Volume 3, Number 5
Nov 1990

The Role of Microorganisms in Papermaking

• We are used to thinking of insects as makers of paper (wasps) and spinners of filaments (spiders, silkworms), but when we hear of a new strain of bacteria that can make cellulose fibers on a commercial scale, it tends to come as a shock. The fiber is chemically identical to the cellulose from wood, but it takes the form of a fine crosslinked network with fibers only 0.1 micron thick, which is 1/300 as thick as softwood pulp fibers. It will be useful in binding, thickening, and coating applications at very low concentrations. Its name is Cellulon.
• Bacteria--specifically the gram-negative bacterium Acetobacter-- have been known for years to produce cellulose, but they quit doing it if the nutrient medium was stirred to introduce oxygen below the surface. Weyerhaeuser Co. worked with Cetus Corp. to develop a bacterium that could tolerate agitation, to scale up the process, analyze the fibers and explore markets. It is expected to market for $6 to $10 per pound, and to be made available soon. [More information in C&EN May 21, 1990, p. 35-37, and Tappi J. Sept. 1990, p. 46.1
• On July 12, 1988, a nasty explosion at Domtar's Trenton containerboard mill killed two workers, under conditions that may become more common as whitewater system are closed up and more alkaline and recycled paper is made. The system was shut down, allowing an anaerobic bacteria (probably clostridium. which thrives at pH 7.0 to 7.4) to multiply and produce hydrogen in significant quantities within 10 to 12 hours of the shutdown. Because of minimal air movement, it collected in a spent process water tank, on which two welders were installing safety railing. The tank blew up and hit the roof, which later collapsed; the water flooded out, washing vehicles into the river; and over $1 million worth of damage was done. Domtar deserves credit for making their experience available to others who face the same conditions. [This information is from a series of letters to the editor in the American Papermaker for August and November 1989, and February 1990.1
• Fungi and the enzymes they produce may one day be separating lignin from fiber in pulp mills. They do this without degrading the cellulose, and save large amounts of energy by shortening the length of the cook, but so far this method, called biopulping, costs too much. Research is continuing at the USDA Forest Products Laboratory, Paprican, Biotechnology Research Institute, and ESPRI. (The fungi are not the same that cause foxing and mold, but are white rot fungi. One species mentioned in the literature is Phanerochaete chrysosporium.)