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- Mineralization of 4-fluorocinnamic acid by a Rhodococcus strainPublication . Amorim, Catarina L.; Ferreira, António César Silva; Carvalho, M.F.; Afonso, Carlos M. M.; Castro, Paula M.L.A bacterial strain capable of aerobic degradation of 4-fluorocinnamic acid (4-FCA) as the sole source of carbon and energy was isolated from a biofilm reactor operating for the treatment of 2-fluorophenol. The organism, designated as strain S2, was identified by 16S rRNA gene analysis as a member of the genus Rhodococcus. Strain S2 was able to mineralize 4-FCA as sole carbon and energy source. In the presence of a conventional carbon source (sodium acetate [SA]), growth rate of strain S2 was enhanced from 0.04 to 0.14 h−1 when the culture medium was fed with 0.5 mMof 4- FCA, and the time for complete removal of 4-FCA decreased from 216 to 50 h.When grown in SA-supplemented medium, 4-FCA concentrations up to 1 mM did not affect the length of the lag phase, and for 4-FCA concentrations up to 3 mM, strain S2 was able to completely remove the target fluorinated compound. 4-Fluorobenzoate (4-FBA) was transiently formed in the culture medium, reaching concentrations up to 1.7 mM when the cultures were supplemented with 3.5mMof 4-FCA. Trans,trans-muconate was also transiently formed as a metabolic intermediate. Compounds with molecular mass compatible with 3-carboxymuconate and 3-oxoadipate were also detected in the culture medium. Strain S2 was able to mineralize a range of other haloorganic compounds, including 2- fluorophenol, to which the biofilm reactor had been exposed. To our knowledge, this is the first time that mineralization of 4-FCA as the sole carbon source by a single bacterial culture is reported.
- Bioaugmentation for treating transient 4-fluorocinnamic acid shock loads in a rotating biological contactorPublication . Amorim, Catarina L.; Duque, Anouk F.; Afonso, Carlos M. M.; Castro, Paula M. L.A rotating biological contactor (RBC) was used to treat shock loadings of 4-fluorocinnamic acid (4-FCA). Intermittent 4-FCA shocks of 35 mg L-1 were applied (ca. 3 months) with only limited mineralization occurring and accumulation of 4-fluorobenzoate (4-FBA) as an intermediate. After bioaugmentation with a degrading bacterium the RBC was able to deal with 4-FCA intermittent loading of 80 mg L-1 however, a gradual decline in RBC performance occurred, leading to 4-FBA accumulation. The degrading strain was recovered from the biofilm during 2 months but intermittent feeding may have led to diminishing strain numbers. Distinct bacterial communities in the 1st and the 5th and 10th stages of the RBC were revealed by denaturating gradient gel electrophoresis. Several isolates retrieved from the RBC transformed 4-FCA into 4-FBA but only two strains mineralized the compound. Bioaugmentation allowed removal of the fluorinated compound however intermittent feeding may have compromised the bioreactor efficiency.