Previous Article | Next Article ![]()
Applied and Environmental Microbiology, June 1999, p. 2471-2477, Vol. 65, No. 6
Forschungszentrum Jülich, Institut
für Chemie und Dynamik der Geosphäre, Institut 6-Biologie
des Stoffaustauschs, D-52425 Jülich,
Germany,1 and Faculty Biology,
Department of MicroPhysiology, Section Microbial Eco-Physiology,
Vrije Universiteit Amsterdam, NL-1081 HV Amsterdam, The
Netherlands2
Received 10 November 1998/Accepted 24 March 1999
Nitrosomonas europaea and Nitrobacter
winogradskyi (strain "Engel") were grown in ammonia-limited
and nitrite-limited conditions, respectively, in a retentostat with
complete biomass retention at 25°C and pH 8. Fitting the retentostat
biomass and oxygen consumption data of N. europaea and
N. winogradskyi to the linear equation for substrate
utilization resulted in up to eight-times-lower maintenance
requirements compared to the maintenance energy demand (m)
calculated from chemostat experiments. Independent of the growth rate
at different stages of such a retention culture, the maximum specific
oxygen consumption rate measured by mass spectrometric analysis of
inlet and outlet gas oxygen content always amounted to approximately 45 µmol of O2 mg
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Maintenance Energy Demand and Starvation Recovery
Dynamics of Nitrosomonas europaea and Nitrobacter
winogradskyi Cultivated in a Retentostat with Complete
Biomass Retention

1 of biomass-C · h
1 for both N. europaea and N. winogradskyi. When bacteria were starved for different time
periods (up to 3 months), the spontaneous respiratory activity after an
ammonia or nitrite pulse decreased with increasing duration of the
previous starvation time period, but the observed decrease was many
times faster for N. winogradskyi than for N. europaea. Likewise, the velocity of resuscitation decreased with
extended time periods of starvation. The increase in oxygen consumption
rates during resuscitation referred to the reviving population only,
since in parallel no significant increase in the cell concentrations
was detectable. N. europaea more readily recovers from
starvation than N. winogradskyi, explaining the occasionally observed nitrite accumulation in the environment after
ammonia becomes available. From chloramphenicol (100 µg · ml
1) inhibition experiments with N. winogradskyi, it has been concluded that energy-starved cells
must have a lower protein turnover rate than nonstarved cells. As
pointed out by Stein and Arp (L. Y. Stein and D. J. Arp,
Appl. Environ. Microbiol. 64:1514-1521, 1998), nitrifying bacteria in
soil have to cope with extremely low nutrient concentrations.
Therefore, a chemostat is probably not a suitable tool for studying
their physiological properties during a long-lasting nutrient shortage.
In comparison with chemostats, retentostats offer a more realistic
approach with respect to substrate provision and availability.
*
Corresponding author. Mailing address:
Forschungszentrum Jülich, Institut für Chemie und Dynamik
der Geosphäre, Institut 6-Biologie des Stoffaustauschs, D-52425
Jülich, Germany. Phone: (49) 2461 614824. Fax: (49) 2461 612492. E-mail: w.tappe{at}fz-juelich.de.
Present address: Zeneca GmbH, D-68723 Plankstadt, Germany.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»