Identification and characterization of Bacillus coagulans strains for probiotic activity and safety

Abstract The 4,6-α-glucanotransferases of the glycoside hydrolase family 70 can convert starch into isomaltooligosaccharides (IMOs). However, no thermostable 4,6-α-glucanotransferases have been reported to date, limiting their applicability in the starch conversion industry. Here we report the identification and characterization of a thermostable 4,6-α-glucanotransferase from Bacillus coagulans DSM 1. The gene was cloned and the recombinant protein, called BcGtfC, was produced in Escherichia coli. BcGtfC is stable up to 66 °C in the presence of substrate. It converts debranched starch into an IMO product with a high percentage of α-1,6-glycosidic linkages and a relatively high molecular weight compared to commercially available IMOs. Importantly, the product is only partly and very slowly digested by rat intestine powder, suggesting that the IMO will provide a low glycaemic response in vivo when applied as food ingredient. Thus, BcGtfC is a thermostable 4,6-α-glucanotransferase suitable for the industrial production of slowly digestible IMOs from starch.

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Identification and Characterization of Leucocyclicin Q, a Novel Cyclic Bacteriocin Produced by Leuconostoc mesenteroides TK41401

Applied and Environmental Microbiology ◽

10.1128/aem.06348-11 ◽

2011 ◽

Vol 77 (22) ◽

pp. 8164-8170 ◽

Cited By ~ 61

Author(s):

Yoshimitsu Masuda ◽

Hiroshi Ono ◽

Hiroshi Kitagawa ◽

Haruo Ito ◽

Fuqin Mu ◽

...

Keyword(s):

Leuconostoc Mesenteroides ◽

Bacillus Coagulans ◽

Antimicrobial Spectrum ◽

Strong Activity ◽

Ionization Time ◽

Content Type ◽

Flight Mass Spectrometry ◽

Identification And Characterization ◽

Tof Ms

ABSTRACTThe culture supernatant ofLeuconostoc mesenteroidesTK41401, isolated from Japanese pickles, possessed antimicrobial activity against broad range of a bacterial genera and particularly strong activity againstBacillus coagulans, the major contaminant of pickles. An antimicrobial peptide was purified in three chromatographic steps, and its molecular mass was determined to be 6,115.59 Da by electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS). The primary structure of this peptide was determined by amino acid and DNA sequencing, and these analyses revealed that it was translated as a 63-residue precursor. This precursor showed high similarity to the precursor of lactocyclicin Q, a cyclic bacteriocin produced byLactococcussp. strain QU 12. The molecular weight calculated after cyclization, which was presumed to involve the same process as in lactocyclicin Q (between L3 and W63), agreed with that estimated by ESI-TOF MS. This peptide was proved to be a novel cyclic bacteriocin, and it was termed leucocyclicin Q. The antimicrobial spectrum of this bacteriocin clearly differed from that of lactocyclicin Q, even though their primary structures were quite similar. This is the first report of a cyclic bacteriocin produced by a strain of the genusLeuconostoc.

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