An improved protocol for inducing the gut cleaning process in earthworm for various experiments

Abstract Earthworms have a complex digestive system consisting of the mouth, pharynx, esophagus, crop, gizzard, and intestine which work together to pass the soil out. The gut soil and associated microbial load in earthworms’ gut hinder the outcome of many experiments like in-vitro regeneration, histology, immunohistochemistry, molecular expression and toxicological studies. Currently, the available gut cleaning techniques are time-consuming and costly. The tissue paper method takes 4-7 days; the agar-agar method takes around 3-5 days to clean the gut. Therefore, refined techniques are needed to reduce the gut cleaning process in a cost-effective and at the same time in a minimum number of days. Bisacodyl is a medication used to treat constipation and it acts as a laxative drug that increases peristatic movement of the gut. It can also be used to cleanse the intestines before a bowel examination or surgery. The present study aims to enhance the gut-cleaning process in earthworm, Eudrilus eugeniae, using the drug bisacodyl. Briefly, the earthworm is exposed to different concentrations (1 mg, 2 mg, 4 mg, 6 mg, 8 mg and 10 mg) of bisacodyl and analyzed for its excretion rate. We observed that 4 mg is more efficient and aids in cleaning the earthworm’s gut within two days. A lower bisacodyl concentration is inefficient in cleaning the gut in a shorter duration while at higher bisacodyl concentrations, worm experienced autotomy. Since the drug was active for only 45 mins, the worm became normal one hour after withdrawal from the experiment. Other than E. eugeniae, for Perionyx excavatus we observed 4 mg bisacodyl drug is efficient and aids in cleaning its gut within two days. Overall, the designed protocol is efficient for gut cleaning in a shorter duration in a cost-effective manner.