TABLE 3.

Effect of cosubstrates and inhibitors on amino acid uptake by Marinobacter arcticus

Substrate	Unamended culture		Amended culture
	Specific affinity (liters g of cells−1 h−1)	Vm (mg of S g of cells−1 h−1)	Unique addition	Specific affinity (liters g of cells−1 h− 1)	Vm (mg of S g of cells−1 h−1)
Glutamate	373	0.58	Acid mixa	1,150	17
Leucine	270	7	Glutamateb	3,100	2.2
Leucine	5,900	NDe	CCCP	27	ND
Toluene	290	0.52	CCCPc	260	ND
Alanined	288	3.4	CCCP	0.0	ND

^aKinetic constants were calculated from the sum of nine added amino acids.

^bK_a = 3.0 μg/liter; K_ΣS = 3 μg of glutamate/liter for glutamate stimulation of leucine uptake by glutamate with maximal increase in leucine specific affinity at 17 μg of glutamate/liter (Fig. 3).

^cForty-five percent of the toluene uptake into cell material and CO₂ was diverted to acid-nonvolatile products.

^dAffinity was measured at 3.9 μg of alanine/liter; the sodium motive force affecting ionophore monensin had no effect.

^eND, not determined.