Exopolysaccharide Formation Research Articles

A multivariate approach to correlate bacterial surface properties to biofilm formation by lipopolysaccharide mutants of Pseudomonas aeruginosa

Bacterial biofilms are involved in various medical infections and for this reason it is of great importance to better understand the process of biofilm formation in order to eradicate or mitigate it. It is a very complex process and a large range of variables have been suggested to influence biofilm formation. However, their internal importance is still not well understood. In the present study, a range of surface properties of Pseudomonas aeruginosa lipopolysaccharide mutants were studied in relation to biofilm formation measured in different kinds of multi-well plates and growth conditions in order to better understand the complexity of biofilm formation. Multivariate analysis was used to simultaneously evaluate the role of a range of physiochemical parameters under different conditions. Our results suggest the presence of serum inhibited biofilm formation due to changes in twitching motility. From the multivariate analysis it was observed that the most important parameters, positively correlated to biofilm formation on two types of plates, were high hydrophobicity, near neutral zeta potential and motility. Negative correlation was observed with cell aggregation, as well as formation of outer membrane vesicles and exopolysaccharides. This work shows that the complexity of biofilm formation can be better understood using a multivariate approach that can interpret and rank the importance of different factors being present simultaneously under several different environmental conditions, enabling a better understanding of this complex process.

Characterization of exopolysaccharide and ropy capsular polysaccharide formation by Weissella

With their broad functional properties, lactic acid bacteria derived high molar mass exopolysaccharides (EPS) and oligosaccharides are of great interest for food, medical and pharmaceutical industry. EPS formation by 123 strains of Weissella cibaria and Weissella confusa, was evaluated. Dextran formation from sucrose was observed for all tested strains while 18 strains produced fructan in addition to dextran. Six isolates synthesized a highly ropy polymer from glucose associated with the formation of a cell-bound, capsular polysaccharide (CPS) composed of glucose, O-acetyl groups and two unidentified monomer components. The soluble EPSs of nine strains were identified as low α-1,3-branched dextran, levan and inulin type polymers using NMR. In addition to glucan and fructan, W. confusa produced gluco- and fructooligosaccharides. Partial dextransucrase and fructansucrase sequences were characterized in the selected Weissella strains. Our study reports the first structural characterization of fructan type EPS from Weissella as well as the first Weissella strain producing inulin. Production of more than one EPS-type by single strains may have high potential for development of applications combining EPS technological and nutritional benefits.

Exopolysaccharides from Sourdough Lactic Acid Bacteria

The use of sourdough improves the quality and increases the shelf life of bread. The positive effects are associated with metabolites produced by lactic acid bacteria (LAB) during sourdough fermentation, including organic acids, exopolysaccharides (EPS), and enzymes. EPS formed during sourdough fermentation by glycansucrase activity from sucrose influence the viscoelastic properties of the dough and beneficially affect the texture and shelf life (in particular, starch retrogradation) of bread. Accordingly, EPS have the potential to replace hydrocolloids currently used as bread improvers and meet so the consumer demands for a reduced use of food additives. In this review, the current knowledge about the functional aspects of EPS formation by sourdough LAB especially in baking applications is summarized.

Antibiofilm efficacy of silver nanoparticles against biofilm of extended spectrum β-lactamase isolates of Escherichia coli and Klebsiella pneumoniae

The ability of bacteria to develop antibiotic resistance and colonize abiotic surfaces by forming biofilms is a major cause of medical implant-associated infections and results in prolonged hospitalization periods and patient mortality. Different approaches have been used for preventing biofilm-related infections in health care settings. Many of these methods have their own demerits that include chemical-based complications; emergent antibiotic-resistant strains, and so on. Silver nanoparticles (AgNPs) are renowned for their influential antimicrobial activity. We demonstrate the biofilm formation by extended spectrum β-lactamases-producing Escherichia coli and Klebsiella spp. by direct visualization applying tissue culture plate, tube, and Congo red agar methods. Double fluorescent staining for confocal laser scanning microscopy (CLSM) consisted of propidium iodide staining to detect bacterial cells and concanavalin A-fluorescein isothiocyanate staining to detect the exopolysaccharides matrix were used. Scanning electron microscopy observations clearly indicate that AgNPs reduced the surface coverage by E. coli and Klebsiella spp. thus prevent the biofilm formations. Double-staining technique using CLSM provides the visual evidence that AgNPs arrested the bacterial growth and prevent the exopolysaccharides formation. The AgNPs-coated surfaces effectively restricted biofilm formation of the tested bacteria. In our study, we could demonstrate the complete antibiofilm activity AgNPs at a concentration as low as 50 μg/ml. Our findings suggested that AgNPs can be exploited towards the development of potential antibacterial coatings for various biomedical and environmental applications. These formulations can be used for the treatment of drug-resistant bacterial infections caused by biofilms, at much lower nanosilver loading with higher efficiency.

Enzymatic and bacterial conversions during sourdough fermentation

Enzymatic and microbial conversion of flour components during bread making determines bread quality. Metabolism of sourdough microbiota and the activity of cereal enzymes are interdependent. Acidification, oxygen consumption, and thiols accumulation by microbial metabolism modulate the activity of cereal enzymes. In turn, cereal enzymes provide substrates for bacterial growth. This review highlights the role of cereal enzymes and the metabolism of lactic acid bacteria in conversion of carbohydrates, proteins, phenolic compounds and lipids.Heterofermentative lactic acid bacteria prevailing in wheat and rye sourdoughs preferentially metabolise sucrose and maltose; the latter is released by cereal enzymes during fermentation. Sucrose supports formation of acetate by heterofermentative lactobacilli, and the formation of exopolysaccharides. The release of maltose and glucose by cereal enzymes during fermentation determines the exopolysaccharide yield in sourdough fermentations.Proteolysis is dependent on cereal proteases. Peptidase activities of sourdough lactic acid bacteria determine the accumulation of (bioactive) peptides, amino acids, and amino acid metabolites in dough and bread.Enzymatic conversion and microbial metabolism of phenolic compounds is relevant in sorghum and millet containing high levels of phenolic compounds. The presence of phenolic compounds with antimicrobial activity in sorghum selects for fermentation microbiota that are resistant to the phenolic compounds.

Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11(T)).

Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales, which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum. Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates (Paramecium spp.). Genomic traits of L. alexandrii DFL-11T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the Marine Microbial Initiative.

Identification of Lactobacillus curvatus TMW 1.624 dextransucrase and comparative characterization with Lactobacillus reuteri TMW 1.106 and Lactobacillus animalis TMW 1.971 dextransucrases

Recently, it was affirmed that the exopolysaccharides (EPSs) of Lactobacillus curvatus TMW 1.624, Lactobacillus reuteri TMW 1.106 and Lactobacillus animalis TMW 1.971 improve the quality of gluten-free breads and that they can be produced in situ to levels enabling baking applications. In this study we provide insight into the molecular and biochemical background of EPS production of these three strains. EPS formation strongly correlated with growth and took place during the exponential phase. Gtf genes were heterologously expressed, purified and their enzymatic properties as well as the structures of the EPSs formed were compared. Structural comparison of EPS formed by heterologously expressed glucosyltransferases (Gtfs) and of those formed by the wildtype lactobacilli confirmed that the respective genes/enzymes were identified and examined. The glucan formed by L. animalis Gtf was identified as a linear low molecular weight dextran. Optimal enzymatic conditions were pH 4.4 and 45 °C for the L. reuteri Gtf and pH 4.4 and 31 °C for L. curvatus Gtf. The Gtf from L. animalis had an optimal pH of 5.8 and displayed more than 50% of activity over a broad temperature profile (22–59 °C). The three Gtfs were stimulated by various mono- and divalent metal ions, dextran, as well as levan to different extents.

Enhanced fed-batch fermentation of 2,3-butanediol by Paenibacillus polymyxa DSM 365

Fed-batch fermentations for the production of 2,3-butanediol (BDL) with Paenibacillus polymyxa DSM 365 were investigated in 2-L-fermenters. A suitable micro-aerobic set-up enabled high product selectivity of up to 98% R,R-BDL towards meso-BDL and acetoin. Up to 111gL−1R,R-BDL within 54h could be achieved with sufficient supply of complex medium (yeast extract). To the best of the knowledge of the authors, this is the highest titer so far reported for P. polymyxa indicating its high potential as a non pathogenic BDL-producer. Fermentation in low nutritional medium (5gL−1 yeast extract) yielded up to 72gL−1 BDL+acetoin (79% R,R-BDL), yet was affected by formation of exopolysaccharides (EPS). In the range of 30–40°C EPS formation decreased with raising temperature although growth rate and BDL-production remained similar. Additionally, Tween80® was found to be a good additive to reduce viscosity caused by EPS.

Comparison of the impact of dextran and reuteran on the quality of wheat sourdough bread

This study investigates the influence of in situ exopolysaccharides (EPS) and organic acids on dough rheology and wheat bread quality. Dextran forming Weissella cibaria MG1 was compared to reuteran forming Lactobacillus reuteri VIP. For in situ production of EPS, sourdoughs were supplemented with 15% sucrose. Control sourdoughs were prepared with the same strain but without sucrose. W. cibaria MG1 and L. reuteri VIP formed 5.1 and 5.8 g kg−1 dextran and reuteran, respectively. Formation of EPS from sucrose led to production of high amounts of acetate by L. reuteri VIP, but only small amounts were detected in W. cibaria MG1 sourdough. EPS containing sourdough or control sourdough was incorporated at 10% and 20% in wheat dough. EPS significantly influenced the rheological properties of the dough, with dextran exhibiting the strongest impact. The addition of dextran enriched W. cibaria MG1 sourdough significantly increased CO2 production, whereas increased acidity in reuteran containing dough reduced gas production. The quality of wheat bread was enhanced when 10% of L. reuteri-sucrose sourdough was added. The positive effect of reuteran was masked by increased acidification after 20% sourdough addition. Incorporation of dextran enriched sourdough (10% and 20%) provided mildly acidic wheat bread with improved bread quality.

Biopolymer Production by the Yeast <i>Rhodotorula glutinis</i>

In this work, exopolysaccharide (EPS) production by the yeast Rhodotorula glutinis was investigated. The results suggest that the synthesis of EPS in batch fermentations was enhanced by using a low C/N ratio to stimulate fast cell growth during the exponential phase and by adding glucose to stationary phase cultures to provide excess carbon for EPS formation. The apparent viscosity and molecular weight of EPS were found to decrease with increasing fermentation time due to the partial hydrolysis of EPS by the acidic fermentation broth (pH 1.8). Maintaining stationary phase cultures at pH 4 was found to be effective in minimizing acid hydrolysis and producing EPS with high molecular weight and apparent viscosity.

Biofiltration of methane and trace gases from landfills: A review

Concerns about biogas from landfills are reviewed in terms of biogas generation, composition, and elimination. Biogas is mainly composed of methane and carbon dioxide but it also contains a few hundred non-methane organic compounds. The solutions available to reduce its harmful effects on the environment and on human health are valorization as electricity or heat, flaring, or biofiltration. The main parameters affecting the biofiltration of methane are reviewed: temperature, moisture content, properties of the packing material, nutrient supply, oxygen requirements, formation of exopolysaccharides, and gas residence time. An analysis is performed on the co-metabolic properties and the inhibition interactions of the methane-degrading bacteria, methanotrophs.

Identification, structure, and characterization of an exopolysaccharide produced by Histophilus somniduring biofilm formation

BackgroundHistophilus somni, a gram-negative coccobacillus, is an obligate inhabitant of bovine and ovine mucosal surfaces, and an opportunistic pathogen responsible for respiratory disease and other systemic infections in cattle and sheep. Capsules are important virulence factors for many pathogenic bacteria, but a capsule has not been identified on H. somni. However, H. somni does form a biofilm in vitro and in vivo, and the biofilm matrix of most bacteria consists of a polysaccharide.ResultsFollowing incubation of H. somni under growth-restricting stress conditions, such as during anaerobiosis, stationary phase, or in hypertonic salt, a polysaccharide could be isolated from washed cells or culture supernatant. The polysaccharide was present in large amounts in broth culture sediment after H. somni was grown under low oxygen tension for 4-5 days (conditions favorable to biofilm formation), but not from planktonic cells during log phase growth. Immuno-transmission electron microscopy showed that the polysaccharide was not closely associated with the cell surface, and was of heterogeneous high molecular size by gel electrophoresis, indicating it was an exopolysaccharide (EPS). The EPS was a branched mannose polymer containing some galactose, as determined by structural analysis. The mannose-specific Moringa M lectin and antibodies to the EPS bound to the biofilm matrix, demonstrating that the EPS was a component of the biofilm. The addition of N-acetylneuraminic acid to the growth medium resulted in sialylation of the EPS, and increased biofilm formation. Real-time quantitative reverse transcription-polymerase chain reaction analyses indicated that genes previously identified in a putative polysaccharide locus were upregulated when the bacteria were grown under conditions favorable to a biofilm, compared to planktonic cells.ConclusionsH. somni is capable of producing a branching, mannose-galactose EPS polymer under growth conditions favorable to the biofilm phase of growth, and the EPS is a component of the biofilm matrix. The EPS can be sialylated in strains with sialyltransferase activity, resulting in enhanced density of the biofilm, and suggesting that EPS and biofilm formation may be important to persistence in the bovine host. The EPS may be critical to virulence if the biofilm state is required for H. somni to persist in systemic sites.

Antioxidant property and production of exopolysaccharide from Armillaria mellea in submerged cultures: Effect of culture aeration rate

AbstractEffects of culture aeration rate on production and antioxidant property of exopolysaccharide (EPS) by Armillaria mellea were investigated in a 5‐L stirred‐tank bioreactor where an optimal biomass aeration rate of 1.2 vvm with 0.22 g/g cell yield and 0.6 vvm EPS formation rate with 7.66 mg/g product yield were achieved. A two‐stage aeration process to maximize the biomass and EPS productions proceeded with a 1.55‐fold enhancement (from 4.28 to 6.65 g/L) in biomass formation and a 2.68‐fold enhancement (from 86.9 to 233.2 mg/L) in the EPS production, as compared with those from the aeration rate of 0.3 vvm. The molecular weights of EPS in cultures of different aeration rates are closely correlated with their protein/polysaccharide ratios (R2=0.830) and EC50 (EC50, the effective concentration where the antioxidant property is 50%) values in antioxidant activity (R2=0.960), reducing power (R2=0.894) and chelating ability (R2=0.954). EPS from the two‐stage aeration rate culture shows a strong antioxidant property by the conjugated diene method, reducing power and chelating ability on ions. Therefore, we present results to regulate and to optimize A. mellea cultures to efficiently produce biomass and EPS. The fermented EPS has the potential to be used as for antioxidant‐related functional foods and pharmaceutical industries.

Modulation of rosR Expression and Exopolysaccharide Production in Rhizobium leguminosarum bv. trifolii by Phosphate and Clover Root Exudates

The acidic exopolysaccharide (EPS) secreted in large amounts by the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii is required for the establishment of an effective symbiosis with the host plant Trifolium spp. EPS biosynthesis in rhizobia is a very complex process regulated at both transcriptional and post-transcriptional levels and influenced by various nutritional and environmental conditions. The R. leguminosarum bv. trifolii rosR gene encodes a transcriptional regulator with a C2H2 type zinc-finger motif involved in positive regulation of EPS synthesis. In silico sequence analysis of the 450-bp long rosR upstream region revealed the presence of several inverted repeats (IR1 to IR6) and motifs with significant identity to consensus sequences recognized by PhoB and LysR-type proteins associated with phosphate- and flavonoid-dependent gene regulation in R. leguminosarum. Using a set of sequentially truncated rosR-lacZ transcriptional fusions, the role of the individual motifs and the effect of phosphate and clover root exudates on rosR expression were established. In addition, the significance of IR4 inverted repeats in the repression, and P2–10 hexamer in the activation of rosR transcription, respectively, was found. The expression of rosR increased in the presence of phosphate (0.1–20 mM) and clover root exudates (10 μM). PHO boxes and the LysR motif located upstream of the rosR translation start site were engaged in the regulation of rosR transcription. The synthesis of EPS and biofilm formation decreased at high phosphate concentrations, but increased in the presence of clover root exudates, indicating a complex regulation of these processes.

TLC method for monitoring the formation and degradation of bacterial exo-polysaccharides

A simple thin-layer chromatography (TLC) method for continuous determination of metabolism of carbohydrate and production of polysaccharides in the course of bacterial fermentations is presented in this paper. Samples were taken from the supernatants of decanted fermentation broth and from the hydrolysates of both the supernatants and the fermentation broth. Hydrolysis of the exo-polysaccharides (EPSs) to the constituent monosaccharides was carried out by 10% v/v hydrochloric acid at 100°C. These samples were applied directly onto a precoated nano silica plate besides a series of mono-, oligo-, and polysaccharide reference solutions.The plates were developed in a twin-trough chamber previously saturated with a solution of chloroform-toluene-35% formic acid-methanol (10:2:2:7 v/v) for 1 h. The plates were placed in the empty trough of the chamber in order to be saturated and then transferred to the trough containing the solvent. After reaching a migration distance of 160 mm, the plates were dried out and p...

Quality Control of Malt: Turbidity Problems of Standard Worts Given by the Presence of Microbial Cells

ABSTRACT J. Inst. Brew. 117(2), 212–216, 2011 Since the main effect on beer colour originates from the chemi-cal composition of malt, the measurement of the colour of wort obtained from malt is one of the most important quality parame-ters to be controlled. Malt colour determination is usually per-formed spectrophotometrically on EBC Congress worts, which are generally bright. The quality control on the malt harvested in the year 2007 highlighted a problem of turbid Congress wort, for a part of Northern Europe samples analyzed, and therefore the spectrophotometric determination of the colour of wort was not possible. Thus both analytical screening of the quality parame-ters of malt and the scanning electron microscope (SEM) were used to identify the nature of the turbidity in the worts. The re-sults obtained suggested that the nature of the turbidity of Con-gress worts could have been due to microbial contamination of the barley, enhanced in particular by the rainy harvest and the consequent formation of exopolysaccharides (EPS) by stressed yeast and bacteria during malting.

How the xap Locus Put Electrical “Zap” in Geobacter sulfurreducens Biofilms

Investigation of microbial mineral respiration remains an experimental challenge. In this issue of Journal of Bacteriology, Rollefson et al. (11) present a foundational study on the functionality of the biofilm matrix in Geobacter sulfurreducens, a model dissimilatory metal respiring bacterium (DMRB). In this study, the investigators identify an extracellular polysaccharide scaffold or network that entraps redox-active proteins, thus positioning these proteins for optimal electron transfer from the membrane-bound respiratory supercomplexes to a mineral phase electron acceptor. The distinguishing feature of this study is the perspective, in that the team examined specifically exopolysaccharide formation and how it enables entrapment and tethering of redox proteins in the vicinity of the cell. Previous studies on Geobacter (10) and Shewanella (4) have focused primarily on the presence and functionality of conductive pili and nanowires, proteinaceous structures that also enable and enhance extracellular electron transfer. Rollefson et al. remind investigators in this field that many microbial systems have redundancy in essential functions, and in the case of DMRB, it is clearly critical that more than one mechanism exists to ensure vectoral electron transport to mineral phase electron acceptors. The major findings of Rollefson et al. (11) were (i) identification of a biofilm locus in G. sulfurreducens that harbors exopolysaccharide synthesis and export genes; (ii) detection of c-type cytochromes in exopolysaccharide materials; (iii) genetic mutation of a gene (xapD [GSU1501], an ATP-dependent ABC transporter) in the locus which results in reduced functionality of the biofilm matrix, i.e., reduced agglutination and attachment, and less matrix-bound cytochrome; and (iv) microscopic confirmation of exopolysaccharide materials in the biofilm matrix. The research employed a combination of traditional microbiological techniques, genetic manipulation and mutation, and fluorescence and electron microscopy to obtain an integrated view of biofilm matrix composition and functionality in G. sulfurreducens. The elegance of the study is in its relative simplicity. For example, while agglutination has been examined in bacteria for decades, basic assessment of this phenomenon has not been made in many DMRB models, thus showing that classical microbiology still can reveal a great deal about DMRB biofilms. For example, Fig. 2 and 3 of the Rollefson et al. paper clearly reveal both macroscopic and microscopic differences in culture and biofilm morphology. Differential extraction procedures purify pili and exopolysaccharide and demonstrate binding of redox proteins and positioning of an extracellular biomolecular conductive network, and although one can argue the efficacy and resolution of these methods, the results seem to suggest that protein-exopolysaccharide complexes can be successfully isolated from biofilm cultures, and these approaches can be reliably used on other model DMRB systems. Unique experiments using polysaccharide binding stains coupled with scanning electron microscopy (SEM) reveal that exopolysaccharide is a key component for attachment and colonization of mineral and electrode surfaces. Indeed, the exopolysaccharide appears as a network of strands wiring cells together and to the substrate. Blocking techniques with safranin O work to strengthen the interpretation of the SEM images by better visualization of the extracellular matrix material.

Investigation of endophytic and symbiotic features of Ralstonia sp. TSC1 isolated from cowpea nodules

Ralstonia sp. TSC1 previously isolated from cowpea nodules was tagged with gfp gene by transposon insertion. The resultant gfp-tagged Ralstonia sp. TSC1 showed no difference in physiological properties such as growth rate, exopolysaccharide formation and colony morphology. When it was co-inoculated with compatible bradyrhizobial strains, the observation of fluorescence microscopy showed that TSC1 strains were colonized in subsurface of cowpea nodules and stems. In addition, TSC1 positively and negatively modulated symbiotic performance with the bradyrhizobia in terms of nodulation and symbiotic nitrogen fixation. The results suggested that Ralstonia sp. TSC1 is an endophyte with beneficial, neutral or detrimental effects on cowpea plants when in presence of effective bradyrhizobia. Key words: Ralstonia sp., cowpea, endophyte, green fluorescent protein,bradyrhizobium, nodulation.

Effect of submerged culture conditions on exopolysaccharides production by Armillaria luteo-virens Sacc QH and kinetic modeling

This work aimed to develop the submerged cultivation conditions for improved exopolysaccharides (EPS) production by Armillaria luteo-virens Sacc. The effects of culture temperature, aeration rate, inoculum level, initial pH, and additives on EPS formation and mycelial growth are investigated. The aeration rate, initial pH, and inoculum level significantly affected EPS production under the submerged cultivation. The developed conditions were as follows: cultivation temperature 23 °C, initial pH 5.0, aeration rate 0.5 vvm, 0.5% Tween 80, inoculum level 5% (v/v), and shaking speed 120 r/min. Under the developed conditions, the highest EPS production was 13.01 g/L at 5 days culture time. EPS production was examined in a 5 L bioreactor, and an unstructured kinetic model for EPS formation was well developed. The verified investigations in the large-scale cultivation system showed that the developed models are able to predict the submerged cultivation process of EPS formation. Current results revealed that the submerged cultivation conditions can be utilized to control EPS production, and the unstructured models developed are suitable for explaining EPS production by A. luteo-virens Sacc QH in a large-scale cultivation bioreactor.

Exopolysaccharide-Forming Weissella Strains as Starter Cultures for Sorghum and Wheat Sourdoughs

The addition of sourdough fermented with lactic acid bacteria synthesizing organic acids and oligo- and exopolysaccharides (EPS) from sucrose enhances texture, nutritional value, shelf life, and machinability of wheat, rye, and gluten-free bread. This study compared acetate, mannitol, and oligosaccharide formation of EPS-producing strains of Weissella and Leuconostoc spp. to the traditional sourdough starter Lactobacillus sanfranciscensis. In broth, Leuconostoc strains generally formed acetate and mannitol, whereas Weissella produced only small amounts of acetate and no mannitol in the presence of sucrose. In the presence of sucrose and maltose, Weissella and Leuconostoc strains synthesized glucooligosaccharides and EPS. Strains of Weissella were employed as starter cultures for wheat and sorghum sourdough and formed 0.8-8 g kg(-1) EPS and gluco-oligosaccharides but only low amounts of acetate and mannitol. In contrast, the formation of EPS from sucrose led to the production of high amounts of acetate and mannitol by L. sanfranciscensis LTH 2950 in wheat sourdough. This study indicates that Weissella strains are suitable starter cultures for wheat and sorghum sourdoughs and efficiently produce gluco-oligosaccharides and EPS.