Tuning the physiochemical properties of bacterial cellulose: effect of drying conditions

Bacteria have an ability to produce cellulose in pure form without any impurities such as hemicellulose and lignin, unlike plant cellulose. Bacterial cellulose as-produced with 3-D interwoven nanofibrous network is superior to plant cellulose in terms of mechanical properties, porosity, crystallinity, water holding capacity, and sustainability. In its natural form, bacterial cellulose is in the form of a hydrogel, which implies high porosity and holding capacity, however, to use it for different applications, water needs to be removed. The physical properties of bacterial cellulose such as morphology, porosity, and mechanical strength are vastly affected by the drying method employed. This paper presents a case study in which we produced bacterial cellulose using two different strains, followed by systematically studying the effect of drying (oven and freeze drying) on physiochemical, morphological, and structural properties of as-produced bacterial cellulose using Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, BET surface area, and tensile testing. Oven-dried bacterial cellulose showed higher crystallinity, reduced fiber diameter, and narrow size distribution and higher mechanical properties as compared to freeze-dried bacterial cellulose. Understanding so developed in this work may allow us to simply tune the bacterial cellulose properties for a given application.