Aeromonas veronii and Plesiomonas shigelloides (Gammaproteobacteria) isolated from Glossogobius aureus (Gobiidae) in Lake Sampaloc, Laguna, Philippines

Abstract

Bacterial infections are high-risk factors in fisheries, with reports of high mortality among diseased fish stocks posing a threat to both capture and aquaculture fisheries in inland waters. Diseases-causing bacteria in fishes may lead to decreased yield and economic loss to fishers, whose livelihood primarily depends on landed catch. Lake fisheries are most affected by such disruptive changes because of limitations in water turnover aggravated by wastewater inputs. In this study, we isolated and characterized gut bacteria from landed catch of the gobiid Glossogobius aureus from Lake Sampaloc, a small but commercially important aquaculture area in Luzon. Isolated axenic gut bacteria were identified through Gram stain reaction, microscopy, API biochemical tests, and 16s rRNA gene sequencing. From these, we identified two species with known fish pathogenicity, namely Aeromonas veronii and Plesiomonas shigelloides which are known to thrive in disrupted and nutrient-rich habitats and cause visible damage to fish health. Interestingly, our samples have shown no such visible signs of the disease. It is therefore important for future researches to determine what conservation and management practices in small inland waters like lakes will limit potential environmental stressors that may trigger susceptibility of both capture and farmed fish species to infection. Ultimately, rehabilitation of inland water aquaculture areas such as Lake Sampaloc is essential not only to fish conservation but also to public health and local food security.