Characterization of the core microbial community governing acidogenic processes for the production of valuable bioproducts

Abstract

Abstract Volatile fatty acids (VFAs) and alcohols generated from acidogenic processes are valuable bioresources. However, how the diversity of acidogenic microorganisms and environmental factors affect their generation are still poorly understood. In this study, 18 different inocula and 42 sludges from acidogenic lab-scale reactors were collected to analyze the microbial communities and their metabolic potential using 16S rRNA genes high throughput sequencing coupled with PICRUSt2. 23 out of 30732 distinctive amplicon sequence variants were identified as the core features and 34.8% of them (e.g., Clostridium spp.) were positively correlated with the generation of the most common product acetate. PICRUSt2 shows that an average of 27% of predicted fermentation-pathway genes was assigned to the core features, suggesting their crucial roles in acidogenesis. From the network aspect, the acidogenic network had a slightly higher number of nodes (12%), but significantly lower numbers of edges (109%) and neighbors (132%) compared with the inoculum network. A total of 28 independent subnetworks from large to small scales were extracted from the acidogenic network. The decentralized distribution of core features in these subnetworks emphasized their non-co-occurring relationships. The electrode potential was the most significant environmental variable (48.2–49.3% of the explanation), positively affecting the distribution of more than 50% of the core features and fermentation pathways. Results of this study emphasized the importance of core features rather than microbial diversity in acidogenic performance and highlighted the response of the core microbial community to environmental changes, which may be applied in practical applications to optimize acidogenic performance.