In this study, auxin (indole-3-acetic acid), gibberellin, cytokinin (zeatin) and abscisic acid production were investigated in the culture medium of the bacteria Proteus mirabilis, P. vulgaris, Klebsiella pneumoniae, Bacillus megaterium, B. cereus, Escherichia coli. To determine the levels of these plant growth regulators, high performance liquid chromatography (HPLC) technique was used. Our findings show that the bacteria used in this study synthesized the plant growth regulators, auxin, gibberellin, cytokinin and abscisic acid.

In this study, the mutagenic and recombinogenic effects of indole-3-acetic acid (IAA), a plant growth regulator naturally synthesized in plants but produced synthetically, and β-naphthoxyacetic acid (BNOA), a synthetic plant growth regulator widely used in agricultural regions, were investigated using the somatic mutation and recombination test (SMART) in Drosophila wings. The effect of the same plant growth regulators against the proliferation and viability of a human immortalized embryonic kidney HEK293 cells which is at the early stage of carcinogenesis were also examined with MTT and trypan-blue exclusion assays. For the SMART assay, two different crosses were used: a standard and a high-bioactivation (HB) cross, involving the flare-3 and the multiple wing hairs markers. The HB cross involved flies characterized by an increased cytochrome P-450-dependent bioactivation capacity, which permits the more efficient biotransformation of promutagens and procarcinogens. In both crosses, the wings of the two types of progeny, inversion-free marker heterozygotes and balancer heterozygotes, were analyzed. The results show that IAA and BNOA are not mutagenic or recombinogenic in the wing cells of Drosophila. Furthermore, neither plant growth regulator affected the proliferation rate of HEK293 cells; however, both of them induced cell death at high concentrations.

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The levels of endogenous free, bound, and total abscisic acid (ABA) and the changes in dry weight of the mycelium depending on the culture periods were examined in Pleurotus florida (Basidiomycetes) cultured both in shaking and static media. The relationship between ABA production and the growth rate of the fungus was determined. Our findings show that this fungus synthesizes ABA as a secondary metabolite and the maximum total ABA is produced on the 24th day of the growth period in both shaking and static conditions. It was observed that, depending on the culture period, the dry weight of mycelium was enhanced in the primary metabolic phase, while it was constant in the secondary metabolic phase.These results show that there is a negative relationship between growth rate of the fungus and ABA synthesis.

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