Cellulose in Nature - Versatile sources for Novel Applications: A Literature Review

Introduction: Cellulose is the most abundant organic compound and the main component of the plant cell wall. However, it can be derived from other sources: tunicates, algae, and bacteria. Different sources of cellulose were shown to produce end-products of different mechanical properties and were considered for producing cellulose in non-industrial conditions. Methods: Procedures for the extraction of cellulose from different sources are described. They are similar for plants and algae, including bleaching and purification processes amongst others, while bacteria found in symbiotic cultures of bacteria and yeasts (SCOBYs) are capable of growing cellulose layers above their cultivation media. After extraction or bacterial cultivation, mechanical treatments are performed in order to modify new cellulose layers for specific applications. Results: Plant sources of cellulose are various and widely available, and often used for the industrial production of cellulose. Algae-derived microcrystalline cellulose (MCC) is similar to that from plant sources, but has higher crystallinity and, often, requires simpler extraction processes. Finally, cellulose grown by bacteria found in SCOBYs is the most optimal for non-industrial conditions, owing to the simplest cultivation and extraction procedures. Discussion: On a large scale, plant sources of cellulose are the optimal ones. The main downside of algal cellulose is that it is season-dependent, and more difficult to acquire than bacterial and plant sources. While having access to laboratory conditions for incubations and using a pure bacterial culture would be preferable, cultivation methods are simple enough to be adapted for home conditions. Also, conditions of incubation can be varied based upon the intended properties of the end-product: the efficiency of cellulose growth and its properties depend on the chosen carbon source. When bacteria produce a cellulose layer or it is extracted from another source, mechanical treatments for tuning porosity and other properties are applied. Conclusion: Sources of cellulose are numerous, and some are more suitable than others for non-industrial production, namely, using easily obtainable SCOBYs. This allows for a wide variety of applications: from artificial skin and face masks, to sustainable batteries and different food products.