A simple method to collect digestive fluid for monitoring digestive enzyme activities and gut microbes of the abalone Haliotis discus discus

Abstract

A simple method using a syringe to collect digestive fluid from the gut of the disc abalone Haliotis discus discus is described. The activities of polysaccharide degrading enzymes and bacterial microflora were compared between the digestive fluid (DF) collected by using a syringe and the digestive diverticulum homogenate (DH) collected by the conventional dissection method. Specific activities of alginate lyase, cellulase and β-1,4-mannanase of DF were higher than those of DH. Viable bacterial count of DF was lower (1.0×107 CFU/mL) than that of DH (2.1×108 CFU/g). Microflora analysis of isolates using the 16S rRNA gene indicated that DF and DH showed a similar microflora composition, in which vibrios including Vibrio halioticoli and V. ezurae were predominant. The present method may be useful to determine changes in the digestive activity and the gut microflora of abalone without sacrificing individuals.