The depressed P cycle contributes to the acquisition of ampicillin resistance in Edwardsiella piscicida.

Antibiotic-resistant bacteria are an increasingly serious threat to human health and aquaculture. To further explore bacterial antibiotic resistance mechanism, iTRAQ is used to identify a differential proteome in ampicillin-resistant LTB4 (LTB4-R), a strain of Edwardsiella piscicida. A total of 102 differentially proteins with 50 upregulation and 52 downregulation are identified. Since many of these changes are related to metabolism, interactive pathways explorer(iPath) is used to understand a global differentially metabolic response in LTB4-R This analysis identifies a global depressed metabolic modulation as the most characteristic feature of LTB4-R. Lower membrane potential and ATP in LTB4-R than control support that the central carbon metabolism and energy metabolism are reduced. Since the pyruvate cycle (the P cycle) plays a key role in the central carbon metabolism and energy metabolism, further investigation focuses on the P cycle and shows that expression of genes and activity of enzymes in the P cycle are decreased in LTB4-R. These results support the conclusion that the depressed P cycle contributes to the acquisition of ampicillin resistance in E.piscicida. These findings indicate that the combination of proteomics and iPath analysis can provide a global metabolic profile, which helps us better understand the correlation between ampicillin resistance and cellular metabolism. SIGNIFICANCE: The present study uses iTRAQ to explore ampicillin resistance mechanism in Edwardsiella piscicida and finds many of these differential abundances of proteins are related to metabolism. IPath further identifies a global depressed metabolic modulation and characterizes the reduced pyruvate cycle as the most characteristic feature of the ampicillin-resistant E. piscicida, which is supported by reduced expression of genes and activity of enzymes in the pyruvate cycle. Consisitently, lower membrane potential and ATP are detetced. These results reveal the metabolic mechanism of ampicillin resistance and provide a solid proof to revert the resistance by reprogramming metabolomics.