LAUSR

g i s o g e a d t i b a s t i e Azospirillum brasilense is a vastly studied plant growthpromoting rhizobacterium, which produces direct and indirect beneficial effects on several crops4. Historically, the culture of this bacterium has been performed using the semisolid NFb medium3, which is a nitrogen-free medium. Although other diazotrophs can grow in this culture medium2, A. brasilense can be isolated and identified by a typical growth after 120 h of incubation3. Other authors have exhaustively described the NFb medium composition and growth of many diazotrophs in semisolid media1. Here, we show pictures of seven stages during the development of A. brasilense in the course of the incubation period. A colony of A. brasilense was inoculated in a vial containing this culture medium. After 24 h of incubation at 30 ◦C, growth development can be observed by a halo formation around the colony as a ‘ghostly-balloon’ (Fig. 1A). The halo