On the Suitability of a Bacterial Consortium To Implement a Continuous PAHs Biodegradation Process in a Stirred Tank Bioreactor

A new microbial consortium made up with two bacterial strains phylogenetically identified as Bacillus pumilus and Staphylococcus warneri was obtained from lab soils polluted with polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Its PAH degradation potential has been demonstrated recently by culturing the consortium in the presence of phenanthrene (PHE), pyrene (PYR), and benzoanthracene (BaA). The efficiency of the proposed degradation process was evaluated at flask and bioreactor scale, operating in fed-batch mode, as a prior step to achieve an effective biodegradation process in continuous mode. An acclimation of the consortium to the selected PAHs has been evidenced in fed-batch cultures after 6 batches (90% of degradation in less than one day). The effect of the dilution rate was analyzed in a continuous stirred tank bioreactor operating for 2 months, observing that some of the dilution rates employed allowed achieving degradation rates higher than 90% per day for all the contaminants.