Lactobacillus delbrueckii

A Microbial Biorealm page on the genus Lactobacillus delbrueckii

Classification

Higher order taxa

Bacteria (Domain); Firmicutes (Phylum); Bacilli (Class); Lactobacillales (Order); Lactobacillaceae (Family)[Others may be used. Use NCBI link to find]

Species

NCBI: Taxonomy

Lactobacillus delbrueckii

subspecies:  bulgaricus, lactis, delbrueckii, and indicus 

Description and significance

Lactobacillus us delbrueckii is a rod shaped, gram positive, non-motile bacterium. Common to the species is its ability to ferment sugar substrates into lactic acid products under anaerobic conditions. As such, L. delbrueckii are found in dairy products such as yogurt, milk, and cheese with the exception of L. delbrueckii subsp. delbruecki which reside in vegetable sources(3). There are four subspecies differentiated by its metabolites and its internal genetics known to date. In 2005, Dellaglio and his team isolated the proposed L. delbrueckii subsp. indicus from an Indian dairy (1).

The properties that define L. delbrueckii as a lactic acid bacteria (LAB) are not confined by its metabolic end product. L. delbrueckii subsp. bulgaricus has been proven to have probiotic affects on humans and animals which include improved lactose tolerance and its ability to stimulate immune responses (4, 5, 7). A phosphopolysaccharide produced by L. delbrueckii subsp. bulgaricus has the capability to enhance phagocytosis of macrophages in mice (6).

Genome structure

The circular genome of Lactobacillus delbrueckii subsp. bugaricus ATCC 11842 was completed in May of 2006. Composed of 1,864,998 nucleotides, it has an unusually high G-C content (49%) in comparison to other species of the genus Lactobacilli to which it belongs. Of the 2,217 genes present 1,562 code for proteins and 533 as pseudo genes (10). Genomic features such as these, as well as insertion sequence patterns are indicative of its adaptation in the dairy industry and support the theory of a rapid evolutionary phase (11).

Of the 1,562 genes that code for proteins prtB and the lac operon are important to the homofermentative properties of L. delbrueckii. Within the lac operon is the lacS, lacZ, and lacR genes that encodes for the uptake and breakdown of lactose.(3)

Cell structure and metabolism

As a gram positive bacterium L. delbrueckii retains its purple stain under the Gram test. Unique to microbes of this type is a thick cell wall and a cell membrane. The absence of an outer membrane which functions as an additional barrier could be a reason for its sensitivity to bacteriophage attacks (2).

Proteases encoded by the prtB gene are found anchored along the cell wall of L. delbrueckii subsp. bulgaricus and lactis ; and most likely in the subsp. indicus. The ability of the subspecies’ to grow in dairy is owed to the enzymatic activity in casein breakdown to expose essential amino acids, in addition, to constitutive or inducible expression of the lacZ gene. (8,4)

Significant to the four L. delbrueckii subspecies are the number and types of substrates it can metabolize. As noted, such properties are restricted to enzyme expression within its genome. L. delbrueckii subsp. bulgaricus and subsp. indicus can metabolize lactose, glucose, fructose, and mannose. In addition to these, L. delbrueckii subsp. lactis catabolizes galactose, sucrose, maltose, threalose and other modified carbohydrates.(4)

Ecology

As an inhabitant of fermented dairy products and producers of lactic acid L. delbrueckii, with the exception of L. subsp. delbrueckii, is the cause of its low acidic environment. The nutritional requirements are adapted to the bacterium’s environment; as such includes but are not limited to amino acids, vitamins, carbohydrates and unsaturated fatty acids (9).

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

1) F., Felis, Giovanna E., Castioni, A., Torriani, S., and Germond, J. “Lactobacillus delbrueckii subsp. indicus subsp. nov., isolated from Indian dairy products”. 2005. International Journal of Systematic and Evolutionary Microbiology. Volume 55. p. 401-404.
2) [Del Rio, B., Binetti, A.G., Martın, M.C., Fernandez, M., Magadan, A.H., and Alvarez, M.A. “Multiplex PCR for the detection and identification of dairy bacteriophages in milk”. Food Microbiology. 2007. Volume 24. p.75-81. ]
3) J., Lapierre, L., Delley, M., Mollet, B., Felis, G., and Dellaglio, F. “Evolution of the Bacterial Speies Lactobacillus delbrueckii: A Partial Genomic Study with Reflections on Prokaryotic Species Concept”. Molecular Biology and Evolution. 2003. Volume 20. p. 93-104.
4) [Kitazawa, H., Yasuyuki, I., Uemura, J., Kawai, Y., Saito, T., Kaneko, T., Noda, K., and Itoh, T. “Augmentation of macrophage functions by an extracellular phophopolysaccharide from Lactobacillus delbrueckii ssp. bulgaricus”. Food Microbiology. 2000. Volume 17. p.109-118. ]
5) M., Callegari, M., Ferrari, S., Bessi, E., Cattibelli, D., Soldi, S., Morelli, L., Feuillerat, N., and Antoine, J. “Survival of Yogurt Bacteria in the Human Gut”. Applied Environmental Microbiology. 2006. Volume 72. p.5113-5117.
6) Velez, M., Hermans, K., Verhoeven, T.L.A., Lebeer, S.E., Vanderleyden, J., and De keersmaecker S.C.J. “Identification and characterization of starter lactic acid bacteria and probiotics from Columbian dairy products”. Journal of Applied Microbiology. 2007. Volume 103. p. 666-674.
7) S., Drescher, K., and Heller, K. “Survival of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus in the Terminal Ileum of Fistulated Gottingen Minipigs. Applied and Environmental Microbiology. 2001. Volume 67. p.4137-4143.
8) C., D. Atlan, B. Blanc, R. Portailer, J. E. Germond, L. Lapierre, and B. Mollet. 1996. “A new cell surface proteinase: sequencing and analysis of the prtB gene from Lactobacillus delbruekii subsp. bulgaricus”. Journal of Bacteriology. 1996. Volume 178. p.3059-3065.
9) [Partanen, L., Marttinen, N., Alatossava, T. “Fats and Fatty Acids as Growth Factors for Lactobacillus delbrueckii”. 2001. Volume 24. p.500-506. ]
10) Center for Biotechnology Information (NCBI) Genome. Lactobacillus delbrueckii subsp. 11842, complete genome.
11) de Guchte, M., Penaud, S., Grimaldi, C., Barbe, V., Bryson, K., and others. “The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution”. PNAS. 2006. Volume 103. p.9274-9279

Edited by student of Rachel Larsen