title: Improved methodology for isolation of Acetobacter diazotrophicus and confirmation of its endophytic habitat.
abstract: Nitrogen-free, semi-solid defined medium with crystallized cane sugar (100 g/l) supplemented with cane juice (5 ml/l) was the most selective for isolating Acetobacter diazotrophicus. Surveys of A. diazotrophicus using this medium showed that >10(3) cells/g fresh wt were present at all sites in all parts of the sugar cane plant and in all trash samples examined, reaching up to 10(7)/g. Additional samples, from forage grasses and cereals and from weed species collected within the sugar cane fields, were all negative. Heat treatment (50°C for 30 min) of the sugar cane setts did not affect A. diazotrophicus numbers within the plant. Nitrogenase activity of intact soil-plant systems in pots planted with heat-treated setts did not respond to inoculation with A. diazotrophicus. The endophytic habitat of this diazotroph and its propagation within the stem cuttings was confirmed.
authors.affiliation: , .
authors.forename: V M
authors.initials: VM
authors.lastname: Reis
authors.forename: F L
authors.initials: FL
authors.lastname: Olivares
authors.forename: J
authors.initials: J
authors.lastname: Döbereiner