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Agrobacterium exopolysaccharides play a major role in the life of the cell. Exopolysaccharides are required for bacterial growth as a biofilm and they protect the bacteria against environmental stresses. Five of the exopolysaccharides made by A. tumefaciens have been characterized extensively with respect to their structure, synthesis, regulation, and role in the life of the bacteria. These are cyclic-β-(1,2)-glucan, cellulose, curdlan, succinoglycan, and the unipolar polysaccharide (UPP). This chapter describes the structure, synthesis, regulation, and function of these five exopolysaccharides.

synthesis, structure, microbiology, immunology, exopolysaccharides, function, Agrobacterium tumefaciens, Biofilm, stress

Publication DOI: 10.1007/82_2018_100
Publisher: Springer, Cham (series: Current Topics in Microbiology and Immunology book series (CT MICROBIOLOGY, volume 418))
Correspondence: ann_matthysse@unc.edu
Editors: Gelvin S
Institutions: Department of Biology, University of North Caroline, Chapel Hill, NC, USA

In recent decades, the composition, structure, biosynthesis, and function of bacterial extracellular polysaccharides (EPS) have been extensively studied. EPS are synthesized through different biosynthetic pathways. The genes responsible for EPS synthesis are usually clustered on the genome or large plasmids of bacteria. Generally, different EPS synthesis gene clusters direct the synthesis of EPS with different chemical structures and biological activities. A better understanding of the gene functions involved in EPS biosynthesis is critical for the production of EPS with special biological activities. Genetic engineering methods are usually used to study EPS synthesis related genes. This review organizes the available information on EPS, including their structures, synthesis of related genes, and highlights the research progress of modifying EPS gene clusters through gene-editing methods.

genetic engineering, gene clusters, bacterial extracellular polysaccharides

Publication DOI: 10.1016/j.ijbiomac.2021.01.139
Journal NLM ID: 7909578
Publisher: Butterworth-Heinemann
Correspondence: jfzhang@mail.njust.edu.cn
Institutions: Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China

Succinoglycan is a type of bacterial anionic exopolysaccharide produced from Rhizobium, Agrobacterium, and other soil bacteria. The exact structure of succinoglycan depends in part on the type of bacterial strain, and the final production yield also depends on the medium composition, culture conditions, and genotype of each strain. Various bacterial polysaccharides, such as cellulose, xanthan, gellan, and pullulan, that can be mass-produced for biotechnology are being actively studied. However, in the case of succinoglycan, a bacterial polysaccharide, relatively few reports on production strains or chemical and structural characteristics have been published. Physical properties of succinoglycan, a non-Newtonian and shear thinning fluid, have been reported according to the ratio of substituents (pyruvyl, succinyl, acetyl group), molecular weight (Mw), and measurement conditions (concentration, temperature, pH, metal ion, etc.). Due to its unique rheological properties, succinoglycan has been mainly used as a thickener and emulsifier in the cosmetic and food industries. However, in recent reports, succinoglycan and its derivatives have been used as functional biomaterials, e.g., in stimuli-responsive drug delivery systems, therapeutics, and cell culture scaffolds. This suggests a new and expanded application of succinoglycan as promising biomaterials in biomedical fields, such as tissue engineering, regenerative medicine, and pharmaceuticals using drug delivery.

bacterial polysaccharides, succinoglycan, application, Biomaterials, hydrogels

NCBI PubMed ID: 35054683
Publication DOI: 10.3390/polym14020276
Journal NLM ID: 101545357
Publisher: Basel: MDPI
Correspondence: Seunho Jung
Institutions: Department of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, Seoul 05029, Korea, Department of Systems Biotechnology, Institute for Ubiquitous Information Technology and Applications (UBITA), Center for Biotechnology Research in UBITA (CBRU), Konkuk University, Seoul 05029, Korea

Natural polysaccharides have attracted considerable interests due to diverse biological activities. Succinoglycan is an extracellular polysaccharide produced by most Agrobacterium strains. Here, we confirmed riclin was a typical succinoglycan by NMR and methylation analysis, and investigated the antitumor effects of riclin in sarcoma 180 tumor-bearing mice. The results showed that riclin inhibited the tumor growth significantly as well as cyclophosphamide (CTX). While CTX caused serious damage to spleen structure, riclin increased the spleen index and promoted lymphocytes proliferation in peripheral blood, spleen and lymph nodes. Riclin decreased splenocytes apoptosis as evidenced by alterations of B-cell lymphoma-2 family proteins and Cleaved Caspase-3 protein. Moreover, 1H nuclear magnetic resonance (NMR)-based metabolomics analysis revealed that riclin partially altered the metabolic profiles of splenocytes. In conclusion, riclin is a succinoglycan that performed strong immunogenicity and suppressed sarcoma growth in mice. Succinoglycan riclin could be a potential antitumor agent for functional food and pharmaceutical purpose.

immunogenicity, Agrobacterium, metabolomics, sarcoma S180, succinoglycan riclin

NCBI PubMed ID: 33436203
Publication DOI: 10.1016/j.carbpol.2020.117370
Journal NLM ID: 8307156
Publisher: Elsevier
Correspondence: J. Zhang
Institutions: Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, 210094, China
Methods: 13C NMR, 1H NMR, methylation, GC-MS, sugar analysis, ESI-MS, biological assays, RT-PCR, statistical analysis, flow cytometry analysis, cell viability assay, RNA extraction, histological analysis