Wang DH, Ni TF, Ju XM, Wei GY Sodium chloride improves pullulan production by Aureobasidium pullulans but reduces the molecular weight of pullulan Applied Microbiology and Biotechnology102(20) (2018)
8921-8930
NCBI PubMed ID:30120520 Publication DOI:10.1007/s00253-018-9292-y Journal NLM ID:8406612 Publisher: Springer Correspondence: Wei GY <weigysuda.edu.cn> Institutions: School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China
The effect of sodium chloride (NaCl) on pullulan production by batch culture of Aureobasidium pullulans CCTCC M 2012259 was investigated. NaCl at 3 g/L improved the pullulan titer by 26.7% but reduced the molecular weight of pullulan to only 46.8% of that obtained in the control without NaCl. In order to elucidate the physiological mechanism underlying the effect of NaCl on pullulan production, assays of key enzyme activity, gene expression, energy metabolism, and intracellular uridine diphosphate glucose (UDP-glucose) content were performed. Results indicated that NaCl increased the activities of α-phosphoglucose mutase and glucosyltransferase involved in pullulan biosynthesis, increased the activities of α-amylase being responsible for pullulan degradation, upregulated the transcriptional levels of pgm1, fks, and amy2 genes, enhanced the driving force for ATP supply, and helped to maintain intracellular UDP-glucose at a high level in A. pullulans CCTCC M 2012259. All these results illuminate the reason by which NaCl increases pullulan titer but reduces the molecular weight of pullulan.
Methods: HPLC, extraction, statistical analysis, viscosity measurements, centrifugation, dinitrosalicylic acid (DNS) method, ultrasonication Enzymes that release or process the structure: UGP, FKS Biosynthesis and genetic data: biochemical data, genetic data Comments, role: addition of NaCl lowers molecular mass
Kasapis S, Morris ER, Gross M, Rudolph K Solution properties of levan polysaccharide from Pseudomonas syringae pv. phaseolicola, and its possible primary role as a blocker of recognition during pathogenesis Carbohydrate Polymers23(1) (1994)
55-64
Taxonomic group: plant / Streptophyta (Phylum: Streptophyta) Organ / tissue:seed
Publication DOI:10.1016/0144-8617(94)90090-6 Journal NLM ID:8307156 Publisher: Elsevier Institutions: Department of Food Research and Technology, Cranfield University, Silsoe College, Silsoe, Bedford MK45 4DT, UK, Institut für Pflanzenpathologie und Pflanzenschutz der Universität Göttingen, Grisebachstr.6, D-3400 Göttingen, Germany
Bacterial levan, a highly branched, high molecular weight polymer of fructose, was purified from culture supernatants of Pseudomonas syringaepv.phaseolicola grown in a liquid high-sucrose medium, and the predominance of β-(2 → 6) linkages was confirmed by 13C NMR. The solution properties of this material resembled those of disordered linear polysaccharides in the response to low-amplitude oscillatory shear (frequency dependence of G′ and G″); the absence of any detectable conformational change with temperature (as monitored by optical rotation); close superposition of steady-shear viscosity (η) and complex dynamic viscosity (gh*) at equivalent values of shear-rate (γs-1) and frequency (ωrad s-1); a similar form of shear-thinning (giving linear plots of η versus ηγ0.76); and the onset of semi-dilute behaviour at a closely comparable degree of space-occupancy (c[η] ≈ 3·6). The intrinsic viscosity, however, was unusually low ([η] ≈ 0·17 dl g−1) and the concentration dependence of ‘zero-shear’ viscosity in the semi-dilute regime unusually high (η0 ∼ c9·3), as anticipated from the densely packed, branched molecular structure. Solutions of levan and pectin, matched to approximately the same initial viscosity, showed a substantial reduction in viscosity when mixed. Similar behaviour was observed for mixed solutions of levan with locust bean gum (LBG), chosen for its structural similarity to cellulose and hemicelluloses of the plant cell wall. Viscosity reduction was eliminated at low concentrations (indicating that it does not arise from heterologous association), but became very pronounced at high concentrations, and was then accompanied by resolution into levan-rich and LBG-rich solution phases. This evidence of strong thermodynamic incompatibility and exclusion behaviour with (1 → 4)-linked plant polysaccharides suggests that the primary role of levan during pathogenesis may be as a barrier to intimate morphological contact (recognition) between plant cell walls and those of the parasite, thus inhibiting initiation of a hypersensitive response by the host.
Structure type: polymer chemical repeating unit ; n is large
Kasapis S, Morris ER, Gross M, Rudolph K Solution properties of levan polysaccharide from Pseudomonas syringae pv. phaseolicola, and its possible primary role as a blocker of recognition during pathogenesis Carbohydrate Polymers23(1) (1994)
55-64
Publication DOI:10.1016/0144-8617(94)90090-6 Journal NLM ID:8307156 Publisher: Elsevier Institutions: Department of Food Research and Technology, Cranfield University, Silsoe College, Silsoe, Bedford MK45 4DT, UK, Institut für Pflanzenpathologie und Pflanzenschutz der Universität Göttingen, Grisebachstr.6, D-3400 Göttingen, Germany
Bacterial levan, a highly branched, high molecular weight polymer of fructose, was purified from culture supernatants of Pseudomonas syringaepv.phaseolicola grown in a liquid high-sucrose medium, and the predominance of β-(2 → 6) linkages was confirmed by 13C NMR. The solution properties of this material resembled those of disordered linear polysaccharides in the response to low-amplitude oscillatory shear (frequency dependence of G′ and G″); the absence of any detectable conformational change with temperature (as monitored by optical rotation); close superposition of steady-shear viscosity (η) and complex dynamic viscosity (gh*) at equivalent values of shear-rate (γs-1) and frequency (ωrad s-1); a similar form of shear-thinning (giving linear plots of η versus ηγ0.76); and the onset of semi-dilute behaviour at a closely comparable degree of space-occupancy (c[η] ≈ 3·6). The intrinsic viscosity, however, was unusually low ([η] ≈ 0·17 dl g−1) and the concentration dependence of ‘zero-shear’ viscosity in the semi-dilute regime unusually high (η0 ∼ c9·3), as anticipated from the densely packed, branched molecular structure. Solutions of levan and pectin, matched to approximately the same initial viscosity, showed a substantial reduction in viscosity when mixed. Similar behaviour was observed for mixed solutions of levan with locust bean gum (LBG), chosen for its structural similarity to cellulose and hemicelluloses of the plant cell wall. Viscosity reduction was eliminated at low concentrations (indicating that it does not arise from heterologous association), but became very pronounced at high concentrations, and was then accompanied by resolution into levan-rich and LBG-rich solution phases. This evidence of strong thermodynamic incompatibility and exclusion behaviour with (1 → 4)-linked plant polysaccharides suggests that the primary role of levan during pathogenesis may be as a barrier to intimate morphological contact (recognition) between plant cell walls and those of the parasite, thus inhibiting initiation of a hypersensitive response by the host.
Publication DOI:10.1016/0144-8617(94)90129-5 Journal NLM ID:8307156 Publisher: Elsevier Institutions: Centre de Recherches sur les Macromolécules Végétales, CNRS, B.P. 53 X, 38041 Grenoble-ćedex 9, France, Laboratoire de Biotechnologie Microbienne, I.U.T., Département de Biologie Appliquée, Avenue des Facultés, Le Bailly, 80025 Amiens, France
The Rhizobium meliloti mutant strain M5N1 C.S. (NCIMB 40472) produces a polyuronic acid as β(1 → 4)-d-glucuronan with molecular weight between 1·5 × 105 and 3 × 105. With a pKo of about 3 and Lp ≈ 110Å, this polyelectrolyte is comparable with alginates and pectins. In solution, acetyl content and high external salt concentrations favour aggregation. At high concentrations the polysaccharide forms thermoreversible or thermally stable gels according to the nature of the counterion, the polymer concentration and the ionic strength.
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(previously named: Dematium pullulans CCTCC M 2012259)
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