Macarena Mellado

Microalgae are valuable biotechnological resources due to their high productivity and their capacity to synthesize compounds with nutritional and antioxidant functions. However, in the Santa Elena Peninsula (Ecuador), their use in aquaculture is limited to commercial strains. In this study, native microalgae were isolated and evaluated for their nutritional value in aquaculture. Samples were collected at five coastal sites, cultivated under controlled conditions, and characterized using optical microscopy and SEM, identified at the molecular level through the 28S rRNA gene, and their biochemical profiles were analyzed, including carotenoid quantification. The isolates were identified as PM-UPSE-006 (Tetradesmus obliquus), PM-UPSE-007 (Conticribra weissflogii), PM-UPSE-016 (Halamphora coffeiformis), PM018 (Dunaliella sp.), and PM-UPSE-022 (Chlorella vulgaris), with T. obliquus and H. coffeiformis being recorded for the first time in the peninsula. The highest growth rates were observed in T. obliquus, Dunaliella sp., and C. vulgaris, while Dunaliella sp. and C. vulgaris stood out for their protein content (57.28% DM and 55.37% DM), T. obliquus for carbohydrates (40.5% DM), and H. coffeiformis, Dunaliella sp., and C. vulgaris for carotenoids (0.53–1.60% DM). These results demonstrate their ex situ adaptability, competitive growth, and noteworthy biochemical profiles, establishing them as promising biotechnological resources for sustainable aquaculture.

Osorno volcano (41.1° S, 72° W) is located in the Andean Southern Volcanic Zone. The volcano lies within a national park as part of the protected areas system. This setting provides an opportunity to compare soil microbial communities between sectors with (H) and without (NI) anthropogenic activities within a volcanic territory. To do so, we selected one of the most visited volcanoes in Chilean Patagonia to examine composition, diversity (taxonomic and phylogenetic), and co-presence and mutual exclusion interaction networks between members of volcanic soil bacterial communities. Soil DNA was extracted, and the 16S rRNA gene was analyzed by high-throughput DNA sequencing, followed by taxonomic identification. The most prevalent phylum across all sites (H and NI) was Pseudomonadota, followed by Acidobacteriota, Actinobacteriota, and Chloroflexota. Based on taxonomic and phylogenetic indices, we found that the diversity of bacteria was significantly less in the humanized area than in the non-intervened areas. Beta diversity analysis also revealed a clear separation between humanized and non-intervened soils. Additionally, a decrease in network connectivity was observed at NI sites. Our results provide clear evidence that anthropogenic factors, such as tourism, vehicle parking, and combustion processes, are key drivers shaping bacterial community structure in volcanic soils, with potential consequences for ecosystem health and the capacity to provide ecosystem services.