FIG 3.
Construction and selection of an HHP-inducible toxin-antitoxin cassette. (A) Genetic organization of the HHP-inducible toxin-antitoxin cassette (HHP-TAC). Phhp1 and Phhp2 are the HHP-inducible promoters. PhmtB and Pgdh are constitutive promoters. The HMG-CoA reductase gene (PF1848 gene) from P. furiosus (P.fu.) was used as a positive selection marker. Antitoxin (PF775) and toxin (PF776) from P. furiosus were used as a counterselectable marker fused with the promoters. The sequence of the shuttle plasmid pLMO12102 is in boldface. RBS, ribosomal binding site. (B) Biomasses of the recombinant strains with different type II TA systems at different pressures. A1/pLMOS776TA, A1/pLMOS812TA, A1/pLMOS839TA, and A1/pLMOS1206TA indicate the A1 strain with the plasmids pLMOS776TA, pLMOS812TA, pLMOS839TA, and pLMOS1206TA, respectively. Black indicates the biomasses of the strains at atmospheric pressure. Dark gray indicates the biomasses of the strains at 52 MPa. The results are from three independent experiments, and the error bars represent the standard deviations. **, P < 0.01.