Bioconversion of mangosteen pericarp extract juice with bacterial cellulose production and probiotic integration: A promising approach for functional food supplement development

This study optimized bioconversion process of mangosteen pericarp extract juice (MPEj) with a single-culture of Komagataeibacter xylinus TISTR 1061, a bacterial cellulose-producing strain and a co-culture with the probiotic Lactiplantibacillus plantarum. K. xylinus TISTR 1061 was identified as the optimal bacterial cellulose-producing strain for fermenting MPEj. Optimal conditions were determined to be 20% (v/v) MPEj supplemented with 7% (w/v) sucrose and 0.2% (w/v) ammonium dihydrogen phosphate as carbon and nitrogen sources, respectively. The growth profile of single K. xylinus was not significantly different from those of the co-culture. They showed good adaptability and cohabited during fermentation without antagonistic effects. Dynamic changes in total titratable acidity (TTA), total soluble solids (TSS), and pH during fermentation were relatively similar for both single- and co-cultures. Post-fermented MPEj with co-culture exhibited significantly higher bioactive activities, particularly antioxidant properties. Significant variations in metabolite concentrations, including 2-aminobutyrate, valine, xylitol, propionate, isoleucine, glucose, and glycerol, were observed. These compounds exhibited significantly higher average concentrations after fermentation, highlighting their potential as biomarkers distinguishing pre- and post-fermentation MPEj. Bacterial cellulose (BC) from single culture exhibited greater thickness and weight, with a more complex and branched structure, while that from co-culture was infused with probiotic cells, showing less complexity allowing the BC from co-culture demonstrated low hardness and chewiness values. The properties of both bioconverted MPEj and BC obtained as observed offer potential for innovative functional drinks and/or dietary supplements with enhanced health benefits.