Antimicrobial cellulose nanocrystals kill food-borne pathogens
doi:10.1038/nindia.2019.23 Published online 23 February 2019
Researchers have synthesised antimicrobial cellulose nanocrystals that can kill specific bacteria known to contaminate fruits and vegetables, making them potentially useful in the preservation of such food1.
Black gram, a widely consumed pulse in India, contains bacteria that break down carbohydrates and produce lactic acid. These bacteria also secrete specific antimicrobial compounds (bacteriocins) that are known to kill food-borne pathogens. Such compounds selectively destroy the pathogens, but spare human tissues.
Scientists from the ICAR-Central Institute for Research on Cotton Technology (ICAR-CIRCOT) in Mumbai, India, coated cotton-derived cellulose nanocrystals with specific antimicrobial compounds extracted from a lactic-acid-producing bacterium found in black gram.
They then tested the efficiency of the coated nanocrystals in inhibiting the growth of specific disease-causing bacteria that thrive in fruits and vegetables.
The coated nanocrystals significantly inhibited the growth of four food-contaminating bacteria: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Erwinia herbicola. The antimicrobial compounds on the nanocrystals bound to the target bacterial cells and then these compounds penetrated into the target cells by forming pores in cell membrane. This, in turn, led to the death of the bacteria.
The antimicrobial compounds retained their antibacterial activity even at 100 degrees Celsius for an hour, suggesting that these compounds are heat stable. Heat stability is an important property for food preservatives because many food-processing techniques require high temperature.
Besides showing antibacterial activity, the antimicrobial-compound-coated nanocrystals could act as potential fillers for improving the mechanical property of food-packaging and bio-composite materials.
1. Bagde, P. et al. Improving the stability of bacteriocin extracted from Enterococcus faecium by immobilization onto cellulose nanocrystals. Carbohydr. Polymer. 209, 172-180 (2019)