Google scholar is a good tool

http://scholar.google.co.in/scholar?as_ylo=2012&q=eutrophic+nitrogen+metabolism&hl=en&as_sdt=0,5&as_vis=1

microbes.kbs.msu.edu/Publications/Burgin%20et%20al.%202012.pdf

Http://biogeosciences-discuss.net/9/6987/2012/bgd-9-6987-2012.pdf

http://link.springer.com/article/10.1007%2Fs11274-012-1090-6?LI=true#page-1

Http://www.sciencedirect.com/science/article/pii/0304377084900597

Thanks!

A reference in one of the papers you have suggested brought part of the answer, though not from the genetic side, but it will suffice.