Identification of the Pseudomonas fluorescens group as being responsible for blue pigment on fresh cheese

Abstract

New cases of blue cheese discoloration has led to recent research to identify the causal agent and factors that favor blue pigment appearing. Nonetheless, very few reports have described the source of contamination and the measurements to eradicate the microbiological source on cheese farms by determining the relation between blue discoloration on fresh cheese and the Pseudomonas fluorescens group. Thus, 60 samples from a cheese farm (cheese, equipment surfaces, tap water, and raw and pasteurized milk) were analyzed by phenotypical, MALDI-TOF, 16S rRNA sequencing and pulsed-field gel electrophoresis tests to determine the causal agent. The results obtained by pulsed-field gel electrophoresis with restriction enzymes XbaI and SpeI confirmed tap water as the initial contaminated source. The above-mentioned result was essential to avoid Pseudomonas contamination due to the most residual microorganisms being inactivated through a new disinfection program.

Identification and Genetic Analysis of Pseudomonas fluorescence in Milk and Milk Products in Mosul City

“…Higher incidence was reported by [41] who found (70%) of cheese in Spain. High percentage of P.flouresence in cheese may be due to inadequate pasteurization of milk and explain the source of environmental contamination especially water used in cheese preparing process therefore after processing, these spoilage organisms most frequently contaminate products [42]. Various preservation methods, such as the direct addition of the preservative to the food product composition or the packaging material, have been suggested to prevent the growth of spoilage microorganisms [43].…”

Genome‐based analysis of Pseudomonas paracarnisRQ057, a strain responsible for blue discoloration spoilage in processed cheese

“…Greater concern about the pigments produced by Pseudomonas has been observed in the dairy industry. Cheeses with high moisture content, even if kept at cold storage, are still prone to the growth of some members of this genus, and these food products have been mostly related to the production of pigments (Cenci-Goga et al 2014;Carrascosa et al 2015Carrascosa et al , 2021. In recent years, Pseudomonas species has been linked to the cheese spoilage by causing blue discoloration, with particular relevance to P. lactis, P. fluorescens, P. carnis and P. paracarnis (Andreani et al 2014;Reichler et al 2019;Rodrigues et al 2021).…”

“…2014; Carrascosa et al . 2015, 2021). In recent years, Pseudomonas species has been linked to the cheese spoilage by causing blue discoloration, with particular relevance to P. lactis , P. fluorescens , P. carnis and P. paracarnis (Andreani et al .…”