An experiment was carried out to examine the effect of carbon source, tryptophan and adenine concentrations on the production of growth regulators by A. chroococcum (R19) and B.megaterium var. phosphaticum (R44). Mannitol and glucose were the best carbon sources for the production of plant growth regulators (PGRs) by A. chroococcum and B. megaterium var. phosphaticum, respectively. A. chroococcum produced higher amounts of zeatin and kinetin compared to those produced by B. megaterium var. phosphaticum while B. megaterium var. phosphaticum produced higher amounts of (9R) benzyl adenine and (9G) benzyl adenine compared with those produced by A. chroococcum. Production of auxins, gibberellic acid (GA3) and cytokinins was increased with increasing tryptophan concentration. The highest amounts of PGRs produced by the two strains were obtained with tryptophan at 1000μM. Highest amounts of PGRs produced by A. chroococcum and B. megaterium var. phosphaticum at 10 and 100 μM of adenine, respectively. Also, the produced amounts of gibberellic acid and cytokinin than that produced by B. megaterium var. phosphaticum. Generally, obtained data showed that the application of the optimal conditions together gave highest amounts of PGRs as compared with the other individual factors. This result is logic and was anticipated.