Comparing poly-3-hydroxybutyrate accumulation in Azospirillum brasilense strains Sp7 and Sp245: The effects of copper(II)

► Two Azospirillum brasilense strains were analysed for poly-3-hydroxybutyrate. ► Epiphytic strain Sp7 and endophyte Sp245 showed differences in PHB accumulation. ► Copper(II) enhanced PHB accumulation rate in Sp7, but not in Sp245, within 2 days. ► The differences are attributable to different adaptive potentials of the strains.