Abstract
Several artisanal cheeses are elaborated in European countries, being commonly curdled with rennets of animal origin. However, in some Spanish regions some cheeses of type “Torta” are elaborated using Cynara cardunculus L. rennets. Two of these cheeses, “Torta del Casar” and “Torta de Trujillo”, are elaborated in Cáceres province with ewe’s raw milk and matured over at least 60 days without starters. In this work, we identified the lactic acid bacteria present in these cheeses using MALDI-TOF MS and pheS gene analyses, which showed they belong to the species Lactobacillus curvatus, Lactobacillus diolivorans, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactococcus lactis and Leuconostoc mesenteroides. The pheS gene analysis also allowed the identification of the subspecies La. plantarum subsp. plantarum, La. paracasei subsp. paracasei and Le. mesenteroides subsp. jonggajibkimchii. Low similarity values were found in this gene for some currently accepted subspecies of Lc. lactis and for the two subspecies of La. plantarum, and values near to 100% for the subspecies of Le. mesenteroides and La. paracasei. These results, which were confirmed by the calculated ANIb and dDDH values of their whole genomes, showed the need to revise the taxonomic status of these species and their subspecies.
Highlights
Lactic acid bacteria (LAB) encompass Gram positive cocci and rods distributed in different genera, species and subspecies belonging to different families from the order Lactobacillales [1]
The strains were isolated from ripened cheeses type “Torta” named “Torta del Casar” (Doña Engracia Torta del Casar, Casar de Cáceres, Spain) and “Torta de Trujillo” (Quesería Finca Pascualete, Trujillo, Spain), both elaborated in Cáceres province
The results of this analysis showed that the isolated strains belong to different genera and species of LAB, namely La. curvatus, La. diolivorans, La. paracasei, La. plantarum, La. rhamnosus, Le. mesenteroides and Lc. lactis
Summary
Lactic acid bacteria (LAB) encompass Gram positive cocci and rods distributed in different genera, species and subspecies belonging to different families from the order Lactobacillales [1]. Cheeses, including artisanal ones, are commonly curdled with rennet of animal origin, the Spanish agronomic writer Columela (4–70 AD) mentioned in his book entitled De Re Rustica that cheese can be curdled with the thistle flowers. This practice is currently maintained in some Spanish regions, where the cheeses of type “Torta” are elaborated using Cynara cardunculus L. rennets. The LAB present in “Torta del Casar” cheese were initially identified using phenotypic traits [4], and more recently through the analysis of the 16S rRNA gene sequences [5], which was the methodology used for the identification of these bacteria in other European artisanal cheeses [6,7,8,9,10,11]
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