Characterization and DNA plasmid analysis of ropy Pediococcus spp. strains isolated from Basque Country ciders

Abstract

Ten strains of Pediococcus spp. causing ropiness were isolated from Basque Country spoiled ciders and characterized with regards to growth at different pHs, temperatures, and ethanol and SO2 concentrations. They grew well at pHs above 3.7 and failed to grow at temperatures over 37°C. In addition, they were tolerant to 10% ethanol and to 15, 25, and 50 mg/l total SO2 (pH 3.8). A selected ropy strain was used to carry out plasmid DNA analysis: the agarose gel pattern showed the presence of 6 bands of plasmid DNA. Plasmid-curing experiments with ethidium bromide and novobiocin suggested that the ropy phenotype was encoded by plasmid DNA. In addition, this nonropy strain lost its resistance to oleandomycin after curing trials.