Comparative transcriptomics elucidates adaptive phenol tolerance and utilization in lipid-accumulating Rhodococcus...

Area of Science:

• Biotechnology
• Microbial Engineering
• Synthetic Biology

Background:

• Phenolic compounds from lignin can inhibit lignocellulose bioconversion.
• Rhodococcus opacus PD630 is a promising host for lignocellulose conversion due to its tolerance to phenolics.

Purpose of the Study:

• To understand the mechanisms of phenolic tolerance and utilization in R. opacus.
• To improve R. opacus for enhanced conversion of lignocellulosic biomass.

Main Methods:

• Adaptive evolution of R. opacus PD630 using phenol as the sole carbon source over 40 passages.
• Characterization of evolved strains, including growth, phenol consumption, and lipid production.
• Whole-genome sequencing and comparative transcriptomics to identify genetic and molecular changes.

Main Results:

• Achieved up to 373% growth improvement over wild-type R. opacus.
• Adapted strains exhibited higher phenol consumption rates (∼20 mg/l/h) and doubled lipid production from phenol.
• Identified upregulated phenolic degradation pathways and putative transporters, suggesting a novel aromatic tolerance mechanism involving phenol import.

Conclusions:

• Adaptive evolution significantly enhances R. opacus's ability to tolerate and utilize phenolic compounds.
• The identified genes and pathways are crucial for improving R. opacus for lignin valorization.
• This study provides a foundation for metabolic engineering of R. opacus for efficient production of lipid-based products from lignocellulose.