EFFECTS OF ANTAGONISTIC FUSARIUM-OXYSPORUM ON FUNCTIONAL-GROUPS OF INDIGENOUS BACTERIA IN SOIL

Before planning the commercial use of microorganisms, genetically mani pulated or not, in agricultural environments, their behavior and poten tial impact on soil ecosystems should be carefully studied as part of risk assessment. The influence of added inoculum of antagonistic Fusar ium oxysporum strains, genetically manipulated (T26/6) or not (233/1) on nitrogen and carbon functional groups were evaluated in three soils from different sites at Albenga in Northwestern Italy, one natural an d two other previously solarized, and in a fourth soil obtained from a site at Carignano (Northwestern Italy) with a 10-year-old poplar stan d. Then were no detectable effects of the antagonistic Fusarium strain s on ammonifiers, ammonium oxidizers, nitrite oxidizers, nonsymbiotic anaerobic nitrogen fixers, nonsymbiotic aerobic nitrogen fixers and de nitrifiers evaluated with the most probable number (MPN) method. Also, no effects were observed on amylolytic, proteolytic, cellulolytic, pe ctolytic and total bacteria evaluated with the plate count (PC) method . Survival and population dynamics of the antagonistic Fusarium strain s were monitored during the experiments, and a decline over time of th e introduced microorganisms was assessed. (C) 1997 Elsevier Science B. V.