Synergistic Antibacterial Effects of Cellulose: TiO₂ Nanocomposite Against Phytopathogens

The persistent use of pesticides and fertilizers in the field of agriculture causes soil pollution and even lead to health diseases like cancer (brain, breast and ovaries cancer). In order to reduce or eliminate the use of these traditional approaches for crop protection, the use of agricultural antibacterial agents are important in improving the soil health and plant growth. This work aims to prepare nanomaterials and nanocomposite exhibiting good antibacterial property against phytopathogens without harming plant health. In this regard, TiO 2 nanoparticles (NPs) and nanocrystalline cellulose have been used to prepare nanocomposite with effective antibacterial properties. However, TiO 2 NPs were synthesized by using hydrothermal method and nanocrystalline cellulose was synthesized by acid hydrolysis of commercially available microcrystalline cellulose (MCC). The commercial MCC are microfibers while the synthesized nanocrystalline cellulose (NCell) exhibit spherical nanoparticles. On the other hand, the Ti02 was transformed to long nanofibers after hydrothermal treatment of bulk Ti02. The nanocomposite NC (Ti02/NCell) was prepared by incorporating Ti02 nanofibres to enhance the antimicrobial property of nanocrystalline cellulose. All the synthesized nanomaterials and the corresponding nanocomposite were characterized by using UV - Visible absorbance spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron spectroscopy. The antibacterial properties of synthesized nanomaterials and nanocomposite (TC) were evaluated individually by using agar well diffusion method against phytopathogen Xanthomonas campestris pv. campestris (Xcc), inciting black rot disease in crucifer crops and biocontrol agent Bacillus subtilis (BS). The outcomes of this study reveal that the nanocrystalline cellulose individually inhibits Xcc growth effectively upto 24 $h$ whereas nanocomposite NC inhibits the growth of Xcc upto 48 $h$ . Thus, the antibacterial potency of nanocrystalline cellulose has successfully enhanced by incorporating TiO 2 nanofibres even though TiO 2 nanofibres individually showed no activity against pathogens. This manifests that the characterized nanocomposite NC has potentials for its future application because of its scalability property and cost-effective technique to manage the bacterial disease in agriculture.