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Appl. Environ. Microbiol., Feb 1995, 592-601, Vol 61, No. 2
D Kightley, DB Nedwell and M Cooper
Laboratory-scale soil microcosms containing different soils were permeated
with CH(inf4) for up to 6 months to investigate their capacity to develop a
methanotrophic community. Methane emissions were monitored continuously
until steady states were established. The porous, coarse sand soil
developed the greatest methanotrophic capacity (10.4 mol of CH(inf4)
(middot) m(sup-2) (middot) day(sup-1)), the greatest yet reported in the
literature. Vertical profiles of O(inf2), CH(inf4), and methanotrophic
potential in the soils were determined at steady state. Methane oxidation
potentials were greatest where the vertical profiles of O(inf2) and
CH(inf4) overlapped. A significant increase in the organic matter content
of the soil, presumably derived from methanotroph biomass, occurred where
CH(inf4) oxidation was greatest. Methane oxidation kinetics showed that a
soil community with a low methanotrophic capacity (V(infmax) of 258 nmol
(middot) g of soil(sup-1) (middot) h(sup-1)) but relatively high affinity
(k(infapp) of 1.6 (mu)M) remained in N(inf2)-purged control microcosms,
even after 6 months without CH(inf4). We attribute this to a facultative,
possibly mixotrophic, methanotrophic microbial community. When purged with
CH(inf4), a different methanotrophic community developed which had a lower
affinity (k(infapp) of 31.7 (mu)M) for CH(inf4) but a greater capacity
(V(infmax) of 998 nmol (middot) g of soil(sup-1) (middot) h(sup-1)) for
CH(inf4) oxidation, reflecting the enrichment of an active high-capacity
methanotrophic community. Compared with the unamended control soil,
amendment of the coarse sand with sewage sludge enhanced CH(inf4) oxidation
capacity by 26%; K(inf2)HPO(inf4) amendment had no significant effect,
while amendment with NH(inf4)NO(inf3) reduced the CH(inf4) oxidation
capacity by 64%. In vitro experiments suggested that NH(inf4)NO(inf3)
additions (10 and 71 (mu)mol (middot) g of soil(sup-1)) inhibited CH(inf4)
oxidation by a nonspecific ionic effect rather than by specific inhibition
by NH(inf4)(sup+).
Copyright © 1995, American Society for Microbiology
Capacity for Methane Oxidation in Landfill Cover Soils Measured in Laboratory-Scale Soil Microcosms
Department of Biology, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom
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