Current challenges, applications and future perspectives of SCOBY cellulose of Kombucha fermentation

SCOBY, a biofilm of cellulose containing the symbiotic culture of bacteria and yeast, is a by-product of Kombucha tea fermentation. Several studies on the kombucha SCOBY are being carried out to exploit all the possibilities of dealing with this cellulose as a suitable raw material in fields like food technology, biomaterial preparation, fashion and textile industries, environmental biotechnology, and so on. This review focusses on elaborating about the microbial ecology present in the kombucha tea fermentation, the production of the extracellular polysaccharide (cellulose) by the bacteria, the cultivation methods of SCOBY, composition, structure, and characteristics of the cellulose biofilms obtained. Genera of bacteria and yeast majorly found in the SCOBY are Gluconobacter, Acetobacter, Zygosaccharomyces, Saccharomyces, and Schizosaccharomyces. Present in a symbiotic relationship in the kombucha tea, these microbes help in producing cellulose fibrils extracellularly forming a biofilm at the air-liquid interface. An overview of the favorable conditions for SCOBY production, prevention of contamination and purification of the cellulose sheets are also discussed and then its suitability for applications in different fields are assessed. The fermentation is mostly done at room temperature and the biofilm is harvested within 30 days according to the required shape and size. Advantages like flexible physical, chemical and biological properties, the requirement of minimum media components, eco-friendly and cost efficiency of this biofilm leading to its utilization in many upcoming fields are elucidated. Optimization of process variables is essential for scale-up to facilitate cost-effective production of SCOBY cellulose for exploring its wide potential in sustainable applications.