Diazotrophic mixed culture of Azotobacter vinelandii and Rhodobacter capsulatus

• Published in: Plant and soil Vol. 137; no. 1; pp. 135 - 138
• Main Author: OELZE, J.
• Format: Journal Article
• Language: English
• Published: Kluwer Academic Publishers 01-11-1991
• Subjects: Alcohols; Alkynes; Azotobacter vinelandii; Cell growth; Cultured cells; Ethanol; Nitrogen; Quaternary ammonium compounds; Rhodobacter capsulatus; Sulfates
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF02187444

The question, whether Azotobacter vinelandii can provide fixed N for the growth of other organisms, was studied with mixed cultures of A. vinelandii and Rhodobacter capsulatus, grown with aeration in the light. N₂-fixation by R. capsulatus was prevented by growing the cultures on either mannitol, glycerol or ethanol, which cannot be used by this organism. In the course of growth with mannitol, cell numbers of both organisms increased largely in parallel and attained a maximal ratio of about one A. vinelandii per ten R. capsulatus. Prolonged growth of mixed cultures with mannitol did not lead to an adaptation of R. capsulatus to this compound. After growth on either one of the three alcohols, mixed cultures exhibited almost twice as high protein levels as pure cultures of A. vinelandii. Up to 80% of the protein of mixed cultures was incorporated into R. capsulatus. The results suggest that A. vinelandii provided an organic N-source for the growth of R. capsulatus.