NITROGEN-FIXING NONSULFUR PURPLE BACTERIA ASSOCIATED WITH NONLEGUMINOUS PLANTS

Thirty-five strains of pink-colored bacteria have been isolated from rhizoplana of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) whose seedlings were pretreated with a diluted extract of the following soils: loess-loamy soil from Eastern Germany, chernozem-like meadow soil from the river Kuban delta and turf-podzolic soil overlaying calcareous rock from the Leningrad region. Based on morphological, cultural, physiological, and biochemical properties, and according to the G+C content of the bacterial DNA and the percentage of DNA - DNA homology with type strains, the new isolates were assigned to the genus Rhodobacter, being most closely related to Rhodobacter sphaeroides. Nitrogenase activity in vitro, as well as in association with plants in situ, has been demonstrated. The ability for photosynthesis under anaerobic conditions in light has been revealed. A positive influence of the isolated bacteria on the increase of the rice upground mass and especially on the nitrogen content in corn of two wheat cultivars has been observed in vegetative experiments.