Five media were evaluated to determine their selectivity for Bifidobacterium sp. in hen and rabbit caecal samples. The colonies arising on the plates inoculated with the caecal samples were Gram stained and screened for the presence of fructose-6-phosphate phosphoketolase activity. Rogosa agar modified by the addition of cysteine-hydrochloride (0.05 % w/v), Beeren's agar (with 5 ml/l of propionic acid as a selective agent), BS 2 agar (containing per one litre sodium propionate 15 g, lithium chloride 3 g, paromomycin sulphate 50 mg, neomycin sulphate 200 mg), and Wilkins-Chalgren agar (MW) modified by the addition of acetic acid (1 ml/l) and mupirocin (100 mg/l) were selective for Bifidobacterium sp. from rabbit caecal samples. In contrast, only MW medium was suitable for the isolation and enumeration of bifidobacteria in hen caecal samples. In conclusion, the results suggest that MW agar showed the greatest selectivity. A further advantage of this medium is its ease of preparation. Therefore this agar could contribute to the study of the effects of the ingestion both probiotics and prebiotics. Finally, it could be noted that the bifidobacteria selective media should be chosen in respect of the animal species origin of the sample tested.
Aims: To compare fermentation pattern in cultures of Bacteroides caccae supplied with pectin and glucose, and identify enzymes involved in metabolism of pectin. Methods and Results: A strain KWN isolated from the rabbit caecum was used. Fermentation pattern, changes of viscosity and enzyme reactions products were determined. Cultures grown on pectin produced significantly more acetate and less formate, lactate, fumarate and succinate than cultures grown on glucose. Production of cell dry matter and protein per gram of substrate used was the same in pectin-and glucose-grown cultures. The principal enzymes that participated in the metabolism of pectin were extracellular exopectate hydrolase (EC 3.2.1.67), extracellular endopectate lyase (EC 4.2.2.2) and cell-associated 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase (EC 4.1.2.14). The latter enzyme is unique to the Entner-Doudoroff pathway. Activities of pectinolytic enzymes in cultures grown on glucose were low. Activity of KDPG aldolase was similar in pectin-and glucosegrown cells. Conclusions: Metabolites and activities of pectin-degrading enzymes differed in cultures of B. caccae KWN grown on pectin and glucose. Yields of dry matter and protein were the same on both substrates. Significance and Impact of the Study: Information on metabolism of pectin in animal strains of Bacteroides is incomplete. This study extends the knowledge on metabolism in bacteria from the rabbit caecum.
Two hundred and thirty colonies from the caecal contents of six rabbits were picked up and, after a 2-d incubation, were microscopically characterized using Gram staining. Large Gram-negative (34%) and small Gram-negative (30%) irregular rods, Gram-negative (27%) and Gram-positive (8%) cocci were found. Eleven isolates (Bacteroides ovatus (6 strains), B. thetaiotamicron, B. caccae, B. stercoris, B. capillosus and Capnocytophaga ochracea) were identified using commercial tests for measuring their catalase activity, metabolite production, etc., and testing their growth in 20% bile. Bacteria belonging to the genus Bacteroides were demonstrated to be the principal pectinolytic organisms in the rabbit caecum.
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...
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