I think that there is a little misunderstanding between you and the review. The nitrogen cycle is very complex and hard to follow. Bacteria, for sure, are the dominant organisms responsible for the full pathway of denitrification from nitrates upto N2. On the other hand, fungal denitrification ends with N2O (lack of N2O reductases). The sentence "other fungi might show great ability to reduce N2O to N2" is to my opinion just a theory - not proven yet. As I wrote previously, there is co-denitrification pathway for N2 production from N2O by fungi as well as nitrifier denitrification pathway.

However there are some errors in this review as I can see - the N2O-reductase is not NOR but shoud be NOS or N2OR!

Try some more papers:

Ma et al., Soil Formate Regulates the Fungal Nitrous Oxide Emission Pathway. Appl. Environ. Microbiol. 74, 6690-6696 (2008); doi: 10.1128/AEM.00797-08.

Siciliano et al. Nitrifier dominance of Arctic soil nitrous oxide emissions arises due to fungal competition with denitrifiers for nitrate. Soil Biology & Biochemistry 41, 1104–1110 (2009); doi:10.1016/j.soilbio.2009.02.024

Hi, I hope I can help you a little bit. The function of p-450nor is to reduce NO to N2O (nitric oxide reductase). The distribution of this enzyme among fungi is still not fully known. However, this enzyme is not able to reduce directly the nitrous oxide into N2 (nitrous oxide reductase activity). So for me, there is no connection between lack of p-450nor and lack of N2O reductases. Fungi are reported not to have any nitrous oxide reductases at all, so therefore the main product of fungal denitrification is usually N2O. There is one process releasing N2 from fungal denitrification, called co-denitrification. For more info, I think these papers can help you a lot:

Hayatsu, M., Tago, K. & Saito, M. Various players in the nitrogen cycle: diversity and functions of the microorganisms involved in nitrification and denitrification. Soil Sci. Plant Nutr. 54, 33–45 (2008); doi: 10.1111/j.1747-0765.2007.00195.x.

Maeda K., et al. N2O production, a widespread trait in fungi Scientific Reports 5, Article number: 9697 (2015); doi:10.1038/srep09697.

Shoun, H. et al. Fungal denitrification and nitric oxide reductase cytochrome P450nor. Philos Trans R Soc Lond B Biol Sci. 367 (1593), 1186-94 (2012); doi: 10.1098/rstb.2011.0335.

Laughlin, R.J., Stevens, R.J. Evidence for fungal dominance of denitrification and codenitrification in a grassland soil. Soil Sci. Soc. Am. J. 66: 1540-1548 (2002); doi: 10.2136/sssaj2002.1540

Thank  you  very  much for  you  answer ! your answer   has  solved  my  question  for  why  some  of  fungus  lack  N2O  reductase? because  there  is  no  any  N2O  reductases  in  fungi. However  I  Believe  that  the  paper “Soil ,a sink  for  N2O?A review”has  misled  me  into  a  wrong  direction,thank  you  very  much  agai  for you  drag me  on  a  right  direction!

In  this  paper  “Soil ,a sink for N2O?A review”says  that bacteria are thought  to be the  dominant  organisms  responsible  for  denitrification.many  lack  N2O reductase ,other  fungi might  show  great  ability  to reduce  N2O  to  N2.Now  I  know  that  this  words  are  wrong,and I  guess that maybe this  paper in 2007   was  regard  as  a  good  and  right  paper,now   I  think that fungi  is  the  domant  organisms  responsible  for   denitrificaion,Whether  you  agree  with  me? hope  for  you  reply!

I think that there is a little misunderstanding between you and the review. The nitrogen cycle is very complex and hard to follow. Bacteria, for sure, are the dominant organisms responsible for the full pathway of denitrification from nitrates upto N2. On the other hand, fungal denitrification ends with N2O (lack of N2O reductases). The sentence "other fungi might show great ability to reduce N2O to N2" is to my opinion just a theory - not proven yet. As I wrote previously, there is co-denitrification pathway for N2 production from N2O by fungi as well as nitrifier denitrification pathway.

However there are some errors in this review as I can see - the N2O-reductase is not NOR but shoud be NOS or N2OR!

Try some more papers:

Ma et al., Soil Formate Regulates the Fungal Nitrous Oxide Emission Pathway. Appl. Environ. Microbiol. 74, 6690-6696 (2008); doi: 10.1128/AEM.00797-08.

Siciliano et al. Nitrifier dominance of Arctic soil nitrous oxide emissions arises due to fungal competition with denitrifiers for nitrate. Soil Biology & Biochemistry 41, 1104–1110 (2009); doi:10.1016/j.soilbio.2009.02.024

Hi,Professor Jiří Jirout :

I am  very  glad  to  communicate  with you  in  last  week.And  I  have  read these  papers  you  recommend. Now  I  want  to  do   the  function  genes   in  the  fungal   denritrificaion,but  I  can  not  find  more  papers  about   it,now  papers  I  find  only   about  nirk and  cyp55, could   you   recommend  me  some  related  papers  about  the genes in  fungal  denitrification ?Especially  about   the  genes  of  nitrate  reductase in  fungal  denitrification? Thank  you  very  much! 

huifangxu

2015.8.36