EBNet loves learning about extremophiles, if only because they teach us humility with respect to the limits of our current understanding of individual organisms; never mind that of the complex microbial communities which we harness for environmental protection and remediation.
In the present example, scientists from Spain and Germany have reported on bacteria capable of surviving and proliferating in very pure heavy water (>99% D2O), in sealed plastic containers for over 30 years, with no external nutrient source. Heavy water is detrimental to key metabolic functions and there are no natural environments in which such high concentrations can be found.
DNA sequencing suggests that the most abundant were from Pseudomonadota and Bacteroidota. The bacteria showed shorter gene lengths and depletion of polar and metabolically costly amino acids in comparison to related species from light water environments. Genes related to DNA transposition, repair and modification were abundant.
The authors explore potential carbon and energy sources, which genetic evidence suggests might include the polyethylene container; and also discuss the evolutionary implications of survival in such an extreme human-made environment.
For more discussion on this fascinating discovery, see the Microbiology Society News item. We congratulate the authors of the paper, and also the microbes themselves.
Metagenomic analysis of heavy water-adapted bacterial communities. Rivas-Santisteban, J., Martínez, J.M., Escudero, C., Hernández-Antolín, R., Cid-Barrio, L., Ellis, G.J., Domingo, E., Sánchez, C., Sobrino, F. and Amils, R., 2025. Microbial Genomics, 11(5), p.001414.