Printer Friendly

Harness Fourier-transform infrared spectroscopy for rapid detection, differentiation of Salmonella enterica serovars in juice.

Techniques for identifying Salmonella are time-consuming, require a pre-enrichment procedure or special worker training. However, Fourier-transform infrared (FT-IR) spectroscopy makes it possible to identify bacteria based on unique, reproducible, biochemical fingerprints of major cellular components.

Scientists at The Ohio State University wanted to develop a simple protocol that could be used to detect and differentiate selected S. enterica serovars in spiked apple juice using FT-IR and multivariate analysis. They determined that FT-IR could be used for rapid, accurate identification of Salmonella at the serovar level.

The researchers streaked selected Salmonella enterica serovars--anatum, heidelberg, kentucky, typhimurium, muenchen and enteritidis--onto Miller-Mallinson (MM) agar. These were incubated at 42 C for 24 hours. Single isolated colonies of about 108 CFU each were suspended in 10 [mu]l of 50% acetonitrile.

The suspensions were placed onto a multiple-bounce zinc-selenide crystal plate for attenuated total reflectance (ATR) analysis. All samples were vacuum-dried. The scientists created and validated soft independent class analogy models from derivatized spectra. These models are statistical methods used to collect data. Then the investigators filtered 100 ml of sterile apple juice, individually spiked in duplicate with Salmonella serovars muenchen, heidelberg and typhimurium, through hydrophobic-grid membranes (HGMs).

The membranes were placed onto MM agar and incubated at 42 C for 24 hours. Isolated colonies treated with acetonitrile (50%) and dried on the ATR crystal were analyzed for microbial identification. The development of a simple protocol combining bacterial growth in selective medium and the unique mid-infrared signature profiles made it possible to chemically classify intact microbial cells.

In the spectral region from 1300 to 900 [cm.sup.-1], multivariate modeling showed well-separated clusters that discriminated among Salmonella serovars, presumably caused by cell lipopolysaccharides. The use of HGMs made it possible to correctly identify Salmonella "unknowns" in the spiked juice, including if any were in the presence of mixed bacterial cultures. The use of HGM and a selective medium could permit recovery and identification of Salmonella serovars at low numbers in apple juice.

Further information. Ahmed E. Yousef, Center for Microbial Interface Biology, The Ohio State University, Tenth Floor, Biomedical Research Tower, 460 W. 12th Ave., Columbus, OH 43210; phone: 614-292-0918; fax: 614.292.9616; email: yousef.1@osu.edu.
COPYRIGHT 2008 Food Technology Intelligence, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2008 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Publication:Microbial Update International
Date:Apr 1, 2008
Words:365
Previous Article:Consider a 10-hour real-time PCR technique for detecting Salmonella in ready-to-eat meats.
Next Article:Determine speed of bacterial growth in infant formula.
Topics:


Related Articles
Salmonella enterica serotype Typhimurium DT 104 antibiotic resistance genomic Island I in serotype Paratyphi B.
Salmonella serovars from humans and other sources in Thailand, 1993-2002.
Salmonella Agona harboring genomic island 1-A.
Integrons in Salmonella Keurmassar, Senegal.
Fluoroquinolone-resistant Salmonella sp. in Carcasses.
Aquariums as reservoirs for multidrug-resistant Salmonella Paratyphi B.
Rapid Salmonella test designed to reduce meat and produce recalls.
Use spectroscopy to detect, differentiate Salmonella enterica serovars in apple juice.
Plasmid-mediated quinolone resistance in Salmonella enterica, United Kingdom.
Consider a 10-hour real-time PCR technique for detecting Salmonella in ready-to-eat meats.

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters