Screening of Marine Spore-forming Bacteria Degrading Polymer Materials

The development of plastic recycling methods requires the search for new microorganisms capable of their biodegradation. The aim of the work was to screen spore-forming bacteria isolated from bottom sediments of the Black Sea for their ability to decompose Impranil and polyethylene terephthalate. Materials and methods. Cultivation of sixty cultures of spore-forming bacteria isolated from the Black Sea was carried out on a solid LB medium supplemented with Impranil (3–4 ml/l) or bis(hydroxyethyl)terephthalate (BHET) (5 mM). The ability of cultures to decompose polymer additives was evaluated by the formation of a transparent zone around the colonies after incubation at 30 ºС and 37 ºС for 14 days. Results. Out of 60 strains, 40 showed a positive result. 22 strains were active towards both plastics, 13 – only towards Impranil, 5 – only BHET. Impranil was decomposed somewhat more actively at 30 °C than at 37 °C. No clear temperature dependence was found in BHET decomposition. The analysis of the species composition showed that 35 of the 40 active strains belonged to seven species of microorganisms. B. subtilis has the highest share of active strains, as this species is represented by 13 strains, each of which was found to be active. The most active strain belonged to the species B. reuszeri. Conclusions. Spore-forming bacteria isolated from the Black Sea are capable of degrading Impranil and BHET. Enzymes degrading above mentioned polymers are the most widespread among the representatives of the species B. subtilis, B. atrophaeus and B. reuszeri. The highest activity towards Impranil showed B. subtilis, towards BHET– P. megaterium, B. reuszeri and B. licheniformis. Impranil degradation was more active under 30 ºС, but no clear dependence between temperature and BHET degradation was detected.