Microbial community dynamics in field-scale biopile bioremediation

Abstract

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.