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Table 1 Commercially important microbial polymers: the most relevant properties and applicationsa

From: Production of biodegradable microbial polymers from whey

Polymer class Producer Monomers Characteristics of primary structure Properties Applications
Xanthan Xanthomonas spp., mainly X. campestris Glucose, mannose and glucuronate β-(1,4)-linked repeating extracellular heteropolymer consisting of pentasaccharide units Hydrocolloid
—High viscosity yield at low shear rates even at low concentrations; —Stability over wide temperature, pH and salt concentrations ranges
Foods, petroleum, industry pharmaceuticals, cosmetics and personal care products, agriculture
Alginate Pseudomonas spp. and Azotobacter spp. Mannuronic acid and guluronic acid β-(1,4)-linked non-repeating non-repeating extracellular heteropolymer Hydrocolloid Gelling capacity Film-forming Food hydrocolloid
Medicine
Surgical dressings
Wound management
Controlled drug release
Gellan Sphingomonas spp. Glucose, rhamnose and glucuronate β-(1,3)-linked repeating extracellular heteropolymer consisting of tetrasaccharide units Hydrocolloid
-Stability over wide pH range
Gelling capacity Thermoreversible gels
Foods
Pet food
Pharmaceuticals
Research: agar substitute and gel electrophoresis
Curdlan Agrobacterium spp., Rhizobium spp. and Cellulomonas spp. Glucose β-(1,3)-linked extracellular homopolymer Gel-forming ability
Water insolubility
Edible and non-toxic
Biological activity
Foods
Pharmaceutical industry
Heavy metal removal
Concrete additive
Dextran Leuconostoc spp. and Streptococcus spp. Glucose α-(1,2)/α-(1,3)/ α-(1,4)-branched α-(1,6)-linked extracellular homopolymer Non-ionic
Good stability
Newtonian fluid behaviour
Foods
Pharmaceutical industry: Blood volume expander
Chromatographic media
Levan Bacillus spp.,Erwinia spp., Halomonas spp,Zymomonas mobilis Fructose β-(2,6)-linked, β-(2,1)-branched extracellular homopolymer Low viscosity, high water solubility, Anti-tumour activity Anti-inflammatory. Adhesive strength, Film-forming capacity Food (prebiotic), Feed, Medicines, Cosmetics Industry
Pullulan Aurebasidium pullulans Cytaria spp. Glucose α-(1,6)-linked maltotriose (α-(1,4)-linked glucose) units extracellular homopolymer Easily water soluble, high adhesion, sticking, lubrication, and film forming abilities, biocompatible Food packaging edible coatings (food, pharmacy tablets), Cosmetics, Paper coating, Flocculating agent
Cellulose Gluconacetobacter spp. (mainly G. xylinus), Komagataeibacter spp., Agrobacterium spp., Alcaligenes spp., Rhizobium spp., Sarcina spp., Azotobacter spp. Glucose β-(1,4)-linked extracellular homopolymer High crystallinity
Insolubility in most solvents
High tensile strength
Moldability
Foods (indigestible fibre)
Biomedical
Wound healing
Tissue engineered blood vessels
Audio transducers diaphragm
Polyhydroxyalkanoates (PHA) (polyesters) Azotobacter spp., Alcaligenes spp., Cupraividus spp., Haloferax spp., Pseudomonas spp.; (R)-3-hydroxy fatty acids Intracellular heteropolymer Thermoplastic or elastomeric materials, with melting points ranging from 40 to 180 °C, resistance to moisture, aroma barrier, UV stable, soluble in halogenated solvents Biodegradable plastics
Drug delivery
Tissue engineering
Food packaging biomaterial and matrices for displaying or binding proteins
  1. aData summarised in several previous reviews (Shanmugam et al. 2019; Freitas et al. 2011; Rehm 2010; Kreyenschulte et al. 2012)