RESUMO
AIMS: The potential use of bifidobacteria as indicators for faecal contamination was studied along a sheep meat production and processing chain. The levels of bifidobacteria were compared with those of Escherichia coli. Total viable counts were followed along the chain (244 samples). METHODS AND RESULTS: Forty-three per cent of the samples contained bifidobacteria, of which 15% were solely detected using a PCR method based on the hsp60 gene and not by a culture-based method. Bifidobacteria were detected in only three of nine sheep faeces samples using one or the other method. However, carcasses (types C and E) were highly contaminated. These sample types (30% and 28%, respectively) were positive for bifidobacteria and negative for E. coli. The species Bifidobacterium pseudolongum and Bif. thermophilum, isolated from faecal samples, were predominant. Bifidobacterium choerinum were found in C, D, E and F sample types. CONCLUSIONS: Bifidobacteria were shown more efficient than E. coli in carcasses samples. The presence of Bif. choerinum suggested a faecal pork contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: Detection and identification of bifidobacteria, in correlation with E. coli counting, should improve hygiene quality of mutton processing chains.
Assuntos
Bifidobacterium/isolamento & purificação , Fezes/microbiologia , Microbiologia de Alimentos , Carne/microbiologia , Matadouros , Animais , Técnicas Bacteriológicas , Bifidobacterium/genética , Chaperonina 60/genética , Contagem de Colônia Microbiana , Escherichia coli/isolamento & purificação , Inspeção de Alimentos/métodos , Indústria de Processamento de Alimentos , Humanos , Produtos da Carne/microbiologia , Reação em Cadeia da Polimerase/métodos , OvinosRESUMO
A new Bifidobacterium species is described based on the study of ten Gram-positive strains with fructose-6-phosphate phosphoketolase activity. They are part of a phenotypic group comprising 141 strains isolated from raw milk and raw milk cheeses in French raw milk cheese factories. This group was separated by a numerical analysis based on API 50CH, API 32A tests and growth at 46 degrees C. A strong similarity of 16S rRNA sequences (99.8%) was shown between strain FR62/b/3(T) and Bifidobacterium psychraerophilum LMG 21775(T). However, low DNA-DNA relatedness was observed between their DNAs (31%). The new isolates are able to grow at low temperatures (all ten strains up to 5 degrees C) and strain FR62/b/3(T) grows under aerobic conditions, as does B. psychraerophilum. However, contrary to B. psychraerophilum, they do not ferment L-arabinose, D-xylose, arbutin or melezitose, but they do acidify lactose. The DNA G+C content of FR62/b/3(T) is 56.4mol%. Therefore, the name Bifidobacterium crudilactis sp. nov. is proposed, with its type strain being FR62/b/3(T) (=LMG 23609(T)=CNCM I-3342(T)).
Assuntos
Bifidobacterium/isolamento & purificação , Queijo/microbiologia , DNA Bacteriano/análise , Leite/microbiologia , RNA Ribossômico 16S/análise , Animais , Técnicas de Tipagem Bacteriana , Bifidobacterium/classificação , Bifidobacterium/genética , Bifidobacterium/crescimento & desenvolvimento , DNA Ribossômico/análise , Dados de Sequência Molecular , Hibridização de Ácido Nucleico/métodos , RNA Ribossômico 16S/genéticaRESUMO
Bifidobacteria were isolated from 122 of 145 samples of animal feces (from cattle, swine, sheep, goats, horses, rabbits, chickens, geese, and pigeons) from farms in France and Austria and from 92 of 955 production and processing chain samples of beef and pork (obtained at slaughter, cutting, and retail). Bacterial strains were identified to species by phenotypic numerical classification based on API 50CH and ID 32A tests and DNA-DNA hybridization. Bifidobacterium pseudolongum was present in 81% (99 of 122 samples) of all Bifidobacterium-positive fecal samples and predominated in samples from all animal species except those from swine from Austria. In these Austrian swine samples, the majority of strains were identified as Bifidobacterium thermophilum (78%), followed by B. pseudolongum (48%). The distribution of B. thermophilum and B. pseudolongum differed significantly between Austrian swine and cattle samples such as those collected along beef and pork production and processing chains. Bifidobacterium animalis was isolated from swine feces, and Bifidobacterium ruminantium was isolated from cow dung. Six fecal isolates (from cattle, swine, rabbits, goats, and horses) were identified as belonging to Bifidobacterium species of predominantly human origin: B. adolescentis, B. bifidum, and B. catenulatum. Only one other species, Bifidobacterium choerinum, was detected with low frequency in a pork processing chain. B. pseudolongum subsp. pseudolongum was predominant in pig feces, whereas B. pseudolongum subsp. globosum was predominant in feces from other animal species. Four strains closely related to both subspecies (58 to 61% DNA reassociation) formed a distinct genomic group. PCR techniques, which are more rapid and sensitive than culture-based methods, could be used to detect directly B. pseudolongum and B. thermophilum as indicators of fecal contamination along the meat processing chain.
Assuntos
Bifidobacterium/isolamento & purificação , DNA Bacteriano/análise , Fezes/microbiologia , Contaminação de Alimentos/análise , Carne/microbiologia , Animais , Áustria , Bifidobacterium/classificação , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Indústria de Processamento de Alimentos/métodos , Indústria de Processamento de Alimentos/normas , França , Filogenia , Especificidade da EspécieRESUMO
Bifidobacteria are well known for their beneficial effects on health and are used as probiotics in food and pharmaceutical products. As they form one of the most important groups in both human and animal feces, their use as fecal indicator organisms in raw milk products has recently been proposed. Bifidobacteria species isolated in humans are different from those isolated in animals. It should therefore be possible to determine contamination origin (human or animal). A method of detecting the Bifidobacterium genus was developed by PCR targeting the hsp60 gene. The genus Bifidobacterium was identified by PCR amplification of a 217-bp hsp60 gene fragment. The degenerated primer pair specific to the Bifidobacterium genus used was tested for it specificity on 127 strains. Sensitivity was measured on artificially contaminated samples. Food can however be a difficult matrix for PCR testing since it contains PCR inhibitors. So an internal PCR control was used. An artificially created DNA fragment of 315 bp was constructed. The PCR detection method was tested on raw milk and cheese samples and compared with three culture-based methods, which comprised enrichment and isolation steps. The enrichment step used Brain Heart Infusion medium with propionic acid, iron citrate, yeast extract, supplemented with mupirocin (BHMup) or not (BH) and the isolation step used Columbia blood agar medium, supplemented with mupirocin (CMup) or not (C). The method using mupirocin at both enrichment and isolation steps and the PCR method performed from the culture in BHMup enrichment medium were shown to be the most efficient. No significant difference was observed in raw milk samples between PCR from BHMup and the culture-based method BHMup/CMup, while a significant difference was noticed between the same methods in raw milk cheese samples, which would favor using PCR. The results suggested that PCR on the hsp60 gene was convenient for a rapid detection of bifidobacteria in raw milk and raw milk cheese samples and that bifidobacteria always present throughout raw milk cheese production could be efficiently used as fecal indicators.
Assuntos
Bifidobacterium/isolamento & purificação , Queijo/microbiologia , Microbiologia de Alimentos , Leite/microbiologia , Reação em Cadeia da Polimerase/métodos , Animais , Bifidobacterium/genética , Técnicas de Cultura de Células , Chaperonina 60/química , Chaperonina 60/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Sensibilidade e EspecificidadeRESUMO
The classification of 169 strains related to the species Enterobacter agglomerans or Erwinia berbicola has been carried out by numerical procedure. The taxonomic position of the strains is discussed in relation to the species Enterobacter sakazakii, Rahnella aquatilis, Escherichia adecarboxylata. Five principal groups can be defined. The Ent. agglomerans or E. herbicola species can be divided into 15 subgroups. Some of the Ent. agglomerans strains are phenotypically related to the Ent. sakazakii and Esc. adecarboxylata strains.
RESUMO
Forty-seven strains of bifidobacteria isolated from meat and meat products have been identified following phenotypic numerical analysis and DNA-DNA hybridization. Twenty-three strains were identified to the species B. thermophilum and 14 to B. pseudolongum subsp. pseudolongum. All others were also of animal origin, except for two strains -- B. longum and B. pseudocatenulatum -- that were of human origin. These strains were isolated from artificially contaminated meat by manual handling.
Assuntos
Bifidobacterium/classificação , Microbiologia de Alimentos , Carne/microbiologia , Animais , Bifidobacterium/química , Bifidobacterium/crescimento & desenvolvimento , Bovinos , DNA Bacteriano/química , Indústria de Processamento de Alimentos , Humanos , Produtos da Carne/microbiologia , Hibridização de Ácido Nucleico , Fenótipo , Filogenia , Suínos , PerusRESUMO
Fifty-eight samples of raw milk from three different farms were examined for the presence of bifidobacteria. Isolates were identified and compared with bifidobacteria isolated from dung of the cows that provided the milk. Of the raw milk samples, 88% harboured Bifidobacterium pseudolongum subsp. globosum, as did 95% of the dung samples.
Assuntos
Bifidobacterium/isolamento & purificação , Bovinos/microbiologia , Fezes/microbiologia , Microbiologia de Alimentos , Leite/microbiologia , Animais , Bifidobacterium/classificação , Feminino , FenótipoRESUMO
The species Rahnella aquatilis has been isolated mostly from water, soil, and, in a few cases, from human clinical specimens; little is known about its ecological role. The application of polyacrylamide gel electrophoresis of soluble proteins, DNA-DNA hybridizations and API 20 E systems has shown that Rahnella aquatilis might also be encountered as a contaminant in lager beer breweries.
Assuntos
Proteínas de Bactérias/análise , Cerveja , DNA Bacteriano/análise , Enterobacteriaceae/classificação , Microbiologia de Alimentos , Eletroforese em Gel de Poliacrilamida , Enterobacteriaceae/análise , Enterobacteriaceae/genética , Hibridização de Ácido Nucleico , Microbiologia do Solo , Microbiologia da ÁguaRESUMO
The API 20 EC and ATB 32 GN identification systems were compared for their ability to identify 231 coliform bacteria strains. Agreement with the identification given by conventional methods was achieved for 96.1 p. cent of strains by the API 20 EC gallery and for 95.9 p. cent by the ATB 32 GN system. Complementary tests were needed to identify 9.5 p. cent of strains using the API 20 EC system but 30.3 per cent using the ATB 32 GN system.
Assuntos
Enterobacteriaceae/isolamento & purificação , Técnicas BacteriológicasRESUMO
OBJECTIVES: The aim of our study was to analyse the antibiotic susceptibility of various strains of Bifidobacterium spp. to a wide range of antimicrobial agents. METHODS: Fifty strains belonging to eight species of bifidobacteria, isolated from humans, animals or probiotic products, were tested for susceptibility to 30 antibiotics by disc diffusion on Brucella agar supplemented with 5% laked sheep blood and vitamin K1 (1 mg/L). MICs of nine anti-anaerobe agents, including three new molecules (telithromycin, linezolid and gatifloxacin), were determined using the reference agar-dilution method. RESULTS: All strains of bifidobacteria, whatever the species, were sensitive to penicillins: penicillin G, amoxicillin (MIC(50) 0.06 mg/L), piperacillin, ticarcillin, imipenem and usually anti-Gram-positive antibiotics (macrolides, clindamycin, pristinamycin, vancomycin and teicoplanin). Susceptibility to cefalothin and cefotetan was variable. Most isolates (70%) were resistant to fusidic acid. As expected, high resistance rates were observed for aminoglycosides. Metronidazole, an agent known for its anti-anaerobe activity, was ineffective against 38% of the strains. The newly commercialized molecules, telithromycin, linezolid and gatifloxacin, were active with MIC(50)S of 1 mg/L. The only variation in susceptibility observed among the different species concerned Bifidobacterium breve, which appeared to be generally more resistant. Potentially acquired resistance was only observed against tetracycline and minocycline, in 14% of the strains. CONCLUSIONS: With regard to a general concern about the safety of probiotics, such as potential transferability of resistance determinants, bifidobacteria, with their low natural and acquired resistance to 30 antibiotics, appear risk-free.
Assuntos
Antibacterianos/farmacologia , Bifidobacterium/efeitos dos fármacos , Animais , Infecções por Bifidobacteriales/microbiologia , Bifidobacterium/classificação , Cárie Dentária/microbiologia , Farmacorresistência Bacteriana , Fezes/microbiologia , Humanos , Lactente , Recém-Nascido , Intestinos/microbiologia , Testes de Sensibilidade Microbiana/métodos , ProbióticosRESUMO
This work studies the classification, by numerical procedure, of 111 strains belonging to the family Enterobacteriaceae. Their taxonomic position is discussed, in relation to the genus Citrobacter, Levinea, Enterobacter, to which some appear to be closely associated. The study is based on the usual biochemical and nutritional characters as shown by the utilisation of substrates tested as sole sources of carbon and energy. Six hierarchical classes can thus be defined. Their degree of affinity with members of the Enterobacteriaceae groups or genera is discussed. The diverse origins of the strains examined (human, soil, aquatic) are certainly the cause for the individualization of the new classes.
Assuntos
Citrobacter/metabolismo , Enterobacteriaceae/classificação , Enterobacteriaceae/metabolismo , Álcoois/metabolismo , Aminas/metabolismo , Aminoácidos/metabolismo , Metabolismo dos Carboidratos , Ácidos Carboxílicos/metabolismo , Citrobacter/classificaçãoRESUMO
A prototype of an expert system for the identification of beta-galactosidase positive Enterobacteriaceae has been developed, for use with the API 20 EC kit. The system is implemented in Prolog on an IBM PC AT with 640 K of central memory and 20 megabytes of secondary memory. Its objectives are to highlight errors that can occur when the kit is in use. It can indicate the presence of new groups or species and give advice or suggest additional tests for the differentiation of the new species from those included in the kit.
Assuntos
Enterobacteriaceae/classificação , Sistemas Inteligentes , Microcomputadores , Enterobacteriaceae/enzimologia , Enterobacteriaceae/isolamento & purificação , Probabilidade , Kit de Reagentes para Diagnóstico , beta-Galactosidase/biossínteseRESUMO
Sugar uptake was measured with 3H-galactose and 14C-glucose. Galactose transport system was not modified by inhibitors of known translocases and did not present a saturation kinetic with high concentration of galactose. Glucose incorporation was inhibited by lasalocid (cation symport inhibitor) and increased by KCl. The kinetic parameters KM and Vmax were respectively 9.16 mM and 26.56 nmol/min/mg cell protein. On the basis of this study, galactose crossed through the membrane by diffusion, and glucose was incorporated by a cation symport which is regulated by K+ ions.
Assuntos
Bifidobacterium/metabolismo , Galactose/metabolismo , Glucose/metabolismo , Transporte Biológico , FosforilaçãoRESUMO
A DNA-DNA hybridization study was carried out to determine the taxonomic position of a new group of enterobacteria (group H2) previously studied by numerical taxonomy. All the strains of this group revealed relatively high reassociation binding ratios with the centrotype; 82% of the strains of the group showed more than 69% of reassociation with the centrotype. In spite of numerical taxonomy conclusions, there was no genetic relationship with the species Enterobacter cloacae (higher reassociation binding ratio: 37%). No significant genetic relationship with the other groups of enterobacteria was found. Rahnella aquatilis was defined from phenotypic and genetic data. The strain 133 (CIP 78-65) is proposed as type strain of the species.
Assuntos
Enterobacter/classificação , Enterobacteriaceae/classificação , DNA Bacteriano/análise , Enterobacter/análise , Enterobacteriaceae/análise , Conformação de Ácido Nucleico , Terminologia como AssuntoRESUMO
The deoxyribonculeic acid (DNA) of 106 strains of Enterobacteria was analysed for the guanine + cytosine (GC) content. These strains, whose origin and principal characters are described in the text, belong to the genera Citrobacter (C. freundii H2S-) and Levinea (L. malonatica and L. amalonatica). Four other groups or classes named C.D.E. and F. could not be classified on the base of the usual phenotypic criteria. DNA from the strains of Levinea has a GC% of 50.3 to 53.3, while DNA from the strains of C. freundii H2S- has a GC% of 48.6 to 51.7. The representative values from the new classes are C, 50.9%; D, 54%; E, 52.7%; F, 49.5%. For the latter a genomic heterogeneity was shown, expressing itself as two subpopulations whose average GC% are 51.7 and 48.6 respectively. Statistical analysis of the averages give a significant individuality to these new classes.
Assuntos
Citosina/análise , DNA Bacteriano/análise , Enterobacteriaceae/análise , Guanina/análise , Citrobacter/análise , Citrobacter/classificação , Enterobacteriaceae/classificação , Estatística como AssuntoRESUMO
AIMS: The effect of salt and acid on the growth and surface properties of two strains of Listeria monocytogenes was investigated. METHODS AND RESULTS: Medium acidification and NaCl supplementation induced a marked increase in the lag and growth times (up to fivefold higher) and a decrease in the maximal optical density. Due to a strong synergic effect of pH and NaCl, growth was only detected after 280 h incubation for Scott A and not detected after 600 h for LO28 at pH 5.0 and 10% NaCl. Furthermore, the addition of NaCl in acidic conditions gave rise to cell filamentation and cell surfaces became strongly hydrophilic. CONCLUSIONS: Some L. monocytogenes strains subjected to high NaCl concentrations in acidic conditions are able to grow but may present altered adhesion properties due to modification of their surface properties. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted that L. monocytogenes do represent a hazard in acid and salted foods, such as soft cheese.
Assuntos
Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/ultraestrutura , Aderência Bacteriana , Humanos , Concentração de Íons de Hidrogênio , Cloreto de Sódio , Solventes , Propriedades de SuperfícieRESUMO
Lactose was fermented but not assimilated by the strain Bifidobacterium bifidum DSM 20082. The sugar uptake was measured with lactose 14C. Km and V(max) values were respectively 2.6 mM and 12.11 nmol/min/mg of cell protein. The lactose transport system and the beta-D-galactosidase were stimulated when the cells were grown with lactose, but isopropyl-beta-D-thiogalactopyranoside had no effect. Lactose uptake was inhibited by compounds which interfered with proton and metal ionophore. Na+, Li+, or K+ did not affect incorporation of lactose. Furthermore, the lactose uptake decreased when an inhibitor of ATP synthesis was used. From the results of this study, the stain contained an active lactose transport system, probably a proton symport as described for Escherichia coli but with a different regulation system.
Assuntos
Bifidobacterium/metabolismo , Inibidores Enzimáticos/farmacologia , Lactose/metabolismo , Bifidobacterium/enzimologia , Bifidobacterium/crescimento & desenvolvimento , Transporte Biológico/efeitos dos fármacos , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Meios de Cultura/química , Dicicloexilcarbodi-Imida/farmacologia , Indução Enzimática , Fluoreto de Sódio/farmacologia , beta-Galactosidase/biossínteseRESUMO
The classification of 175 strains related to the genus Enterobacter has been carried out by numerical procedure, with usual biochemical and nutritional characters as shown by the utilization of substrates tested as sole sources of carbon and energy. The taxonomic position of the strains is discussed in relation to the species E. cloacae, E. hafniae, E. aerogenes, E. agglomerans and Serratia liquefaciens. By the system of data analysis used (hierarchical agregation method) five principal classes can be defined. The individualization of new classes closely bound to the diverse origins of the strains examined (human, soil, aquatic).
Assuntos
Enterobacteriaceae/classificação , Enterobacteriaceae/metabolismo , Métodos , Terminologia como AssuntoRESUMO
Many psychrotrophic coliform organisms are isolated from samples of water supply. They are coming from water or soil and not from animal faeces. It is therefore necessary to identify coliform organisms to interpret accurately the results of potability analysis.
Assuntos
Enterobacteriaceae/isolamento & purificação , Microbiologia da Água , Fezes/microbiologia , França , Abastecimento de Água/normasRESUMO
A DNA-DNA hybridization study was carried out on a new group of enterobacteria (group H1) previously studied by numerical taxonomy work on the genus Enterobacter. This group showed a very high genetic homogeneity since the average relative binding ratio of nine analysed strains is equal to 91%. The taxonomic position of this group into the family of enterobacteria is discussed with the species E. cloacae (37 to 61%), K. pneumoniae (44 to 60%), K. oxytoca (57-58%), L. malonatica (syn. Citrobacter intermedius, a:46 to 54%), L. amalonatica (syn. C. intermedius, b: 51%), and the group H3 (52-61%). The group H1 is defined on phenotypic and genetic data.