Saccharomyces cerevisiae entrapped in chrysotile increases life-span for up to 3 years

Long-term viability of microorganisms has seldom been reported but is important from the technological and scientific point of view. In this work we show that Saccharomyces cerevisiae, a well known biocatalyst, remains viable and active in fermentation experiments for up to 3 years, in the absence of nutrients, when supported on chrysotile fibers. This long-term viability is ascribed to a latency state which the cells enter after about 4 months storage, induced by entrapment of the cells within the chrysotile fibers. Adhered chrysotile fibers do not penetrate the cell. TEM results show that the fibers are adhered only to the external cellular wall layer, and that no damage is caused to the cell wall structure. No fibers were ever found inside the cells. The entrapping fibers could be observed as a distinctive, well preserved silk nest in preparations in which the cells were not fixed chemically. No degradation of the chrysotile adhered fibers was observed. The entrapment is ascribed to the chrysotile flexibility and the size of the cells, which maximize adhesion by electrostatic and van der Waals interactions between the fibers and the cell surface polysaccharides. (C) 2003 Elsevier B.V. All rights reserved.