Marjorie Jazmin Salazar Orellana

Ecuador is recognized for having a high diversity of anuran species, which are distributed mainly south of the Andes mountains. However, due to their geographic location and accessibility, there are few studies related to the culturable microbiota of these amphibians in this region. The objective of this study was to explore the bacterial and fungal biodiversity present on the skin of wild anuran species in the southern Andes of Ecuador and to observe whether geographical barriers in the region could increase the variability of the culturable microbiota through MALDI-TOF mass spectrometry. This analysis revealed the presence of 29 bacterial taxa and 9 fungal taxa, consisting mainly of: Pseudomonas chlororaphis (28%), Acinetobacter iwoffii (14%), Pseudomonas fluorescens (14%), and Hortaea werneckii (26.4%), Fusarium solani (20.5%), Syncephalastrum spp. (20.5%), respectively. Diversity varied across the five sampling locations, with geographic location proving to be a significant driver of diversity. Some of the most abundant bacterial and fungal genera have important associations with skin diseases in wildlife and humans. This work represents a glimpse into the complex biodiversity of bacteria and fungi that inhabit the skin substrate, and further studies will be needed to better understand bacterial and fungal biodiversity with potential implications for establishing conservation strategies, along with the development of necessary animal protection measures.

Nitrification is part of the nitrogen cycle that occurs naturally in ecosystems. It is related to the presence of microorganisms and their metabolism, especially bacteria, which are involved in oxidizing compounds such as NH₄⁺ and NO₂⁻ to NO₃⁻. In this study, we evaluated the nitrification potential in 12 bacteria strains that belong to the genera Aeromonas, Bacillus, Buttiauxella, Mycobacterium, Paenibacillus, Serratia, and Yersenia, which are part of the cultivable microbial community from soil in a native forest and pine forest in The Labrado area within the Machangara micro-watershed in the Andes located in the south of Ecuador. This investigation aims to identify heterotrophic and lithoautotrophic strains using specific culture media for ammonium oxidative (AOL-AOH) and nitrate oxidation bacteria (ONL-ONH). The formation of nitrifying halos in the culture media allowed the identification of 10 strains with nitrifying potential. Five strains were from the pine forest, four were isolated from the native forest, and one strain was shared between both forests. The Serratia and Yersinia genera have a high NO₂⁻ oxidation capacity. Their inoculation in synthetic water rich in nitrogenous products allowed us to determine 40% and 94% nitrite reduction percentages and cell retention times of 20 to 40 days. Our results are promising for their possible potential use in environmental bioremediation processes through inoculation in wastewater for the biological removal of nitrogenous compounds.