There are various types of rhizospheric bacteria which are
documented for the production of IAA, exploit different IAA
biosynthesis pathways and single bacterial strain sometimes
encompassing more than one pathway [14,15]. With reference to
earlier data, IAA production by bacteria can vary among different
species and strains, and it is also influenced by culture condition,
growth stage and substrate availability [1]. In our results the MPB 2.1
strain of B. subtilis LK14 showed the highest results (165.53 μM in
50 mL culture broth) for IAA production, while B. subtilis LK15
produced a little amount (32.01 μM in 50 mL culture broth)as
compared to B. subtilis LK14 (Fig. 3; Table 1). Similarly, the study of
Fuentes-Ramirez et al. [19] showed that various strains of Acetobacter
diazotrophicus produced IAA in defined culture medium and their
HPLC analyses revealed that A. diazotrophicus strains produced from
0.14 to 2.42 μg IAA mL-1 in culture medium.