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Cellular and molecular physiology of volume-sensitive anion channels 总被引:39,自引:0,他引:39
Strange K.; Emma F.; Jackson P. S. 《American journal of physiology. Cell physiology》1996,270(3):C711
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S. Handysides 《BMJ (Clinical research ed.)》1994,308(6922):179-182
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A two-stage fermentation process was established for the production of pigment-free pullulan by the yeast-like fungus Aureobasidium pullulans (ATCC 42023). In the first stage, starting at pH 4.5 with soy bean oil as the carbon source and glutamate as the nitrogen source, a cell mass of about 15 g l–1 dry cell weight was obtained, the population being restricted mainly to the yeast form of the microorganism (yeast form more than 90% of total cells) and the formation of pigment in the culture being prevented. Small amounts of pullulan (less than 2 g l–1) are produced at this phase, and the viscosity remained low throughout the entire growth stage. When the oil and glutamate source were nearly exhausted (below 5% of initial amounts), the cells were shifted to a production stage with sucrose as the carbon source with continued nitrogen depletion. Production of pullulan started immediately with no lag period. During 50 h of the production phase more than 35 g l–1 of pullulan was produced (productivity approx. 0.7 g l–1), resulting in a large increase in the viscosity of the broth. The production yield of pollulan on the sugar was about 0.6 g g–1. Morphogenesis from the yeast form of the microorganism to chlamydospores was still restrained and no pigment was formed in the culture during the production stage. A pigment-free polysaccharide, with a molecular mass in the range of 600–750 kDa, was recovered from the supernatant of the broth after solvent precipitation. 相似文献