Contribution of bacterial biodiversity on the operational stability of a styrene biotrickling filter

Long-term operational stability of biotrickling filters (BTFs) degrading volatile organic compounds (VOCs) is dependent on both physicochemical as well as biological properties. Interactions between microbial structure within BTFs and increasingly stressful levels of VOC pollutants is not well understood, especially for VOCs such a styrene. Therefore, the temporal dynamics of a biofilm from a biotrickling filter subjected to stepwise increasing levels of air polluted with styrene was examined using pyrosequencing and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). Microbial community composition and structure were distinctly altered as contaminant loads were increased. Although temporary reductions in known styrene-degrading bacterial genera (Pseudomonas and Rhodococcus) occurred under increased styrene loads, stable BTF performance was maintained due to functional redundance. New candidate genera for styrene degradation (Hydrogenophaga, Azoarcus, Spirochaeta, Dokdonella among others) were identified in conditions of high styrene loads, and may have supported the observed stable BTF performance throughout the experiment. Styrene inlet loads and nutrient concentrations, particularly nitrate, were found to be important modulators of community composition and large reductions may have been partly responsible for the observed reductions of Pseudomonas. Notable differences between dominant genera and species detected via pyrosequencing compared to PCR-DGGE suggests that simulatenous implementation of both techniques is valuable to fully characterizing dynamic microbial communities.