Résumé
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 percent of the oil, respectively, after 1 month of impregnation.
Sujets)
Archives , Dépollution biologique de l'environnement , Industrie chimique , Retrait des Contaminants , Hydrocarbures , Pétrole/classification , Pétrole/effets indésirables , Rhodococcus/composition chimique , Interprétation statistique de données , Méthodes , ToxicitéRésumé
"Cryptosporidium" is an emergent pathogen that causes profuse diarrhea in humans. Outbreaks of human crypstosporidiosis have implicated water as a possible source of contamination. In this study the presence of "Cryptosporidium" sp. oocysts was investigated as well as the fecal contamination in groundwater for consumption in Itaquaquecetuba - São Paulo. Therefore, it was possible to notice that the septic tanks were located close to the wells, exposing them to the risk of contamination. As a consequence of these results and observations efficient disinfecting practices and groundwater monitoring are recommended.