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高富硒酵母菌种选育研究 总被引:2,自引:1,他引:1
以富硒酵母Y2为出发菌株,通过60Coγ射线照射诱变育种,筛选获得了一株生物量和富硒能力都较高的突变菌株YR166。通过正交实验确定变异株最适发酵培养基配方为:麦芽汁10%,(NH4)2SO4 1.0%,KH2PO4 0.2%,Se4+浓度为50μg/mL。在培养温度30℃,500mL三角瓶装量60mL,摇瓶培养6h加硒无机硒后,继续摇瓶培养30h,酵母硒含量达到2531.4μg/g,较原菌株提高了74.2%,酵母生物量达到14.9g/L,较原菌株提高36.7%。 相似文献
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We have developed a model to test several underlying assumptions of bacterial source tracking (BST) when the BST method is based on detection of discrete genetic markers from source-specific bacteria. The model consists of an environment and discrete-time input signals that represent sources of contamination partitioned into marker-bearing and nonmarker-bearing units "shed" into the environment. Simulations run for different types of environmental contamination patterns indicate that if hosts shed different percentages of BST markers, the environment cannot be accurately characterized unless a correction method is used. The correction method, which requires the solution to a linear system, reduces the mean error in estimating the proportions of host contamination to below 3%. The effectiveness of the method depends on accurate knowledge of the occurrence and prevalence of markers in the various hosts; this may be a challenging task, especially if these values vary across populations in space and time. In addition, the correction method does not compensate for environments with low-density or unmixed contamination. In conclusion, our simulations highlight several fundamental challenges that may prevent absolute quantification of fecal input using discrete marker BST. 相似文献
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