Direct detection of recombinant gene expression by two genetically engineered yeasts in soil on the transcriptional and translational levels

Magnetic capture-hybridization method for purification and probing of mRNA for neutral protease of Bacillus cereus

A magnetic capture-hybridization method was assessed for the isolation of prokaryotic mRNA for the neutral protease of B. cereus from liquid culture. A biotin-labeled specific probe was hybridized to the mRNA transcripts and subsequently captured by streptavidin-coated paramagnetic beads. mRNA was detected by dot-blot hybridization with a ds DIG-labeled DNA-probe. The magnetic capture hybridization is a rapid and simple method and has a promising potential for gene expression studies in complex samples.

Direct detection of viable bacteria, molds, and yeasts by reverse transcriptase PCR in contaminated milk samples after heat treatment

A fast, sensitive, and target contaminant-modulable method was developed to detect viable bacteria, molds, and yeasts after heat treatment. By reverse transcriptase PCR with elongation factor gene (EF-Tu or EF-1 alpha)-specific primers, the detection level was 10 cells ml of milk-1. The simplicity and rapidity (4 h) of the procedure suggests that this method may be easily transposable to other foods and other contaminants.

Fate of three 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 by insertion of a nucleotide sequence encoding for aprotinin was studied in three different soils. Corynebacterium glutamicum carried the recombinant gene on plasmid pUN1, Saccharomyces cerevisiae carried the gene on plasmid p707, and in Pichia angusta (formerly Hansenula polymoropha) LR9-Apr8, the gene was chromosomally inserted with eight tandem repeats. Corynebacterium glutamicum persisted longer than both yeast strains. In a sandy loam of pH 5.9, recovery rates of cultured cells were lower than in a clay silt or a silty sand, with pH values of 7.1 and 6.7, respectively. Generally, persistence at 10 °C was higher than at 20 °C. An adaptation of the genetically engineered strains resulting in higher soil persistence was not observed for any of the 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.Key words: ecological risk assessment, genetic engineering, nondeliberate release, soil inoculation, aprotinin.