Date Published: February 22, 2017
Publisher: Public Library of Science
Author(s): Luz A. Betancur, Sandra J. Naranjo-Gaybor, Diana M. Vinchira-Villarraga, Nubia C. Moreno-Sarmiento, Luis A. Maldonado, Zulma R. Suarez-Moreno, Alejandro Acosta-González, Gillermo F. Padilla-Gonzalez, Mónica Puyana, Leonardo Castellanos, Freddy A. Ramos, Marie-Joelle Virolle.
Marine bacteria are considered as promising sources for the discovery of novel biologically active compounds. In this study, samples of sediment, invertebrate and algae were collected from the Providencia and Santa Catalina coral reef (Colombian Caribbean Sea) with the aim of isolating Actinobateria-like strain able to produce antimicrobial and quorum quenching compounds against pathogens. Several approaches were used to select actinobacterial isolates, obtaining 203 strains from all samples. According to their 16S rRNA gene sequencing, a total of 24 strains was classified within Actinobacteria represented by three genera: Streptomyces, Micromonospora, and Gordonia. In order to assess their metabolic profiles, the actinobacterial strains were grown in liquid cultures, and LC-MS-based analyses from ethyl acetate fractions were performed. Based on taxonomical classification, screening information of activity against phytopathogenic strains and quorum quenching activity, as well as metabolic profiling, six out of the 24 isolates were selected for follow-up with chemical isolation and structure identification analyses of putative metabolites involved in antimicrobial activities.
During the second half of the twentieth century, one of the major concerns in agriculture was focused on pollution originated by the extensive use of highly toxic agrochemicals such as pesticides [1, 2]. Studies since the 1970s have shown that, besides the harmful effects at the public-health level, the use of pesticides have led to the emergence of phytopathogen resistance caused by the systematic use of a product . As the presence of pathogens in crops of global economic importance is persistent, both industry and academy have increased their efforts in finding solutions to this problem.
At this stage, our integrative strategy using taxonomical information, bioactivity and metabolic profiling tools along with dereplication procedures allowed us to select six strains of Actinobacteria recovered from marine environments (161a, 208, 5, 9, 182 and 102N), as a source of novel and active compounds against phytopathogens. The preliminary identification of bioactive compounds using dereplication procedures, suggests that these strains are a rich source of compounds, including well known and novel bioactive metabolites. Our data suggest that active strains could act by means of antibiotic (antibacterial and antifungal) or quorum quenching compounds. These strains could be used for biotechnological production of biocontrol agents or for compounds production for agrochemical purposes. This study also contributed to investigate the biodiversity in the southwest Caribbean Sea as a source of unexploited microbial diversity, which has enormous potential to provide chemical compounds to develop novel biotechnological products with possible applications in the field of agriculture and environmental preservation.