Table 1. Glutamine synthetase activity of an S. meliloti Δhfq mutant growing in complex and defined media.

	Growth medium
Strain (genotype)	TY	MDM-NH4 +1% (w/v)
2011 (wild type)	2224.51±355.96 a	3221.69±574.29 a
20PS01 (Δhfq)	2026.49±206.57 a	4741.83±974.29 b

Data correspond to average GS activity (Units/mg protein) of n = 3 replicate cultures ± SD. Different letters indicate statistically significant differences among strains based on pairwise comparisons (Student’s t-test, P<0.05).