Canadian Plastics

A quintessentially Canadian biopolymer

F or most Canadians, maple trees -- and the maple leaf, prominently featured on our flag -- are a prominent symbol of our national identity.

June 1, 2008   By Umair Abdul, Assistant Editor



For most Canadians, maple trees — and the maple leaf, prominently featured on our flag — are a prominent symbol of our national identity.

But thanks to new research by the National Research Council, our fondness for the majestic maple isn’t just limited to “sappy” Canadian sentimentality. Dr. Jalal Hawari, a researcher at the NRC Biotechnology Research Institute, has found a way to use the sap from maple trees to produce a biopolymer.

“A few years ago we started to look at areas in Canada where we could work with bioproducts,” said Hawari. “We started working with residues from industry such as agricultural food waste like orange juice and cardboard boxes.”

Then, Hawari and his postdoctoral fellow Dr. a. Yezza heard about a surplus of maple sap, which is derived from maple trees and commonly used to produce maple syrup. Hawari’s team had been working with bacteria that grow in several feedstocks including sucrose and methanol, and decided to use maple sap in their experiments.

“We thought, ‘okay, the sap is sweet and must have sugar, and the bacteria would love that,'” he explained. “We screened several bacteria that we know grow in sucrose, and added it to the maple sap.”

Hawari and his associates fed the maple sap to the Alcaligenes latus bacteria, which in turn fermented the sugar into a biologically inert polyhydroxyalkanoates (PHA) called poly-3-hydroxybutyrate (PHB). PHB is best known in the plastics community as a bio-based plastic that exhibits properties similar to those of polypropylene. For instance, U. S.-based Metabolix Inc. has received a lot of press for their Mirel family of products, which are made using corn sugar.

“There are several countries in the world that are doing transformations with the feedstocks in their background, abundant and within their country,” noted Hawari. “Canada has its maple sap and Brazil has sugarcane, the U. S. has corn and other countries are using rice and potatoes to generate PHA.”

In addition to PHB’s ability to emulate traditional petroleum- based plastics, Hawari and his associates are exploring other value-added applications for the PHB such as medical drug-delivery films and food packaging.

“Our role is to do the research, and to scale it up to certain limits,” said Hawari. “The yield is not as high as we need to have for full scale up and commercialization, but the concept worked very well.”

The biotechnology research team has scaled the process up to a 20 litre line, and is currently speaking with potential industry partners. Additionally, NRC-BRI is also trying to develop lactic acid — which is used to make bio-based, biodegradable polylactic acid (PLA) resin — using maple sap as a feedstock.

Dr. Jalal Hawari (Montreal, Que.); www.irb-bri.cnrc-nrc.gc.ca; 514-496-6100


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