Location: Poultry Microbiological Safety and Processing Research UnitTitle: Impact of enrichment media on H2S negative salmonella isolated from xylose-lysine-tergitol 4 agar (XLT4)
|RICHARDSON, KURT - Anitox Corp|
|Cox, Nelson - Nac|
|HOLCOMBE, NICOLE - Anitox Corp|
|WELLER, CHERYL - Anitox Corp|
Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2019
Publication Date: 9/27/2019
Citation: Richardson, K.E., Cox Jr, N.A., Cosby, D.E., Holcombe, N., Weller, C. 2019. Impact of enrichment media on H2S negative salmonella isolated from xylose-lysine-tergitol 4 agar (XLT4). Journal of Applied Poultry Research. 0:1-7. https://doi.org/10.3382/japr/pfz093.
Interpretive Summary: The recovery of Salmonella from feed and feed ingredients is difficult because of the environmental changes in the pre-enrichment and enrichment media which can prevent injured Salmonella from recovering. This prevents the Salmonella from growing to a level which can be recovered with cultural methods because of changes in the ability of the Salmonella to produce H2S on certain media. This study attempted to determine the ability of Salmonella serotypes recover after incubation in various enrichment broths to improve the knowledge of how these Salmonella serotypes react in the enrichment broths after being injured and stressed in the production of poultry feed. The results indicate that some Salmonella serotypes are not able to recover the ability to produce H2S after enrichment in various broths. This would prevent the identification of Salmonella in feed.
Technical Abstract: Salmonella from feed/ingredients. Depending on feed/ ingredient type, the pH of the pre-enrichment media can decrease during incubation to a pH 4.0 - 5.0. Acidic conditions can: 1) injure Salmonella, 2) kill Salmonella and/or 3) affect their biochemical pathways. Most strains of Salmonella produce hydrogen sulfide (H2S) from thiosulfate and/or sulfide on selective agars which is utilized to differentiate Salmonella from other microorganisms. The ability of isolates to produce H2S on xylose-lysine-tergitol 4 agar (XLT4) is dependent on the acidic conditions that can occur during pre-enrichment, the strain of Salmonella and the stress status of the isolate. Enrichment media are often used to recover injured Salmonella with respect to cell multiplication but have not been examined for their ability to repair damage to biochemical pathways. In this study, isolates of Salmonella that had previously been exposed to acidic conditions and lost the ability to produce H2S on XLT-4 agar were grown in various enrichment media. After 24 h of enrichment, H2S positive and negative colonies were enumerated. The impact of enrichment media on cell multiplication was dependent on enrichment media, incubation temperature, Salmonella strain, stress status and H2S status. None of the enrichment media restored the ability of the isolate to produce H2S on XLT-4 agar at 24h. After an additional 24 h incubation, (48 h total) the ability of some isolates to produce H2S was restored.