Sunday, April 29, 2007

Carbohydrase expression during degradation of whole plant material by Saccharophagus degradans

Haitao Zhang, Ronald M. Weiner, and Steven W. Hutcheson. Dept. Cell Biology and Molecular Genetics, University of Maryland, Microbiology Bldg, College Park, MD 20742

Saccharophagus degradans 2-40 is a marine bacterium capable of degrading all of the polymers found in the higher plant cell wall using secreted and surface-associated enzymes. This bacterium has the unusual ability to saccharify whole plant material without chemical pretreatments. For example, this bacterium is able to utilize as sole carbon sources (generation time at same concentration, h): glucose (2.6), Avicel (2.25), oat spelt xylan (1.6), newsprint (3.4), whole and pulverized Zea mays leaves (>6), and pulverized Panicum vigatum leaves (>6), indicating the production of synergistically-acting hemicellulases, pectinases, cellulases, and possibly ligninases. Analysis of the genome sequence predicts this bacterium produces at least 12 endoglucanases, 1 cellobiohydrolase, 2 cellodextrinases, 3 cellobiases, 7 xylanases, 10 “arabinases”, 5 mannases, and 14 pectinases. Analysis of zymograms and proteomic analyses of cultures revealed subsets of these enzymes are induced during growth on each of the aforementioned substrates. Induction of specific enzymes is being assessed by qRT-PCR.