ISSN:
1572-9729
Keywords:
Acinetobacter
;
biodegradation
;
carbon nitrogen ratio
;
kinetics
;
phenol
;
sand
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract In polluted soil or ground water, inorganic nutrients such as nitrogen may be limiting, so that Monod kinetics for carbon limitation may not describe microbial growth and contaminant biodegradation rates. To test this hypothesis we measured14CO2 evolved by a pure culture ofAcinetobacter johnsonii degrading 120 µg14C-phenol per ml in saturated sand with molar carbon:nitrogen (CN) ratios ranging from 1.5 to 560. We fit kinetics models to the data using non-linear least squares regression. Phenol disappearance and population growth were also measured at CN1.5 and CN560. After a 5- to 10-hour lag period, most of the14CO2 evolution curves at all CN ratios displayed a sigmoidal shape, suggesting that the microbial populations grew. As CN ratio increased, the initial rate of14CO2 evolution decreased. Cell growth and phenol consumption occurred at both CN1.5 and CN560, and showed the same trends as the14CO2 data. A kinetics model assuming population growth limited by a single substrate best fit the14CO2 evolution data for CN1.5. At intermediate to high CN ratios, the data were best fit by a model originally formulated to describe no-growth metabolism of one substrate coupled with microbial growth on a second substrate. We suggest that this dual-substrate model describes linear growth on phenol while nitrogen is available and first-order metabolism of phenol without growth after nitrogen is depleted.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00695259
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