Previous works developed in our laboratories has been reported that Y.lipolytica lipase is preferentially cell bound, only appearing in the bulk of the liquid medium at stationary cell phase, such as is produced independently of the lipid presence in the culture medium. Moreover, when the polysaccharides (glycogen, pectin and polygalacturonic acid) were added to the culture at different times and to crude preparations samples obtained from the cultivation, the results obtained showed that all polysaccharides assayed promote enzyme release of the cell surface to the culture media, indicating that the interactions between hydrosoluble polysaccharides and lipase are very significant. In such case, it was also possible to observe that lipase-polysaccharide complex is protected against protease action and thermal inactivation to different levels.

Particularly, glycogen at low concentration (0.5%) shows high capacity of lipase activation "in vitro", while pectin and polygalacturonic acid seem to immobilize it.

On the other hand, it is known that in Saccharomyces cereviseae cells, glycogen occurs preferentially in periplasmic space and it is recycled quickly in cellular stress responses. Then, the aim of this work was investigation of the relationship between glycogen recycle and lipase liberation from Y.lipolytica cells growing in YPD medium (yeast extract 1%, peptone 0.64%, glucose 2%).

The results obtained indicated that exponential growth cells under heat-shock (37oC / 1h) was completely finished. In this condition, the extracellular glucose showed high level of oscillation, but the glycogen recycle was less detected when compared to control cells. A similar result was obtained when cells were submitted to heat shock onset stationary phase. In the same way, glucose oscillation was strongly observed but the glycogen recycle was lower. It is important to note that glucose was measured by glucose oxidase and HPLC methods.

Although the physiological and molecular basis of the interactions between glycogen recycle and lipase liberation in these effects is still unclear, very useful information were obtained.

The results presented here led us to conclude that Y.lipolytica shows different behavior with relation to both glucose consumption and glycogen recycle ability, when compared to S.cereviseae in the same conditions.

Finally, may be possible to control the lipase-glycogen interactions and use it to design the enzyme rate liberation from cell wall to liquid medium without polysaccharide addition.