Thermus and the Pink Discoloration Defect in Cheese

Abstract

Pink discoloration in cheese is a defect affecting many cheeses throughout the world, leading to significant financial loss for the dairy industry. Despite decades of research, the cause of this defect has remained elusive. The advent of high-throughput, next-generation sequencing has revolutionized the field of food microbiology and, with respect to this study, provided a means of testing a possible microbial basis for this defect. In this study, a combined 16S rRNA, whole-genome sequencing, and quantitative PCR approach was taken. This resulted in the identification of Thermus, a carotenoid-producing thermophile, in defect-associated cheeses and the recreation of the problem in cheeses to which Thermus was added. This finding has the potential to lead to new strategies to eliminate this defect, and our method represents an approach that can be employed to investigate the role of microbes in other food defects of unknown origin.

Emerging DNA-based technologies to characterize food ecosystems

“…Again, in the case of wine, the wine cellar yeasts and bacteria could actively contribute to the chemical modification of grape juice to obtain wine with specific organoleptic properties (Bokulich, Ohta, Richardson, & Mills, 2013;David et al, 2014). Environmental microorganisms represent an important source of biodiversity to differentiate a certain food product from the others, even at a reduced spatial production scale (Quigley et al, 2012;Riquelme et al, 2015). For these reasons, modern food companies should not underestimate the importance of knowing the composition of microbial community accompanying food from farms to consumer's fork or glass.…”

“…Depending on the level of investigation required, the taxonomic resolution of microorganisms can vary. For example, the genus rank could be sufficient when monitoring changes in microbial community during a biotransformation or treatment process of food raw material (e.g., fermentation, pasteurization) (Quigley et al, 2012). In contrast, species or strains have to be precisely identified in case of pathogen detection analyses, or to assess the efficacy of a certain probiotic.…”

“…As a result, the microbiota of different cheeses varies considerably depending on the type of fermentation adopted (Quigley et al, 2012). Due to the complexity of biotransformation processes, diversity, not only at the species level but also at the strain one is pivotal for industrial purposes.…”

“…The modern molecular approach to study microbiota composition can contribute to clarify the role of raw milk quality and added ingredients in dairy transformation processes. Many studies showed how cheese microbiota structure can vary according to the animal origin of the milk (Coppola, Blaiotta, Ercolini & Moschetti, 2001;Quigley et al, 2012), its preliminary treatments (e.g., pasteurization, Delgado et al, 2013) and additional ingredients used during production (Ercolini, De Filippis, La Storia, & Iacono, 2012). In a survey However, in dairy production, one of the possible risks occurring in the passage from artisanal to industrial manufacturing could be the loss of flavors and aromas which are characteristic of the product.…”

Strain-Level Metagenomic Analysis of the Fermented Dairy Beverage Nunu Highlights Potential Food Safety Risks

“…Metagenomic sequencing enables elucidation of the roles of microorganisms during food production (7)(8)(9), and it can be used to track microorganisms of interest through the food production chain, as illustrated by Yang et al (10), who used whole-metagenome shotgun sequencing to track pathogenic species in the beef production chain. Indeed, metagenomic sequencing can be used to detect pathogens in foods to monitor outbreaks of foodborne illnesses (11), but few studies have done so, because of the limited taxonomic resolution achievable using these methods.…”