Potential microbial applications of co-cultures involving ligninolytic fungi in the bioremediation of recalcitrant xenobiotic compounds

Recalcitrant xenobiotic compounds are a major source of concern due to their resistance to degradation and persistency in the environment. Xenobiotic compounds pose a serious threat to the environment as they tend to distort the nutrient cycling and affect non-target organisms. These recalcitrant compounds include heavy metals, halocarbons, polychlorinated biphenyls, polycyclic aromatic compounds, synthetic polymers, alkyl benzyl sulphonates, nitroaromatics, dioxins, synthetic dyes, chlorophenols, certain herbicides and pesticides as well as lignins that are ubiquitous in nature. Xenobiotic compounds find their way into the environment either through intentional release as happens with pesticides and herbicides spray or accidentally in the form of oil spills and persist as sediments and complexes, thereby reducing the quality of soil and water bodies and consequently creating the need for removal and/or remediation processes. White rot fungi which degrade the most recalcitrant natural polymer, lignin, have been shown to degrade a wide range of recalcitrant xenobiotic compounds. Recently, the use of co-cultures of white rot has been a subject of research. Owing to the variation in the ligninolytic machinery and rates of degradation, the use of co-cultures is attractive as it offers the advantage of combining the degradative capabilities of different fungi to bring about complete degradation of the parent compounds as well as the metabolites.