Adaptation The Fifteenth Marjory Stephenson Memorial Lecture

Clarke, Paul

doi:10.1099/00221287-126-1-5

Cited by 5 publications

(2 citation statements)

References 42 publications

(20 reference statements)

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“…Kinetics of induction. Induction usually requires only minutes (43) to hours (18,29), compatible with our findings, considering the low temperature. We found that both the time and concentration dependency of induction changed with the initial level of induction, and the process could take as long as 11 days.…”

Section: Discussionsupporting

confidence: 89%

Toluene Induction and Uptake Kinetics and Their Inclusion in the Specific-Affinity Relationship for Describing Rates of Hydrocarbon Metabolism

Robertson

Button

1987

Appl Environ Microbiol

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The kinetics of concentration-dependent toluene metabolism were examined by evaluating each term in the second-order rate equation. Marine and freshwater pseudomonads were used. Uptake for Pseudomonas sp. strain T2 was characterized by a completely saturatable system with small transport constant (K, = 44 ,ug/liter) and large specific affinity. Kinetics for Pseudomonas putida PpF1 were similar. Induction had little effect on K,, but it caused the specific affinity to increase from about 0.03 to 320 liters/g of cells per h. The level of induction depended on the time of exposure, the concentration of inducer, and the initial level of induction. If loss of the inducible system was not severe, toluene caused a linear increase in specific affinity with time, and the maximal value achieved at intermediate times (1 to 3 days) was hyperbolic with concentration when Kind was 96 ,ug/liter (A. T. Law and D. K. Button, Appl. Environ. Microbiol. 51:469-476, 1986). As repression became complete, specific affinities were greatly reduced. Then induction required higher toluene concentrations and longer times, and the shape of the specific-affinity curve became sigmoidal with concentration. Cell yields (0.10 to 0.17 g of cells per g of toluene used) were low owing to liberation of organic products: 2-hydroxy-6-oxohepta-2,4dienoic acid, toluene dihydrodiol, 3-methylcatechol, acetate, formate, and possibly pyruvate, which in turn caused lower rates of growth. Michaelis constants for the reaccumulation of products exceeded those for toluene, but specific affinities were lower and maximal velocities were higher, so that recycling was favored in cultures with high toluene concentration. Although these kinetics predict deviation from the linear relationship between uptake rate and biomass, we could detect none. Effects of saturation and induction were incorporated into the basic specific-affinity relationship. The result appears to be an improvement in the equation used for describing the kinetics of uptake and growth.

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Section: Discussionsupporting

confidence: 89%

Toluene Induction and Uptake Kinetics and Their Inclusion in the Specific-Affinity Relationship for Describing Rates of Hydrocarbon Metabolism

Robertson

Button

1987

Appl Environ Microbiol

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“…It is usually thought to depend on the amount, activity, and sequestering ability of transporters and is therefore affected by induction (184). Since transport capacity can exceed growth requirements at saturation, activity is also thought to be under metabolic control in many situations (46,58,63,106,189,195). For example, maximal uptake values of ammonia for Phaedactylum tricornutum increased by a factor of 130 in response to increased limitation due to NH4' and shortening the observation time to 15 s (85).…”

Section: Kinetic Constantsmentioning

confidence: 99%