TABLE 1.

nif promoter-lacZ expression in M. maripaludis^a

nif promoter region	Result with nitrogen source:
	Ammonia	Alanine	Dinitrogen
Wild type	21 ± 15	56 ± 10	129 ± 19
Mutation in first operator	452 ± 155	530 ± 177	458 ± 118
Mutation in second operator	29 ± 20	220 ± 27	227 ± 26

^aValues are in Miller units. Means and standard deviations are for triplicate cultures.