Caracterización de las comunidades microbianas aerobias que habitan en las heces fecales de las iguanas verdes (Iguana iguana) y evaluación de la capacidad celulolítica de los aislados.

Abstract

The green iguana, Iguana iguana, is one of the iconic reptiles of the city; however, many aspects of its ecology are unknown including the number of populations that inhabit the region, the number of individuals that conform each population and the phylogenetic diversity of their intestinal microbiota. Previous studies suggested that this reptile belongs to the group of Reptiles Associated with Salmonellosis (RAS), which implies that its intestinal tract may be the natural host of Salmonella, thus, green iguanas are considered as a possible transmission vector of zoonotic and enteropathogenic diseases especially to humans that maintain close contact with this reptile. In order to dismiss the presence of this pathogenic bacterium, it was necessary to characterize the microbiota that inhabits the feces of green iguanas using microbiological, biochemical and machine learning approaches. Stool samples of 6 iguanas were collected in sterile containers, the feces samples were subsequently seeded for 24 h at 37°C in solid (general and selective) and liquid culture media. Six bacterial strains were isolated, purified and tentatively identified by the following biochemical tests: IMVIC, TSI and LIA. To detect the presence of Salmonella, the stool samples were enriched in peptone water and subsequently in RPV, the samples were incubated for 48 h at 42°C, then the samples that exhibited an abundant growth in RPV were seeded on XLD agar for 24 h at 37°C. The presence of Salmonella was not detected in any of the analyzed samples. The cellulolytic capacity of the bacteria that inhabit the feces was qualitatively determined in nutrient agar supplemented with 1% of CMC, a promising strain was isolated to be grown in selective CRC medium. The quantitative determination of cellulases was carried out in triplicate using test tubes containing 5 mL of the liquid selective medium CRC, the tubes were incubated for 96 h at 37°C, and the measurement of the released cellulases was performed by spectrophotometry at 48, 72 and 96 h using the method of quantification of reducing sugars by DNS. It was determined that the cellulolytic capacity of the promising bacterium was 17% lower than the positive control.