The influence of different nutrients on biosurfactant production by Rhodococcus erythropolis was investigated. Increasing the concentration of phosphate buffer from 30 up through 150 mmol/L stimulated an increase in biosurfactant production, which reached a maximum concentration of 285 mg/L in shaken flasks. Statistical analysis showed that glycerol, NaNO3,MgSO4 and yeast extract had significant effects on production. The results were confirmed in a batchwise bioreactor, and semi-growth-associated production was detected. Reduction in the surface tension, which indicates the presence of biosurfactant, reached a value of 38 mN/m at the end of 35 hours. Use of the produced biosurfactant for washing crude oil-contaminated soil showed that 2 and 4 times the critical micellar concentration (CMC) were able to remove 97 and 99% of the oil, respectively, after 1 month of impregnation.

O presente estudo objetivou a investigação da capacidade degradadora de uma linhagem bacteriana autóctone (isolada de amostras de solo contaminadas com derivados de petróleo) contra hidrocarbonetos de querosene de aviação. A linhagem foi caracterizada como Nocardia sp. A avaliação do seu potencial degradador deu-se realizada mediante testes com indicador redox e observações na redução da tensão superficial na fase aquosa. A degradação do querosene foi avaliada por métodos cromatográficos. Os experimentos foram realizados utilizando-se duas taxas de bioestímulo. Uma linhagem bacteriana Pseudomonas aeruginosa UFPEDA 39 foi utilizada como referência. A linhagem autóctone demonstrou alta eficiência na degradação de hidrocarbonetos do querosene bem como para produzir compostos ativos de superfície quando comparada com a linhagem de referência.

The aim of this study was to investigate the potential of degradation of an autochthonous bacterial strain, isolated from petroleum derivatives contaminated soil samples against jet fuel hydrocarbons. The autochthonous bacterial strain was characterized as Nocardia sp. Evaluation of their degrading abilities was carried out by presumptive assays as redox indicator test and by observations of surface tension decreases in aqueous medium. Degradation of jet fuel hydrocarbons was evaluated by chromatographic methods. Experiments were performed in flasks at two biostimulation rates. A bacterial strain of Pseudomonas aeruginosa UFPEDA 39 was utilized as a reference microorganism. The bacterial strain, identified as Nocardia sp, demonstrate high ability to degrade jet fuel compounds as well as to produce surface active compounds when compared to the reference microrganism.

O objetivo deste trabalho foi investigar a potencialidade de leveduras que degradam óleo Diesel, visando aplicação em processo de biorremediação de áreas impactadas pelo referido poluente. As culturas, identificadas como Rhodotorula aurantiaca UFPEDA 845 e Candida ernobii UFPEDA 862, foram as selecionadas na etapa inicial. Quanto aos ensaios de biodegradabilidade, a levedura Candida ernobii UFPEDA 862 degradou totalmente: tetradecano, 5 metil-octano e octadecano, e parcialmente decano (60,8%) e nonano (21,4%), enquanto que a Rhodotorula aurantiaca UFPEDA 845 apresentou percentuais de degradação de 93,0% para decano, 38,4% para nonano e 22,9% para dodecano.

The aim of this work was to investigate the potential of the diesel oil degrading yeasts to use them in bioremediation of areas contaminated by this pollutant. The cultures, identified as Rhodotorula aurantiaca UFPEDA 845 and Candida ernobii UFPEDA 862, were selected at the initial stage. In the course of the biodegradation assays, C. ernobii degraded tetradecane, 5 methyl-octane and octadecane completely and decane (60.8%) and nonane (21.4%) partially whilst R. aurantiaca presented degradation percentages of 93% for decane, 38.4% for nonane and 22.9% for dodecane.