Gutiérrez Moraga, Ana

Cancer is the second leading cause of death in the world and colorectal cancer is the only cancer that has shown a sustained increase in mortality in the last decade. In the search for new chemotherapeutic agents against cancer, extremophilic microorganisms have shown to be a potential source to obtain molecules of natural origin and with selective cytotoxic action towards cancer cells. In this work we analyzed the ability of a collection of Antarctic soil bacteria, isolated on Collins Glacier from the rhizosphere of Deschampsia antarctica Desv plant, to secrete molecules capable of inhibiting cell proliferation of a colorectal cancer tumor line. Our results demonstrated that culture supernatants from the Antarctic bacteria K2I17 and MI12 decreased the viability of LoVo cells, a colorectal adenocarcinoma cell line. Phenotypic and genotypic characterization of the Antarctic bacteria showed that they were taxonomically related and nucleotide identity analysis based on the 16S rRNA gene sequence identified the bacterium K2I17 as a species belonging to the genus Bacillus. © 2023, Universidad de la Frontera. All rights reserved.

In this study, bacterial isolates C1-4-7, D2-4-6, and M1-4-11 from Antarctic soil were phenotypically and genotypically characterized, and their antibacterial spectrum and that of cell-free culture supernatant were investigated. Finally, the effect of temperature and culture medium on the production of antimicrobial compounds was investigated. The three bacteria were identified as different strains of the genus Pseudomonas. The three bacteria were multi-drug resistant to antibiotics. They exhibited different patterns of growth inhibition of pathogenic bacteria. M1-4-11 was remarkable for inhibiting the entire set of pathogenic bacteria tested. All three bacteria demonstrated optimal production of antimicrobial compounds at 15 °C and 18 °C. Among the culture media studied, Nutrient broth would be the most suitable to promote the production of antimicrobial compounds. The thermostability exhibited by the antimicrobial molecules secreted, their size of less than 10 kDa, and their protein nature would indicate that these molecules are bacteriocin-like compounds. © 2024 by the authors.