Efficient removal of sulfide following integration of multiple copies of the sulfide-quinone oxidoreductase gene (sqr) into the Escherichia coli chromosome

Citation
H. Shibata et al., Efficient removal of sulfide following integration of multiple copies of the sulfide-quinone oxidoreductase gene (sqr) into the Escherichia coli chromosome, J BIOSCI BI, 91(5), 2001, pp. 493-499
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biotecnology & Applied Microbiology",Microbiology
Journal title
JOURNAL OF BIOSCIENCE AND BIOENGINEERING
ISSN journal
1389-1723 → ACNP
Volume
91
Issue
5
Year of publication
2001
Pages
493 - 499
Database
ISI
SICI code
1389-1723(200105)91:5<493:EROSFI>2.0.ZU;2-C
Abstract
For the oxidation and removal of hydrogen sulfide, which causes an offensiv e odor from the contents of animal intestines, recombinant strains of Esche richia coli were constructed. The sulfide-quinone oxidoreductase gene (sqr) from Rhodobacter capsulatus was integrated in low copy numbers into the ch romosome of Escherichia coli W3110. Multiple copies of sqr on plasmids were also delivered into the cytoplasm of the same strain. The sqr genes were h omologously transducted onto the chromosomal lacZ region and their existenc e there was verified by Southern blot analysis. Sulfide oxidation in a chem ical medium effectively increased for the recombinant strains which carried 2 similar to3 copies of sqr under the control of the lac or tac promoter i n the chromosome, and also for strains which carried 10 copies of sqr under the control of the lac or tac promoter on plasmids. In both types of recom binant, the tac promoter was more effective for SQR expression than the lac promoter. Construction of a recombinant with 3 copies of sqr under the con trol of the tac promoter in the chromosome was unsuccessful. In recombinant s with SQR activity lower than 700 nmol/mg cell protein/min, oxygen consump tion increased proportionally to SQR activity. An elevation in SQR activity in this range resulted in an increase in oxygen consumption and a decrease in sulfide concentration. When the recombinant cells were cultured until t he 160th generation, WL2, WL3 and WT2, which carried 2, 3 and 2 copies of s qr in the chromosome, respectively, retained SQR activity similar to that o f the first generation. For WL300 and WT20 which carried multi-copies of sq r in plasmids SQR activity was undetectable. The recombinant with 2 copies of sqr in the chromosome regulated by the tac promoter was most suitable fo r sulfide oxidation and growth of the cells.