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Microorganisms synthesize intracellular, structural and extracellular polymers also referred to as biopolymers for their function and survival. These biopolymers play specific roles as energy reserve materials, protective agents, aid in cell functioning, the establishment of symbiosis, osmotic adaptation and support the microbial genera to function, adapt, multiply and survive efficiently under changing environmental conditions. Viscosifying, gelling and film forming properties of these have been exploited for specific significant applications in food and allied industries. Intensive research activities and recent achievements in relevant and important research fields of global interest regarding film forming microbial biopolymers is the subject of this review. Microbial polymers such as pullulan, kefiran, bacterial cellulose (BC), gellan and levan are placed under the category of exopolysaccharides (EPS) and have several other functional properties including film formation, which can be used for various applications in food and allied industries. In addition to EPS, innumerable bacterial genera are found to synthesis carbon energy reserves in their cells known as polyhydroxyalkanoates (PHAs), microbial polyesters, which can be extruded into films with excellent moisture and oxygen barrier properties. Blow moldable biopolymers like PHA along with polylactic acid (PLA) synthesized chemically in vitro using lactic acid (LA), which is produced by LA bacteria through fermentation, are projected as biodegradable polymers of the future for packaging applications. Designing and creating of new property based on requirements through controlled synthesis can lead to improvement in properties of existing polysaccharides and create novel biopolymers of great commercial interest and value for wider applications. Incorporation of antimicrobials such as bacteriocins or silver and copper nanoparticles can enhance the functionality of polymer films especially in food packaging applications either in the form of coatings or wrappings. Use of EPS in combinations to obtain desired properties can be evaluated to increase the application range. Controlled release of active compounds, bioactive protection and resistance to water can be investigated while developing new technologies to improve the film properties of active packaging and coatings. An holistic approach may be adopted in developing an economical and biodegradable packaging material with acceptable properties. An interdisciplinary approach with new innovations can lead to the development of new composites of these biopolymers to enhance the application range. This current review focuses on linking and consolidation of recent research activities on the production and applications of film forming microbial polymers like EPS, PHA and PLA for commercial applications. © 2014 Informa Healthcare USA, Inc.

exopolysaccharides, fermentation, antimicrobial films, biodegradable, polyhydroxyalkanoates, polylactic acid

NCBI PubMed ID: 23919238
Publication DOI: 10.3109/07388551.2013.798254
Journal NLM ID: 8505177
Publisher: CRC Press
Correspondence: Vijayendra SV ; Vijayendra SV
Institutions: Food Microbiology Department, CSIR-Central Food Technological Research Institute (A constituent laboratory of Council of Scientific and Industrial Research, New Delhi), Mysore, Karnataka, India

Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only a few bacterial (e.g. xanthan, levan, dextran) and fungal (e.g. pullulan) EPS have reached full commercialization. During the last years, other microbial EPS producers have been the subject of extensive research, including endophytes, extremophiles, microalgae and Cyanobacteria, as well as mixed microbial consortia. Those studies have demonstrated the great potential of such microbial systems to generate biopolymers with novel chemical structures and distinctive functional properties. In this work, an overview of the bioprocesses developed for EPS production by the wide diversity of reported microbial producers is presented, including their development and scale-up. Bottlenecks that currently hinder microbial EPS development are identified, along with future prospects for further advancement.

bacteria, Extremophiles, exopolysaccharide (EPS), fungi, mixed microbial consortia

NCBI PubMed ID: 28554522
Publication DOI: 10.1016/j.biortech.2017.05.092
Journal NLM ID: 9889523
Publisher: Elsevier
Correspondence: amr@fct.unl.pt
Institutions: UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal

Pullulan is a water-soluble polysaccharide produced by yeast-like fungus Aureobasidium pullulans. It is a regularly repeating copolymer with the chemical structure {→6)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→}n and viewed as a succession of α-(1→6)-linked (1→4)-α-D-triglucosides i.e. maltotriose (G3). Pullulan has a wide range of commercial applications in biomedical and food industries. Because of its strictly linear structure, pullulan is also a very valuable tool in basic research as well as a well-defined model substance. This chapter focuses on the current literature on pullulan mainly its microbial sources, structural geometry, fermentative production, biosynthesis aspects, peculiar characteristics and varied applications.

biosynthesis, structure, fermentative production, pullulan, Aureobasidium pullulans, food and biomedical applications

Publication DOI: 10.1007/978-94-007-2214-9_24
Publisher: Springer Science+Business Media B.V.
Correspondence: rssingh11@lycos.com
Editors: Satyanarayana T, Johri BN
Institutions: Carbohydrate and Protein Biotechnology Laboratory, Department of Biotechnology, Punjabi University, Patiala, India

Exopolysaccharides are unique polymers generated by living organisms such as algae, fungi and bacteria to protect them from environmental factors. After a fermentative process, these polymers are extracted from the medium culture. Exopolysaccharides have been explored for their anti-viral, anti-bacterial, anti-tumor, and immunomodulatory effects. Specifically, they have acquired massive attention in novel drug delivery strategies owing to their indispensable properties like biocompatibility, biodegradability, and lack of irritation. Exopolysaccharides such as dextran, alginate, hyaluronic acid, pullulan, xanthan gum, gellan gum, levan, curdlan, cellulose, chitosan, mauran, and schizophyllan exhibited excellent drug carrier properties. Specific exopolysaccharides, such as levan, chitosan, and curdlan, have demonstrated significant antitumor activity. Moreover, chitosan, hyaluronic acid and pullulan can be employed as targeting ligands decorated on nanoplatforms for effective active tumor targeting. This review shields light on the classification, unique characteristics, antitumor activities and nanocarrier properties of exopolysaccharides. In addition, in vitro human cell line experiments and preclinical studies associated with exopolysaccharide-based nanocarriers have also been highlighted.

exopolysaccharide, drug delivery, Anticancer, nanocarriers, targeted

NCBI PubMed ID: 37059549
Publication DOI: 10.1016/j.carbpol.2023.120821
Journal NLM ID: 8307156
Publisher: Elsevier
Correspondence: P.K. Singh
Institutions: Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research, Hyderabad 500037, India