Cell-based high-throughput screening of polysaccharide biosynthesis hosts

Abstract

Valuable polysaccharides are usually produced using wild-type or metabolically-engineered host microbial strains through fermentation. These hosts act as cell factories that convert carbohydrates, such as monosaccharides or starch, into bioactive polysaccharides. It is desirable to develop effective in vivo high-throughput approaches to screen cells that display high-level synthesis of the desired polysaccharides. Uses of single or dual fluorophore labeling, fluorescence quenching, or biosensors are effective strategies for cell sorting of a library that can be applied during the domestication of industrial engineered strains and metabolic pathway optimization of polysaccharide synthesis in engineered cells. Meanwhile, high-throughput screening strategies using each individual whole cell as a sorting section are playing growing roles in the discovery and directed evolution of enzymes involved in polysaccharide biosynthesis, such as glycosyltransferases. These enzymes and their mutants are in high demand as tool catalysts for synthesis of saccharides in vitro and in vivo. This review provides an introduction to the methodologies of using cell-based high-throughput screening for desired polysaccharide-biosynthesizing cells, followed by a brief discussion of potential applications of these approaches in glycoengineering.

Marine Microbial Polysaccharides: An Untapped Resource for Biotechnological Applications

“…Although polysaccharides can be produced by different types of organisms (e.g., bacteria, fungi, algae, crustaceans, and plants), those from bacteria and fungi have been highly popular as they replicate rapidly, are easier to manipulate, and are abundant producers of those polymers, with the latter also more easily separated than those from non-microbial counterparts [2,3]. Furthermore, in addition to their biological activities, they also display low toxicity, biocompatibility, biodegradability, and other physical and chemical characteristics [4][5][6][7]. Thus, without undermining the value of nonmicrobial sources of polysaccharides, this review mainly focuses on those obtained from bacteria and fungi in order to highlight their potential for future studies, especially in view of developing polymers for practical applications.…”