Could co-substrate sodium acetate simultaneously promote Chlorella to degrade amoxicillin and produce bioresources?

Highlights: • Acetate enhanced amoxicillin removal rate by 13 times. • Acetate activated enzymes for amoxicillin degradation. • Acetate enhanced cell-specific growth rate by 77% and increased biomass by 36%. • The production of lipid, carbohydrate, and protein were all significantly improved. • Glutathione and peroxisome metabolism were activated for alleviating the toxicity. Integrating microalgae culture and wastewater purification is a promising technology for sustainable bioresource production. However, the challenge is that toxins in wastewater usually limit risk elimination and cause poor bioresource production. Easy-to-biodegrade substrates could alleviate the resistant stress on a bacterial community but we know little about how they function with microalgae. In this study, we tested if Easy-to-biodegrade substrates could simultaneously promote Chlorella to degrade antibiotic amoxicillin (AMO) and produce bioresources. Sodium acetate (NaAC) was used as the representative co-substrate. The results showed NaAC could enhance AMO removal by 76%. The β-lactam structure was destroyed and detoxified to small molecules, due to the up-regulation of hydrolase, oxidoreductase, reductase, and transferase. Chlorella biomass production increased by 36%. The genes encoding the glutathione metabolism and peroxisome pathways were significantly up-regulated to alleviate the antibiotic stress, and the DNA replication pathway was activated. As a result, the production of lipid, carbohydrate, and protein was enhanced by 61%, 122%, and 34%, respectively. This study provides new insights for using microalgae to recover bioresources from toxic wastewater and reveals the critical underlying mechanisms.