Utilization of some phenolic compounds by Azotobacter chroococcum and their effect on growth and nitrogenase activity.

Azotobacter chroococcum MH1 was grown in a mannitol and nitrogen free medium supplemented with p-hydroxybenzoic acid, resorcinol, catechol or vanillic acid as a sole carbon source. Growth and nitrogenase activity of p-hydroxybenzoic acid were supported by 8, 6 and 4 mM of p-hydroxybenzoic acid, resorcinol and catechol, respectively. The generation time of 1.71 h in p-hydroxybenzoic acid did not differ from a generation time of 1.64 h, when grown in mannitol. The compound p-hydroxybenzoic acid was utilized rapidly. However, the decomposition of other phenolic compounds tested proceeded slowly. These results suggested that phenolic compounds released during biodegradation of plant wastes could be utilized as carbon sources for both growth and nitrogen fixation of Azotobacter chroococcum.