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Appl. Environ. Microbiol., 07 1997, 2578-2585, Vol 63, No. 7
SK Rhee, GM Lee, JH Yoon, YH Park, HS Bae and ST Lee
New denitrifying bacteria that could degrade pyridine under both aerobic
and anaerobic conditions were isolated from industrial wastewater. The
successful enrichment and isolation of these strains required selenite as a
trace element. These isolates appeared to be closely related to Azoarcus
species according to the results of 16S rRNA sequence analysis. An isolated
strain, pF6, metabolized pyridine through the same pathway under both
aerobic and anaerobic conditions. Since pyridine induced NAD-linked
glutarate-dialdehyde dehydrogenase and isocitratase activities, it is
likely that the mechanism of pyridine degradation in strain pF6 involves
N-C-2 ring cleavage. Strain pF6 could degrade pyridine in the presence of
nitrate, nitrite, and nitrous oxide as electron acceptors. In a batch
culture with 6 mM nitrate, degradation of pyridine and denitrification were
not sensitively affected by the redox potential, which gradually decreased
from 150 to -200 mV. In a batch culture with the nitrate concentration
higher than 6 mM, nitrite transiently accumulated during denitrification
significantly inhibited cell growth and pyridine degradation. Growth yield
on pyridine decreased slightly under denitrifying conditions from that
under aerobic conditions. Furthermore, when the pyridine concentration used
was above 12 mM, the specific growth rate under denitrifying conditions was
higher than that under aerobic conditions. Considering these
characteristics, a newly isolated denitrifying bacterium, strain pF6, has
advantages over strictly aerobic bacteria in field applications.
Copyright © 1997, American Society for Microbiology
Anaerobic and aerobic degradation of pyridine by a newly isolated denitrifying bacterium
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, Korea.
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