The Characterization of Bacterial Cellulose Produced by Acetobacter xylinum and Komgataeibacter saccharovorans under Optimized Fermentation Conditions

Abstract

Aims: studying the biological activities of A. xylinum ATCC 10245 (as reference strain) and K. saccharivoransPE5 for bacterial cellulose production (B.C) under optimized fermentation conditions and the structural characteristics of cellulose produced. Study Design: The production of bacterial cellulose under optimal fermentation conditions by investigated strains then the purified cellulose was characterized by different techniques. Place and Duration of Study: Agric. Microbiology Dept., Fac. of Agriculture, Ain Shams Univ., Cairo, Egypt. Methodology: A. xylinum ATCC 10245 and K. saccharivorans PE5 strain were used as producers of bacterial cellulose. These strain were grown on productive medium under optimal fermentation conditions. The parameters of growth and B.C production were determined during the fermentation period. The specific growth rate, doubling time. Multiplication rate and generation number were calculated during the exponential phase of growth. Purified polymers were characterized and the properties of paper sheet were detected. Results: Results indicated that the exponential phase of Komagataeibacter saccharivorans PE 5 and Acetobacter xylinum ATCC 10245 growth was detected during the first 48 to 144 hrs and during 168 hrs in productive media, respectively. The highest cellulose concentration and yield were obtained after 336 hrs by both tested strains being 11.11 gl-1 & 74.1% for Acetobacter xylinum ATCC 10245 and being 12.61 gl-1 & 84.11% for Komgataeibacter saccharivorans PE 5. The structure of BC produced from the tested strains was assayed by scanning electron microscope, fourier transform- infrared spectrum (FT-IR) and x-ray diffraction. It was revealed the diameter of thin ribbons ranged from 34.34 nm to 39.16 nm and the shape of FT-IR spectra for the two stains is similar to pure cellulose. The crystalinity index of A. xylinum ATCC 10245 is 54.14% and 52.76% for K. saccharivorans PE 5. Also, the properties of paper sheet from K. saccharivoransPE 5 cellulose increased about 1.19, 1.25, 1.33, 1.91 and 1.27 fold for wet tensile strength, dry tensile strength, degree of polymerization, brightness and opacity, respectively than A. xylinum ATCC 10245 cellulose.