Levan-producing Lactobacillus strain and method of preparing human or pet food products using the same

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Within the following description, the following abbreviations have been used: GRAS, generally recognized as safe; HMBC, heteronuclear multiple-bond correlation; PEP-HSQC, preservation of equivalent pathways in heteronuclear single-quantum coherence; NMR, nuclear magnetic resonance; NOESY, nuclear Overhauser effect spectroscopy; RAPD PCR, Random Amplified Polymorphic DNA polymerase chain reaction; TOCSY, total correlation spectroscopy; TPPI, time proportional phase increments.
Finally, "NCC" designates Nestlé Culture Collection (Nestlé Research Center, Vers-chez-les-Blanc, Lausanne, Switzerland).
According to a first aspect, the present invention relates to an isolated and purified strain of the species Lactobacillus sanfranciscensis, which produces levan.
Indeed, it has been surprisingly found that Lactobacillus sanfranciscensis originally used in traditional dough fermentation, can produce a highly soluble fructose-containing carbohydrate, especially levan and a minimal amount of glucose polymer.
Preferably, the Lactobacillus sanfranciscensis strain is L.
sanfranciscensis NCC 2729, having the deposit number CNCM I-2588 or L.
sanfranciscensis NCC 2731, having the deposit number CNCM I-2589 or L.
sanfranciscensis NCC 2733, for example.
Although levans are more soluble than inulin, their solubility at low temperature is variable and tends to be low (Han, Y.
W.
, (1990) Adv.
Appl.
Microbiol.
, 35, 171-194).
In contrast, the levan produced by Lactobacillus sanfranciscensis is highly soluble even at low temperature.
The levan produced by fermentation of Lactobacillus sanfranciscensis NCC 2729 was analysed by NMR.
The major (>95%) product is a levan and the secondary product (