Extraction and characterization of endogenous cellulases in Achatina fulica for lignocellulose digestion

The giant African land snail, Achatina fulica (Gastropoda: Pulmonata) acts as a prolific pest of over 500 crop species. Its major digestive enzymes responsible for digestion and assimilation of lignocellulose are not well studied. In this regard, we attempted to investigate the endogenous cellulases secreted by the snail which have been largely ignored due to more focus on its gut symbionts. However, the pH of the gut regions was found to be acidic ranging between pH. 3.0 to 6.2 in most of the regions which plays a pivotal role for the cellulose digestion. The study revealed that snail also secrets its own enzymes depicting some evolutionary significance. The crop, stomach and intestinal extracts showed maximum activity at 60 ᴼC. The enzyme extracts except crop region exhibited susceptibility to temperature showing least stability. Similarly, the optimum pH of the gut extracts was depicted to be 3.0 showing a positive corroboration with digestive physiology of the snail. The undertaken gut extracts showed more preference towards cellulosic substrates such as carboxymethyl cellulose (CMC), avicel and xylan, signifying the herbivorous pest nature of the snail. The presented study provides vital baseline data to prospect for novel cellulase genes within snails by using functional-genomic analysis.