6533b7ddfe1ef96bd1273c28

RESEARCH PRODUCT

Preservation of Microbial Strains in the Wine Industry

subject

description

Publisher Summary This chapter provides a general description of the most commonly used methods for the preservation of microbial strains. Long-term preservation methods are considered the most appropriate option wherever possible, since they involve stopping the growth of the microbial cells and keeping them in a viable state. This guarantees maximum genetic stability by preventing the appearance of successive generations. Nevertheless, the possibility that the preparation method itself leads to changes cannot be ruled out. There are two preservation methods belonging to this group: freezing and lyophilization. In the first long-term preservation method, the cells are frozen suspended in a liquid medium containing a cryoprotective agent and stored at temperatures below 0oC. As a result, intracellular and extracellular water is maintained in a solid state. The reduced cell metabolism caused by the low temperature and the absence of liquid water prevents growth. Lyophilization is a gentle process in which water is removed from the cells to stop their growth. The genetic stability obtained with this method is high, although not always as high as that seen with freezing, since lyophilization is achieved by sublimation of the ice in the cells. First, the free water in the cells must be frozen and then eliminated by vacuum without increasing the temperature, as this would affect the viability of the microorganism.