Effects of medium composition and nutrient limitation on loss of the recombinant plasmid pLG669-z and β -galactosidase expression by Saccharomyces cerevisiae
Effects of medium composition and nutrient limitation on loss of the recombinant plasmid pLG669-z and β -galactosidase expression by Saccharomyces cerevisiae
复制标题
培养基组成和营养限制对酿酒酵母重组质粒pLG669-z和β-半乳糖苷酶表达丢失的影响
DOI：
--
复制
发表时间：
1997
影响因子：
3.4
通讯作者：
J. Patching
中科院分区：
文献类型：
--
作者：
R. O'kennedy;J. Patching
在分批培养和恒化培养条件下，研究了培养基组成、营养限制和稀释率对重组质粒pLG 669-z丢失和质粒携带的β -半乳糖苷酶表达的影响。测定了无质粒和含质粒细胞之间的生长速率差异（Δμ）和分离速率（R），并确定了培养基组成对质粒丢失影响的一些共同因素。在限定培养基上生长的CGpLG的葡萄糖限制恒化器培养物在较高稀释率下更稳定，并表现出Δμ主导的质粒损失动力学。在复合培养基上生长的类似培养物在较低稀释率下更稳定，并表现出R主导的质粒丢失动力学。总体质粒稳定性是最大的磷酸盐限制恒化培养生长在确定的培养基上，是最不稳定的镁限制培养生长在确定的培养基上。无论培养基成分如何，Δμ均随稀释率的增加而减小，R均随稀释率的增加而增大。在高或低稀释率下增加的质粒损失率似乎分别是由R或Δμ主导的损失动力学的特征。与在限定培养基上生长的培养物相比，在复合培养基上生长的葡萄糖限制恒化器培养物降低Δμ值，但增加R值。复合介质诱导的Δμ降低可能赋予的任何增加的稳定性被增加的R值抵消。只有在限定培养基上生长的葡萄糖限制恒化培养物中，β-半乳糖苷酶生产率的增加与质粒稳定性的增加相关，而在复合培养基上生长的培养物中则不相关。以前的研究已经就稀释率对S.啤酒。我们的研究结果可以解释这些差异，并可能是普遍有效的类似酵母质粒构建体的稳定性。这一信息将有助于设计的生物过程中，重组质粒的不稳定性的结果，在降低的文化生产力。
The effects of medium composition, nutrient limitation and dilution rate on the loss of the recombinant plasmid pLG669-z and plasmid-borne β -galactosidase expression were studied in batch and chemostat cultures of Saccharomyces cerevisiae strain CGpLG. The difference in growth rates between plasmid-free and plasmid-containing cells (Δμ) and the rate of segregation (R) were determined and some common factors resulting from the effect of medium composition on plasmid loss were identified. Glucose-limited chemostat cultures of CGpLG grown on defined medium were more stable at higher dilution rates and exhibited Δμ -dominated plasmid loss kinetics. Similar cultures grown on complex medium were more stable at lower dilution rates and exhibited R-dominated plasmid loss kinetics. Overall plasmid stability was greatest in phosphate-limited chemostat cultures grown on defined medium and was least stable in magnesium-limited cultures grown on defined medium. Δμ decreased and R increased with increased dilution rate, irrespective of medium composition. Increased plasmid loss rates at high or low dilution rates would appear to be characteristic of loss kinetics dominated by R or Δμ, respectively. Growth of glucose-limited chemostat cultures on complex medium decreased Δμ values but increased R values, in comparison to those cultures grown on defined medium. Any increased stability that a complex medium-induced reduction of Δμ may have conferred was counteracted by an increased R value. Increased β-galactosidase productivity was correlated with increased plasmid stability only in glucose-limited chemostat cultures grown on defined medium and not in those grown on complex medium. Previous studies have yielded contrasting responses with regard to the effect of dilution rate on recombinant plasmid loss from S. cerevisiae. Our findings can account for these differences and may be generally valid for the stability of similar yeast plasmid constructs. This information would facilitate the design of bioprocesses, where recombinant plasmid instability results in reduced culture productivity.