Ana-Maria Tanase

Newly isolated alkalophilic Advenella species bioaugmented in activated sludge for high p-cresol removal.

In this work, an alkalophilic bacterium (LVX-4) capable of using p-cresol as sole source of carbon and energy was screened and isolated from soil polluted by used oil. Phylogenetic (16S rRNA) and phenotypic characterization using Biolog GN microplates and API 20NE strips indicated that LVX-4 strain is a new Advenella species. It showed both the capability to degrade of p-cresol at high concentrations (750 mg/L) and to use p-cresol for growth in a pH from 7 to 10, although the optimum pH was 9. Moreover bioaugmentation of activated sludge with this strain lead to the complete removal of p-cresol in less than 100 h. This is the first study that shows the potential of Advenella sp. to be bioaugmented in activated sludge system for p-cresol biodegradation.

Microbial Community Dynamics in Field-Scale Biopile Bioremediation

Understanding the microbial communities responses to biopile procedures is an essential step in the field of microbial ecology and in bioremediation applications. In order to estimate metabolic dynamics at a microbial community level, we used Biolog Ecoplates. Assays showed that the bacterial communities from all samples were capable of utilizing a great variety from the 31 carbon substrates. Shannon’s diversity index values were between 2.711±0.303 in August and 3.262±0.062 in April, recording a general variation of 0.5 that is similar to other studies. Statistical analysis showed a good correlation coeficient for 2-hydroxybenzoic acid, a compound that is metabolized through the nafhthalene degradation pathway. Results showed a metabolic shift of the microbial community determined by temperature and the decrease of aromatic hydrocarbon concentrations. The shift was observed in the dynamics of MPN from 9x106 to 1x109 cell/g of soil. Even if the initial total petroleum hydrocarbon concentration from the biopile matrix was much higher than in other studies (10.25 g/kg), at the end of the evaluation the pollutant content of the biopile matrix had a removal rate between 92-98% for monoaromatic hydrocarbons and 57-75% for poliaromatic hydrocarbons.