DAHM, HANNA, HENRYK RÓZYCKI, KATARZYNA REDLAK & EDMUND STRZELCZYK.
Department of Microbiology, Institute of General & Molecular Biology, Nicholas Copernicus University, Gagarina 9, 87-100 Toruñ, POLAND.
Azospirillum brasilense and Bacillus polymyxa affected the biomass production by 6 of 8 of ectomycorrhizal fungi studied. The simultaneous inoculation of the fungal biomass yield or did not affect its mycelial growth. Only in one case A. brasilense inoculated simultaneously with the fungus or inoculated one week after inoculation of the medium with the fungus - was the dry mass yield of ectendomycorrhizal fungus stimulated (isolate HC 30311). Inoculation of the 1-week old fungal culture with the bacterium in most cases did not affect the fungal biomass production. Only in the case of two fungal isolates (30362K and HC 30311) did A. brasilese and B. polymyxa stimulate their mycelial growth. Ectendomycorrhizal fungi and mycorrhiza-associated bacteria: Azospirillum brasilense and Bacillus polymyxa produced hydroxamate siderophores. Amounts of hydroxamate siderophores detected in fungal cultures were 2-4-fold higher than those in bacterial cultures. In most cases fungi synthesized similar amounts of siderophores, but two isolates (JL 30086 II and 30362K) excreted significantly more of these compounds than the remaining ones. Although in bacterial post-culture liquids significantly smaller amounts of hydroxamate siderophores were detected than those in fungal cultures, bacteria could however also synthesize catechol siderophores. Both bacteria did not differ in amounts of siderophores they produced.
Key words: ectendomycorrhizal fungi, biomass production, "helper" bacteria, siderophores.