Exploring the metabolic potential of Aeromonas to utilise the carbohydrate polymer chitin

Members of the Aeromonas genus are commonly found in natural aquatic ecosystems. However, they are also frequently present in non-chlorinated drinking water distribution systems. High densities of these bacteria indicate favorable conditions for microbial regrowth, which is considered undesirable. Studies have indicated that the presence of Aeromonas is associated with loose deposits and the presence of invertebrates, specifically Asellus aquaticus . Therefore, a potential source of nutrients in these nutrient poor environments is chitin, the structural shell component in these invertebrates. In this study, we demonstrate the ability of two Aeromonas strains, commonly encountered in drinking water distribution systems, to effectively degrade and utilize chitin as a sole carbon and nitrogen source. We conducted a quantitative proteomics study on the cell biomass and secretome of both strains, revealing a dedicated and diverse spectrum of hydrolytic enzymes and pathways for the uptake and metabolism of chitin. Furthermore, when the primary nutrient source was switched from glucose to chitin, more than half of the Aeromonas proteome showed significant changes. Additionally, a genomic analysis of Aeromonas species found in drinking water distribution systems suggests a general potential ability of this genus to degrade and utilize a variety of carbohydrate biopolymers. This study indicates the relation between the utilization of chitin by Aeromonas and their association with invertebrates such as A. aquaticus in loose deposits in drinking water distribution systems. This knowledge provides the foundation for the development of more effective water sanitation strategies.