The attachment process and physiological properties of Escherichia coli O157:H7 on quartz
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RESEARCH ARTICLE
Open Access
The attachment process and physiological properties of Escherichia coli O157:H7 on quartz Liliang Wang, Yichao Wu, Peng Cai* and Qiaoyun Huang
Abstract Background: Manure application and sewage irrigation release many intestinal pathogens into the soil. After being introduced into the soil matrix, pathogens are commonly found to attach to soil minerals. Although the survival of mineral-associated Escherichia coli O157:H7 has been studied, a comprehensive understanding of the attachment process and physiological properties after attachment is still lacking. Results: In this study, planktonic and attached Escherichia coli O157:H7 cells on quartz were investigated using RNA sequencing (RNA-seq) and the isobaric tagging for relative and absolute quantitation (iTRAQ) proteomic method. Based on the transcriptomic and proteomic analyses and gene knockouts, functional two-component system pathways were required for efficient attachment; chemotaxis and the Rcs system were identified to play determinant roles in E. coli O157:H7 attachment on quartz. After attachment, the pyruvate catabolic pathway shifted from the tricarboxylic acid (TCA) cycle toward the fermentative route. The survival rate of attached E. coli O157:H7 increased more than 10-fold under penicillin and vancomycin stress and doubled under alkaline pH and ferric iron stress. Conclusions: These results contribute to the understanding of the roles of chemotaxis and the Rcs system in the attachment process of pathogens and indicate that the attachment of pathogens to minerals significantly elevates their resistance to antibiotics and environmental stress, which may pose a potential threat to public health. Keywords: Escherichia coli O157:H7, Chemotaxis, Rcs system, Fermentative route, Stress susceptibility
Background Escherichia coli O157:H7 is one of the most ubiquitous foodborne zoonotic pathogens [1–3]. Sewage irrigation and manure application to soil have caused the pathogen to seep into soil matrices [4]. After introduction into the soil environment, this pathogen can be further transmitted to sediment, water, crops, and livestock, which have been directly linked to many cases of E. coli O157:H7 infection [5, 6]. Bacteria in the soil matrix proliferate in both sessile and planktonic states. In the environment, the sessile state is the dominant lifestyle of microorganisms, providing * Correspondence: [email protected] State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
physical, chemical, and biological protection to the microorganisms [7–9]. Therefore, understanding the attachment process and physiological features of surfaceattached E. coli O157:H7 in the soil environment is key to assessing the potential risks of this bacterium to public health [10]. As a general observation, most regulatory pathways participating in attachment are part of two-component signal transduction systems (TCS), which consist of a membrane-anchored signal s
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