Hierarchical Nanofeatures Promote Microbial Adhesion in Tropical Grasses: Nanotechnology Behind Traditional Disinfection

Abstract

Desmotachya bipinnata L. (Darbha) is a tropical grass used as an inevitable material in traditional practices and rituals of the Indian Hindus. Darbha, the sacred grass has been used to prevent spoilage of fermentable food during solar and lunar eclipses, which is being followed even today. However, the reason for choosing this grass among several other grass species has not been reported. In this work, while exploring the reason behind the choice of this grass for traditional practices, interesting hierarchical nanoscale morphology of Darbha grass revealed in scanning electron microscopy. To understand the role of Darbha in food preservation during eclipse, cow’s curd has been chosen a representative fermentable food item. Systematic investigation on Darbha grass grown in three different microhabitats has been performed, and their effect on the population and diversity of lactobacilli from cow’s curd has been studied. Interestingly, the grass with the most prominent nanoscale features is found to remove most of the lactobacilli from cow’s curd. Thus, Darbha reduces microbial accumulation in fermentable food items when the bactericidal ultraviolet and blue radiations are not available to the earth surface during eclipse. The disinfecting ability of Darbha is compared with five other tropical grasses chosen on the basis of presence/absence of micro/nanofeatures, antibacterial effect and hydrophobic surface. The other grasses used in this study are Chloris Barbata L., Apluda aristata L., Cynodon dactylon L., Bamboosa arundinacae L. and Cymbopogon citratus L. Based on comparative studies with these grasses, the mechanism of disinfecting ability of Darbha is attributed mainly to the hierarchical micro/nanofeatures present on the grass surface. The results of the present investigation could be used to design novel biomimetic antibacterial surfaces for applications including health care.