Inhibition of Erythromycin on Fermentative Hydrogen Production: Focusing on the Shifted Bacterial Communities and Functional Genes

Abstract

Dark fermentation is a renewable technology to produce hydrogen fuel. Erythromycin (ERY), a macrolide antibiotic, has been detected in various feedstocks of dark fermentation. However, the impact and related mechanism of ERY on fermentative H2 production has rarely been studied. The present study evaluated the potential inhibitory impact of ERY on dark fermentation, and analyzed the underlying mechanisms from the perspectives of bacterial communities and functional genes. It was found that, when the exposure levels were higher than 1 mg/L, ERY significantly inhibited fermentative H2 production. Bacterial community analysis showed that ERY reduced the abundance of high-yielding H2-generating bacteria (e.g. Clostridium sp.), but improved the abundance of bacteria that act in H2 consumption (e.g. Enterococcus). Metagenomic analysis further demonstrated that the abundances of the genes involved in glycolysis (e.g. HK, ppgk and PK) and three main hydrogen-producing pathways (e.g. rnfA, aceE and E1.12.7.2) decreased remarkably upon ERY exposure. The present work would deepen the comprehension of how antibiotics inhibit bioH2 production and provide theoretical basis for reducing potential inhibitory effects.

Keywords: Biohydrogen, dark fermentation, Erythromycin, Inhibition, Bacterial community, Metagenomic analysis