Isolation, Identification and Characterization of Rabbit Caecal Mucinolytic Bacteria

Abstract

Sirotek K., E. Santos, V. Benda, M. Marounek: Isolation, Identification and Characterization of Rabbit Caecal Mucinolytic Bacteria. Acta Vet. Brno 2003, 72: 365-370.The aim of our study was to isolate, identify and characterize mucinolytic bacteria from the rabbit caecum. Two hundred and thirty mucin-grown colonies from the caecal contents of 7 rabbits were examined microscopically after the Gram staining. Gram-negative irregular rods were the most numerous mucinolytic isolates (34.1%), followed by gram-negative cocci and short rods (22.5%), gram-positive rods (17.3%), gram-positive cocci (16.6%) and gram-positive sporeforming rods (9.5%). An attempt was done to identify 31 typical isolates on basis of their morphology, biochemical characteristics and production of metabolites. In addition, bacterial cells were hybridized with fluorescently labelled probes for Bacteroides/Prevotella and Clostridium genus. Four isolates were identified at the species level as Mitsuokella multiacidus, three isolates as Bacteroides capillosus and one isolate as Actinomyces izraeli. All isolates except the last one belong to the Bacteroidaceae family. One strain could be assigned to the Bacteroides/Prevotella genus on basis of the hybridization test. Other mucinolytic isolates were not identified as their characteristics did not correspond to any previously described bacterial species. No Clostridium sp. strain was detected. In two M. multiacidus strains high activities of extracellular mucin lyases were found. The pH-optimum of lyases was 6.2. Calcium cations were necessary for their optimal function. This work extends general knowledge about fermentation of carbohydrate and nitrogen substrates in rabbit caecum. Rabbit, caecum, mucin, bacteriaMucin is a glycoprotein present in the mucosal layer lining mammalian gastrointestinal, respiratory and reproductive tract. The carbohydrate moiety can be either an acidic mucopolysaccharide containing uronic acids and hexosamines or an oligosaccharide containing L-fucose and sialic acid (S alyers and Leedle 1983). Mucin composition is tissue specific and differs in different animal species. Mucin is a part of the defense mechanism as it prevents bacteria, viruses and dietary lectins from attaching to the intestinal or other epithelium. Another mucin function is the protection of the mucosal epithelium against acidic and proteolytic damage in the stomach and intestine. In the digestive tract, mucin insures a smooth passage of the foodpulp. Holmes et al. (1974) observed in pigs that large amounts of mucin were not digested in the small intestine, but fermented in the hindgut. Microorganisms responsible for mucin fermentation in the human colon are partially known. Salyers et al. (1977) isolated from the human colon several Bacteroides strains able to degrade mucins and plant polysaccharides. B ayliss and Houston (1984) identified some mucin fermenters as members of the Bacteroides genus, other resembled Bifidobacterium sp., Clostridium septicum, and Eubacterium sp. Crociani et al. (199...

New trends in rabbit feeding: influence of nutrition on intestinal health. A review

“…Bacteroides, a significant genus in humans and rabbits, seems to have mucinolytic properties (Hill, 1986;Marounek et al, 2000;Sirotek et al, 2003). In humans, B. thetaiotaomicron also has mucinolytic capacity.…”

New concepts and objectives for protein-amino acid nutrition in rabbits: a review.

“…Some of the most frequent isolated caecal bacteria (Bacteriodes spp.) are the most active genera in mucin digestion (Hill, 1986;Sirotek et al, 2003). Also, Emaldi et al (1979) observed that the main activities of caecal microbiota were in decreasing order: ammonia-user, ureolytic, proteolytic and cellulolytic.…”

Morphology, chemical composition, and bacterial concentration of airborne particulate matter in rabbit farms

“…In poultry and pigs, Cambra-López et al (2011a) found a higher proportion of particles from faecal material in PM10 and PM2.5 than in our study. Perhaps the nature of rabbit's hard faeces, which are highly compressed and have a mucin cover (Sirotek et al, 2003), could probably explain such figure 2: Particulate matter airborne samples collected on polycarbonate filters viewed using scanning electron microscopy (600×), from PM2.5 (a), PM10 (b) and TSP (c) samples from fattening rabbit farm. Note: 5 µm diameter filter pores are shown as round dark holes.…”