Fig. 2.

Growth kinetics of Azospirillum oryzae NBT506 and Bacillus velezensis UTB96 in monoculture and co-culture systems. (a) Optical density at 600 nm of monocultures of Azospirillum oryzae NBT506 (open circle) and Bacillus velezensis UTB96 (open square) during 24 h. Stars indicate significant difference between both species at each time (* P < 0.05; ** P < 0.01; *** P < 0.001). (b) Log CFU (CFU.ml^− 1) of monocultures of Azospirillum oryzae NBT506 (open circle), monoculture of Bacillus velezensis UTB96 (open square), co-culture of the same population size of each strain (10⁸ CFU/ml; grey triangle) and co-culture when NBT506 (10¹⁰ CFU/ml) population is two-fold more than UTB96 (10⁸ CFU/ml) during 24 h. In (a) and (b), standard errors were too small to be visible on the graph and have thus been omitted