Crop Biotech Update

Colloidal Sugar Cane Bagasse as Natural Substrate for High Throughput Screening of Cellulolytic Enzymes from Termites

November 25, 2011

In the production of cellulose-ethanol (orethanol from plant cellulosic biomass), cellulolytic enzymes (collectively called, "cellulases") are used to convert the cellulose molecules in the biomass into simple sugars that can be fermented to ethanol. The search for more effective cellulolytic enzymes from novel sources is an area of active research, as these new enzymes might lower the production cost of cellulose ethanol.

A collaborative team of scientists from different universities and research institutes in Brazil, are looking at Brazilian termites and screening termite-gut extracts for good cellulolytic activities which might find potentially useful and commercial applications. They noted however, that in the determination of cellulotyic enzyme activities using commercially available substrates (such as carboxymethyl cellulose), the reported activities do not always correspond to activities against natural lignocellulosic substrates. They also noted that the ‘macroscopic characteristics of the raw material, such as insolubility and heterogeneity, hinder its use for high throughput screenings". Thus, they attempted to develop a more"natural" substrate with better macroscopic homogeneity, for use in determining cellulolytic enzyme activities, as a possible replacement to commercial (non-natural) cellulose-based substrates. They tried to use "colloidal sugar cane bagasse" (CSCB) as the substrate for enzyme activity measurements, in their high throughput screenings of Brazilian termites. The researchers mentioned that the preparation of CSCB involved "minimal chemical change in the lignocellulosic material".

The results of their study showed that "important differences between the use of the natural substrate and commercial cellulase substrates, such as carboxymethyl cellulose or crystalline cellulose, were observed". They were also able to demonstrate that CSCB can be a useful substrate in high throughput assays. Based on their screening studies using CSCB, they found that wood feeding termites (in contrast to litter feeding termites) "may not be the best source for enzymes which can degrade sugarcane biomass". The full paper is published in the open access journal, Biotechnology for Biofuels (URL above).