 45.0–65.8 g chemical oxygen demand (COD)/L were maintained at each pH. The maximum concentrations of SCCAs obtained at pH 8 (63.8 g COD/L) under alkaline conditions and at pH 5 (65.8 g COD/L) under acidic conditions were similar, yet there was a pronounced effect of pH on SCCA distribution as acetate and butyrate were the primary products at pH 6, while lactate was dominant at pH 8–10 and at pH 5–4. Key populations involved in acidogenesis at different pHs included Bifidobacterium (acetate fermenter at pH 6–7), Corynebacterium (acetate and lactate fermenter at pH 8–10), Acidipropionibacterium (propionate fermenter at pH 7–10), Clostridium (acetate, propionate, and butyrate fermenter at pH 6–5), and Lactobacillus (lactate fermenter at pH 5). This study enhances our understanding of the underlying microbial mechanism governing SCCA production from fruit waste with pH regulation, and provides guidance for the development of production processes for waste-based metabolites useful for the chemical industry. •Anaerobic SCCA production from fruit waste at pH 4–10.•High SCCA concentrations (45.0–65.8 g COD/L) were achieved upon pH shifts.•pH changes altered SCCA profile and enhanced lactate production at high and low pH.•Changing pH shifted acidogenic microbiome and metabolic pathways.•Functional similarity of microbiota drove stable SCCA production at different pHs.