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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Poultry Microbiological Safety and Processing Research Unit » Research » Publications at this Location » Publication #301743

Title: Effect of Beef Extract Concentration on Growth of Campylobacter in Media Incubated Aerobically

Author
item Hinton Jr, Arthur

Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2014
Publication Date: 9/3/2014
Citation: Hinton Jr, A. 2014. Effect of Beef Extract Concentration on Growth of Campylobacter in Media Incubated Aerobically. Journal of Food Protection. 77:39.

Interpretive Summary: Campylobacter is a major foodborne pathogen associated with poultry and other meats. Although Campylobacter are generally cultured under microaerophilic atmospheres, recent findings have indicated that this pathogen can be cultured aerobically in media containing appropriate growth factors. Purpose: In this study, media supplemented with various concentrations of beef extract were examined for the ability to support aerobic growth of Campylobacter. Methods: Basal broth composed of tryptose, yeast extract, bicarbonate, and agar was supplemented with 0.0, 2.5, 5.0, or 7.5% (wt/vol) beef extract and inoculated with approximately 103 cfu/ml Campylobacter coli, Campylobacter fetus, Campylobacter jejuni 2b, Campylobacter jejuni 33560, or Campylobacter lari. Aliquots of inoculated media were transferred to wells of honeycomb plates, placed in a Bioscreen Microbiology Reader, and optical densities (OD) were measured during incubation for 48 h at 37C (n = 5). Inoculated media supplemented with 5.0% beef extract was also incubated aerobically in culture flasks for 72 h at 37C, and cfu/ml were enumerated after 48 and 72 h incubation by plating serial dilutions of cultures on selective Campylobacter agar (n = 3). Results: OD of isolates cultured in media supplemented with 2.5, 5.0, or 7.5% beef extract was significantly (P < 0.05) greater than OD of isolates cultured in media not supplemented with beef extract. Optimal growth of most isolates was generally produced in media supplemented with 5.0 or 7.5% beef extract. There were approximately 5 to 6 log increases in cfu/ml of Campylobacter recovered from inoculated media supplemented with 5% beef extract and incubated aerobically. Additionally, there was no significant difference in the number of cfu/ml recovered from supplemented media incubated for 48 or 72 h. Significance: Findings indicate that beef extract contains metabolites that may support aerobic growth of this foodborne pathogen. Use of these media may provide a less expensive method for culturing Campylobacter.

Technical Abstract: Campylobacter is a major foodborne pathogen associated with poultry and other meats. Although Campylobacter are generally cultured under microaerophilic atmospheres, recent findings have indicated that this pathogen can be cultured aerobically in media containing appropriate growth factors. Purpose: In this study, media supplemented with various concentrations of beef extract were examined for the ability to support aerobic growth of Campylobacter. Methods: Basal broth composed of tryptose, yeast extract, bicarbonate, and agar was supplemented with 0.0, 2.5, 5.0, or 7.5% (wt/vol) beef extract and inoculated with approximately 103 cfu/ml Campylobacter coli, Campylobacter fetus, Campylobacter jejuni 2b, Campylobacter jejuni 33560, or Campylobacter lari. Aliquots of inoculated media were transferred to wells of honeycomb plates, placed in a Bioscreen Microbiology Reader, and optical densities (OD) were measured during incubation for 48 h at 37C (n = 5). Inoculated media supplemented with 5.0% beef extract was also incubated aerobically in culture flasks for 72 h at 37C, and cfu/ml were enumerated after 48 and 72 h incubation by plating serial dilutions of cultures on selective Campylobacter agar (n = 3). Results: OD of isolates cultured in media supplemented with 2.5, 5.0, or 7.5% beef extract was significantly (P < 0.05) greater than OD of isolates cultured in media not supplemented with beef extract. Optimal growth of most isolates was generally produced in media supplemented with 5.0 or 7.5% beef extract. There were approximately 5 to 6 log increases in cfu/ml of Campylobacter recovered from inoculated media supplemented with 5% beef extract and incubated aerobically. Additionally, there was no significant difference in the number of cfu/ml recovered from supplemented media incubated for 48 or 72 h. Significance: Findings indicate that beef extract contains metabolites that may support aerobic growth of this foodborne pathogen. Use of these media may provide a less expensive method for culturing Campylobacter.