Effect of soil bacteria on hyphal growth of the arbuscular mycorrhizal fungus Glomus claroideum

The effect of 46 bacterial strains isolated from tilled and non-tilled soil s collected at 3 localities on the growth of intraradical hyphae of the arb uscular mycorrhizal (AM) fungus Glomus claroideum was demonstrated. A large r number of stimulatory bacterial isolates was obtained from tilled soils, but the bacteria showing the strongest stimulation of hyphal growth were is olated from a soil that had not been cultivated. Isolates obtained from hyp hae of AM fungi showed no substantial stimulatory effects, but produced mor e uniform effects on hyphal growth than the isolates of bacteria obtained f rom soil. Bacterial cenoses present in 3 different soils differ significant ly in their effects on AM fungi.