Assessment of Vibrio populations in a transect of Rhizophora mangle in Punta Galeta, Panamá: culture-dependent analyses reveal biotechnological applications.

Abstract

Rhizophora mangle is considered an ecological niche for microorganisms with potentially novel and complex degrading enzymes. To characterize Vibrio populations using culture-dependent methods, using samples collected from sediments and water along a red mangrove transect composed of three sites. Strains were characterized according to their distribution, capacity to degrade of organic matter and other environmental parameters. Additionally the sequence diversity was assessed using 16S rRNA sequencing. Bacterial densities were strongly associated with temperature and salinity. A total of 87 good-quality sequences representing the isolates from the three sites, were binned into eight OTUs (Operational taxonomic units). Taxonomic assignment indicated that the dominant members were Vibrionaceae. Beta diversity analyses showed that bacterial communities clustered by sample source rather than spatial distribution, and that alpha diversity was found to be higher in water than in sediment. Three percent of the strains from water samples could degrade carboxyl-methyl cellulose with the smallest enzymatic indexes compared to 4 % of the strains from sediment samples that showed the highest enzymatic indexes. Two strains identified as Vibrio agarivorans degraded cellulose and agarose, producing the highest enzymatic indexes. We found higher bacterial densities and diversity in the bacterial communities of the water samples compared to the sediment, with different OTUs including those similar to Ferrimonas, Providencia, or Shewanella which were not isolated in the sediment. Vibrio OTUs were shown to degrade cellulose in both sample types. The results of this study highlight the importance of red mangroves as Vibrio habitats and as reservoirs of potential enzyme sources with biotechnological applications.