Open AccessSelective stimulation of type I methanotrophs in a rice paddy soil by urea fertilization revealed by RNA‐based stable isotope probing
Author(s) -
Noll Matthias,
Frenzel Peter,
Conrad Ralf
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00497.x
Subject(s) - biology , stable isotope probing , human fertilization , paddy field , isotopes of nitrogen , nitrogen , methylamines , urea , nitrogen cycle , agronomy , bacteria , botany , environmental chemistry , biochemistry , genetics , microorganism , chemistry , physics , quantum mechanics , catalysis
Methane‐oxidizing bacteria (MOB) in soil are not only controlled by their main substrates, methane and oxygen, but also by nitrogen availability. We compared an unfertilized control with a urea‐fertilized treatment and applied RNA‐stable‐isotope‐probing to follow activity changes upon fertilization as closely as possible. Nitrogen fertilization of an Italian rice field soil increased the CH 4 oxidation rates sevenfold. In the fertilized treatment, isopycnic separation of 13 C‐enriched RNA became possible after 7 days when 300 μmol 13 CH 4 g dry soil −1 had been consumed. Terminal‐restriction fragment length polymorphism (T‐RFLP) fingerprints and clone libraries documented that the type I methanotrophic genera Methylomicrobium and Methylocaldum assimilated 13 CH 4 nearly exclusively. Although previous studies had shown that the same soil contains a much larger diversity of MOB, including both type I and type II, nitrogen fertilization apparently activated only a small subset of the overall diversity of MOB, type I MOB in particular.