Lactobacillus delbrueckii subsp. bulgaricus
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Firmicutes, Class Bacilli, Order Lactobacillales, Family Lactobacillaceae, Genus Lactobacillus [fermentation-type Group A
lactobacilli (obligately homofermentative), Lactobacillus delbrueckii phylogenetic-group],
Lactobacillus delbrueckii subsp. bulgaricus
(Orla-Jensen 1919) Weiss et al. 1984.

Historical synonym:
Thermobacterium bulgaricum Orla-Jensen 1919, Lactobacillus bulgaricus Rogosa and Hansen 1971.
Gram-positive rods with rounded ends, 0.5-0.8 x 2.0-9.0 µm, occuring singly and in
short chains; internal granulation may be revealed with methylene blue stain.
Nonmotile.
Extracellular heteropolysaccharides are produced in small amounts; these strains
are utilized for production of yogurt as they positively affect the rheological properties
with regard to texture, shear stability of the gel, decreased syneresis, and viscosity.
Colonies are normally rough and non-pigmented becoming smooth and compact in
the presence of Tween 80 or sodium oleate. Surface growth is greatly enhanced by
reduced O
2-tension or anaerobiosis.
Optimum temperature for growth is 40-44 ºC. Variable growth at 48-52 ºC. Can grow
at 45 ºC. No growth at 15 ºC. Optimum pH for growth 5.5-6.2. Can grow at pH 5.0.
Growth factor requirements: pantothenic acid and niacin generally essential;
riboflavin, folic acid, vitamin B
12, and thymidine are essential for particular strains.
Isolated from yogurt and cheese.
Produce pyroglutamic acid (2-pyrolidone-5 carboxylic acid) with activity against
Bacillus subtilis, Panothoea agglomerans, and
Pseudomonas spp.
Thirty-one strains used in yogurt cultures had an intrinsic resistance toward mycostatin, nalidixic acid, neomycin, polymyxin B,
trimethoprim, colimycin, sulfomethoxazol & sulfonamides
None.
  1. Hammes W.P. and Hertel C., 2009. Genus I. Lactobacillus Beijerinck 1901. In: (Eds.) P.D. Vos, G. Garrity, D. Jones, N.R. Krieg, W.
    Ludwig, F.A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3: The Firmicutes,
    Springer, 465-511.
  2. Rogosa M., 1974. Genus I. Lactobacillus Beijerinck 1901. In: (Eds.) Buchanan R.E. and Gibbons N.E., Bergey’s Manual of
    Determinative Bacteriology, Eighth Edition, The Williams & Wilkins Company, Baltimore, 576-593.
  3. Kudo Y, Oki K, Watanabe K. Lactobacillus delbrueckii subsp. sunkii subsp. nov., isolated from sunki, a traditional Japanese
    pickle. Int J Syst Evol Microbiol 2012; 62:2643-2649.
Obligately homofermentative (hexoses are fermented almost exclusively to lactic acid by the Embden-Meyerhof pathway; pentoses or
gluconate are not fermented).

Positive results for fermentation of: fructose, glucose (without gas production), and lactose.

Negative results for arginine hydrolysis, casein digestion, catalase, esculin hydrolysis, gelatin liquefaction, H
2S production, indole
production, nitrate reduction, oxidase, fermentation of: amygdalin, arabinose, esculin, galactose, gluconate, maltose, mannitol,
mannose, melezitose,  melibiose, raffinose, rhamnose, ribose, salicin, sorbitol, sucrose, trehalose, and xylose.

Variable results for cellobiose fermentation.
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Differential characters of Lactobacillus delbrueckii subspecies:
Legend: +  positive 90-100%, - negative 90-100%, [+] positive 75-89%, [-] negative 75-89%, d positive 25-74% of strains
 
Amygdalin
Cellobiose
Lactose
Maltose
Mannose
Salicin
Sucrose
Trehalose
subsp. bulgaricus
-
d
+
-
-
-
-
-
subsp. delbrueckii
-
-
-
d
+
-
+
d
subsp. indicus
-
-
+
-
+
-
d
-
subsp. lactis
+
d
+
+
+
+
+
+
subsp. sunkii
+
+
-
+
+
+
+
+