Enrichment and characterisation of lactic acid elongating microbial community

Medium chain carboxylic acids (MCCA), such as caproic acid, are high-value chemicals with many industrial applications. The development of a biological mixed culture chain elongation (CE) process, using waste-derived lactic acid and butyric acids offers an opportunity to sustainably produce MCCA, such as caproic acid. However, the nature of the biological conversions in mixed communities are still poorly understood. In particular, the microbial groups involved in the synthesis of caproic acid are still to be uncovered. In this study, Strategies for development and optimisation of the CE community were investigated and the developed communities were characterised using DNA and RNA based 16S rRNA gene illumina sequencing. DNA and cDNA microbial community profiling from samples collected during period spanning the caproic acid accumulation lag, exponential and stationary phases during the enrichment of caproic acid producers revealed species affiliated with Ruminococcaceae were likely involved in the caproic acid synthesis. This finding will help shape the CE microbiome and allow for future precision management or engineering of the microbial communities underpinning the process.