Source: UNIVERSITY OF GEORGIA submitted to NRP
ALLIANCE FOR FOOD PROTECTION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
SPECIAL GRANT
Reporting Frequency
Annual
Accession No.
0191747
Grant No.
2002-34352-11932
Cumulative Award Amt.
(N/A)
Proposal No.
2002-06029
Multistate No.
(N/A)
Project Start Date
Jul 1, 2002
Project End Date
Jun 30, 2004
Grant Year
2002
Program Code
[KY]- (N/A)
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
CENTER FOR FOOD SAFETY
Non Technical Summary
Studies will address: (1) the fate of Bacillus anthracis in foods; (2) the conditions that influence extracellular polysaccharide production by E. coli on lettuce leaves; (3) the efficacy of chlorine in killing E. coli O157 in biofilms on lettuce leaves; and (4) the identification of antimicrobials to Campylobacter.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
71240101100100%
Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
4010 - Bacteria;

Field Of Science
1100 - Bacteriology;
Goals / Objectives
Research activities of the University of Georgia for 2002-2004 will include: (1) determine the fate of Bacillus anthracis in foods; (2) determine conditions that influence extracellular polysaccharide production by E. coli on lettuce leaves; (3) determine the efficacy of chlorine in killing E. coli O157:H7 colonized in biofilms on lettuce leaves; and (4) identify antimicrobials to Campylobacter.
Project Methods
Studies on B. anthracis will determine the survival and growth characteristics and spore stability of this pathogen in different foods. Studies on E. coli O157:H7 on lettuce leaves will determine the influence of temperature on production of protective polysaccharide material (EPS) of E. coli O157:H7, and the efficacy of antimicrobials in killing E. coli O157:H7 in the presence of EPS-containing biofilms. Studies on Campylobacter will identify combinations of antimicrobials that effectively kill this pathogen on poultry.

Progress 07/01/02 to 06/30/04

Outputs
Exopolysaccharides (EPS) produced by E. coli O157:H7 can provide protection to the pathogen under conditions of environmental stress. Studies were done to determine the influence of environmental conditions during growth on EPS production by E. coli O157. Results revealed a negative correlation between extracellular carbohydrate complex production and cell growth of E. coli O157. This suggests that when exposed to adverse conditions in which E. coli O157 does not grow well, the pathogen produces extracellular carbohydrates to protect itself from injurious environmental conditions. This may help in part explain how E. coli O157 acquires extraordinary tolerance to acidic and other environmental stresses. The resistance of E. coli O157:H7 to chlorine increased significantly as cells formed biofilm on coupons; strain ATCC 43895+ was the most resistant. Population sizes of strains ATCC 43895+ and ATCC 43895- in biofilm formed at 12 degrees C were not significantly different, but cells of strain ATCC 43895+ showed significantly higher resistance than did cells of strain ATCC 43895-. Campylobacter jejuni is present on ca. 60% of retail fresh broilers. Practical and effective treatments are needed to reduce this pathogen load for greater public health protection. Studies with a variety of chemicals that are generally recognized as safe for use in foods were done to identify which combinations were effective in killing C. jejuni on fresh chicken wings at 4 degrees C and would be practical to use. Results revealed that most chemical treatments reduced C. jejuni populations by less than 2 log/g. However, treatment with a combination of acidic calcium sulfate, lactic acid and ethanol plus surfactants reduced C. jejuni populations by greater than 5 log/g after 30 sec of exposure. This appears to be both a highly effective and practical treatment to inactivate C. jejuni on refrigerated fresh poultry. Studies on the fate of Bacillus anthracis Stern strain in pasteurized whole and skim milk held at 4 or 12 degrees C revealed there was little to no change in spore numbers for at least 2 weeks.

Impacts
Understanding factors that influence the unusual tolerance of E. coli O157:H7 to environmental stresses such as acidic and alkaline conditions can be useful in developing practical treatments to inactivate this microbe in foods. A highly effective chemical treatment was developed for inactivating C. jejuni on fresh poultry at 4 degrees C.

Publications

  • Ryu, J.-H., and L. R. Beuchat. 2003. Development of a method to quantify extracellular carbohydrate complexes produced by Escherichia coli O157:H7. J. Appl. Microbiol. 95:1304-1314.
  • Ryu, J.-H., and L. R. Beuchat. 2004. Factors affecting production of extracellular carbohydrates by Escherichia coli O157:H7. Int. J. Food Microbiol. 95:189-204.
  • Ryu, J.-H. and L. R. Beuchat. 2005. Biofilm formation by Escherichia coli O157:H7 on stainless steel: Effect of exopolysaccharide and curli production on its resistant to chlorine. Appl. Environ. Microbiol. 71:247-254.
  • Ryu, J.-H., H. Kim, and L. R. Beuchat. 2004. Attachment and biofilm formation by Escherichia coli O157:H7 on stainless steel as influenced by exopolysaccharide production, nutrient availability, and temperature. J. Food Prot. 67:2123-2131.
  • Ryu, J. H., H. Kim, J. F. Frank, and L. R. Beuchat. 2004. Attachment and biofilm formation on stainless steel by Escherichia coli O157:H7 as affected by curli production. Lett. Appl. Microbiol. 39:359-362.
  • Sharma, M., J -H. Ryu, and L. R. Beuchat. 2005. Inactivation of Escherichia coli O157:H7 in biofilm on stainless steel by treatment with an alkaline cleaner and bacteriophage. J. Appl. Microbiol. (Submitted)
  • Ryu, J.-H., H. Kim, and L. R. Beuchat. 2005. Spore formation by Bacillus cereus in broth as affected by temperature, nutrient availability, and manganese. J. Food Prot. (Submitted)
  • Kim, H., J. H. Ryu, J. F. Frank, and L. R. Beuchat. 2004. Role of curli production in attachment and biofilm formation by Escherichia coli O157:H7 on stainless steel. Inst. Food Technol. Annu. Mtg. Book of Abstracts, 12-16 July, Las Vegas, NV, p. 264.
  • Ryu, J. H., and L. R. Beuchat. 2003. Development of a method to quantify extracellular carbohydrate complexes produced by Escherichia coli O157:H7. Inst. Food Technol. Annu. Mtg., Book of Abstracts, 13-17 July, Chicago, IL, p. 196.
  • Ryu, J.-H., H. Kim, and L. R. Beuchat. 2004. Attachment and biofilm formation by Escherichia coli O157:H7 on stainless steel as affected by exopolysaccharide production, nutrient availability, and temperature. Inst. Food Technol. Annu. Mtg., Book of Abstracts, 12-16 July, Las Vegas, NV, p. 264.
  • Ryu, J.-H., H. Kim, and L. R. Beuchat. 2005. Spore formation by Bacillus cereus in broth and biofilm on stainless steel as affected by nutrient availability, temperature, and relative humidity. Inst. Food Technol. Annu. Mtg., Book of Abstracts, 17-20 July, New Orleans, LA.
  • Sharma, M., J.-H. Ryu, and L. R. Beuchat. 2005. Inactivation of Escherichia coli O157:H7 in biofilm on stainless steel by treatment with an alkaline steel and bacteriophage. Int. Assn. Food Prot., Prog. Abst. Book, 14-17 August, Baltimore, MD.
  • Ryu, J.-H. 2004. Production of exopolysaccharide and curli by enterohemorrhagic Escherichia coli O157:H7 as affected by temperature, pH, and nutrient availability, and its influence on attachment, biofilm formation, and resistance to chlorine. Ph.D. Dissertation, University of Georgia. 200 pp.


Progress 01/01/03 to 12/31/03

Outputs
Exopolysaccharides (EPS) produced by E. coli O157:H7 can provide protection to the pathogen under conditions of environmental stress. Studies were done to determine the influence of environmental conditions during growth on EPS production by E. coli O157. Results revealed a negative correlation between extracellular carbohydrate complex production and cell growth of E. coli O157. This suggests that when exposed to adverse conditions in which E. coli O157 does not grow well, the pathogen produces extracellular carbohydrates to protect itself from injurious environmental conditions. This may help in part explain how E. coli O157 acquires extraordinary tolerance to acidic and other environmental stresses. Campylobacter jejuni is present on ca. 60% of retail fresh broilers. Practical and effective treatments are needed to reduce this pathogen load for greater public health protection. Studies with a variety of chemicals that are generally recognized as safe for use in foods were done to identify which combinations were effective in killing C. jejuni on fresh chicken wings at 4 degrees C and would be practical to use. Results revealed that most chemical treatments reduced C. jejuni populations by less than 2 log/g. However, treatment with a combination of acidic calcium sulfate, lactic acid and ethanol plus surfactants reduced C. jejuni populations by greater than 5 log/g after 30 sec of exposure. This appears to be both a highly effective and practical treatment to inactivate C. jejuni on refrigerated fresh poultry.

Impacts
Understanding factors that influence the unusual tolerance of pathogens to environmental stresses such as acidic conditions can be useful in developing practical treatments to inactivate harmful microorganisms in foods. A highly effective chemical treatment was developed for inactivating C. jejuni on fresh poultry at 4oC.

Publications

  • Ryu, J.-H., and L. R. Beuchat. 2003. Development of a method to quantify extracellular carbohydrate complexes produced by Escherichia coli O157:H7. J. Appl. Microbiol. 95:1304-1314.
  • Ryu, J.-H., and L. R. Beuchat. 2004. Factors affecting production of extracellular carbohydrate complexes by Escherichia coli O157:H7. Int. J. Food Microbiol. (Accepted for publication)


Progress 01/01/02 to 12/31/02

Outputs
Several media were evaluated for recovery of vegetative cells of Bacillus species which serve as surrogates of B. anthracis, according to a modified ecometric technique. Results indicate PLET medium is a superior recovery medium. A procedure was developed to quantify extracellular carbohydrate complexes produced by E. coli lO157:H7. The procedure differentiates carbohydrates that are secreted by cells and are easily detached by mild mechanical force from capsular carbohydrates that are attached to the cell surface. More than fifty bacterial isolates from chickens that did not fecally excrete Campylobacter jejuni were highly antagonistic to C. jejuni. Most of these isolates were determined to be gram-positive rods, oxidase-negative, catalase-negative and grow well at 37oC.

Impacts
Media were validated for recovering surrogates of B. anthracis to enable the study of inactivation of B. anthracis in foods. A protocol was developed to enable the study of the effect of extracellular polysaccharide production by E. coli O157:H7 on biofilm formation. Microbes inhibitory to Campylobacter jejuni were assayed to determine their growth characteristics and presumptive identity. This information will be beneficial in identifying conditions to culture and preserve these strains for use in animal production.

Publications

  • No publications reported this period