Phylum Firmicutes, Class Bacilli, Order Lactobacillales, Family Streptococcaceae, Genus Streptococcus, Streptococcus lactarius
Martin et al. 2011.
Gram-positive cocci, 1.0-1.3 μm in diameter, occurring as pairs or short chains.
Colonies on Columbia sheep or horse-blood agar plates after 2 days of incubation
are about 0.3–0.5 mm in diameter, circular, flat, greyish, nonpigmented and alpha-
haemolytic. Facultatively anaerobic, grows better under anaerobic conditions. Under
anaerobic conditions, haemolysis is visible only when the plates have been taken out
of the anaerobic chamber for more than 1 hour.
Isolated from breast milk samples collected from three healthy women. Resistant to optochin.
- Virginia Martin, Rosario Manes-Lazaro, Juan Miguel Rodriguez, and Antonio Maldonado-Barragan. Streptococcus lactarius sp.
nov., isolated from breast milk of healthy women. Int J Syst Evol Microbiol May 2011 61:1048-1052.
Positive results for arginine dihydrolase, alkaline phosphatase, alanine phenylalanine
proline arylamidase, aesculin hydrolysis, beta-glucosidase, glycyl tryptophan
arylamidase, hippurate hydrolysis, acid production from: lactose, maltose & sucrose.
Negative results for beta-glucuronidase, alpha-galactosidase, pyrrolidonyl arylamidase, N-acetyl-beta-glucosaminidase and beta-
mannosidase, Voges–Proskauer reaction, acid production from: L-arabinose, D-arabitol, cyclodextrin, glycogen, methyl beta-D-
glucopyranoside, mannitol, melibiose, melezitose, pullulan, raffinose, ribose, sorbitol, tagatose & trehalose.
Variable results for beta-galactosidase.
(c) Costin Stoica