A rapid mechanical lysing procedure for routine analysis of plasmids from lactobacilli, isolated from sourdoughs.

Variations in cell wall composition of lactobacilli complicate attempts to standardize plasmid detection on the basis of enzymatic lysing procedures. Mechanical disruption of cell walls by a horizontal mixer-mill proved to be more effective, rapid and reproducible. In order to judge the risk of damaging plasmid deoxyribonucleic acids (DNA) in this way, plasmid profiles obtained after enzymatic lysing and mechanical disruption of cell walls were compared. As no differences were detected the mechanical procedure was accepted as a suitable method for routine analysis of plasmid profiles.