Vyas V V, Gupta S, Sharma P
Department of Microbiology, Panjab University, Chandigarh, India.
Enzyme Microb Technol. 1994 Mar;16(3):240-6. doi: 10.1016/0141-0229(94)90049-3.
The recombinant shuttle plasmid pCPPS-31, which confers carboxymethylcellulase (CMCase) production and neomycin resistance (Ner), was segregationally but not structurally unstable in both B. subtilis (50-60%) and Escherichia coli (80-90%) when grown in serial batch cultures for 72 h diluting 1:1,000 with fresh medium every 24 h. The plasmid showed 80-100% segregational and complete structural stability in B. subtilis during batch, fed-batch, and continuous culture fermentations in minimal M9 medium. In E. coli the instability was > or = 50% in 36 h of batch or continuous culture and approached 100% in 72 h of continuous fermentation. The plasmid was more stable (> or = 60%) during fed-batch fermentation. Stability in B. subtilis and instability in E. coli may be attributed to (i) the significant growth-rate advantage of plasmid-free (P-) cells over plasmid-harboring (P+) cells in the case of E. coli, an advantage that was absent in B. subtilis, and (ii) the existence of plasmid in oligomeric forms in E. coli and in mainly monomeric forms in B. subtilis.
重组穿梭质粒pCPPS - 31可产生羧甲基纤维素酶（CMCase）并具有新霉素抗性（Ner），当在分批培养中连续培养72小时，每24小时用新鲜培养基按1:1000稀释时，在枯草芽孢杆菌（50 - 60%）和大肠杆菌（80 - 90%）中该质粒会发生分离但结构稳定。在M9基本培养基中进行分批、补料分批和连续培养发酵时，该质粒在枯草芽孢杆菌中表现出80 - 100%的分离稳定性和完全的结构稳定性。在大肠杆菌中，分批培养或连续培养36小时时不稳定性≥50%，连续发酵72小时时接近100%。在补料分批发酵过程中该质粒更稳定（≥60%）。枯草芽孢杆菌中的稳定性和大肠杆菌中的不稳定性可能归因于：（i）在大肠杆菌中无质粒（P - ）细胞比携带质粒（P + ）细胞具有显著的生长速率优势，而在枯草芽孢杆菌中不存在这种优势；（ii）大肠杆菌中质粒以寡聚体形式存在，而枯草芽孢杆菌中主要以单体形式存在。
