Abstract

The invention discloses a bacterial strain of non pathogenic Cobetia marina useful in aquaculture, corresponding to an isolated Cobetia marina strain, Gram negative, oxidase positive, deposited under registry number CECT N° 7764; grows with dibenzothiophene (DBT) as the only carbon source. Also disclosed is a method to obtain a biosurfactant surfactant extract comprising growing strain Cobetia marina (MM1IDA2H-1) CECT N° 7764 in a reactor with liquid growth medium from 24 to 48 hours at a temperature between 10 and 35° C., pH 6 to 8; constant stirring between 100 to 400 rpm and oxygen saturation between 10 to 21%; until obtaining a grown cell culture and extracellular products plus inorganic salts; separating the cells, lyophilizing supernatant, sieve the obtained powder and dry. Further disclosed is a biosurfactant surfactant and uses thereof for treating infectious pathologies in aquaculture; use as additive for paint formulations for submergible surfaces; and use as food additive for fish, for inducing an immune response.