Jorge León

Bacterias marinas productoras de compuestos antibacterianos aisladas a partir de invertebrados intermareales

Prospective sampling activities of intertidal invertebrates in the Ancon Bay (Lima, Peru) were done in order to select marine bacteria producing antimicrobial substances. The study included the isolation of bacteria in marine agar, in vitro antimicrobial susceptibility testing and electronic microscopic observations. We report the isolation, phenotypical characterization and antimicrobial properties of 10 strains of marine bacteria including the genus Vibrio, Pseudomonas, and Flavobacterium, and the order Actinomycetae that inhibit human pathogens. The results indicate that the marine invertebrates would be sources of bacteria producing antibiotic substances.

Estudio de actinomicetos marinos aislados de la costa central del Perú y su actividad antibacteriana frente a Staphylococcus aureus Meticilina Resistentes y Enterococcus faecalis Vancomicina Resistentes

Objectives. To determine the antimicrobial potential of marine actinomycetes against drug-resistant pathogens represented by strains of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE). Materials and methods. Strains of actinomycetes (29) isolated from marine sediment were evaluated by their characteristics in two culture media and by testing their inhibitory capacity by in vitro antagonism against multi-drug resistant (MDR) pathogenic bacteria for MRSA and VRE. Organic extracts of 3 selected actinomicetes were processed to determine the minimum inhibitory concentration (MIC) of the active compound. Results. Most isolated actinomycetes belong to a homogeneous group of write-gray actinomycetes with a good growth in Marine Agar. The inhibitory rates of the isolates were above 85% for both pathogens with inhibition zones greater than 69 and 78 mm in diameter for MRSA and VRE respectively. Dichloromethane extracts of 3 isolates (I-400A, B1-T61, M10-77) showed strong inhibitory activity of both pathogens, M10-77 being the highest actinomycete strain with antibiotic activity against methicillin-resistant S. aureus ATCC 43300 and vancomycin-resistant E. faecalis ATCC 51299 with a minimum inhibitory concentrations (MIC) of 7.9 and 31.7 μg/ml respectively. Phylogenetic analysis of M10-77 strain showed 99% similarity with the marine species Streptomyces erythrogriseus. Conclusions. Marine sediments of the central coast of Peru, are a source of actinomycetes strains showing high capacity to produce bioactive compounds able to inhibit pathogens classified as multi-drugresistant such as methicillin-resistant S. aureus and vancomycin-resistant E. faecalis.

Actinomicetos aislados de Argopecten purpuratus productores de enzimas extracelulares y con actividad inhibitoria de patógenos marinos

espanolEl presente trabajo tiene como objetivos evaluar actinomicetos aislados de Argopecten purpuratus y su capacidad de producir enzimas extracelulares (EEC), asi como determinar su actividad antagonista frente a patogenos de importancia en acuicultura. Se aislaron 27 cepas de actinomicetos a partir de la masa visceral de especimenes adultos de A. purpuratus colectados en la localidad de Pisco y Pucusana (Lima) - Peru. El 81,5 y 59,2% de los aislados mostraron actividad proteolitica y lipolitica, respectivamente. Asimismo, las cepas senaladas como ARG 9-II, ARG 10-II, ARG 12-II y ARG 14-II mostraron mayor actividad antimicrobiana contra los patogenos Vibrio anguillarum, V. vulnificus, V. alginolitycus, Lactococcus garvieae, Streptococcus iniae, Carnobacterium piscicola y Yersinia ruckeri. La cepa ARG 4-II exhibio la mayor actividad inhibitoria. La Concentracion Minima Inhibitoria (CMI) del extracto diclorometanico de la cepa ARG 12-II frente a V. anguillarum y V. alginolyticus fue calculada en 250 y 500 µg ml-1 respectivamente. Las cepas ARG 9-II, ARG 12-II y ARG 14-II sobre la base del analisis de su ARNr 16S fueron identificadas como Streptomyces variabilis, St. labedae y St. rochei, respectivamente. Los resultados senalan a A. purpuratus como una fuente promisoria de aislamiento de nuevas cepas de Streptomyces con alta capacidad bioactiva y antagonista contra patogenos de importancia en acuicultura y con posibilidades de ser desarrolladas como potenciales agentes probioticos en el futuro. EnglishThe present study was aimed at isolating Argopecten purpuratus-associated actinomycetes strains, and evaluating their capacity of production of extracellular enzymes (ECE), as well as inhibitory compounds against relevant pathogens in commercial aquaculture. Twenty seven strains were isolated from the gut of A. purpuratus adult specimens that were collected in the city of Pisco and Pucusana (Lima) _ Peru; 81.5 and 59.2% of the isolates showed proteolytic and lipolytic activity, respectively. In addition, the strains ARG 9-II, ARG 10-II, ARG 12-II and ARG14-II evidenced broad-spectrum antimicrobial activity against the pathogens Vibrio anguillarum, V. vulnificus, V. alginolitycus, Lactococcus garvieae, Streptococcus iniae, Carnobacterium piscicola, and Yersinia ruckeri. The strain ARG 4-II produced the highest inhibitory effect against S. iniae. The Minimum Inhibitory Concentration (MIC) of the dichloromethane extract obtained from the strain ARG 12-II supernatant was 250 and 500 µg ml-1 against V. anguillarum and V. alginolyticus, respectively. Based on 16S rRNA sequence analysis, strains ARG 9-II, ARG 12-II and ARG 14-II were identified as Streptomyces variabilis, St. labedae and St. rochei, respectively. Results indicate that A. purpuratus is a promissory source for the isolation of new strains of Streptomyces with high bioactivity and antagonistic capacity against relevant pathogens in aquaculture. These strains have high potential for being developed as probiotic agents in the future.