Extraction and Characterization of Bacterial Cellulose Nanofibers Isolated from a Nata-De-Coco Producing Culture System

Abstract

Nata-de-coco is formed by the fermentation of coconut water, which gels through the fabrication of bacterial cellulose nanofibers, typically by Acetobacter xylinum. The present study was based on the extraction and characterization of bacterial cellulose (BC) nanofibers produced from isolated A. xylinum from pineapple peels (PC) and vinegar starter culture (VC). The strain from PC was maintained in the Hestrin-Schramm medium containing 2% D-glucose, 0.5% peptone, 0.5% yeast extract, 0.27% Na2HPO4 and 0.2% acetic acid. It was subsequently transferred into Tomato Agar slant for isolation of A. xylinum. Nata- de-coco was produced from PC (TSS=150Brix, 1:5 ratio, pH=4) and VC (TSS=130Brix, 1:4 ratio, pH=3.8). Bacterial nano cellulose was extracted by centrifugation after purifying the BC pellicles with 2% NaOH (w/w) until a neutral pH was obtained. The BC was lyophilized. The resulting BC powder and commercially available pure cellulose (Micro crystalline cellulose-MCC) were used for characterization. Fourier Transform Infrared spectra revealed the presence of the characteristic anomeric carbon regions (950-750 cm–1) which includes the band at 833.17 cm-1, confirming the presence of β, 1-4 glycosidic linkages. X-ray diffraction pattern for PC gave peaks at 50, 100, 190 and VC gave peaks at 60, 180 and 230 of 2θ. MCC gave peaks at 150 and 220. Fourier Transform Infrared spectra and X-ray diffraction patterns confirmed the purity and the higher chemical stability of BC compared to MCC. The crystallinity of BC in VC was higher to that of MCC. Scanning Electron Microscope revealed the cellulose ultrafine network like structure in BC. Particle size of BC nanofibers gave two distinct diameters for width and length due to its fibrous structure. Nanofibers in PC gave the smallest width 142.2 nm compared to VC and MCC. The widths recorded for BC nanofibers in VC and MCC were 224.1 nm and 166.4 nm respectively. The study also confirmed that nata-de-coco is a rich source of bacterial cellulose. The high degree of purity of BC in nata-de- coco renders it suitable for potential applications in bio-nanotechnology.