Identifying biodegradation pathways of cetrimonium bromide (CTAB) using metagenome, metatranscriptome, and metabolome tri-omics integration

Traditional research on biodegradation of emerging organic pollutants involves slow and labor-intensive experimentation. Currently, fast-developing metagenome, metatranscriptome, and metabolome technologies promise to expedite mechanistic research on biodegradation of emerging organic pollutants. Integrating the metagenome, metatranscriptome, and metabolome (i.e., tri-omics) makes it possible to link gene abundance and expression with the biotransformation of the contaminant and the formation of metabolites from this biotransformation. In this study, we used this tri-omics approach to study the biotransformation pathways for cetyltrimethylammonium bromide (CTAB) under aerobic conditions. The tri-omics analysis showed that CTAB undergoes three parallel first-step mono-/di-oxygenations (to the alpha, beta, and co-carbons); intermediate metabolites and expressed enzymes were identified for all three pathways, and the beta-carbon mono-/di-oxygenation is a novel pathway; and the genes related to CTAB biodegradation were associated with Pseudomonas spp. Four metabolites - palmitic acid, trimethylamine N-oxide (TMAO), myristic acid, and betaine - were the key identified biodegradation intermediates of CTAB, and they were associated with first-step mono-/di-oxygenations at the alpha/beta-C. This tri-omics approach with CTAB demonstrates its power for identifying promising paths for future research on the biodegradation of complex organics by microbial communities.

Automated summary

Traditional research methods for the biodegradation of emerging organic pollutants are slow and labor-intensive, but new metagenome, metatranscriptome, and metabolome technologies offer a faster and more efficient approach. By integrating these three "omics" approaches, it is possible to link gene abundance and expression with the biotransformation of the pollutants and the formation of metabolites. In this study, the tri-omics approach was used to study the biotransformation pathways of cetyltrimethylammonium bromide (CTAB) under aerobic conditions. The analysis revealed three parallel first-step oxygenation pathways and identified key intermediates and enzymes involved in the biotransformation of CTAB. This study highlights the potential of the tri-omics approach for future research on complex organic biodegradation by microbial communities.