Application of Fungal Denitrification to Sewage Disposal

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1. Mechanisms of the Denitrifying Systems of FungiWe isolated cDNAs and genes of cytochrome P450nor isoforms, and studied transcriptional regulation mechanisms of their expression. We showed that denitrifying systems of Fusarium oxysporum and Cylindrocarpon tonkinense localize at mitochondria and act as anaerobic respiration coupling to the synthesis of ATP.We found a prosequence in the cDNAs that is similar to the targetting sequence for transportation to mitochondria.2. Screening of novel denitrifying systems and their characterizationWe found many microorganisms in fungi, yeasts, and actinomycetes which exhibit denitrifying activities. Fungal systems are unique as compared with those of bacteria in that they contain P450 as nitric oxide reductase, they exhibit strong codenitriying activities and they lack nitrous oxide reductase (Nos), whereas nitrate reductase and nitrite reductase systems are very similar to those of bacteria3. Co-denitrification by Fusariium solaniWe screened and found the fungus F.solani IFO 9425 as a denitrifier that shows a potent co-denitrifying activity, and characterized the system.4. Application to Sewage DisposalTo supplement a Nos gene to the fungal system, construction of the transformation system in denitrifying fungi is now underway.