Exploring the symbiotic bacterial community from the digestive gland of Pomacea canaliculata: phylogenetic insights, metabolic profiling, and implications on host physiology

DELLAGNOLA FEDERICO; SANCHEZ PUERTA, MARÍA VIRGINIA; CASTRO VAZQUEZ ALFREDO; VEGA, ISRAEL A

Congreso; XII CLAMA; 2023

The apple snail Pomacea canaliculata (Lamarck, 1822) is a freshwater gastropod native to the Plata basin that has spread to several locations worldwide. This snail engages in numerous and diverse endosymbiotic associations, suggesting that these interactions between the host and symbiont play a crucial role in providing nutritional benefits to the host. In this study, we provide a comprehensive description of the taxonomy, phylogeny, and metabolic profile of bacterial symbionts residing in the digestive gland (DG), a vital organ involved in multiple physiological processes such as extracellular digestion, metabolism, and xenobiotic detoxification. A library of symbiotic 16S rDNA gene was built and analysed in silico. The rDNA 16S sequences were classified into seven bacterial phyla: Bacillota (44 clones), Pseudomonadota (28 clones), Thermodesulfobacteriota (18 clones), Bacteroidota (7 clones), Chlorobiota (4 clones), Chloroflexota (2 clones), and Verrucomicrobiota (1 clone). It was defined 26 Operational Taxonomic Units (OTUs) at 97% of genetic distance. Rarefaction curves and biodiversity analyses showed that the DG bacterial community was diverse but non-evenness, with Lachnospiraceae and Azonexaceae as dominant OTUs. The phylogenetical reconstruction at low taxonomical levels permitted us to infer the functional profiles of these symbionts. The majority of eubacterial OTUs (up to 90%) were strict/facultative anaerobes, capable of digesting dietary β-polysaccharides (cellulose and chitin) and proteins (~65%), reducing metals (>50%) and fixing nitrogen (~37%). Interestingly, the most abundant OTUs were lactic acid-producing bacteria (LAB; ~40%) and/or short-chain fatty acids-producing bacteria (SCIFAs Clostridium-like; >35%), sulfate-reducing bacteria (38%) and perchlorate-reducing bacteria (17%). We hypothesize that bacterial symbionts may partially explain the host´s invasiveness by enhancing extracellular digestion capabilities, nitrogen assimilation, and the ability to tolerate different aquatic xenobiotics.