Transcriptomic insights into lower biomass and higher cell-surface hydrophobicity of Dietzia natronolimnaea S-XJ-1 grown on alkanes compared to fatty acid esters

Production of microbial biomass, microbial cell properties, and biological function significantly vary with hydrophobic organic compound (HOC) types used by microorganisms. However, metabolic responses underlying such variations are unclear. Herein, we identified and selected a biodemulsifier, Dietzia natronolimnaea S-XJ-1, as a model bacterium utilizing different HOCs, and performed comparative transcriptomic analyses to investigate metabolic responses induced by alkanes and fatty acid esters. As compared to the rapeseed oil-cultured S-XJ-1, the liquid paraffin-cultured S-XJ-1 possessed lower biomass production and higher cell-surface hydrophobicity. For the latter, transcriptomic data revealed the upregulation of ATP-binding cassette transporters, the down regulation of transporters for hydrophilic nutrients and cell division genes such as ftsZ andftsE, indicating higher energy consumption, lower nutrient availability, and limited cell division, respectively. These metabolic responses can be responsible for lower biomass production in liquid paraffin-cultured S-XJ-1. Moreover, the upregulation of genes involved in the biosynthesis of surface proteins, poly-L-glutamine layer, and mycolic acids, such as secD, glnA, pks13, and fadD32, enhanced cell-surface hydrophobicity and the biodemulsifying activity of liquid paraffin-cultured S-XJ-1. The key genes and metabolic pathways identified in this study can direct research toward a more effective biodemulsifier design and understanding complex metabolic response profiles induced by different HOCs.

Automated summary

The production of microbial biomass, microbial cell properties, and biological function are significantly influenced by different hydrophobic organic compounds (HOCs). This study investigated the metabolic responses in Dietzia natronolimnaea S-XJ-1, a biodemulsifier, when utilizing alkanes and fatty acid esters as HOCs. The transcriptomic analyses revealed the upregulation of ATP-binding cassette transporters and the downregulation of transporters for hydrophilic nutrients and cell division genes, which may explain the lower biomass production in liquid paraffin-cultured S-XJ-1. In addition, the upregulation of genes involved in surface protein biosynthesis, poly-L-glutamine layer, and mycolic acids enhanced the cell-surface hydrophobicity and biodemulsifying activity of liquid paraffin-cultured S-XJ-1. These findings can contribute to the design of more effective biodemulsifiers and deepen our understanding of complex metabolic responses induced by different HOCs.