Gene expression system in green sulfur bacteria by conjugative plasmid transfer

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Green sulfur bacteria are important photosynthetic microorganisms.
• Establishing efficient gene transfer and expression systems is crucial for their study.
• Previous methods for genetic manipulation in these bacteria were limited.

Purpose of the Study:

• To establish a reliable gene transfer and expression system for green sulfur bacteria using bacterial conjugation.
• To demonstrate the stable maintenance of plasmids and functional gene expression in these bacteria.
• To provide a versatile tool for future molecular biological research on green sulfur bacteria.

Main Methods:

• Bacterial conjugation between Escherichia coli and green sulfur bacteria (Chlorobaculum tepidum and Chlorellae limnaeum).
• Utilized RSF1010-derivative broad-host-range plasmids (pDSK5191, pDSK5192) conferring antibiotic resistance.
• Constructed expression plasmids by incorporating genomic regions for promoter and terminator elements.

Main Results:

• Successfully achieved conjugative plasmid transfer to thermophilic and mesophilic green sulfur bacteria with frequencies around 10(-5).
• Demonstrated stable plasmid maintenance in C. tepidum under antibiotic selection.
• Showcased functional gene expression, including rescue of mutant phenotypes and enhanced production of photosynthetic reaction center complex.

Conclusions:

• Developed a robust and applicable gene transfer and expression system for green sulfur bacteria via conjugative plasmids.
• This system facilitates genetic manipulation and molecular studies, advancing research in these organisms.
• The established system offers a valuable tool for understanding the biology of green sulfur bacteria.