Project Number: 8042-42000-006-00
Start Date: Mar 21, 2011
End Date: Mar 20, 2016
Objective 1: A proteomic approach will be applied for developing the surface profiling technologies. Various cell surface proteins will be harvested using sheering or enzymatic shaving techniques or membrane- impermeable biotin mediated affinity purification. Proteins and peptides will be identified using MALDI-TOF mass spectrometry and various liquid chromatography (LC) coupled MS detection technology. Besides the proteomic approach, antibody and micelle glycoprotein libraries will be tested in collaboration with CRADA partners. Similar approaches wil be used to determine the effects of environmental factors on the expression of surface proteins. Selected genes for targeted cell surface proteins will be mutated using site directed allelic change procedures and the effect of mutation on cell interacting with plant and environments will be studied using genetic and proteomic tools. Objective 2: Short-term and long-term nutrient starvation studies using Salmonella and E. coli O157:H7 under varying physiological conditions will be applied to determine the role of rpoS mediated adaptive mutations. In vitro growth conditions such as nutrient limited chemostat cultures, or vegetable wash waters in batch cultures will be utilized. Induction of acid tolerance by EHEC during different packaging conditions on various acidic and non-acidic produce during storage will be characterized. In collaboration with Dr. Sadowsky (U. Minisoda), natural Salmonella and E. coli O157:H7 isolates undergone minimal subculturing (>3) in the laboratory media will be used to determine rpoS heterogeneity. Genes encoding for osmoregulated cytoplasmic glucans (OPGs) will be cloned and characterized using site directed mutagenesis. Functions of OPGs in cell surface and cytoplasmic protein expression, cell motility, biofilm formation and survival in adverse environments will be studied using genetics and proteomic approaches.