TABLE 2.

Methylene-H₄folate reductase activity in cell extracts of bacteria grown with different C₁ sources

CM4 strain	Sp act (nmol min−1 mg−1)
	MeOH	MeOH-CH3Cl	CH3Cl
Wild type	<0.7	158 ± 20	245 ± 44
		6.5 ± 0.6a	<0.5b
metF	<0.4	<0.5a	NGc
metF(pME1793)	8.5 ± 0.9	931 ± 52	1,378 ± 77

^aGrown with 20 mM methanol and induced with 2% CH₃Cl for 8 h.

^bExtract was boiled for 5 min before measurement.

^cNG, no growth.