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AME 38:125-133 (2005)
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Abstract
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Growth efficiency and respiration at different growth rates in glucose-limited chemostats with natural marine bacteria populations
Ramón Cajal-Medrano1, Helmut Maske2,*
1Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, PO Box 453 Ensenada, CP 22880,Baja California, Mexico 2Centro de Investigación Científica y Educación Superior de Ensenada, km 107
carretera Tijuana-Ensenada, Ensenada,Baja California, Mexico
*Corresponding author. Email: hmaske@cicese.mx
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ABSTRACT: Chemostats with glucose-enriched seawater and inoculated with natural populations of heterotrophic marine bacteria were run at different dilution rates (0.05 to 1.0 d1), at constant temperature (22°C) and with low organic
substrate medium (20 µM glucose). The following parameters were measured: cell abundance, POC, PON and total CO2 produced. The results demonstrated an increase in growth efficiency with higher specific growth rates within the growth rate
range investigated here that is typical for oceanic samples. The results were parameterized according to the Pirt model, with a maximum efficiency of substrate conversion (ε = 0.57) and a specific rate of maintenance metabolism (a = 0.41
d1), although the experimental results within the limited growth rate range investigated here are not statistically different from a linear relationship. On first principals it can be argued that the growth efficiency has to pass through
the origin and have a maximum efficiency below 1.0, thus suggesting an asymptotic relationship like the Pirt model. Applying the iterative method of model parameter adjustment to previously published data, similar growth efficiency versus growth rate
relationships were arrived at. Our results confirm that at a particular temperature a proportionately higher fraction of dissolved organic material is remineralized in oligotrophic oceans that support lower growth rates than in waters supporting higher
growth rates. Consequently, in the latter waters, the efficiency of transfer of dissolved organic material into the particulate form is supposed to be higher.
KEY WORDS: Bacterial growth efficiency · Respiration · Chemostats · Glucose
Full text in pdf format
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Published in AME Vol.
38, No. 2
(2005) on February 9
Print ISSN: 0948-3055; Online ISSN: 1616-1564.
Copyright © Inter-Research, Oldendorf/Luhe, 2005
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