The influence of fermentation condition on production and molecular mass of EPS produced by Streptococcus thermophilus 05-34 in milk-based medium

Li, Dan; Li, Jiaxi; Zhao, Feng; Qin, Qianqian; Hao, Yanbin

doi:10.1016/j.foodchem.2015.10.129

Cited by 47 publications

(45 citation statements)

References 25 publications

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“…Crude EPS was precipitated by adding cold ethanol to the supernatant at a ratio of 3:1 (v/v), mixed thoroughly and kept for 24 h at 4 C. The pellet containing EPS was obtained by centrifugation, dialyzed and freeze-dried. The crude EPS was purified as previously described (Li et al, 2016). The yield of EPS was quantified using the phenol-sulfuric method using glucose as a standard (DuBois et al, 1956).…”

Section: Isolation and Purification Of Epsmentioning

confidence: 99%

“…The monosaccharide composition was determined by gas chromatography coupled with mass spectrograph (GC-MS). Some pretreatments were performed as previously described (Li et al, 2016). The treated samples were used for GC-MS with the conditions as follows: initial column temperature was set at 140 C with a rate of 1.5 C/min to reach 200 C and with a rate of 10 C/min to 250 C, then the highest temperature was held for 5 min, and samples were injected into the column with N 2 as the carrier gas at a flow rate of one mL/min.…”

Section: Molecular Mass and Monosaccharide Composition Of Epsmentioning

confidence: 99%

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The N-terminal domain of rhamnosyltransferase EpsF influences exopolysaccharide chain length determination in Streptococcus thermophilus 05-34

Xie

Zhai

et al. 2020

PeerJ

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Glycosyltransferases are key enzymes involved in the assembly of repeating units of exopolysaccharides (EPS). A glycosyltransferase generally consists of the N-terminal and the C-terminal domain, however, the functional role of these domains in EPS biosynthesis remains largely unknown. In this study, homologous overexpression was employed to investigate the effects of EpsFN, a truncated form of rhamnosyltransferase EpsF with only the N-terminal domain, on EPS biosynthesis in Streptococcus thermophilus 05-34. Reverse transcription qPCR and Western blotting analysis confirmed the successful expression of epsFN in 05-34 at the transcription and translation level, respectively. Further analysis showed that the monosaccharide composition and yield of EPS were not affected by the overexpression of epsFN, whereas the molecular mass decreased by 5-fold. Accordingly, the transcription levels of genes involved in EPS biosynthesis, including chain-length determination gene epsC, were down-regulated by 5- to 6-fold. These results indicated that the N-terminal domain of EpsF alone could influence the molecular mass of EPS, probably via lowering the concentration of sugar precursors, which may lead to decreased expression of genes responsible for chain-length determination.

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Section: Isolation and Purification Of Epsmentioning

confidence: 99%

Section: Molecular Mass and Monosaccharide Composition Of Epsmentioning

confidence: 99%

The N-terminal domain of rhamnosyltransferase EpsF influences exopolysaccharide chain length determination in Streptococcus thermophilus 05-34

Xie

Zhai

et al. 2020

PeerJ

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“…[77,80,81]. In general, the amount of EPS produced by S. thermophilus is at relatively low levels, i.e., 50 to 400 mg/L in milk medium.…”

Section: Technological and Functional Properties Of S Thermophilusmentioning

confidence: 99%

“…The EPS yield of S. thermophilus 05-34 reaches 250 mg/L in 10% reconstituted skim milk with 80 g/L sucrose and 30 g/L soy peptone at an initial pH 7.0 and 37 °C for 30 h [81]. The research indicated that the molecular mass of EPS is 4.7 × 10 5 Da, which is increased by 9 times compared with non-optimal fermentation conditions, while monosaccharide composition does not change.…”

Section: Technological and Functional Properties Of S Thermophilusmentioning

confidence: 99%

New Insights into Various Production Characteristics of Streptococcus thermophilus Strains

Cui

et al. 2016

IJMS

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Streptococcus thermophilus is one of the most valuable homo-fermentative lactic acid bacteria, which, for a long time, has been widely used as a starter for the production of fermented dairy products. The key production characteristics of S. thermophilus, for example the production of extracellular polysaccharide, proteolytic enzymes and flavor substances as well as acidifying capacity etc., have an important effect on the quality of dairy products. The acidification capacity of the strains determines the manufacturing time and quality of dairy products. It depends on the sugar utilization ability of strains. The production of extracellular polysaccharide is beneficial for improving the texture of dairy products. Flavor substances increase the acceptability of dairy products. The proteolytic activity of the strain influences not only the absorption of the nitrogen source, but also the formation of flavor substances. Different strains have obvious differences in production characteristics via long-time evolution and adaptation to environment. Gaining new strains with novel and desirable characteristics is an important long-term goal for researchers and the fermenting industry. The understanding of the potential molecular mechanisms behind important characteristics of different strains will promote the screening and breeding of excellent strains. In this paper, key technological and functional properties of different S. thermophilus strains are discussed, including sugar metabolism, proteolytic system and amino acid metabolism, and polysaccharide and flavor substance biosynthesis. At the same time, diversity of genomes and plasmids of S. thermophilus are presented. Advances in research on key production characteristics and molecular levels of S. thermophilus will increase understanding of molecular mechanisms of different strains with different important characteristics, and improve the industrialization control level for fermented foods.

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“…Another aspect to consider is the possible change in the composition and/or proportion of polysaccharides in the total EPS extract after the optimisation. For example, Li et al () optimised the production of EPS from Streptococcus thermophilus 05‐34, evidencing that, although the monosaccharide composition did not change, the optimised EPS presented a molecular mass of 4.7

\times

10 2 kDa, which was increased by nine times compared with that obtained under the nonoptimal fermentation condition. They explained this fact by showing an increased transcription level of epsC , responsible for chain length determination.…”

Section: Discussionmentioning

confidence: 99%

Statistical optimisation of the exopolysaccharide production by Lactobacillus fermentum Lf2 and analysis of its chemical composition

Ale

Batistela

Olivar

et al. 2019

Int J of Dairy Tech

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Lactobacillus fermentum Lf2 produces high amounts of exopolysaccharides (EPS) (~1 g/L) with demonstrated functional and technological roles when applied as a food ingredient in dairy matrices, properties that made these EPS interesting in comparison with other similar molecules from lactic acid bacteria (LAB). Those characteristics encouraged us to optimise the production. The EPS extract is composed of a high molecular mass b-glucan and a medium molecular mass heteroglycan. In the present work, the optimal conditions that doubled the EPS yield using a semidefined medium (SDM, 0.63% yeast nitrogen base, 0.53% bacto casitone, 0.53% ammonium citrate, 6.25% sucrose, pH 6.5) were found by means of response surface methodology (RSM). The chemical characterisation indicated that under optimised conditions the synthesis of the heteroglycan was favoured compared with that of the b-glucan.

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The influence of fermentation condition on production and molecular mass of EPS produced by Streptococcus thermophilus 05-34 in milk-based medium

Cited by 47 publications

References 25 publications

The N-terminal domain of rhamnosyltransferase EpsF influences exopolysaccharide chain length determination in Streptococcus thermophilus 05-34

The N-terminal domain of rhamnosyltransferase EpsF influences exopolysaccharide chain length determination in Streptococcus thermophilus 05-34

New Insights into Various Production Characteristics of Streptococcus thermophilus Strains

Statistical optimisation of the exopolysaccharide production by Lactobacillus fermentum Lf2 and analysis of its chemical composition

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