Isolation and characterization of polyhydroxyalkanoate-producing bacteria from seawater samples (Tumaco)

Abstract. Introduction. Polyhydroxyalkanoate (PHA) is a useful, carbon-neutral polymer that can be produced from renewable carbon sources by microorganisms, making it a sustainable and environmentally friendly material. Currently, production of the biopolymer is not competitive in terms of cost and yield; however, production by different bacterial strains may provide economic viability, especially since substituting biodegradable plastics for nondegradable synthetic plastics has drawn interest from both academia and the commercial world. Objective. The aim of this work was to describe the isolation and partial characterization of PHA-producing bacteria isolated from five sites (gas stations) in coastal regions of Tumaco Island, Nariño-Colombia, and classify different physicochemical parameters of granules that show the production of the biopolymer. Materials and methods. A viable colony staining method using Nile red was used to preliminarily screen for PHA-producing bacteria. Colonies were isolated, characterized via biochemical, microbial, and molecular methods, and tested for antimicrobial susceptibility and fermentation. Results. More than thirty-eight strains were identified as potential PHA-positive isolates from this screening approach but, just one isolated was viable in PHA production (T2-25A). All isolates were resistant to metronidazole, ampicillin, trimethoprim sulfamethoxazole, cephalothin, ceftriaxone, and cefazolin, and 27.3 % of isolates were resistant to novobiocin. Conclusions. One promising PHA-producing isolate was obtained. Nevertheless, this information will complement future studies of the conditions necessary to produce PHA. Moreover, antibiotic resistance data have attracted attention, especially because of the origin of the source waters of the isolates.