Azospirillum spp . metabolize [ 17 , 17 -

; Azospirillum spp. are endophytic bacteria with beneficial effects on cereals — effects partially attributed to gibberellin production by the microorganisms. Azospirillum lipoferum and Azospirillum brasilense inoculated to rice dy mutant reversed dwarfism in seedlings incubated with [17,17-H2]GA20 with formation of [17,17H2]GA1, showing the in vivo capacity to perform the 3 -hydroxylation. When Prohexadione-Ca, an inhibitor of late steps in gibberellin biosynthesis, was added to the culture medium, no complementation was observed and no [17,17-H2]GA1 was produced. The latter suggests that the bacterial operating enzyme may be a 2-oxoglutarate-dependent dioxygenase, similar to those of plants.