Uptake of radiolabeled dimethylsulfoniopropionate (35S-DMSP) by E. coli wild-type and mutant strains complemented with candidate DMSP transporter genes from Ostreococcus tauri

Uptake (as dpm/mL/OD) of 35S-DMSP by several strains of Escherichia coli: (a) the wild type DH5α, which harbors a betaine-carnitine-choline transporter (BCCT); (b) MKH13, a mutant that is BCCT deficient ; (c) MKH13 + BCCT-1, a MKH13 that has been complemented with the BCCT-1 gene (as DMSP carrier candidate) from the picaoalga Ostreococcus tauri; (d) MKH13 + BCCT-2, a MKH13 that has been complemented with the BCCT-2 gene (as DMSP carrier candidate) from the picaoalga Ostreococcus tauri; (e) MKH13 + empty vector, a MKH13 complemented with the empty plasmid pBAD33 used above as the expression vector for BCCT genes. Killed controls (where the strains had been killed with fixatives before being assayed for 35S-DMSP uptake) are also shown a a 'zero 'reference.大肠杆菌（Escherichia coli）多菌株对³⁵S标记的二甲基巯基丙酸内盐（³⁵S-DMSP）的摄取量（以每分钟衰变数/毫升/光密度，即dpm/mL/OD为单位）：(a) 野生型DH5α，该菌株携带甜菜碱-肉碱-胆碱转运蛋白（betaine-carnitine-choline transporter, BCCT）；(b) MKH13，一种BCCT缺陷型突变菌株；(c) MKH13 + BCCT-1：向MKH13中互补表达源自超微藻奥氏微球藻（Ostreococcus tauri）的BCCT-1基因（作为DMSP转运蛋白候选）的重组菌株；(d) MKH13 + BCCT-2：向MKH13中互补表达源自超微藻奥氏微球藻的BCCT-2基因（作为DMSP转运蛋白候选）的重组菌株；(e) MKH13 + 空载体：向MKH13中转入空质粒pBAD33的重组菌株，该空质粒为上文用于BCCT基因表达的载体。灭活对照组（即先经固定剂处理灭活待测菌株，再开展³⁵S-DMSP摄取检测的样本组）亦作为‘零值’参照予以呈现。