As shown in Fig. 5a, P. p/LV_V 9-TapA p/LV_V 9-TapA ± 1.6 mg/L lovastatin, which was 69 and 520% higher than the producedvity of P. p/LV_V#9 and of the single-copy strain (Liu et al. 2018), respectively.
Based on Saccharomyces cerevisiae as a heterogeneous expression system, we engineered a high copy strain expressing human ATAD3A-Myc-HIS at a relative high level (2.5 mg/l of yeast culture) without significantly affecting yeast growth.
Depending on the cultivation conditions used, relatively low cyanophycin contents between 2.2% and 7.7% (w/w) of CDW were reproducibly detected, which might be due to weak expression or low gene dosage in the single cphA copy strain of R. eutropha.
In accordance with the enzymatic activity measurements, the increase in the gene expression was higher in the double-copy strain than in the single-copy strain.
The expression of bxl1 was improved only in the double-copy strain.
Possible reasons for the advantage of the 2-copy strain over the 4-copy or 8-copy strain in terms of protein modification, transport pathways, and unfolded protein response (UPR -related genes are considered in the 'DiscUPR -relatedion.
In the 4-copy strain, the transcriptional levels of four UPR-related genes were all higher than that of 2-copy strain, it seems that protein folding generated obstacles and was unable to improve enzyme activity or protein secretion.
The genomic DNA of the single-copy strain was used to establish the standard curve (Additional file 2: Figure S2).
In conclusion, the lipase with maximal enzyme activity was secreted by the 2-copy strain (mα-2pRML-X33).
All three isolates showed a drastically reduced penicillinV titre, comparable to that of the single-copy strain Wisconsin54-1255.
The transgenic SOD1G93A mice used for these studies were the hybrid, high-copy strain (B6SJL-Tg (SOD1G93A) 1Gur/J, stock no.
