A novel P450-initiated biphasic process for sustainable biodegradation of benzo[a]pyrene in soil under nutrient-sufficient conditions by the white rot fungus Phanerochaete chrysosporium.
High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) such as benzo[a]pyrene (BaP) are resistant to biodegradation in soil. Conventionally, white rot fungus Phanerochaete chrysosporium has been investigated for HMW-PAH degradation in soil primarily using nutrient-deficient (ligninolytic) conditions, albeit with limited and non-sustainable biodegradation outcomes. In this study, we report development of an alternative novel biphasic process initiated under nutrient-sufficient (non-ligninolytic) culture conditions, by employing an advanced experimental design strategy. During the initial nutrient-sufficient non-ligninolytic phase (16 days), the process showed upregulation (3.6- and 22.3-fold, respectively) of two key PAH-oxidizing P450 monooxygenases pc2 (CYP63A2) and pah4 (CYP5136A3) and formation of typical P450-hydroxylated metabolite. This along with abrogation (84.9%) of BaP degradation activity in response to a P450-specific inhibitor implied key role of these monooxygenases. The subsequent phase triggered on continued incubation (to 25 days) switched the process from non-ligninolytic to ligninolytic resulting in a significantly higher net degradation (91.6% as against 67.4% in the control nutrient-limited set) of BaP with concomitant de novo ligninolytic enzyme expression making it a biphasic process yielding improved sustainable bioremediation of PAH-contaminated soil. To our knowledge this is the first report on development of such biphasic process for bioremediation application of a white rot fungus.
Department of Environmental Health, University of Cincinnati, Cincinnati, OH, USA.
Sukanta S
SS
Bhattacharya
Khajamohiddin
K
Syed
Jodi
J
Shann
Jagjit S
JS
Yadav
D001564:Benzo(a)pyrene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D020075:Phanerochaete / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism*
D012989:Soil Pollutants; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System
Genetic algorithm; Non-ligninolytic; P450; PAH biodegradation; Response surface methodology; Transcript analysis in soil