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Use of new strains of Rhodobacter sphaeroides and a modified simple culture medium to increase yield and facilitate purification of the reaction centre
- Source :
- Photosynthesis Research. 120:197-205
- Publication Year :
- 2013
- Publisher :
- Springer Science and Business Media LLC, 2013.
-
Abstract
- A new gene expression system was developed in Rhodobacter sphaeroides, replacing a pRK415-based system used previously. The broad host-range IPTG-inducible plasmid pIND4 was used to create the plasmid pIND4-RC1 for expression of the puhA and pufQBALMX genes, encoding the reaction centre (RC) and light-harvesting complex 1 (LH1) proteins. The strain R. sphaeroides ΔRCLH was used to make a knockout of the rshI restriction endonuclease gene, enabling electroporation of DNA into the bacterium; a subsequent knockout of ppsR was made, creating the strain R. sphaeroides RCx lacking this oxygen-sensing repressor of the photosynthesis gene cluster. Using pIND4-RC1, LH1 levels were increased by a factor of about 8 over pRS1 per cell in cultures grown semi-aerobically. In addition, the ppsR knockout allowed for photosynthetic pigment-protein complex synthesis in the presence of high concentrations of molecular oxygen; here, LH1 levels per cell increased by 20 % when grown under high aeration conditions. A new medium (called RLB) is the E. coli medium LB supplemented with MgCl2 and CaCl2, which was found to increase growth rates and final cell culture densities, with an increase of 30 % of LH1 per cell detected in R. sphaeroides RCx(pIND4-RC1) grown in RLB versus LB medium. Furthermore, cell density was about three times greater in RLB compared to semi-aerobic conditions. The combination of all the modifications resulted in an increase of LH1 and RC per mL of culture volume by approximately 35-fold, and a decrease in the length of culture incubation time from about 5 days to ~36 h.
- Subjects :
- biology
Strain (chemistry)
Electroporation
Photosynthetic Reaction Center Complex Proteins
Rhodobacter sphaeroides
Cell Biology
Plant Science
General Medicine
biology.organism_classification
Biochemistry
Molecular biology
Culture Media
Microbiology
Plasmid
Bacterial Proteins
Cell culture
Gene expression
Gene cluster
Bacteria
Subjects
Details
- ISSN :
- 15735079 and 01668595
- Volume :
- 120
- Database :
- OpenAIRE
- Journal :
- Photosynthesis Research
- Accession number :
- edsair.doi.dedup.....2e37c92db872449a83ee29aada3eefb3