Gastric and intestinal proteases resistance of chicken acidic chitinase nominates chitin-containing organisms for alternative whole edible diets for poultry

Abstract

Chitin, a polymer of N-acetyl-D-glucosamine (GlcNAc), functions as a major structural component in crustaceans, insects and fungi and is the second most abundant polysaccharide in the nature. Although these chitin-containing organisms have been suggested as novel animal feed resources, chitin has long been considered as indigestible fibers in the animal body. Recently, we reported that acidic chitinase (Chia) is a protease-resistant major glycosidase in mouse gastrointestinal tract (GIT) and that it digests chitin in the mouse stomach. However, the physiological role of Chia in other animals including poultry remains unknown. Here, we report that Chia can function as a digestive enzyme that breaks down chitin-containing organisms in chicken GIT. Chia mRNA is predominantly expressed in the glandular stomach tissue in normal chicken. We also show that chicken Chia has a robust chitinolytic activity at pH 2.0 and is highly resistant to proteolysis by pepsin and trypsin/chymotrypsin under conditions mimicking GIT. Chia degraded shells of mealworm larvae in the presence of digestive proteases and produced (GlcNAc)2. Thus, functional similarity of chicken Chia with the mouse enzyme suggests that chitin-containing organisms can be used for alternative poultry diets not only as whole edible resources but also as enhancers of their nutritional value.

Mouse acidic mammalian chitinase exhibits transglycosylation activity at somatic tissue pH

“…Acidic mammalian chitinase is thought to play important physiological roles in defense and nutrition of the organism. Recently, we showed that mouse AMCase and chicken Chia, a homolog of AMCase, can function as digestive enzymes in their gastrointestinal tracts . This observation is consistent with the present assumption of AMCase predominantly fulfilling a food‐processing role as hydrolase in the stomach .…”

The Antisteatotic and Hypolipidemic Effect of Insect Meal in Obese Zucker Rats is Accompanied by Profound Changes in Hepatic Phospholipid and 1‐Carbon Metabolism

“…In line with this, protein digestibility of honey bee protein concentrate being free of chitin is higher than that of whole dried honey bees containing 11% chitin . Despite evidence has been gained that many monogastric animals, such as birds including broilers and mammals, can partially digest chitin in the small intestine due to chitinase secretion in the stomach, the reduction of protein digestibility by chitin‐containing insect meal in broilers and rats indicates that the chitinolytic activity in the small intestine is obviously not sufficient to allow complete digestion of insect protein. In contrast to small intestine, chitin is significantly degraded in the large intestine by the action of microbial chitin‐hydrolyzing enzymes into the N ‐acetyl‐ d ‐glucosamine monomers, which serve as substrates for bacterial fermentation.…”

The hydroxyproline content of fish bone gelatin from Indonesian Pangasius catfish by enzymatic hydrolysis for producing the bioactive peptide

“…Furthermore the hydroxyproline in mice after feeding was 50 mg/kg, 100 mg/kg and 200 mg/kg fish gelatin was 0.018 mg/mL, 0.020 mg/mL and 0.022 mg/mL respectively (Sun et al 2012). The hydrolysis of fish skin gelatin in intestine of animal occurs due to the protease that contains in digestive tract (Tabata et al 2017).…”