Listeria and Omics Approaches for Understanding Its Biology
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Listeria and Omics Approaches for Understanding Its Biology

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Presented at 2013 Arkansas Association for Food Protection annual conference.

Presented at 2013 Arkansas Association for Food Protection annual conference.

Janet R. Donaldson, Ph.D.
Mississippi State University
Department of Biological Sciences

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Listeria and Omics Approaches for Understanding Its Biology Listeria and Omics Approaches for Understanding Its Biology Presentation Transcript

  • Janet R. Donaldson, Ph.D. Mississippi State University Department of Biological Sciences donaldson@biology.msstate.edu
  • Listeria monocytogenes  One of the deadliest food- borne pathogens  Cantaloupe outbreak in 2011 was the third most deadly outbreak since 1924; killed 30 people  1st: E. coli O104:H4 outbreak of 2011; Killed 53  2nd: Listeria outbreak in 1985; Killed 52
  •  Soil bacterium  Infects both humans and animals  Low pH, intracellular growth, high bile salts  5-10% of population are asymptomatic carriers  Grows in a wide range of temperatures (2°C to 39°C) and environmental conditions (salt, mildly acidic)  Major problems with ready to eat foods, such as smoked fish industry, deli meats, and cheese Survives a variety of environments
  • It’s complicated…  Many factors contribute to the complications of studying Listeria monocytogenes  13 different serotypes, 4 genetic lineages  Most food-borne outbreaks are related to serotype 4b, but 1/2a, 1/2b, and 4a are also important for human and animal health  Conversion to L-forms  Formation of biofilms  Advances in molecular biology allowed for huge advancements to be made in terms of monitoring strain persistence in food processing plants
  • GOLDEN AGE OF OMICS
  • Advances in Omics  Vast amount of information  Transcriptomics  Proteomics  Secretomics  Metabolomics  Interactomics
  • Functional Proteomics Approach to Answer Complicated Questions  How do basic metabolic processes differ between different serotypes?  What are the mechanisms that allow for survival of Listeria monocytogenes in stressful environments?  How do these strategies for survival differ between different serotypes of Listeria monocytogenes?
  • Proteomics Analysis  Preparation of protein samples  Analyzed by HPLC coupled with nano-LTQ linear ion trap mass spectrometer  Spectra analyzed against trypsin digested FASTA database with converted file  Protein modifications need to be analyzed; analysis run against decoy database  Protein expression comparisons made based on spectral intensity  Significantly expressed proteins assigned to classification category based on ListiList
  • Variations in proteome expression  EGDe (1/2a serotype) and F2365 (4b) proteomes differ in stationary phase F2365 total: 1427 (350) EGD total: 1754 (677) Common (1077) Donaldson et al, 2009 Appl Environ Microbiol F2365 EGDe
  •  Expression of 322 proteins was significantly increased in EGDe in comparison to F2365  Mostly in cell wall physiology and cell wall anchor proteins  Stress response proteins UvrC, UvrA, MutS, MutY, RecN, GroEL, GroES, DnaK  Expression of 91 proteins was significantly decreased in F2365 in comparison to EGDe  Flagellar biosynthesis protein  Chemotaxis protein CheY  Catalase  Thiol peroxidase Proteins Differentially Expressed Donaldson et al, 2009 Appl Environ Microbiol
  • Functional Proteomics Approach to Answer Complicated Questions  How do basic metabolic processes differ between different serotypes?  What are the mechanisms that allow for survival of Listeria monocytogenes in stressful environments?  How do these strategies for survival differ between different serotypes of Listeria monocytogenes?
  • Mechanisms that allow for survival in stressful environments  Minimal exposure to one stressor can influence resistance to another stressor  Methods used can increase resistance of Listeria monocytogenes to other stressors encountered and also influence its persistence in facilities  Studies have suggested overlap in adaptive mechanisms used by L. monocytogenes to cold stress and osmotic stress
  • Cold Smoking Process  Process involves:  Freeze/ thaw of fish to remove parasites  Brining with salt  Exposure to smoking conditions for less than 24 h  Packaging and storage Can exposure to cold influence survival under osmotic stress?
  • Functional Proteomics Approach to Answer Complicated Questions  How do basic metabolic processes differ between different serotypes?  What are the mechanisms that allow for survival of Listeria monocytogenes in stressful environments?  How do these strategies for survival differ between different serotypes of Listeria monocytogenes?
  • Other studies…  Variations in the mechanism by which avirulent and virulent strains of Listeria monocytogenes respond to bile salt environments  Efficient repair mechanisms are essential for long term survival  Variations in intracellular v. extracellular growth between virulent and avirulent strains Payne et al, 2013 J Med Microbiol
  • Conclusions  Proteomics has advanced our understanding of the biology of Listeria monocytogenes  Variations between serotypes: provide insight into ecological niches  Mechanisms for survival in presence of stressors:  Cross adaptation between cold and osmotic stress:  Proteins involved re-modeling of the cell wall and cell membrane allow for the integrity and fluidity of the cell to be maintained in response to osmotic stress  Variations between different serotypes in response to stressors  Avirulent strains possess different mechanism to try to survive in presence of bile salts than virulent strains
  • Thank You!  MSU  Joseph Pittman  Kendrick Currie  Jessica Grissett-Wilson  Gabe Posadas  Stephanie Vamenta  Angela Payne  Susan Bridges  Chamali Thanthiriwatte  Justin Thornton  Mark Lawrence  Bindu Nanduri  Tibor Pechan  Shane Burgess, Univ. AZ  Ken Pendarvis, Univ. AZ  Todd Callaway, USDA-ARS  Jeff Carroll, USDA-ARS  Joe Buntyn, UNL  Ty Schmidt, UNL  Tjakko Abee, Wageningen University Funding: MSU ORED MSU Dept. of Biological Sciences DOE Sustainable Energy Research Center MAFES Special Research Initiatives NIH (T35RR007071)