A multiparametric PCR-based tool for fast detection and identification of spore-forming bacteria in food

• Published in: International journal of food microbiology Vol. 142; no. 1; pp. 78 - 88
• Main Authors: Postollec, Florence, Bonilla, Stéphane, Baron, Florence, Jan, Sophie, Gautier, Michel, Mathot, Anne Gabrielle, Hallier-Soulier, Sylvie, Pavan, Sonia, Sohier, Danièle
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.08.2010; [Amsterdam; New York, NY]: Elsevier Science; Elsevier
• Subjects: Bacillus; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; bacterial contamination; Bacterial Typing Techniques - methods; Clostridium; Contaminants; detection; DNA, Bacterial - genetics; domain_sdv.ida.sma; equipment performance; feed composition; feed contamination; Food; food contamination; Food Contamination - analysis; Food engineering; Food Microbiology; forage evaluation; Life Sciences; Limit of Detection; model food systems; multiparametric polymerase chain reaction; PCR; polymerase chain reaction; Polymerase Chain Reaction - methods; psychrotrophic bacteria; rapid methods; Specificity; Spoilage; Spore-forming; spore-forming bacteria; Spores, Bacterial - classification; Spores, Bacterial - genetics; Spores, Bacterial - isolation & purification; Validation; Clostridium; Validation; Specificity; Spore-forming; Spoilage; Bacillus; PCR; Food; raw-milk; proposal; clostridium-tyrobutyricum spores; 100 milliliters; gen-nov; real-time pcr; strains; bacillus-cereus group; rdna; sp-nov
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2010.06.005

The presence of psychrotrophic or highly thermoresistant spore-forming bacteria in food and feedstuff responsible for food poisoning and spoilage raises major safety and economical issues. The aim of this study was to evaluate the performances of a ready-to-use PCR assay (alternative method) in comparison with the standard microbiological plating method regarding spore-forming bacteria detection in food samples. An overnight sample enrichment was selected to increase sporeformer diversity recovery, spore germination, bacterial growth and favour DNA extraction. A total of 180 sporeformer isolates representing 38 different species and 8 genera were tested in the PCR assays. Inclusivity and exclusivity results ensured specific detection and identification of the majority of targeted genera and species. Validation studies carried on artificially contaminated food samples showed detection of the inoculated contaminants in most cases, with increased detection limit for the alternative method which enabled detection with up 1 spore of B. cereus in 25 g food sample. Using naturally contaminated food samples, standard method comforted the alternative method. In a number of cases, the alternative method was able to identify species not detected with the standard method. In addition, identification and discrimination between the B. cereus group members was possible. Thus, associated to a key element, i.e., the enrichment step, the developed multiparametric PCR-based assays reported in this study provide a fast, sensitive and reliable detection and identification tool for mostly encountered spore-forming food contaminants.