Bacterial cellulose: A promising biopolymer with interesting properties and applications

Abstract

The ever-increasing demands for materials with desirable properties led to the development of materials that impose unfavorable influences on the environment and the ecosystem. Developing a low-cost, durable, and eco-friendly functional material with biological origins has become necessary to avoid these consequences. Bacterial cellulose generated by bacteria dispenses excellent structural and functional properties and satisfies these requirements. BC and BC-derived materials are essential in developing pure and environmentally safe functional materials. This review offers a detailed understanding of the biosynthesis of BC, properties, various functionalization methods, and applicability in biomedical, water treatment, food storage, energy conversion, and energy storage applications.

Introduction

Cellulose is one of the highly abundant biopolymers in nature and forms the principal structural component of green plants and wood, along with hemicellulose and lignin. The purest form of cellulose, called bacterial cellulose (BC), is produced by various species of Acetobacter, Rhizobia, Agrobacteria, and the gram-positive genus Sarcina through oxidative fermentation [1]. In 1886, Brown discovered that the bacterial species, Acetobacter xylinum or Gluconacetobacter xylinum produces a tough gelatinous film of pure cellulose. The bacterium was later known as ‘the vinegar plant’ since it forms the principal source of acetic acid [2]. The chemical structure of BC is the same as that of plant cellulose. It displays unusual physio-chemical properties like high crystallinity, better thermal and mechanical properties, excellent tensile properties, ultrafine fiber network, polyfunctionality, hydrophilicity, nontoxicity, transparency, and moldability [3]. These outstanding features of BC make it supreme for potential applications in biomedical, electronic, industrial, food, agricultural, etc. [4], [5], [6].

Hence BC gained ample attention due to these unique physicochemical properties. Many works have been published addressing various synthetic methods, their properties, and their applications in various constraints. A handful of reviews were published recently with discussions on their general characteristics, structure, production, or some of the specific applications [7], [8], [9], [10], [11], [12], [13]. For instance, Shah et al. [14] had reviewed synthetic approaches for the BC composites elaborately. On the other hand, Gorgieva et al. [15] exclusively reviewed the microbial aspects suitable for the production of BC to be used explicitly in biomedical applications or as medical products. Along the same line, the manufacturing of BC fibers for the specific wound healing application was reviewed by Ahmed et al. [16] while He et al. reviewed various functionalization methods of BC material to be suitable as wound healing materials [17].

On the other hand, in this comprehensive review article, we assemble the prevailing knowledge in the evolution of BC, the biosynthetic pathways, synthetic methods, various modifications methods, and the applicability of BC in water treatment, biomedical, food/food storage, sensor devices, electroconductive materials etc. with critical discussions on the recent progress. Recent developments on general applications of bacterial cellulose with special reference to unique properties have been discussed in detail. Understanding the rationale for developing and applying BC and BC-based functional materials for different applications is another objective of this review.