Abstract
The novel Acidipropionibacterium genus encompasses species of industrial importance but also those associated with food spoilage. In particular, Acidipropionibacterium acidipropionici, Acidipropionibacterium thoenii, and Acidipropionibacterium jensenii play an important role in food fermentation, as biopreservatives, or as potential probiotics. Notably, A. jensenii and A. thoenii can cause brown spot defects in Swiss-type cheeses, which have been tied to the rhamnolipid pigment granadaene. In the pathogenic bacterium Streptococcus agalactiae, production of granadaene depends on the presence of a cyl gene cluster, an important virulence factor linked with haemolytic activity. Here, we show that the production of granadaene in pigmented Acidipropionibacterium, including A. jensenii, A. thoenii, and Acidipropionibacterium virtanenii, is tied to haemolytic activity and the presence of a cyl-like gene cluster. Furthermore, we propose a PCR-based test, which allows pinpointing acidipropionibacteria with the cyl-like gene cluster. Finally, we present the first two whole genome sequence analyses of the A. jensenii strains as well as testing phenotypic characteristics important for industrial applications. In conclusion, the present study sheds light on potential risks associated with the presence of pigmented Acidipropionibacterium strains in food fermentation. In addition, the results presented here provide ground for development of a quick and simple diagnostic test instrumental in avoiding potential negative effects of Acidipropionibacterium strains with haemolytic activity on food quality.
Highlights
Acidipropionibacterium jensenii belongs to the newly created genus Acidipropionibacterium that originates from the former genus Propionibacterium, currently divided into four genera: Propionibacterium, Acidipropionibacterium, Cutibacterium, and Pseudopropionibacterium [1]
A. jensenii was first isolated from buttermilk by van Niel [2] and the species belonged to the traditional group of “classic” or “dairy” propionibacteria distinguished from the skin-associated, “cutaneous” reclassified corynebacteria [1,3]
Lack of haemolysis/pigmentation-encoding genes can be used as one of the selection criteria for new propionibacteria strains to be used in food production and/or in search of new probiotics
Summary
Acidipropionibacterium jensenii belongs to the newly created genus Acidipropionibacterium that originates from the former genus Propionibacterium, currently divided into four genera: Propionibacterium, Acidipropionibacterium, Cutibacterium, and Pseudopropionibacterium [1]. While Propionibacterium freudenreichii is the main “dairy” species used as a ripening starter in Swiss-type cheese production, A. jensenii, among other species, is frequently isolated from milk as well as Swiss and other type of cheeses [4] In addition to their role in cheese production, the potential applications of dairy propionibacteria include their use as probiotics and biopreservatives in food, as well as the production of biomolecules like vitamins, conjugated linoleic acid, exopolysaccharides, and trehalose [5,6,7,8,9]. “dairy” propionibacteria are not known to carry virulence factors [16], some strains of A. jensenii and Acidipropionibacterium thoenii were shown to have β-haemolytic activity [17]. We complement genomic findings related to B12 vitamin synthesis, genome integrity, haemolytic activity and carbohydrate fermentation profiles with necessary bioinformatic and phenotypic analyses
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