Marine macroalgae are living hosts for a variety of bacteria ( epiphytic bacteria ) that participate in relevant physiological processes of the macroalgae. In turn, macroalgae have a high content of water, carbohydrates, proteins and lipids. Likewise, algal monosaccharides and complex polysaccharides are a source of carbon and energy for epiphytic bacteria. Bacteria also benefit from other organic compounds produced by the macroalgal host and synthesize a variety of enzymes that are able to assimilate these compounds.
Our research aimed to study the epiphytic bacteria community from macroalgae of the species Ulva lactuca growing in the Santa Marta region (Colombian Caribbean Sea). Therefore, We used metagenomic and culture-dependent approaches to describe the epiphytic bacteria community and to evaluate the production of enzymes and siderophores by epiphytic bacteria, which could be of interest in biotechnological applications due to their functional properties.
The results of our study show that the genus Vibrio is one of the most abundant cultivable constituents on the macroalgal surface. The metagenomics approach indicated that the samplings performed during the years 2014−2016 represented the diversity of epiphytic bacteria. Proteobacteria, Bacteroidetes, Cyanobacteria, Deinococcus-Thermus and Actinobacteria were the most representative phyla. Likewise, Flavobacteriaceae, Saprospiraceae, Flammeovirgaceae, Rhodobacteraceae, Hyphomonadaceae, Erythrobacteraceae and Trueperaceae were the most abundant families.
On the other hand, the production of enzymes and siderophores, we isolated 207 bacteria species from the surface of the macroalga Ulva lactuca and found that many of them are promising sources of amylases, cellulases, lipases, agarases and siderophores of marine origin. These results have been published in the journal ‘Aquatic Biology’ (https://www.int-res.com/abstracts/ab/v27/p107-118/).
In conclusion our findings contribute to a better knowledge regarding the composition of epiphytic bacteria community. They also represent a first step in the isolating and characterization of enzymes and bioactive compounds synthesized by bacteria from the cultivable microbiota associated with green macroalgae located in the Santa Marta area. This study showed that U. lactuca offers a promising biotic environment in the search for enzymes and bioactive compounds of marine origin and potential biotechnological applications.
Natalia Beatriz Comba González