FATE OF 3 GENETICALLY-ENGINEERED, BIOTECHNOLOGICALLY IMPORTANT MICROORGANISM SPECIES IN SOIL - IMPACT OF SOIL PROPERTIES AND INTRASPECIES COMPETITION WITH NONENGINEERED STRAINS

The fate of a bacterium and two yeast species genetically engineered b y insertion of a nucleotide sequence encoding for aprotinin was studie d in three different soils. Corynebacterium glutamicum carried the rec ombinant gene on plasmid pUN1, Saccharomyces cerevisiae carried the ge ne on plasmid p707, and in Pichia angusta (formerly Hansenula polymoro pha) LR9-Apr8, the gene was chromosomally inserted with eight tandem r epeats. Corynebacterium glutamicum persisted longer than both yeast st rains. In a sandy loam of pH 5.9, recovery rates of cultured cells wer e lower than in a clay silt or a silty sand, with pH values of 7.1 and 6.7, respectively. Generally, persistence at 10 degrees C was higher than at 20 degrees C. An adaptation of the genetically engineered stra ins resulting in higher soil persistence was not observed for any of t he three species tested. Competition experiments between nonengineered and genetically engineered strains in presterilized soils revealed a reduced fitness of the engineered strains. However, a more competitive C. glutamicum pUN1 evolved after reinoculation of cells, preselected by a preceding competition experiment.