280165 Screening Wood-Decay Fungi for Demethylation of Kraft Lignin Using Two Novel Assays with Applications in Producing Bio-Methanol and Formaldehyde-Based Polymers

Thursday, November 1, 2012: 2:10 PM
303 (Convention Center )
Andrew Gibson, Biotechnology, Lakehead University, Thunder Bay, ON, Canada

Screening Wood-decay Fungi for Demethylation of Kraft Lignin using Two Novel Assays with Applications in Producing Bio-Methanol and Formaldehyde-based Polymers

Andrew Gibson 1,2, Balaji Venkatesagowda 1, Iryna Kandybovich 1,

Aneli M. Barbosa 1, Brian Ross 2, Lada Malek 2, Robert F.H. Dekker 1

1 Biorefining Research Institute, 2 Department of Biology, 3 Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1

Lignin, the most abundant aromatic polymer present in the biosphere, is found in the cell walls of plants rendering the plant resistant to microbial attack and degradation. This biopolymer has potential applications, yet is currently considered a waste product (black liquor) in Kraft pulp and paper mills. By enzymatically modifying Kraft lignin, two immediate products can be obtained: a modified lignin with a higher phenolic content, and bio-methanol. The first can be used in formaldehyde-based polymer applications, while the second can be used in industrial processes and as biofuel. We have developed two specific assay procedures to screen for enzymatic activity that would produce these products; selected ion flow tube-mass spectrometry (SIFT-MS) and Ti(III)-nitriloacetic acid colorimetry. SIFT-MS is a highly sensitive technique capable of measuring trace amounts of gases including methanol (ppb levels) in the headspace of flask-cultivated fungi, while the Ti(III)-NTA assay measures the changes in vicinal hydroxyl groups during the modification of lignin by various fungal species. The Mycological Herbarium at Lakehead University in conjunction with the Biorefining Research Institute has a collection of >450 fungal isolates from the Boreal Forest in northern Canada; 20 of which were screened using these techniques. Fungal cultures were grown under stationary conditions on a Kraft lignin-minimum salts (Vogel) nutrient medium for 3 weeks at room temperature. The fungal isolates showed a reduction of up to 45% of O-methyl content using the Ti(III)-NTA assay, and a 10-fold increase in methanol concentration as measured by SIFT-MS compared to controls. The research presents evidence of new enzyme activities that specifically cleave O-methyl groups from the lignin molecule. Further work will continue and confirm the existence of these enzyme activities through their isolation and purification.

Supported by funds from NSERC-CRD (CRDPJ 38079-09: Dekker) Canada

 


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