New research has shown that a sediment-living bacterium is capable of churning out extracellular polysaccharides from the cellulose of jute fibre. The extracellular polysaccharides have industrial applications as an emulsifier and thickener.
Jute fibre is rich in cellulose, hemicelluloses, lignin, water-soluble compounds, fats and waxes. It is a potential carbon source that microorganisms could utilize to yield polymers such as extracellular polysaccharides. These polymers, usually primary or secondary metabolites of the microorganisms, remain attached to the microbial cell surface or are released as extracellular slime in cell surroundings. However, microorganisms find it difficult to produce polymers by exploiting the lignocellulosic material of jute fibre during the microbial fermentation process.
To achieve a high yield of polysaccharides, the researchers immersed 1 g of 30-mm-long jute fibre in a mineral salt solution, to which they added glucose and a cultured population of Bacillus megaterium RB-05. They then incubated the culture at 33 °C for 90 hours.
The bacterium showed no significant activity of cellulase enzyme during the first 36 hours of fermentation, leaving jute's cellulosic material unused. Decreasing the pH during this period only helped to break down the hemicellulose part of jute into consumable sugars. The activity of bacterial cellulase enzyme gradually increased after 36 hours, breaking down the cellulose and thus aiding bacterial growth.
The extracellular polysaccharides yield rate increased with bacterial cellulase activity, and was found to be significant at the end of a 72 hours fermentation period only after consuming most of the cellulose material.
"This research is significant as it offers a cost-effective substitute for conventional microbial growth and polymer production in an eco-friendly way," says lead researcher Ramkrishna Sen.