IAFP 2009 Program Book and Abstract Book - AB184

P3-96 Survival of Lactic Acid Bacteria in Various Water Sources and Sandy Loam Soil DSC ANGELA M. LAURY and Mindy M. Brashears Texas Tech University, Animal and Food Sciences, Lubbock, TX, USA Introduction: Lactic acid bacteria are known to have antagonist properties that are capable of reducing E. coli O157:H7 in multiple environments. Soil and water has been identified as vectors for transmission of E. coli O157:H7 onto fresh produce and onto live cattle. Purpose: The objective of this study was to evaluate the survival of lactic acid bacteria (LAB) in three types of water sources (tap water, well water, and autoclaved water) and in sandy loam soil to determine if water and soil applications could serve as interventions. Methods: Lubbock municipal tap water (very hard, 289 ppm), a local farm well water (moderately hard, 110 ppm) and autoclaved softened water (soft, 40 ppm) and local sandy loam soil were inoculated separately with a lactic acid bacteria 5-strain inoculum at a 108 and 1010 CFU/(ml/g) load, respectively. Water samples and soil were placed within a plant growth chamber set at fall in central California for 48 h (0, 6, 12, 18, 24, 48 h) or 28 days (0, 1, 7, 10, 14, 21, 28 days), respectively. On each sample day, samples were diluted, plated onto MRS and incubated at 37°F for 48 h. The data were analyzed using a descriptive analysis in SAS program. Results: In the water study, the tap water maintained a significantly lower LAB count than the other water sources, regardless of the sampling time (P < 0.03). Although there was a sampling time effect reported (P = 0.0325), all water sources had less than 0.8 log CFU/ml reductions of LAB found over the 48-h study. Within the soil study, the lactic acid bacteria were significantly reduced by 3.0 log cycles by the end of the study. LAB reduction was found within the first week (P < 0.02) and another log CFU/g was found between day 21 and 28 (P < 0.001). Significance: Water applications of LAB will likely be performed within 48 h. According to this study, addition of a 1 log higher dose of the LAB to the water might be necessary to ensure proper application rates, depending on the water type. In sandy loam soil, a 1 log increase in the initial population should be added as well, and this should give a protective effect for up to 21 days before another application of the LAB would be needed. Use of LAB in the soil and water has potential application in produce and animal environments to reduce foodborne pathogens. P3-97 Withdrawn P3-98 Application of a Novel Single Bacterial Cell Manipulation Technique Listeria monocytogenes DSC BARBARA RÖDER, Martin Wagner and Peter Rossmanith University of Veterinary Medicine Vienna, Dept. of Veterinary Public Health and Food Science, Vienna, Austria Introduction: Highly diluted suspensions of bacterial cells are distributed according to the Poisson distribution. Quantitative microbiological methods (Most Probable Number, MPN) are based on this prerequisite. Nevertheless, predictions on the growth performance of single bacterial cells are not possible due to these statistical effects. A new method that avoids these influences was developed which enables the physical manipulation of single bacterial cells. Based on this method the investigation of autonomous growth of low bacterial cell inocula (< 10) was performed. Purpose: The purpose of this study was to evaluate the growth performance of single bacterial cells without the influence of statistics within dilution series. Furthermore, the necessity of chemical and physical cell-to-cell interactions for bacterial growth was investigated. Methods: Listeria monocytogenes EGDe bacteria from the lag-phase, the mid-exponential phase, and the stationary phase were used to produce single cell inocula with the newly developed single bacterial cell manipulation technique (SBCM). Growth in tryptone soy broth with 0.6% yeast was evaluated after 24 h at 37°C by measurement of optical density and by selective and non-selective plating. Results: For 110 manipulated single cells, growth was detectable in 79 samples (71.5%), with a final optical density of 1.21 × 109 CFU/ml (± 9.07%). In 31 samples (28.5%) growth was not detectable. The live/dead ratio of the initial culture was 20.9% (± 20.6%) as obtained by live/dead staining. These results show a good correlation of live/dead ratios before and after the SBCM, indicating the ability for autonomous growth. Significance: These data suggest that the investigated single bacterial cells are able to multiply independently under optimal conditions. Poster P3-99 Evaluation of a New Automated Method for Enumerating Yeast and Mold in Food Products GREGORY DEVULDER bioMérieux, Marcy l’Etoile, France Introduction: Yeast and Mold (YM) enumeration in food is useful in evaluating its quality and the degree of deterioration and is often an essential component in microbiological quality assurance programs. Purpose: In this study, we compared the TEMPO automated method for the enumeration of YM to the FDA-BAM recommended procedure: Dichloran rose bengal chloramphenicol (DRBC) or Dichloran 18% glycerol agar (DG18) media depending on the food product aw, and to Potato Dextrose Agar (PDA). Methods: TEMPO™ enumeration is based on the well known Most Probable Number (MPN) procedure. The method uses a selective dehydrated culture medium and an enumeration card for the automatic determination of the MPN. A total of 400 naturally contaminated products were tested. These products represented a wide range of food categories, including dairy products, raw and cooked meats, poultry, fish and seafood, vegetables, Ready-to-Eat foods (RTE) and environmental 184 — Abstract Book

IAFP 2009 Program Book and Abstract Book

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