AUSTIN, Texas—Cellulose in a new group of organisms may be a promising new resource for the industrial production of the substance and could eventually eliminate the need to harvest trees for wood or pulp, researchers at The University of Texas at Austin say.
The discovery of cellulose biosynthesis in nine species of cyanobacteria, or blue-green algae, also may be the source of the genetic material used for cellulose biosynthesis in present-day plants such as trees and cotton.
The findings of the researchers, who include David R. Nobles, Dr. Dwight K. Romanovicz and Dr. R. Malcolm Brown Jr., have been published in the October issue of Plant Physiology.
Nobles, lead author of the paper, is a third-year graduate student with Brown, who holds the Johnson and Johnson Centennial Chair in Plant Biology, in the Section of Molecular Genetics and Microbiology in the School of Biological Sciences. Romanovicz is a research associate in the Brown laboratory.
Blue-green algae are among the most ancient of today’s living organisms and have been in existence for more than 2.8 billion years. Fossils of forms that resemble cyanobacteria have been dated as far back as 3.5 billion years. Cellulose is a biopolymer that plants use as the primary building block for their cell walls. Cellulose is important economically because it is the major source of such significant and useful plant products as wood, cotton and flax.
“Although cellulose biosynthesis among the cyanobacteria has been suggested previously, we present the first conclusive evidence, to our knowledge, of the presence of cellulose in these organisms,” Nobles said.
Brown said an exciting future possibility based on this discovery could be industrial production of cellulose from cyanobacteria. He said, “if industrial production from this source were to be achieved, we might never need to harvest trees again for wood or pulp. In the future, we could possibly use cyanobacterial cellulose.”
Brown said cyanobacteria inhabit vast, incredibly diverse environments ranging from freshwater lakes and ponds, to hypersaline water, to deserts where rainfall never has been recorded. Cyanobacteria are common in the dry valleys of Antarctica and can live embedded in the surface of rocks. Some cyanobacteria do not require fresh water, nitrate-based fertilizer or even arable land to grow and flourish.
From the standpoint of the evolutionary history of life, Brown said the discovery also “has shown that the cyanobacterial genes for cellulose production are closely related to those genes in land plants. This strongly suggests that the genetic code for the major building blocks for cellulose production of land plants came directly from the cyanobacteria.”
The researchers reviewed databases developed from recent gene sequencing projects at in their lab at The University of Texas at Austin and throughout the world looking for evidence of the presence of cellulose in diverse types of cyanobacteria. No previous research has demonstrated biosynthesis taking place in these types of microorganisms.
The researchers used microscopy and x-ray analysis to determine that cellulose was present in six strains of five genera of blue-green algae. Brown said colloidal gold can be coupled with an enzyme, cellubiohydrolase I as a tag. This enzyme specifically binds to cellulose as it begins to degrade in nature. Thus, it is possible to identify cellulose using this approach. Brown said gold labeling alone indicated the presence of cellulose in four additional strains.
“The genetic analysis suggestions a close relationship between vascular plants and cyanobacterial cellulose synthases,” Nobles said.