Pullulan

Abstract

Introduction Historical Outline Chemical Structure Physiological Function Chemical Analyses Occurrence Biosynthesis Culture Conditions and Cell Morphology Biosynthetic Mechanism Genetics and Molecular Biology Biodegradation Production Properties and Applications Patents Outlook and Perspectives

Adhesion of Aureobasidium pullulans Is Controlled by Uronic Acid Based Polymers and Pullulan

“…Strain variability plays an important role in determining how biosynthesis proceeds, and factors such as carbon source, cell morphology, oxygen concentration, temperature, shear stress (i.e., in a fermentor), and trace amounts of vitamins and minerals all affect pullulan production. 1 Some studies have shown that pullulan is produced more in stationary, compared to exponential-phase, growth. 6,57 This is consistent with the idea that pullulan is a secondary metabolite, and so it is produced only when growth decreases, although by a strict definition, secondary metabolites refer to diffusible products, and thus pullulan would not be such a compound.…”

“…1 It is frequently categorized as a mild plant pathogen, particularly for grapes, and plays a vital role in the post-harvest decay of many crops. A. pullulans is also an opportunistic human pathogen, especially in immuno-compromised hosts.…”

“…Although fungal cells often produce polysaccharide for the purpose of energy storage, this does not appear to be the function of pullulan in A. pullulans, since the microbe cannot break the polysaccharide down to easily metabolized sugars. 1 While pullulan is most likely not a storage material, it is believed to serve for cell protection and to aid in adhesion of A. pullulans to surfaces in the environment, 1 such as leaf surfaces 14 or wood. 15 If the adhesion of A. pullulans is believed to be governed by polymer production, and this production depends on growth phase, then it is logical to assume that the physiological state of the organism would impact its adhesive properties.…”

“…Therefore, it can be produced more when growth becomes limited or as the cells approach stationary phase. 1 Molecules additional to pullulan that are also produced by this fungus have received even less study. Use of molecular-level tools, such as the AFM, represents a powerful approach to directly probe and quantify microbial interactions and to study fungal macromolecules.…”

Aureobasidium thailandense sp. nov. isolated from leaves and wooden surfaces

“…Aureobasidium proteae was reported to cause chronic fungal meningitis (Kutleša et al, 2012) as well as a leaf spot disease of Proteaceae (Crous et al, 2011). Some isolates of A. pullulans produce semiochemicals (Davis et al, 2012) that influence wasp behaviour in nature and that may be involved in dispersal of members of the genus Aureobasidium, while other isolates produce large amounts of the extracellular polysaccharide (EPS) pullulan (Manitchotpisit et al, 2009), a polysaccharide with many valuable industrial and medical uses (Leathers, 2002;Cheng et al, 2011). Still other isolates biosynthesize products that have commercial value such as laccase (Rich et al, 2011), xylanase (Manitchotpisit et al, 2009) or poly b-L-malic acid (Manitchotpisit et al, 2012).…”