All blue cheeses are made by inoculating spores of the P. roqueforti fungus, which contributes to maturation and makes the final product veined throughout with blue mold and with a distinct smell. Two differentiated cheese populations of P. roqueforti were identified previously, corresponding to strains used for different types of cheeses1, with different phenotypic traits, e.g. different growth rates on cheese, different abilities to exclude other micro-organisms, and different colors. Many specific traits are strictly associated in each of the two lineages and each lineage underwent strong genetic bottlenecks, losing virtually most of their genetic diversity. Because of this lack of genetic variability in P. roqueforti, innovation possibilities in blue cheese making are limited.
The PoC BLUE project therefore aimed at generating a sexual progeny carrying novel combinations of traits in Penicillium roqueforti, as well as to verify the feasibility of the production of cheeses of industrial interest using these strains. In preparation of the exploitation of this research by the food industry, the PoC BLUE project aimed also at investigating food legislative framework and international market conditions.
Progeny among P. roqueforti strains were obtained and analysed in BLUE. We optimized the protocol for isolating sexual progeny from asexual spores. A total of 1077 offspring strains were obtained, from five different crosses. We analysed the phenotypes for these offspring strains in terms of growth, color as well as lipolytic and proteolytic activities. We found that offspring strains had new combinations of traits, and with trait values going far beyond parental traits. This will lead to new features in cheeses that have a huge innovative potential. The outcomes of the Blue PoC project thus have the potential of yielding innovative cheese products that could solve current industrial issues as well as create new products. The consumers will also benefit from improved cheese quality and from new types of blue cheeses.
We made cheeses in the INRA Aurillac facilities in April 2018, in conditions close to industrial conditions, for three offspring and the Roquefort parent (three replicates of each). We analysed microbiology and volatile compounds in these cheeses. We developed 200 markers based on the parental genomes and genotyped 350 offspring. We transferred knowledge and protocols between the private firm and academic labs, in both directions, in terms of performing crosses, genotyping them and analyzing phenotypes.
We studied the applicable French and European legislative frameworks regarding the use of novel fungal strains for food making. Jurists established that there was no issue of GMO, as the strain represent a sexual progeny, or Nagoya protocol provided the parental strains have been isolated before the publication of French laws on this protocol. A law was published in July 2017 for non-domesticated organisms and there is still no law for domesticated organisms. There can be a debate about whether Penicillium cheese fungi are domesticated so we will only use parents isolated before 2017. Jurists established that, for the progeny resulting from crosses between strains already used for cheese making to not be considered as “novel food” (which would demand unrealistic administrative and scientific work for obtaining authorizations to sell them), one needs to show that the nutritional values of the cheese produced with the offspring strains are similar to those produced by the parental strains.
