Utilizing rice straw hydrolysate for sustainable bacterial nanocellulose production by <i>Acetobacter hansenii</i> : A response surface optimization study

Abstract Despite its amazing properties, which include high purity (free from lignin and hemicellulose), excellent mechanical strength, a nanofibrillar 3D network with high crystallinity, high water‐holding capacity, good thermochemical stability, biocompatibility, non‐toxicity, and biodegradability, the commercial applications of bacterial nanocellulose (BNC) remain limited due to its higher production costs and limited productivity. To address this, the current study investigated rice straw hydrolysate (RSH) as a cost‐effective substitute for an expensive carbon source. The rice straw was pretreated with 2% sodium hydroxide, followed by enzymatic hydrolysis, forming a hydrolysate containing reducing sugars (29.37 ± 0.4 g/L). The BNC production by utilizing RSH medium was later optimized by employing the BBD (Box–Behnken design). Under optimized conditions (such as pH 6, RSH: water (1:1), and 32.5°C incubation temperature), the BNC yield after 2 weeks of incubation reached 6.26 ± 0.05 g/L, which is considerably higher than yields reported from other lignocellulosic feedstocks by Acetobacter hansenii . The resulting BNC films were characterized by using SEM, XRD, and FTIR, and their structural and physicochemical characteristics were compared to BNC produced in standard Hestrin‐Schramm (HS) medium. SEM study verified the characteristic nanocellulose fibrillar 3D network, XRD analysis exhibited peaks conforming to the cellulose I structure, and FTIR spectra discovered absorption bands representative of BNC‐specific functional groups. Overall, the use of RSH medium did not substantially affect the fundamental properties of BNC, apart from minor alterations. These results suggest that rice straw hydrolysate holds promise as an economical and sustainable substrate for industrial‐scale BNC production.