The secret(ome) behind microbial survival in nutrient poor aquatic environments

Water scarcity has become a prevalent challenge worldwide due to climate change and poor water management. Therefore, safe, and clean water becomes of utmost importance for governments and major efforts are made to ensure bacteriological stable and high-quality drinking water. Bacteria of the genus Aeromonas, which include potential pathogens, are ubiquitous in aquatic environments and are also commonly found in drinking water distribution systems. Despite the nutrient-poor environment of these systems, Aeromonas species can survive and thrive, posing a health risk to vulnerable groups such as children, the elderly, and immunocompromised patients. Studies have shown that the presence of Aeromonas is associated with loose deposits and the presence of invertebrates, specifically Asellus aquaticus. Chitin, the structural shell component of these invertebrates, may serve as a potential nutrient source in these otherwise nutrient-poor environments. Biological polymers are among the most abundant and rich carbon sources on Earth. However, their complex structures and chemistry often make them resistant to microbial degradation and utilization as a carbon source. In this study, we demonstrate that two Aeromonas strains, commonly found in drinking water distribution systems, can efficiently degrade and utilize chitin as a sole carbon and nitrogen source. Through quantitative proteomics analysis of the cell biomass and secretome, we have identified a dedicated and diverse array of hydrolytic enzymes and pathways for chitin uptake and metabolism.¹ An extended study on a broader range of natural biopolymers revealed that Aeromonas species are capable of degrading and utilizing a variety of polymers, including starch and collagen.

In summary, this study illustrates how microbes like Aeromonas, by linking to invertebrates and other biopolymer carbon sources, can sustain themselves in nutrient-poor drinking water distribution systems. This insight lays the groundwork for developing more effective water sanitation strategies.

References:

Tugui, Claudia, et al. "Exploring the metabolic potential of Aeromonas to utilise the carbohydrate polymer chitin." bioRxiv (2024): 2024-02.