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United States Department of Agriculture

Agricultural Research Service

Research Project: Optical Detection of Food Safety and Food Defense Hazards

Location: Quality and Safety Assessment Research Unit

Title: The effect of nutrient media water purity on LIBS based identification of bacteria

Author
item Gamble, Gary

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 20, 2014
Publication Date: N/A

Technical Abstract: Single pulse laser induced breakdown spectroscopy (LIBS) is used as the basis for discrimination between 3 genera of Gram-negative bacteria and 2 genera of gram-positive bacteria representing pathogenic threats commonly found in poultry processing rinse waters. Because LIBS-based discrimination relies primarily upon the relative proportions of inorganic cell components including sodium, potassium, magnesium and calcium, this study aims to determine the effects of trace mineral content found in the water source used to culture the bacteria upon the reliability of the resulting discriminant analysis. All five genera were cultured using tryptic soy agar (TSA) as the nutrient medium, and were grown under identical environmental conditions. The only variable introduced is the source water used to make the TSA growth medium. Three cultures of each bacteria were produced using deionized water, distilled water, and tap water. After three days of culture growth, the bacteria were centrifuged and washed three times in the same water source. Bacteria were then freeze dried, mixed with microcrystalline cellulose, and a pellet was made for LIBS analysis. Preliminary results suggest that for each water treatment, discrimination between the five genera can be achieved, but that the resulting model for one water treatment does not transfer to the other water treatments.

Last Modified: 12/18/2014
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