Lactococcus carnosus sp. nov. and Lactococcus paracarnosus sp. nov., two novel species isolated from modified-atmosphere packaged beef steaks

As part of a study investigating the spoilage microbiome of modified-atmosphere packaged beef from Germany, four novel strains of lactic acid bacteria were isolated and subsequently taxonomically characterized by a polyphasic approach, which revealed that they could not be assigned to known species. The isolates were Gram-staining-positive, coccoid, facultatively anaerobic, non-motile, catalase-negative and oxidase-negative. Morphological, physiological and phylogenetic analysis revealed a distinct lineage within the genus Lactococcus , with Lactococcus piscium and Lactococcus plantarum as closest relatives. Results indicated that they represented two different novel species with two strains, (TMW 2.1612 T /TMW 2.1613 and TMW 2.1615 T /TMW 2.1614), respectively. The two strains of both novel species shared identical 16S rRNA gene sequences but a MLSA allowed their intraspecies differentiation. The 16S rRNA gene sequences of TMW 2.1612 T and TMW 2.1615 T had a similarity of 99.85 % to each other and a similarity of 99.85 and 99.78 % the most closely related type strain of Lactococcus piscium , respectively. However, the ANIb value between the respective type strains TMW 2.1612 T and TMW 2.1615 T , and the type strain of Lactococcus piscium was only 94.3 and 92.0 %, respectively, and 92.9 % between TMW 2.1612 T and TMW 2.1615 T . The in silico DDH estimate value between the respective type strain TMW 2.1612 T and TMW 2.1615 T and the most closely related type strain of Lactococcus piscium was only 59.9 and 48.9 %, respectively, and 51.1 % between TMW 2.1612 T and TMW 2.1615 T . Peptidoglycan type of strain TMW 2.1612 T is Lys–Thr–Ala and major fatty acids are summed feature 8 and C 16 : 0 . Peptidoglycan type of strain TMW 2.1615 T is Lys–Ala and major fatty acids are C 16 : 0 , C 19 : 0 cyclo ω8 c and summed feature 8. On the basis of polyphasic evidence, the meat isolates represent two novel species of the genus Lactococcus , for which the names Lactococcus carnosus sp. nov and Lactococcus paracarnosus sp. nov are proposed. The designated respective type strains are TMW 2.1612 T (=DSM 111016 T =CECT 30115 T ) and TWM 2.1615 T (=DSM 111017 T =CECT 30116 T ).