Heterofermentative pattern and exopolysaccharide production by Lactobacillus helveticus ATCC 15807 in response to environmental pH

Torino, María Inés; Taranto, María Pía; Sesma, Fernando; Valdez, Graciela Font de

doi:10.1046/j.1365-2672.2001.01450.x

Cited by 118 publications

(76 citation statements)

References 23 publications

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“…Up to now, no results have been published investigating the regulation of L. reuteri genes involved in EPS production. However, EPS production has been shown to be affected by environmental factors, like temperature and pH, e.g., in Lactobacillus helveticus ATCC 15807 (40,41) and Streptococcus thermophilus 1275 (46). Therefore, it is tempting to speculate that L. reuteri LTH5531 may synthesize EPS in sourdough under control of the transcriptional regulator that we have detected.…”

Section: Discussionmentioning

confidence: 81%

Inducible Gene Expression in Lactobacillus reuteri LTH5531 during Type II Sourdough Fermentation

Bello

Walter

Roos

et al. 2005

Appl Environ Microbiol

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Lactobacillus reuteri LTH5531 is a dominant member of the microbiota of type II sourdough fermentations. To investigate the genetic background of the ecological performance of LTH5531, in vivo expression technology was used to identify promoters that show elevated levels of expression during growth of this organism in a type II sourdough fermentation. Thirty-eight sourdough-induced fusions were detected, and 29 genes could be identified on the basis of the available sequence information. Four genes encoded stress-related functions (e.g., acid and general stress response), reflecting the harsh conditions prevailing during sourdough fermentation. Further, eight genes were involved in acquisition and synthesis of amino acids and nucleotides, indicating their limited availability in sourdough. The remaining genes were either part of functionally unrelated pathways or encoded hypothetical proteins. The identification of a putative proteinase and a component of the arginine deiminase pathway is of technological interest, as they are potentially involved in the formation of aroma precursors. Our study allowed insight into the transcriptional response of Lactobacillus reuteri to the dough environment, which establishes the molecular basis to investigate bacterial properties that are likely to contribute to the ecological performance of the organism and influence the final outcome of the fermentation.Sourdough is an intermediate product in bread production and contains a microbiota comprised of lactic acid bacteria and yeasts (reviewed in reference 16). Microbiological studies have revealed that 43 species of lactic acid bacteria, mostly species of the genus Lactobacillus, and more than 23 species of yeast occur in this ecological niche. The metabolic activity of these microorganisms leads to an acidification of the dough and the development of aroma precursors and is therefore of major importance for the quality of the final product. Sourdough breads are characterized by their unique flavor and texture, enhanced nutritional value, and favorable technological properties, such as prolonged shelf life and delayed staling (reviewed in reference 15). Type II sourdoughs serve mainly as dough acidifiers and are fermented for long periods (up to 5 days) at temperatures of Ͼ30°C and with high dough yields to permit pumping of the dough. Strains of Lactobacillus reuteri have been shown to be highly competitive in type II sourdough fermentations and persist over several years of continuous propagation in industrial fermentation processes (13,22). Numerous ecological factors affect the competitiveness of lactobacilli in sourdough fermentations, i.e., temperature, ionic strength, dough yield, and microbial products, such as lactate, acetate, CO 2 , and ethanol as well as factors resulting from substrates present in the cereal fraction and from enzymatic reactions (6, 22). The properties and genetic background responsible for the ecological performance of L. reuteri in sourdough fermentation are, however, poorly understood.In vivo ex...

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Section: Discussionmentioning

confidence: 81%

Inducible Gene Expression in Lactobacillus reuteri LTH5531 during Type II Sourdough Fermentation

Bello

Walter

Roos

et al. 2005

Appl Environ Microbiol

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“…In general, phosphate, Mn 2 and citrate are essential for the growth and production of exopolysaccharide by lactic acid bacterial strains. 14,15) It can be concluded that the exopolysaccharide production of Lactobacillus fermentum TDS030603 in the cheese whey medium is favored by the presence of macro elements of Mn 2 .…”

Section: Culture Condition Using Whey-mediated Brothmentioning

confidence: 99%

Studies on a Neutral Exopolysaccharide of Lactobacillus fermentum TDS030603

レオ¹,

修吉²,

大樹³

et al. 2007

J. Appl. Glycosci.

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A neutral exopolysaccharide produced in large amounts by Lactobacillus fermentum TDS030603 was purified from culture supernatants and its structure determined by monosaccharide analysis, methylation analysis and 1 H-NMR spectroscopy. Optimum conditions for the production of this exopolysaccharide by the above bacterial strain, when cultured using cheese whey medium or MRS broth, were also investigated. The exopolysaccharide was found to be composed of D-galactose and D-glucose in the molar ratio of 1:2.5 and to consist of one major as well as one minor saccharide, both of which contained a tetrasaccharide repeating unit consisting of two α and two β anomers. The major saccharide contained non-reducing glucopyranose, O-3 substituted glucopyranose, O-6 substituted galactopyranose and O-2,3 disubstituted glucopyranose. The minor saccharide consisted of non-reducing galactopyranose, O-3 substituted glucopyranose, O-6 substituted galactopyranose and O-2,3 disubstituted glucopyranose. The results suggest that these exopolysaccharides are novel saccharides that differ from previously reported products of Lactobacillus fermentum strains. Their presence may contribute to the ropy properties of the medium.

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“…1.73 ± 0.14 270 ± 41 46.6 ± 2.1 210.3 ± 1.2 homolactic to heterolactic fermentation for certain lactobacilli (Borch et al, 1991;Torino et al, 2001) and lactococci (Hofvendahl et al, 1999) and from acidogenesis to solventogenesis in ABE fermentation by C. acetobutylicum (Girbal et al, 1995;Rogers and Gottschalk, 1993). Different patterns of organic acid production were also observed in C. sporogenes fermentation at different pHs, and butyric acid production was favored at pH 5.5 (Montville et al, 1985).…”

Section: Effect Of Ph On Metabolic Pathwaymentioning

confidence: 99%

Effect of pH on metabolic pathway shift in fermentation of xylose by Clostridium tyrobutyricum

Zhu

Yang

2004

Journal of Biotechnology

210

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The effect of pH (between 5.0 and 6.3) on butyric acid fermentation of xylose by Clostridium tyrobutyricum was studied. At pH 6.3, the fermentation gave a high butyrate production of 57.9 g l −1 with a yield of 0.38-0.59 g g −1 xylose and a reactor productivity up to 3.19 g l −1 h −1 . However, at low pHs (<5.7), the fermentation produced more acetate and lactate as the main products, with only a small amount of butyric acid. The metabolic shift from butyrate formation to lactate and acetate formation in the fermentation was found to be associated with changes in the activities of several key enzymes. The activities of phosphotransbutyrylase (PTB), which is the key enzyme controlling butyrate formation, and NAD-independent lactate dehydrogenase (iLDH), which catalyzes the conversion of lactate to pyruvate, were higher in cells producing mainly butyrate at pH 6.3. In contrast, cells at pH 5.0 had higher activities of phosphotransacetylase (PTA), which is the key enzyme controlling acetate formation, and lactate dehydrogenase (LDH), which catalyzes the conversion of pyruvate to lactate. Also, PTA was very sensitive to the inhibition by butyric acid. Difference in the specific metabolic rate of xylose at different pHs suggests that the balance in NADH is a key in controlling the metabolic pathway used by the cells in the fermentation.

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Heterofermentative pattern and exopolysaccharide production by Lactobacillus helveticus ATCC 15807 in response to environmental pH

Cited by 118 publications

References 23 publications

Inducible Gene Expression in Lactobacillus reuteri LTH5531 during Type II Sourdough Fermentation

Inducible Gene Expression in Lactobacillus reuteri LTH5531 during Type II Sourdough Fermentation

Studies on a Neutral Exopolysaccharide of Lactobacillus fermentum TDS030603

Effect of pH on metabolic pathway shift in fermentation of xylose by Clostridium tyrobutyricum

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