Steric-hyperlayer sedimentation field flow fractionation and flow cytometry analysis applied to the study of Saccharomyces cerevisiae

Sedimentation field flaw fractionation separation associated with flow cytometry has been used for the characterization of several commercial Saccharomyces cerevisiae yeasts used for wine production. A new type of channel 80 mum thick and new operating conditions, such as sample introduction when field and flow are established and a channel inlet connected to the accumulation wall, were used. Good repeatability (5% RSD) and reduced analysis time (2-10 min) were obtained. The avoidance of the stop-flow relaxation process in conjunction with the use of a channel of reduced thickness has demonstrated that an effective "steric-hyperlayer" mode driving to a major focusing effect of the species in the channel thickness is involved in the elution of the yeast cells. Flow cytometry analyses were performed, and the forward scattering and side scattering yeast characteristics correlation maps were obtained. Field flow fractionation and flow cytometry information obtained indicated that the fractogram profiles of the yeast cell depended not only on the size, but also on the shape and density.