Azospirillum brasilense produces gibberellin in pure culture on chemically-defined medium and in co-culture on straw

• Published in: Soil biology & biochemistry 1992, Vol.24 (10), p.1061-1064
• Main Authors: Janzen, R.A., Rood, S.B., Dormaar, J.F., McGill, W.B.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Azospirillum brasilense; barley straw; Biochemistry and biology; Biological and medical sciences; biological production; Chemical, physicochemical, biochemical and biological properties; culture media; Fundamental and applied biological sciences. Psychology; gibberellins; Hypocrea lixii; Microbiology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Rhizobiales; Soil science; substrates; Trichoderma harzianum
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(92)90036-W

Rhizobacteria have been shown to produce gibberellin (GA)-like substances, but this evidence has been obtained primarily from analysis by bioassay, usually on chemically-defined medium, and always in systems containing a single microorganism. We examined, by capillary gas chromatography-mass spectrometry, the production of GAs by Azospirillum brasilense (1) in pure culture on chemically-defined medium and (2) in co-culture with Trichoderma harzianum, a fungus which degrades cellulose and controls some bacterial and fungal phytopathogens, in a barley straw decomposition culture. Pure cultures of Azospirillum brasilense contained Ga 3 > iso- Ga 3 > GA 1, but no precursors thereto were detected. In the Azospirillum + Trichoderma straw culture 0.5 ng Ga 1 g −1 straw was measured. This is direct, analytical evidence that Azospirillum brasilense produces GA in the presence of complex biochemicals and another microorganism.