Integrative analyses to investigate the link between microbial activity and molecules degradation during anaerobic digestion

Anaerobic digestion (AD) is a promising biological process which converts waste into sustainable energy. To fully exploit ADs capability, we need to deepen our knowledge of the microbiota involved in this complex bioprocess. High-throughput methodologies open new perspectives to investigate AD process at the molecular level, supported by recent data integration methodologies to extract relevant information. In this study, we investigated the link between microbial activity and substrate degradation in a lab-scale anaerobic co-digestion experiment, where bioreactors were fed with 9 different mixtures of three co-substrates (fish waste, sewage sludge, and grass). Samples were profiled using 16S rRNA sequencing and untargeted metabolomics. In this article, we propose a suite of multivariate tools to statistically integrate these data and identify coordinated patterns between groups of microbial and metabolic profiles specific of each co-substrate. Five main groups of features were successfully evidenced, including cadaverine degradation found to be associated with the activity of microorganisms from the order Clostridiales and the genus Methanosarcina. This study highlights the potential of data integration towards a comprehensive understanding of AD microbiota.