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Challenges and perspectives in combinatorial assembly of novel exopolysaccharide biosynthesis pathways.

Becker A - Front Microbiol (2015)

Bottom Line: However, previous manipulations primarily focused on increasing polysaccharide yield, with structural modifications restricted to removal of side chains or non-sugar decorations.This article outlines the biosynthetic pathways of the bacterial heteroexopolysaccharides xanthan and succinoglycan, which are used as thickening and stabilizing agents in food and non-food industries.Challenges and perspectives of combining synthetic biology approaches with directed evolution to overcome obstacles in assembly of novel EPS biosynthesis pathways are discussed.

View Article: PubMed Central - PubMed

Affiliation: LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-University of Marburg , Marburg, Germany.

ABSTRACT
Because of their rheological properties various microbial polysaccharides are applied as thickeners and viscosifiers both in food and non-food industries. A broad variety of microorganisms secrete structurally diverse exopolysaccharides (EPS) that contribute to their surface attachment, protection against abiotic or biotic stress factors, and nutrient gathering. Theoretically, a massive number of EPS structures are possible through variations in monosaccharide sequences, condensation linkages and non-sugar decorations. Given the already-high diversity of EPS structures, taken together with the principal of combinatorial biosynthetic pathways, microbial polysaccharides are an attractive class of macromolecules with which to generate novel structures via synthetic biology approaches. However, previous manipulations primarily focused on increasing polysaccharide yield, with structural modifications restricted to removal of side chains or non-sugar decorations. This article outlines the biosynthetic pathways of the bacterial heteroexopolysaccharides xanthan and succinoglycan, which are used as thickening and stabilizing agents in food and non-food industries. Challenges and perspectives of combining synthetic biology approaches with directed evolution to overcome obstacles in assembly of novel EPS biosynthesis pathways are discussed.

No MeSH data available.


Related in: MedlinePlus

Repeat unit structure of xanthan and succinoglycan. The polysaccharides consist of a variable number of these repeats. While carbohydrate structure is uniform along the polysaccharide chain, decorations with non-sugar groups are variable. Ac, acetyl group; Gal, galactosyl group; Glc, glucosyl group; GlcA, glucuronyl group; Man, mannosyl group; Pyr, pyruvyl group; Suc, succinyl group, variable and fixed positions of succinylation are denoted in grey and by an asterisk, respectively.
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Figure 1: Repeat unit structure of xanthan and succinoglycan. The polysaccharides consist of a variable number of these repeats. While carbohydrate structure is uniform along the polysaccharide chain, decorations with non-sugar groups are variable. Ac, acetyl group; Gal, galactosyl group; Glc, glucosyl group; GlcA, glucuronyl group; Man, mannosyl group; Pyr, pyruvyl group; Suc, succinyl group, variable and fixed positions of succinylation are denoted in grey and by an asterisk, respectively.

Mentions: The broad range of structural diversity of secreted branched heteropolysaccharides makes their biosynthetic pathways ideal candidates for design of novel structures by synthetic biology approaches. Such polysaccharides are typically built from repeat units that are assembled by the Wzx/Wzy-dependent pathway. Through more detailed elucidation of this biosynthetic pathway, novel tailored EPS may eventually be generated via combinatorial strategies using an engineered modular apparatus. However, to date the most successful engineering approaches addressed improvements in the yield or production process, alterations in the degree of polymerization, removal of side chains or non-sugar substituents, or heterologous expression of EPS biosynthesis gene clusters (Rehm, 2009; Ullrich, 2009). This review outlines the well-studied biosynthetic pathways of the acidic heteroexopolysaccharides xanthan and succinoglycan applied in cosmetics, food and oil industry (Becker et al., 1998; Fink, 2003a,b; De et al., 2015; Figure 1). It discusses obstacles, perspectives, and the needs for research of molecular mechanisms operating at different steps of biosynthesis to promote synthetic biology approaches toward assembly of pathways producing novel EPS structures.


Challenges and perspectives in combinatorial assembly of novel exopolysaccharide biosynthesis pathways.

Becker A - Front Microbiol (2015)

Repeat unit structure of xanthan and succinoglycan. The polysaccharides consist of a variable number of these repeats. While carbohydrate structure is uniform along the polysaccharide chain, decorations with non-sugar groups are variable. Ac, acetyl group; Gal, galactosyl group; Glc, glucosyl group; GlcA, glucuronyl group; Man, mannosyl group; Pyr, pyruvyl group; Suc, succinyl group, variable and fixed positions of succinylation are denoted in grey and by an asterisk, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496566&req=5

Figure 1: Repeat unit structure of xanthan and succinoglycan. The polysaccharides consist of a variable number of these repeats. While carbohydrate structure is uniform along the polysaccharide chain, decorations with non-sugar groups are variable. Ac, acetyl group; Gal, galactosyl group; Glc, glucosyl group; GlcA, glucuronyl group; Man, mannosyl group; Pyr, pyruvyl group; Suc, succinyl group, variable and fixed positions of succinylation are denoted in grey and by an asterisk, respectively.
Mentions: The broad range of structural diversity of secreted branched heteropolysaccharides makes their biosynthetic pathways ideal candidates for design of novel structures by synthetic biology approaches. Such polysaccharides are typically built from repeat units that are assembled by the Wzx/Wzy-dependent pathway. Through more detailed elucidation of this biosynthetic pathway, novel tailored EPS may eventually be generated via combinatorial strategies using an engineered modular apparatus. However, to date the most successful engineering approaches addressed improvements in the yield or production process, alterations in the degree of polymerization, removal of side chains or non-sugar substituents, or heterologous expression of EPS biosynthesis gene clusters (Rehm, 2009; Ullrich, 2009). This review outlines the well-studied biosynthetic pathways of the acidic heteroexopolysaccharides xanthan and succinoglycan applied in cosmetics, food and oil industry (Becker et al., 1998; Fink, 2003a,b; De et al., 2015; Figure 1). It discusses obstacles, perspectives, and the needs for research of molecular mechanisms operating at different steps of biosynthesis to promote synthetic biology approaches toward assembly of pathways producing novel EPS structures.

Bottom Line: However, previous manipulations primarily focused on increasing polysaccharide yield, with structural modifications restricted to removal of side chains or non-sugar decorations.This article outlines the biosynthetic pathways of the bacterial heteroexopolysaccharides xanthan and succinoglycan, which are used as thickening and stabilizing agents in food and non-food industries.Challenges and perspectives of combining synthetic biology approaches with directed evolution to overcome obstacles in assembly of novel EPS biosynthesis pathways are discussed.

View Article: PubMed Central - PubMed

Affiliation: LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-University of Marburg , Marburg, Germany.

ABSTRACT
Because of their rheological properties various microbial polysaccharides are applied as thickeners and viscosifiers both in food and non-food industries. A broad variety of microorganisms secrete structurally diverse exopolysaccharides (EPS) that contribute to their surface attachment, protection against abiotic or biotic stress factors, and nutrient gathering. Theoretically, a massive number of EPS structures are possible through variations in monosaccharide sequences, condensation linkages and non-sugar decorations. Given the already-high diversity of EPS structures, taken together with the principal of combinatorial biosynthetic pathways, microbial polysaccharides are an attractive class of macromolecules with which to generate novel structures via synthetic biology approaches. However, previous manipulations primarily focused on increasing polysaccharide yield, with structural modifications restricted to removal of side chains or non-sugar decorations. This article outlines the biosynthetic pathways of the bacterial heteroexopolysaccharides xanthan and succinoglycan, which are used as thickening and stabilizing agents in food and non-food industries. Challenges and perspectives of combining synthetic biology approaches with directed evolution to overcome obstacles in assembly of novel EPS biosynthesis pathways are discussed.

No MeSH data available.


Related in: MedlinePlus