Rapid detection of Geobacillus and Anoxybacillus species by quantitative qPCR (qPCR) in commercial dairy products

• Published in: Journal of food safety Vol. 42; no. 2
• Main Authors: Karaca, Basar, Karakaya, Ayse Busra, Ozcan, Birgul, Coleri Cihan, Arzu
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-04-2022; Blackwell Publishers Inc
• Subjects: Bacilli; Biofilms; Cell culture; Dairy industry; Dairy products; Food contamination; Food processing; Food safety; Geobacillus; Hygiene; Microorganisms; Polymerase chain reaction; Primers; Spores; Sporulation; Thermophilic bacteria
• ISSN: 0149-6085; 1745-4565
• DOI: 10.1111/jfs.12964

Thermophilic spore‐forming bacteria, especially Anoxybacillus and Geobacillus species, are a major problem for dairy industry. The presence of these thermophilic bacilli in the dairy products is considered a poor hygiene indicator during product processing. The commonly preferred culture‐dependent detection methods are time consuming. Therefore, the development of rapid and reliable molecular approaches for the detection of these problematic microorganisms in food processing is essential. In this context, specific primers for the gene (spo0A) that initiates sporulation were designed for Anoxybacillus kamchatkensis subsp. asaccharedens (F81) and Geobacillus thermodenitrificans (DSM 465T), which have been shown to be strong biofilm producers in dairy products. For this purpose, a quantitative polymerase chain reaction (qPCR) assay was developed. The qPCR standard curves obtained with these primers allowed a total viable cell count in the range of 101–108 CFU/ml for G. thermodenitrificans, while the spore count was in the range of 103–108 CFU/ml. The primer developed for A. kamchatkensis subsp. asaccharedens was able to detect viable total cells and spores with much higher sensitivity (101–108 CFU/ml viable total cells, 102–108 CFU/ml spores). The primers developed in this study allowed separate detection of Anoxybacillus and Geobacillus in dual culture experiments. The primers and method developed in this study can also be used for rapid detection of Anoxybacillus and Geobacillus contamination in mixed cultures.
This study demonstrates rapid and reliable detection and enumeration of some Geobacillus and Anoxybacillus species by quantitative PCR (qPCR) using primers specific for spo0, a gene responsible for the initiation of sporulation.