Lerminiaux Nicole A, Kaufman Jaycee M, Schnell Laura J, Workman Sean D, Suchan Danae M, Kröger Carsten, Ingalls Brian P, Cameron Andrew D S
Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada.
Department of Biology, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada.
ISME J. 2025 Jan 2;19(1). doi: 10.1093/ismejo/wraf032.
The diffusible toxin ColIb produced by Salmonella enterica serovar Typhimurium SL1344 is a potent inhibitor of Escherichia coli growth. To identify and parameterize metabolic cross-feeding in states of competition, we established defined communities in which E. coli was the only species able to access a sole carbon source, lactose. Although ColIb was predicted to undermine cross-feeding by killing the lactose-converting E. coli, S. enterica populations thrived in co-culture. We discovered that ColIb caused the release of active β-galactosidase from E. coli cells, which induced galactose uptake by S. enterica. Although iron limitation stimulates ColIb production and makes E. coli more sensitive to the toxin, ColIb killing in iron-limited conditions did not enhance iron acquisition or siderophore scavenging by S. enterica. Also unexpected was the rapid rate at which resistance to ColIb evolved in E. coli through spontaneous mutation of the ColIb receptor gene cirA or horizontal acquisition of the S. enterica colicin immunity gene imm. Mathematical modelling effectively predicted the growth kinetics of E. coli and S. enterica populations, revealing a tractable system in which ColIb can shrink a competitor population while simultaneously amplifying the metabolic contributions of the suppressed population.
肠炎沙门氏菌鼠伤寒血清型SL1344产生的可扩散毒素ColIb是大肠杆菌生长的有效抑制剂。为了识别和参数化竞争状态下的代谢交叉喂养，我们建立了特定的群落，其中大肠杆菌是唯一能够利用单一碳源乳糖的物种。尽管预计ColIb会通过杀死转化乳糖的大肠杆菌来破坏交叉喂养，但肠炎沙门氏菌群体在共培养中却蓬勃发展。我们发现ColIb导致大肠杆菌细胞释放活性β-半乳糖苷酶，从而诱导肠炎沙门氏菌摄取半乳糖。尽管铁限制会刺激ColIb的产生并使大肠杆菌对该毒素更敏感，但在铁限制条件下ColIb的杀伤作用并未增强肠炎沙门氏菌的铁摄取或铁载体清除。同样出乎意料的是，大肠杆菌通过ColIb受体基因cirA的自发突变或水平获得肠炎沙门氏菌大肠杆菌素免疫基因imm，对ColIb的抗性进化速度很快。数学建模有效地预测了大肠杆菌和肠炎沙门氏菌群体的生长动力学，揭示了一个易于处理的系统，其中ColIb可以缩小竞争群体的规模，同时放大受抑制群体的代谢贡献。
