Abstract
Two bacterial strains were isolated from the breast milk of two healthy nursing mothers. The isolates were Gram-positive, catalase-negative, coccus-shaped, chain-forming organisms. Analysis of the 16S rRNA gene sequences of strain IMAU99125T shared 99.7 and 99.6% similarity with Streptococcus mitis ATCC 49456 T and Streptococcus pseudopneumoniae ATCC BAA-960 T, respectively. The nearly complete 16S rRNA gene sequences of IMAU99125T and IMAU99674 strains were very closely related (with only 0.06% difference between them). Sequence analysis of the gyrB and rpoB genes also indicated that IMAU99125T was closely related to S. mitis ATCC 49456 T (94.7% and 97.1%, respectively) and S. pseudopneumoniae ATCC BAA-960 T (94.4% and 97.1%, respectively). Average nucleotide identity (ANI) values between strain IMAU99125T and S. mitis ATCC 49456 T and S. pseudopneumoniae ATCC BAA-960 T, were 93.3% and 92.7%, respectively. Genome-to-genome distance (GGD) values between strain IMAU99125T and S. mitis ATCC 99125 T and S. pseudopneumoniae ATCC BAA-960 T were 53.4% (50.7–56.0) and 50.4% (47.7–53.0), respectively. The major fatty acids of the strain were C16:0 (51.4%). On the basis of the results of phenotypic and phylogenetic analyses, we propose that the two strains be classified as representing a novel species of the genus Streptococcus, namely Streptococcus humanilactis sp.nov. The type strain is IMAU99125T (= GDMCC 1.1876 T = KCTC 21157 T). The genome of Streptococcus humanilactis sp. nov. is comprised of 2,027,143 bp. The DNA G + C content of the strain is 40.0 mol%.
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Abbreviations
- ATCC:
-
American-type culture collection
- LPSN:
-
List of prokaryotic names with standing in nomenclature
- ANI:
-
Average nucleotide identity
- NCBI:
-
National center for biotechnology information
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Acknowledgements
The authors wish to thank the Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering for providing funding and instruments. We would also like to thank the friends who work together.
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Inner Mongolia Autonomous Region Science and Technology Project (2021GG0080).
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XG, FH, LC, YL and YW designed the experiments. XiG, FH, LC, YL, YW, CL, JY, and RN, conducted experiments and data analyses. XG drafted the manuscript. All authors contributed to the final manuscript. All authors read and approved the final manuscript.
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Communicated by Erko Stackebrandt.
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The GenBank/EMBL/DDBJ/PIR accession number for the 16S rRNA gene sequence of strains IMAU99125T and IMAU99674 are MZ322807 and MZ322808, respectively. The Whole Genome Shotgun sequences of strains IMAU99125T and IMAU99674 have been deposited at GenBank/EMBL/DDBJ/PIR under the accession numbers JAHXBZ000000000 and JAIBNW000000000, respectively.
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Guo, X., Han, F., Cong, L. et al. Streptococcus humanilactis sp.nov., isolated from healthy nursing mother's breast milk. Arch Microbiol 204, 654 (2022). https://doi.org/10.1007/s00203-022-03249-2
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DOI: https://doi.org/10.1007/s00203-022-03249-2