{"title":"Modeling the survival of Campylobacter jejuni in raw milk considering the viable but non-culturable cells (VBNC)","authors":"Anna-Delia Knipper, Carolina Plaza-Rodríguez, Matthias Filter, Imke F. Wulsten, Kerstin Stingl, Tasja Crease","doi":"10.1111/jfs.13077","DOIUrl":null,"url":null,"abstract":"<p><i>Campylobacter</i> spp. cannot grow in raw milk, but it is able to transform into a viable but non-culturable (VBNC) state enabling the survival in such harsh conditions. In this study, <i>Campylobacter jejuni</i> survival in raw milk was investigated taken into consideration colony-forming units (CFUs) and VBNC cells. CFU from two different strains of <i>C. jejuni</i> (DSM 4688 and BfR-CA-18043) were enumerated at three temperatures (5°C, 8°C, and 12°C). In parallel, a viability real-time PCR was conducted to quantify intact and putatively infectious units (IPIUs) (comprising CFU and VBNC bacteria). The data generated were used to model the viability of <i>C. jejuni</i> during raw milk storage. Here, a one-step fitting approach was performed using parameter estimates from an intermediate two-step fit as starting values to generate tertiary models. Different primary model equations (Trilinear and Weibull) were required to fit the CFU and the IPIU data. Strain-specific linear secondary models were generated to analyze the effect of storage temperature on the maximum specific inactivation rate of the CFU data. The time of the first decimal reduction parameter of the IPIU models could be modeled by a strain-independent linear secondary model. The developed tertiary models for CFU and IPIU differ significantly in their predictions, for example, for the time required for a one log<sub>10</sub> reduction. Taken into consideration that VBNC could revert to a culturable state during the raw milk storage, our results underline the importance of considering IPIU and not only CFU to avoid underestimation of the survival of <i>C. jejuni</i> in raw milk.</p>","PeriodicalId":15814,"journal":{"name":"Journal of Food Safety","volume":"43 6","pages":""},"PeriodicalIF":1.9000,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfs.13077","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Food Safety","FirstCategoryId":"97","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/jfs.13077","RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"BIOTECHNOLOGY & APPLIED MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Campylobacter spp. cannot grow in raw milk, but it is able to transform into a viable but non-culturable (VBNC) state enabling the survival in such harsh conditions. In this study, Campylobacter jejuni survival in raw milk was investigated taken into consideration colony-forming units (CFUs) and VBNC cells. CFU from two different strains of C. jejuni (DSM 4688 and BfR-CA-18043) were enumerated at three temperatures (5°C, 8°C, and 12°C). In parallel, a viability real-time PCR was conducted to quantify intact and putatively infectious units (IPIUs) (comprising CFU and VBNC bacteria). The data generated were used to model the viability of C. jejuni during raw milk storage. Here, a one-step fitting approach was performed using parameter estimates from an intermediate two-step fit as starting values to generate tertiary models. Different primary model equations (Trilinear and Weibull) were required to fit the CFU and the IPIU data. Strain-specific linear secondary models were generated to analyze the effect of storage temperature on the maximum specific inactivation rate of the CFU data. The time of the first decimal reduction parameter of the IPIU models could be modeled by a strain-independent linear secondary model. The developed tertiary models for CFU and IPIU differ significantly in their predictions, for example, for the time required for a one log10 reduction. Taken into consideration that VBNC could revert to a culturable state during the raw milk storage, our results underline the importance of considering IPIU and not only CFU to avoid underestimation of the survival of C. jejuni in raw milk.
期刊介绍:
The Journal of Food Safety emphasizes mechanistic studies involving inhibition, injury, and metabolism of food poisoning microorganisms, as well as the regulation of growth and toxin production in both model systems and complex food substrates. It also focuses on pathogens which cause food-borne illness, helping readers understand the factors affecting the initial detection of parasites, their development, transmission, and methods of control and destruction.