Pollutant interactions during the biodegradation of phenolic mixtures with either 2- or 3-mononitrophenol in a continuously operated packed bed reactor

Bioreactors based on immobilized fungi: bioremediation under non-sterile conditions

White-rot fungi are renowned for their remarkable potential to degrade a wide range of organic pollutants. They are applicable in standard bioreactors offering both the use of the continuous mode of action and easy upscaling of the biodegradation process. The recent advance in this field consisted in the use of various fungi and different types of reactors in the treatment of real wastewaters. Most degradation studies involving white-rot fungi carried out so far used controlled, aseptic conditions. However, during bioremediation of real wastewaters, the degradation capacity of the fungi would be significantly affected by autochthonous microorganisms. Consequently, for the development of sustainable bioremediation technologies, it is important to understand the mechanisms involved in the intermicrobial interactions occurring during the bioremediation process. This review summarizes recent applications of white-rot fungi to biodegradation of recalcitrant organopollutants under non-sterile conditions describing the invading microorganism(s) and the way how they affect the stability and degradation efficiency of the fungal bioreactor cultures. In addition, studies where fungal cultures were exposed to defined microbial stress are also reported documenting the effect and mechanisms of microbial interactions. Advanced OMICs techniques, specifically the genomics and metabolomics analyses, are suggested to help in identification of the invading microorganisms and in discovery of mechanisms taking part in the interspecific interactions.

Interactions among mononitrophenol isomers during biodegradation of their mixtures

Continuous aerobic biodegradation of 4-NP, 3-NP and 2-NP mixture was monitored in a packed bed reactor in simulated wastewater with a mixed microbial culture immobilized on expanded slate. Substrate loading was varied by increasing the concentration of one isomer while keeping the other two at constant levels, all at a constant residence time of 60 min. At large concentrations, all of the individual NP isomers suppressed the degradation rates of the other isomers at steady state; however, the observed patterns and threshold concentrations were different for all three substrates. As a result, conditions were determined for stable and efficient removal of NP mixtures. Changes of the biofilm composition during a long-term operation were identified.