More Than Meets the Eye in Bacterial Cellulose: Biosynthesis, Bioprocessing, and Applications in Advanced Fiber Composites

Abstract

Bacterial cellulose (BC) nanofibers are one of the stiffest organic materials produced by nature. It consists of pure cellulose without the impurities that are commonly found in plant-based cellulose. This review discusses the metabolic pathways of cellulose-producing bacteria and the genetic pathways of Acetobacter xylinum. The fermentative production of BC and the bioprocess parameters for the cultivation of bacteria are also discussed. The influence of the composition of the culture medium, pH, temperature, and oxygen content on the morphology and yield of BC are reviewed. In addition, the progress made to date on the genetic modification of bacteria to increase the yield of BC and the large-scale production of BC using various bioreactors, namely static and agitated cultures, stirred tank, airlift, aerosol, rotary, and membrane reactors, is reviewed. The challenges in commercial scale production of BC are thoroughly discussed and the efficiency of various bioreactors is compared. In terms of the application of BC, particular emphasis is placed on the utilization of BC in advanced fiber composites to manufacture the next generation truly green, sustainable and renewable hierarchical composites.

Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

“…used in medical wound dressings, high-end acoustics, and many other products (7), and in the laboratory has been used to create biodegradable tissue scaffolds (13), nanoreinforcements (19), and artificial blood vessels (18), as well as sensors (20), flexible electrodes (21), organic light-emitting diode (OLED) displays, and other materials (22).…”

“…Functionalization or modification of bacterial cellulose has mainly been achieved by chemical or mechanical modifications of the cellulose matrix or via changing culturing conditions (7,22), whereas only a few attempts at genetic engineering have been made (13,23). However, genetic engineering may allow a greater range of materials to be produced, by enabling fine control over cellulose synthesis genes and production of proteincellulose composite biomaterials.…”

“…Cellulose nanofibers are synthesized from UDP-glucose by the acs (Acetobacter cellulose synthase) operon proteins AcsA and AcsB (9) and secreted by AcsC and AcsD, forming an interconnected cellulose "pellicle" around cells (7). Although it is still unclear why Acetobacteraceae produce bacterial cellulose in nature (7), it has been shown to confer the host with a high resistance to UV light and a competitive advantage in colonization over other microorganisms (10).…”

“…Cellulose nanofibers are synthesized from UDP-glucose by the acs (Acetobacter cellulose synthase) operon proteins AcsA and AcsB (9) and secreted by AcsC and AcsD, forming an interconnected cellulose "pellicle" around cells (7). Although it is still unclear why Acetobacteraceae produce bacterial cellulose in nature (7), it has been shown to confer the host with a high resistance to UV light and a competitive advantage in colonization over other microorganisms (10). In materials science, genetic engineering has been used to create several novel biomaterials, such as strong underwater protein-based adhesives (11), self-assembling, functionalized amyloid-based biofilms (12), biodegradable bacterial cellulose-based tissue engineering scaffolds (13), and many others.…”

Biochemical and cellular properties of Gluconacetobacter xylinus cultures exposed to different modes of rotating magnetic field

“…horizontal lift reactor, aerosol bioreactor) or agitated conditions using different types of process devices (e.g. stirred tank mixers or reactors, airlift bioreactors, rotary bioreactor, membrane bioreactor) 22 . Regardless of the production method, to obtain a higher BC yield, a high substrate and oxygen transfer rate are necessary.…”