Salinas Lagoon RAMSAR in Arequipa, Peru: A reservoir of halotolerant microorganisms

Díaz-Valencia Y.; Enríquez-Fernández P.C.; Rosell-Paredes L.Y.; Azurín-Muñoz J.F.; Valdez-Begazo I.L.; Ita-Balta Y.A.; Alanoca-Apaza C.M. · Microbe (Netherlands) (2025) · DOI: 10.1016/j.microb.2025.100584

Resumen

Environmental pollution in Peru, particularly from industrial effluents with high salinity or in naturally saline environments, requires sustainable solutions such as bioremediation. However, the effectiveness of conventional microorganisms is often limited under such extreme conditions. This study aimed to evaluate the diversity and metabolic capabilities of halotolerant bacteria isolated from Salinas Lagoon, located in Arequipa, Peru, a natural environment characterized by high salinity. The specific objectives were to isolate and characterize halotolerant bacteria from Salinas Lagoon, genetically identify them, and assess their metabolic activity under extreme saline conditions. Water, sediment, and soil samples were collected from various areas of the lagoon. Bacterial strains were isolated using culture BHI media with different NaCl concentrations. The most salt-resistant strains were selected and identified through 16S rRNA gene sequencing. Standard biochemical tests (TSI, LIA, MR-VP, SIM, citrate, urea, and nitrate reduction) were then conducted under increasing saline conditions (0 %, 7.5 %, and 15 % w/v NaCl) to evaluate metabolic changes in response to salinity. The results showed that lagoon water and salt flat soil samples had the highest salinity levels (up to 204 g/L) and supported the greatest bacterial growth in media containing 7.5–25 % NaCl. Eight pure halotolerant bacterial isolates were identified, representing five genera Bacillus, Marinobacterium, Oceanobacillus, Vreelandella, and Idiomarina. Biochemical analyses demonstrated that these bacteria possess considerable metabolic versatility and can adapt to varying salinity gradients. Notably, Vreelandella and Idiomarina species exhibited high salt tolerance with potential for bioremediation of heavy metals and hydrocarbons. This study provides new insights about of halotolerant microorganisms from Salinas Lagoon useful for future investigations.

Instituciones: Universidad Católica de Santa María; Universidad Católica San Pablo