Pseudomonas kielensis sp. nov. and Pseudomonas baltica sp. nov., isolated from raw milk in Germany

In this study, nine Gram-negative, motile and rod-shaped bacteria were isolated during a Germany-wide investigation of raw milk microbiota. The strains could be differentiated from their closest relatives by phenotypic and chemotaxonomic characterization and average nucleotide identity (ANIb) values calculated from draft genome assemblies. Strains MBT-1(T), MBT-8, MBT-9, MBT-10, MBT-11 and MBT-12 were related to the Pseudomonas chlororaphis subgroup. Isolates MBT-2(T), MBT-13 and MBT-14 were closely related to Pseudomonas rhizosphaerae DSM 16299(T) with an ANIb of 88.2% and a genome-to-genome distance result of 36.0 %. The G+C content of the DNA of strains MBT-1(T) and MBT-2(T) was 60.84 and 62.48mol%, respectively. The major fatty acids were C-16:1 omega 7c (summed feature 3), C-16:0 and C-18:1 omega 7c (summed feature 8). The strains were catalase-positive, while production of urease, beta-galactosidase and indole were negative. Growth occurred at 4-30 degrees C and at pH values of pH 6.0-8.0. Based on these results, we conclude that the strains belong to two novel species, for which the names Pseudomonas kielensis sp. nov. and Pseudomonas baltica sp. nov. are proposed. The type strains are MBT-1(T) (=DSM 111668(T)=LMG 31954(T)) and MBT-2(T) (=DSM 111761(T)=LMG 31955(T)).

Automated summary

This study isolated nine Gram-negative, motile and rod-shaped bacteria from raw milk microbiota in Germany. Through phenotypic and chemotaxonomic characterization, the strains were identified as two novel species, Pseudomonas kielensis and Pseudomonas baltica. These findings contribute to our understanding of the microbial diversity in raw milk.