Comparative analyses of proteolytic activities in seven species of synanthropic acaridid mites

Abstract

Microplate assays with 96 wells were optimized to screen proteolytic activities in mite homogenates. Whole-mite extracts of Acarus siro, Aleuroglyphus ovatus, Tyrophagus putrescentiae, Tyroborus lini, Carpoglyphus lactis, Lepidoglyphus destructor, and Dermatophagoides farinae exhibited non-specific proteolytic activity in buffers from pH 2 to 12, and three peaks of highest activity at pH 3, 5-6, and 10 were distinguished. The reducing agent Tris(2-carboxyethyl)phosphine hydrochloride decreased general proteolytic activity on azocasein at pH 5 and 6. The results obtained on two non-specific substrates, azocasein and azoalbumin, showed highly different ranks of the species at pH 5 and 6. Proteolytic activities toward N(α)-Benzoyl-D,L-arginine 4-nitroanilide hydrochloride, N-Succinyl-L-alanyl-L-alanyl-L-prolyl-L-phenylalanine 4-nitroanilide, N-Succinyl-L-alanyl-L-alanyl-L-alanine 4-nitroanilide, Benzyloxycarbonyl-L-arginine-L-arginyl 4-nitroanilide, and N-Methoxysuccinyl-L-alanyl-L-alanyl-L-prolyl-L-methionine 4-nitroanilide (MAAPMpNA) were highest at alkaline pH, but the activity toward MAAPMpNA was also high at pH 5 and 6. In contrast, N-Succinyl-L-alanyl-L-alanyl-L-phenylalanine 4-nitroanilide (AAPpNA) and L-arginyl 4-nitroanilide (ArgpNA) had the highest activity recorded at pH 6. The high activities observed on AAPpNA, ArgpNA, and MAAPMpNA at digestive pH suggest that enzymes present in these extracts could have the majority of proteolysis in the mite gut. Evidence of the presence of proteolytic activities on all tested substrates and in all the tested mite homogenates suggests that the proteolytic activities may contribute to allergenicity. Poor or undetected hydrolytic activities of mite extracts toward substrates for keratin and collagen at digestive pH underline the importance of ecological interactions between mites and microorganisms in the utilization of such substrates.

Feather mites play a role in cleaning host feathers: New insights fromDNAmetabarcoding and microscopy

“…Overall, many other species of sarcoptiform mites, including many free‐living Astigmata, are functionally defined as fungivore–microbivore–detritivores (e.g., Pyroglyphidae and most oribatid mites, Walter & Proctor 2013a,b), and our results also support this classification for feather mites. In fact, our results are in large agreement with previous studies on microbes found in other mite species (Chaisiri, McGarry, Morand, & Makepeace, ; Hubert et al., ), where strong evidence has been found for the utilization of bacteria as a food source in free‐living astigmatan species (Erban & Hubert, , ; Hubert, Nesvorna, Kopecký, Ságová‐Marečková, & Poltronieri, ; Hubert et al., ). In these studies, microbiomes composed of highly diverse taxa in low abundance have been interpreted as evidence for microbivory.…”

Carpoglyphus lactis(Acari: Astigmata) from various dried fruits differed in associated micro-organisms

“…The microbial diets of mites can supply proteins, starch, nitrogen and lipids (Erban and Hubert ). The gut of C. lactis has enzymes (lysozyme and proteases) with hydrolytic activity against bacterial and yeast cell walls (Childs and Bowman ; Erban and Hubert , ,b, ). The gut environment is suitable for enzymatic activities because the pH of mesodeum was in the range 4·5–5 in ventriculus and caeca, 5–6 in colon and 5·5–7 in postcolon (Erban and Hubert ).…”

Visualization of protein digestion in the midgut of the acarid mite Lepidoglyphus destructor

“…Scale: 100 mm. mesodeum of L. destructor was studied using whole mite extracts and both unspecific and specific substrates (Bowman, 1981;Erban and Hubert, 2010a). For better understanding of protein digestion in mites, it is necessary to demonstrate the localization of the activities in the gut and/or to determine enzymatic activity in feces.…”