Avaliação de fenazinas sintéticas na biodegradação de óleos pesado por Pseudomonas aeruginosa TGC04

Abstract

Between 2019 and 2020, 40% of Brazil's coastal areas suffered the most extensive oil spill in a tropical zone in history, causing negative impacts at all levels of the food chain, as well as marine ecosystem services. Many bacteria can be used in oil removal, but Pseudomonas aeruginosa is notoriously potential because it is capable of degrading hydrocarbons (HC) shortly after exposure to oil. Previous studies have shown that pyocyanin (PYO) and other intermediate phenazines help the HC transformation process by bacteria. This study aimed to verify the effect of phenazine methosulfate (PMS) on the biodegradation of sandy soil oil by allochthonous bioaugmentation with P. aeruginosa TGC04. Microcosms were prepared containing 50 g of fine sand and 150 g of beach sand contaminated with heavy oil. The pre-inoculum was prepared in 100 g of pasteurized sand and supplemented with 0.5% (w/w) of barley malt bagasse, to which 5 mL of the bacterial suspension was added, enriched with 10 µmol/L of PMS and incubated at 29±1°C for 10 days. Afterwards, portions of the inoculum were added to the microcosms (1:10; 1:100 and 1:1000). Total petroleum hydrocarbons (TPH) were reduced by up to ≈49%, while the 16 priority polycyclic aromatic hydrocarbons (HPAs) were reduced by between ≈37 and 56%. P. aeruginosa TGC04 preferentially degraded 4-6 ring HPA (80-89%), but 2-3 ring HPA were removed by up to ≈37%. In the presence of PMS there was a significant reduction in HC, however the highest rates of daily HC removal were observed in the 1:100 condition without PMS. Zea mays seeds were planted in the soil and plant development was observed for 15 days, determining important reductions in the plant's biophysical parameters. As a contribution, this study expands the knowledge that the hydrocarbonoclastic activity of P. aeruginosa is not increased by the addition of exogenous phenazines, but favors the removal of 4-6 ring HPA and that allochthonous bioaugmentation is a strategy of interest in the early stages of an oil spill accident.