Pseudomonas aeruginosa ethanol oxidation by AdhA in low oxygen environments.
2019 Sep 16;pii: JB.00393-19. doi: 10.1128/JB.00393-19
has a broad metabolic repertoire that facilitates its co-existence with different microbes. Many microbes secrete products that can then catabolize, including ethanol, a common fermentation product. Here, we show that under oxygen limiting conditions utilizes AdhA, an NAD-linked alcohol dehydrogenase, as a previously undescribed means for ethanol catabolism. In a rich medium containing ethanol, AdhA, but not the previously described PQQ-linked alcohol dehydrogenase, ExaA, oxidizes ethanol and leads to the accumulation of acetate in culture supernatants. AdhA-dependent acetate accumulation, and the accompanying decrease in pH, promotes survival in LB-grown stationary phase cultures. The transcription of is elevated by hypoxia and in anoxic conditions, and we show that it is regulated by the Anr transcription factor. We have shown that mutants, which lack an important quorum sensing regulator, have higher levels of Anr-regulated transcripts in low oxygen conditions compared to their wild type counterparts. Here, we show that a mutant, when grown with ethanol, has an even larger decrease in pH than WT that is dependent on both and The large increase in AdhA activity is similar to that of a strain expressing a hyperactive Anr-D149A variant. Ethanol catabolism in by AdhA supports growth on ethanol as a sole carbon source and electron donor in oxygen-limited settings and in cells growing by denitrification in anoxic conditions. This is the first demonstration of a physiological role for AdhA in ethanol oxidation in Ethanol is a common product of microbial fermentation, and the response to and utilization of ethanol is relevant to our understanding of its role in microbial communities. Here, we report that the putative alcohol dehydrogenase, AdhA, is responsible for ethanol catabolism and acetate accumulation in low oxygen conditions and that it is regulated by Anr.
J Bacteriol|2019 Sep 16