Environmental influences on exopolysaccharide formation in Lactobacillus reuteri ATCC 55730

Årsköld, Emma; Svensson, Martina; Grage, Halfdan; Roos, Stefan; Rådström, Peter; Niel, Ed W. J. van

doi:10.1016/j.ijfoodmicro.2006.12.010

Cited by 48 publications

(20 citation statements)

References 33 publications

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“…ADH uses both NADH and NADPH and thus can be used to regenerate NADP ϩ if needed. Previous work has shown that mannitol dehydrogenase prefers NADPH over NADH in this strain (2).…”

Section: Resultsmentioning

confidence: 56%

“…(i) Metabolic flux analysis exposed the flux distribution, (ii) bioinformatics provided information about the presence of the genes encoding both pathways on the genome, (iii) enzyme assays proved the activities of the key enzymes, and (iv) 31 P NMR showed the simultaneous presence of metabolites of both pathways. So far, the operation of two glycolytic pathways has been described in L. plantarum and in L. salivarius, but only from a genetic level (2,20).…”

Section: Discussionmentioning

confidence: 99%

“…Sucrose is converted into lactate, acetate, ethanol, CO 2 , and mannitol with this strain, whereby the latter is formed from the fructose half that functions solely as an electron acceptor (2).…”

mentioning

confidence: 99%

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Phosphoketolase Pathway Dominates in Lactobacillus reuteri ATCC 55730 Containing Dual Pathways for Glycolysis

et al. 2008

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Metabolic flux analysis indicated that the heterofermentative Lactobacillus reuteri strain ATCC 55730 uses both the Embden-Meyerhof pathway (EMP) and phosphoketolase pathway (PKP) when glucose or sucrose is converted into the three-carbon intermediate stage of glycolysis. In all cases studied, the main flux is through the PKP, while the EMP is used as a shunt. In the exponential growth phase, 70%, 73%, and 84% of the flux goes through the PKP in cells metabolizing (i) glucose plus fructose, (ii) glucose alone, and (iii) sucrose alone, respectively. Analysis of the genome of L. reuteri ATCC 55730 confirmed the presence of the genes for both pathways. Further evidence for the simultaneous operation of two central carbon metabolic pathways was found through the detection of fructose-1,6-bisphosphate aldolase, phosphofructokinase, and phosphoglucoisomerase activities and the presence of phosphorylated EMP and PKP intermediates using in vitro 31 P NMR. The maximum specific growth rate and biomass yield obtained on glucose were twice as low as on sucrose. This was the result of low ATP levels being present in glucose-metabolizing cells, although the ATP production flux was as high as in sucrose-metabolizing cells due to a twofold increase of enzyme activities in both glycolytic pathways. Growth performance on glucose could be improved by adding fructose as an external electron acceptor, suggesting that the observed behavior is due to a redox imbalance causing energy starvation.Lactic acid bacteria (LAB) employ a few glycolytic pathways to funnel carbohydrates into the common three-carbon intermediate stage of glycolysis. In general, homofermentative LAB convert carbohydrates into lactate using the Embden-Meyerhof pathway (EMP), whereas heterofermentative LAB produce lactate, ethanol, and carbon dioxide using the phosphoketolase pathway (PKP) (8). The PKP is usually used by LAB to ferment pentoses (9), and it has a poor energy yield compared to that of the EMP (16). This disadvantage can be compensated for by the addition of external electron acceptors, which creates alternative pathways for NAD(P)H reoxidation and may stimulate growth (33). A part of the acetyl phosphate can then be converted into acetate instead of ethanol, thereby gaining one additional ATP, making the PKP as efficient as the EMP.Lactobacillus reuteri ATCC 55730 has been described as a heterofermentative bacterium using the PKP (9) for converting glucose to lactate, ethanol, and CO 2 . Sucrose is converted into lactate, acetate, ethanol, CO 2 , and mannitol with this strain, whereby the latter is formed from the fructose half that functions solely as an electron acceptor (2).Heterofermentative lactobacilli take up sugars by nonphosphorylating permease systems, but several possess the phosphotransferase system for the uptake of fructose, which is inevitably connected to a fully operating EMP instead of the PKP because of the requirement of the production of two phosphoenolpyruvates (PEP) per sugar unit (18, 25).In the current study, we describe and s...

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“…ADH uses both NADH and NADPH and thus can be used to regenerate NADP ϩ if needed. Previous work has shown that mannitol dehydrogenase prefers NADPH over NADH in this strain (2).…”

Section: Resultsmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 99%

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Phosphoketolase Pathway Dominates in Lactobacillus reuteri ATCC 55730 Containing Dual Pathways for Glycolysis

et al. 2008

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“…11) In order to enhance EPS production, a conventional method via one factor at a time or response surface methodology can be used. 1,12,13) However, the conventional method is time consuming and requires a large number of experiments to determine the optimal conditions. The use of response surface methodology determined several levels of various parameters with interactions among them.…”

Section: Optimization Of Exopolysaccharide Overproduction By Lactobacmentioning

confidence: 99%

Optimization of Exopolysaccharide Overproduction byLactobacillus confususin Solid State Fermentation under High Salinity Stress

Seesuriyachan

Kuntiya

Hanmoungjai

et al. 2012

Bioscience, Biotechnology, and Biochemistry

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It is believed that high concentrations of sodium chloride (NaCl) suppress the biosynthesis of exopolysaccharide (EPS) in lactic acid bacteria (LAB). Nevertheless, overproduction of EPSs due to high salinity stress in solid state fermentation performed on an agar surface was demonstrated in this study using a response surface methodology via a central composite design (CCD). Under optimized conditions with NaCl 4.97% and sucrose 136.5 g/L at 40.79 h of incubation, the EPS yield was 259% (86.36 g/L of EPS), higher than the maximum yield produced with the modified MRS medium containing only 120 g/L of sucrose without NaCl (33.4 g/L of EPS). Biosynthesis of EPS by Lactobacillus confusus TISTR 1498 was independent of biomass production. Our results indicated that high salinity stress can enhance EPS production in solid state fermentation.

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“…The present effort in India focuses on determining the diversity of Lactobacillus species in dairy products such as traditional fermented milk (dahi) and cheeses to result in a formidable repertoire of diverse Lactobacillus strains that could be functionally and genetically explored in the immediate and near future to reveal strains that have strong functional and probiotic attributes, and various industrially important uses. These strains could then be exploited to produce various useful compounds [low-molecular mass compounds such as hydrogen peroxide (H 2 O 2 ) [5], carbon dioxide (CO 2 ) [6], diacetyl (2,3-butanedione) [7]; high molecular mass compounds such as bacteriocins [8] and other uncharacterized compounds; commercial Lactic Acid [9]; exopolysaccharides [10]; low calorie sweeteners [11]; alcohols for industrial, transportation and beverage use [12]; oils and fats [13]; and by the use of genetically modified strains, vitamins [14], enzymes [15] and hormones [16].…”

Section: Introductionmentioning

confidence: 99%

A Simple Method for the Efficient Isolation of Genomic DNA from Lactobacilli Isolated from Traditional Indian Fermented Milk (dahi)

Kaur

Roy

et al. 2010

Indian J Microbiol

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A simple, inexpensive and effective genomic DNA isolation procedure for Lactobacillus isolates from traditional Indian fermented milk (dahi) is described. A total of 269 Lactobacillus isolates from fermented milk collected from four places in North and west India were tested for lysis by an initial weakening of the Gram positive cell wall with Ampicillin followed by Lysozyme treatment. The average genomic DNA yield was *50 lg/ml log phase culture. Quality and repeatability of the method was found to be adequate for subsequent molecular applications. The quality of the genomic DNA isolated by this method was verified by restriction digestion and polymerase chain reaction (PCR). No inhibition was observed in subsequent PCR amplification and restriction digestion. The presented method is rapid, cheap and useful for routine DNA isolation from gram positive bacteria such as Lactobacillus.

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Environmental influences on exopolysaccharide formation in Lactobacillus reuteri ATCC 55730

Cited by 48 publications

References 33 publications

Phosphoketolase Pathway Dominates in Lactobacillus reuteri ATCC 55730 Containing Dual Pathways for Glycolysis

Phosphoketolase Pathway Dominates in Lactobacillus reuteri ATCC 55730 Containing Dual Pathways for Glycolysis

Optimization of Exopolysaccharide Overproduction byLactobacillus confususin Solid State Fermentation under High Salinity Stress

A Simple Method for the Efficient Isolation of Genomic DNA from Lactobacilli Isolated from Traditional Indian Fermented Milk (dahi)

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