PLASMID RETENTION AND GENE-EXPRESSION IN SUSPENDED AND BIOFILM CULTURES OF RECOMBINANT ESCHERICHIA-COLI DH5 ALPHA(PMJR1750)
PLASMID RETENTION AND GENE-EXPRESSION IN SUSPENDED AND BIOFILM CULTURES OF RECOMBINANT ESCHERICHIA-COLI DH5 ALPHA(PMJR1750)
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DOI：
10.1002/bit.260410207
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发表时间：
1993-01-20
影响因子：
3.8
通讯作者：
BRYERS, JD
中科院分区：
文献类型：
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作者：
HUANG, CT;PERETTI, SW;BRYERS, JD
研究了大肠杆菌DH 5 α（pMJR 1750）悬浮培养和生物膜培养中质粒保留和表达的差异。提出了一种替代的数学模型，它允许在两个悬浮批次和连续进料的生物膜培养的质粒损失概率的测定。在我们的实验中，E. coli DH 5 α（pMJR 1750）在无抗生素选择压力和诱导剂的条件下分批培养时的最低抑菌浓度为0.0022。在0.17 mM IPTG诱导下，悬浮分批培养中质粒携带细胞的最大生长速率从0.45 h-1下降到0.35 h-1，诱导开始后4 h，β-半乳糖苷酶浓度达到实验最大值0.32 pg/cell。在0.34和0.51 mM IPTG下，分批培养物中的生长速率降低至0.16 h-1，约为无IPTG的生长速率的36%，并且β-半乳糖苷酶浓度在诱导后3小时达到0.47 pg/细胞的实验最大值。在没有诱导剂和任何抗生素选择压力的情况下，携带质粒和无质粒的细胞都随时间增加，96小时后达到稳定水平。生物膜结合E. coliDH 5 α（pMJR 1750）的群体平均数为0.017。一旦加入诱导剂IPTG，生物膜中携带质粒的细胞的浓度急剧下降，而无质粒的细胞数量保持不受影响。β-半乳糖苷酶浓度在诱导后24小时在所有生物膜实验中达到最大值;在0.17、0.34和0.51 mM IPTG下分别为0.08、0.1和0.12 pg/细胞。
Differences in plasmid retention and expression are studied in both suspended and biofilm cultures of Escherichia coli DH5alpha(pMJR1750). An alternative mathematical model is proposed which allows the determination of plasmid loss probability in both suspended batch and continuously fed biofilm cultures. In our experiments, the average probability of plasmid loss of E. coli DH5alpha(pMJR1750) is 0.0022 in batch culture in the absence of antibiotic selection pressure and inducer. Under the induction of 0.17 mM IPTG, the maximum growth rate of plasmid-bearing cells in suspended batch culture dropped from 0.45 h-1 to 0.35 h-1, and the beta-galactosidase concentration reached an experimental maximum of 0.32 pg/cell 4 hours after the initiation of induction. At both 0.34 and 0.51 mM IPTG, growth rates in batch cultures decreased to 0.16 h-1, about 36% of that without IPTG, and the beta-galactosidase concentration reached an experimental maximum of 0.47 pg/cell 3 hours after induction.In biofilm cultures, both plasmid-bearing and plasmid-free cells increase with time reaching a plateau after 96 hours in the absence of both the inducer and any antibiotic selection pressure. Average probability of plasmid loss for biofilm-bound E. coli DH5alpha(pMJR1750) population was 0.017 without antibiotic selection. Once the inducer IPTG was added, the concentration of plasmid-bearing cells in biofilm dropped dramatically while plasmid-free cell numbers maintained unaffected. The beta-galactosidase concentration reached a maximum in all biofilm experiments 24 hours after induction; they were 0.08, 0.1, and 0.12 pg/cell under 0.17, 0.34, and 0.51 mM IPTG, respectively.