Agarose gel electrophoresis results of PCR products.

Lane M: DNA molecular weight standard. (a) The fusion PCR result from the upstream and downstream homologous recombinant arms of crc and a kanamycin-resistant gene. Lane 1: Targeting sequences with a length of 3232 bp, containing upstream homologous recombination arm (918bp)–coding sequence of kanamycin resistant gene- downstream homologous recombination arm (847bp). (b) The fusion PCR from the upstream and downstream homologous recombinant arms of crcY and kanamycin-resistant gene. Lane 1: Targeting sequence with a length of 3167 bp, containing upstream homologous recombination arm (809bp) -coding sequence of kanamycin resistant gene-downstream homologous recombination arm (891bp). (c) The fusion PCR from upstream and downstream homologous recombination arms of crcZ and gentamicin-resistance gene. Lane 1: Targeting sequence with a length of 2611 bp, containing upstream homologous recombination arm (776bp) -coding sequence of gentamicin resistant gene-downstream homologous recombination arm (946bp). d-e: PCR products with internal identified primers in CCR gene knockout strains. (d) PCR of crc knockout strain. Lane 1–20: The amplification results of colonies No.1-20. If crc was knockout, no product could be detected; Lane 21: The amplification result of the original strain, and the length of product was 223 bp; Lane 22: The amplification result of negative control, and no product was amplified. (e) PCR of crcY knockout strain. Lane 1–10: The amplification products of colonies No. 1–10. If crcY was knockout, no product could be detected; Lane 11: The amplification results of the original strain, and the length of the product was 146 bp; Lane 12: The amplification result of negative control, and no product was amplified. (f) The PCR identification result of crcZ knockout strain. Lane 1–7: The amplification results of colonies No. 1–7. If crcZ was knockout, no product could be detected; Lane 8: The amplification results of the original strain, and the length of the product was 149 bp; Lane 9: The amplification results of negative control, and no product was amplified. g-h: PCR products using external identified primers in CCR gene knockout strains. (g) PCR identification result of crc knockout strain. Lane 1: The amplification result of No.1 colony. (h) The PCR product of the crcY knockout strain. Lane 1: The amplification result of No.1 colony. (i) The PCR identification result of crcZ knockout strain. Lane 1: The amplification result of No.1 colony.