Lactobacillus sanfranciscensis

Taxobox | name = "Lactobacillus sanfranciscensis"
regnum = Bacteria
divisio = Firmicutes
classis = Bacilli
ordo = Lactobacillales
familia = Lactobacillaceae
genus = "Lactobacillus"
species = "L. sanfranciscensis"
binomial = "Lactobacillus sanfranciscensis"
binomial_authority = (ex Kline & Sugihara 1971)
Weiss & Schillinger 1984

"Lactobacillus sanfranciscensis" (formerly "L. sanfrancisco") is a species of lactic acid bacteria that helps give sourdough bread its characteristic taste.cite book | author = Karel Kulp, Klaus Lorenz | title = Handbook of Dough Fermentation | edition = | publisher = CRC Press | year = 2003 | id = ISBN 0-8247-4264-8 ]

Sourdough starters are leavened by a mixture of yeast and lactobacilli in a ratio of about 1:100. The yeast is most commonly "Candida milleri". This yeast cannot metabolize the maltose found in the dough, while the "Lactobacillus" needs maltose.cite journal | author=Neubauer H, Glaasker E, Hammes WP, Poolman B, Konings WN | title=Mechanism of maltose uptake and glucose excretion in "Lactobacillus sanfrancisco" | journal=J Bacteriol | year=1994 | pages=3007–12 | volume=176 | issue=10 | pmid=8188601 [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=205458 fulltext] ] They therefore act without conflict for substrate, with the "Lactobacillus" utilizing maltose and the yeast utilizing the other sugars, including the glucose produced by the "Lactobacillus". The lactobacilli produces an antibiotic cycloheximide which kills many organisms (but not the "Candida"), and the "Candida" tolerates the acetic acid produced by the lactobacilli.

For commercial use, specific strains of the "L. sanfranciscensis" are grown on defined media, freeze-dried, and shipped to bakeries worldwide.

References