Fishing for bacteria reels in huge health challenge

Winter 2017
BIOCHEMISTRY

UNICEF will be field testing DipTreat, which uses the capillary action of blotting paper treated with Moringa oleifera to attract and then kill E. coli.

UNICEF will be field testing DipTreat, which uses the capillary action of blotting paper treated with Moringa oleifera to attract and then kill E. coli. Photo credit: York University

A sophisticated understanding of biochemistry and microfluidics has yielded a simple, cost-effective way of dealing with contaminated water, a problem facing more than a billion people in the developing world. Among the most prominent threats is Escherichia coli (E. coli). Some strains of this common bacterium can cause severe gastrointestinal infections. Identifying and eliminating this agent from drinking water can dramatically improve the quality of life for entire communities.

In search of a solution, public health authorities from India approached Sushanta Mitra, a mechanical engineering professor at the Lassonde School of Engineering, York University in Toronto, who runs a laboratory that specializes in micro- and nano-scale transport. “We understand how fluids flow in narrow confinement,” Mitra says, adding that some of the facility’s work had dealt with enzymatic mechanisms associated with the behaviour of E. coli. However, Mitra immediately realized that any practical solution could not take the form of expensive sensing technology. “We wanted something that would have no energy demands, be environmentally sustainable and extremely low cost.”

Mitra and his colleagues therefore took advantage of the capillary action found in blotting paper, a result they outlined in a recent article in Environmental Science: Water Research & Technology. A three-stage system based on paper strips makes it possible to “fish, trap and kill” E. coli, starting with basic sugar as an embedded chemoattractant that draws the bacterium so that it can be held in place by the porous substrate of the paper. Each strip has also been treated with seed extract of Moringa oleifera, a medicinal plant found in Africa and Asia that is lethal to E. coli but leaves no toxic residue. 

Mitra has met with UNICEF to prepare for field trials of the product, which costs about 10 cents per application and has been dubbed DipTreat, as it is simply dipped into water. A spin-off company called Glacierclean Technologies is now scaling up in anticipation of production.