Protists and bacteria interactions in the presence of oil

Abstract

Little is known about the role of protists and bacteria interactions during hydrocarbon biodegradation. This work focused on the effect of oil on protists from three different locations in Guanabara Bay and bacteria from Caulerpa racemosa (BCr), Dictyota menstrualis (BDm) and Laurencia obtusa (BLo) during a 96 h bioassay. Cryptomonadida (site 1, 2 and 3), Scuticociliatida (site 2) and Euplotes sp.1 and Euplotes sp.2 (site 3) appeared after incubation. The highest biomass observed in the controls was as follows: protist site 3 (6.0 µgC.cm–3, 96 h) compared to site 3 with oil (0.7 µgC.cm–3, 96 h); for bacteria, 8.6 µgC.cm–3(BDm, 72 h) and 17.0 µgC.cm–3(BCr with oil, 24 h). After treatment, the highest biomasses were as follows: protists at site 1 and BLo, 6.0 µgC.cm–3 (96 h), compared to site 1 and BLo with oil, 3.31 µgC.cm–3 (96 h); the bacterial biomass was 43.1 µgC.cm–3 at site 2 and BDm (96 h). At site 3 and BLo with oil, the biomass was 18.21 µgC.cm–3 (48 h). The highest biofilm proportions were observed from BCr 1.7 µm (96 h) and BLo with oil 1.8 µm (24 h). BCr, BLo and BDm enhanced biofilm size and reduced the capacity of protists to prey.

Translated abstract

Pouco se sabe sobre o papel dos protistas e as interações bacterianas durante a biodegradação de hidrocarbonetos. Este trabalho se concentrou no efeito do óleo sobre protistas de três localidades diferentes na Baía de Guanabara e bactérias de Caulerpa racemosa(BCr), Dictyota menstrualis(BDm) e Laurencia obtusa(BLo) durante 96 h de bioensaio. Cryptomonadida (locais 1 , 2 e 3), Scuticociliatida (local 2) e Euplotes sp.1 e Euplotes sp.2 (local 3) apareceram após incubação. As biomassas mais elevadas observadas nos controles foram como se segue: protista local 3 (6,0 µgC.cm–3, 96 h) comparado com o local 3 com óleo (0,7 µgC.cm–3, 96 h); para as bactérias, 8,6 µgC.cm–3 (BDm, 72 h) e 17,0 µgC.cm–3 (BCr com óleo, 24 h). Após o tratamento, as maiores biomassas foram como se seguem: protistas no local 1 e BLo, 6,0 µgC.cm–3 (96 h), em comparação com o local 1 e BLo com óleo, 3,31 µgC.cm–3 (96 h), a biomassa bacteriana foi de 43,1 µgC.cm–3 no local 2 e BDm (96 h). No local 3 e BLo com óleo, a biomassa foi 18,21 µgC.cm–3 (48 h). As maiores proporções de biofilme foram observadas de 1,7 µm BCr(96 h) a 1,8 µm BLo com óleo (24 h). BCr, BLo e BDm aumentaram o tamanho do biofilme e reduziram a capacidade dos protistas predarem.