Characterization of Saccharomyces cerevisiae CBS 7764 isolated from rainbow trout intestine

A wild-type Saccharomyces cerevisiae, strain CBS 7764, isolated from the in testine of rainbow trout, was analyzed with respect to general growth param eters and global protein expression. Characterization of this strain was of interest since previous data show non-typical S. cerevisiae cell surface p roperties and because data suggest a probiotic potential of CBS 7764. The h eat production rate (dQ/dt), monitored by microcalorimetry, showed that the typical growth phases resulting from diauxic growth on glucose were presen t in the fish isolate. However, CBS 7764 differentiated from a reference st rain by becoming limited in the respiratory phase as demonstrated by a plat eau in the dQ/dt signal. The global protein expression, as studied by two-d imensional gel electrophoresis (2D-PAGE), revealed a large degree of resemb lance of the fish isolate to the reference strain, however, also clear qual itative and quantitative expression differences were detected; e.g. 14% of the proteins differed in expression level by a factor of at least 2. In add ition, the fish isolate expressed 12 unique proteins. The heat shock protei ns, which for other organisms have been identified as important in mucosal colonization, were generally expressed to a higher level in CBS 7764.