Media composition, influence nutrients

Continuous cultures require more sophisticated equipment and long-term operation extending to several weeks. But, as a major advantage, nutrient and metabolite concentrations can be maintained constant for several days, which allows a more precise analysis of the influence of medium composition on cellular activity... 

The most important factor influencing the uptake of strontium by plants is the Ca status of the soil, other factors include the pH and organic matter content. Lem-brechts et al. (1990) have investigated the relation between soil solution composition and 85Sr uptake by young lettuce plants. A close relationship was shown between the Sr concentrations in the plants and the Sr/Ca ratio in solution either in nutrient medium, or in soil solution. It was suggested that plants primarily withdraw their nutrients from the soil liquid phase. 

The overall activity of the triorganotin and -lead compounds is about the same, that of the germanium compounds is much lower. Optimum activity for germanium occurs with ethyl and propyl, for tin with propyl and butyl, and for lead with butyl and pentyl substituents. There was little or no influence of the composition of the nutrient medium nor of its pH on activity. 

Soils are extremely important environmentally, for they provide the medium and the essential nutrients for plant growth and strongly influence the chemical composition of surface- and groundwaters. Soils are also called upon to remove or attenuate contaminants derived from the atmosphere or released from the surface or near-surface disposal of wastes. We will limit our discussion of soils to a few basic principles. For a more thorough treatment of soil geochemistry the reader is referred to books by Loughnan (1969), Greenland and Hayes (1978), Lindsay (1979), Rose et al. (1979), Bolt (1979), Drever (1985), and Sposito (1989). 

The culture medium of a S. cerevisiae strain used for alcohol production influenced the surface composition. Phosphate depletion in the culture medium led to a lower phosphate concentration at the cell surface depletion of other nutrients resulted in an increase of phosphate surface concentration due to a lower amount of biomass. 

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