Identification and biotechnological potential of novel purple non-sulfur bacteria (PNSB) from aquatic environments in Puerto Rico

Abstract

The anoxygenic photosynthetic purple non-sulfur bacteria (PNSB) have caught the attention of the scientific community due to their metabolic diversity. These microorganisms have the ability to adapt to fluctuations in oxygen levels and can use a great variety of carbon sources. In addition to their metabolic diversity, these microorganisms are widely distributed in nature and have different applications in the biomedical field, industrial processes, production of biofuels, among many others. Despite the promising and broad applications of these bacteria, there is only one study about the isolation of these microorganisms from Puerto Rico; however, their biotechnological potentials were not explored. The main focus of the current research was to identify PNSB isolates from different aquatic environments in Puerto Rico and to suggest possible biotechnological applications of these bacteria in the 1) biomedical field, 2) metal bioremediation, 3) hydrocarbon degradation and 4) hydrogen production. For the identification of the PNSB isolates, the recommended standards for the description of new species of anoxygenic phototrophic species, in accordance with the International Code of Nomenclature of Bacteria, were used. For the study of potential biotechnological applications, the following were evaluated:1) bacterial growth under different concentrations of lead, copper, and mercury, 2) the use of phenanthrene and naphthalene as the sole carbon source under anaerobic conditions, 3) antimicrobial substance production, and 4) hydrogen production. In terms of the PNSB isolates, we found that 16 of the isolates are potentially new species of PSNB. Moreover, 2 of these bacteria were isolated from the Heliconia phytotelmata being the first PNSB isolated from this environment. Also, this is the first study to report whole genome sequences of PNSB from Puerto Rico. In terms of the biotechnological application, it was found that 100% and 50% of the studied isolates were able to grow in the presence of lead and copper, respectively. Similarly, 88% of the isolates produced antimicrobial substances against Bacillus subtilis, and 38% were able to generate hydrogen under anaerobic conditions. These findings confirm the biotechnological potential of PNSB isolates from ecosystems in Puerto Rico. More studies about the capabilities of these isolates are strongly encouraged to have a clear understanding and profiles about other biotechnological and industrial applications (e.g. as producers of enzymes such as proteases, amylases, lipases, etc.). This will also promote the exploration and study of ecosystems in Puerto Rico as bioprospecting niches for the discovery of organisms with commercial applications.