Genera Citrobacter Research Articles

Biosynthetic Pathway and Genes of Chitin/Chitosan-Like Bioflocculant in the Genus Citrobacter.

Chitin/chitosan, one of the most abundant polysaccharides in nature, is industrially produced as a powder or flake form from the exoskeletons of crustaceans such as crabs and shrimps. Intriguingly, many bacterial strains in the genus Citrobacter secrete a soluble chitin/chitosan-like polysaccharide into the culture medium during growth in acetate. Because this polysaccharide shows strong flocculation activity for suspended solids in water, it can be used as a bioflocculant (BF). The BF synthetic pathway of C. freundii IFO 13545 is expected from known bacterial metabolic pathways to be as follows: acetate is metabolized in the TCA cycle and the glyoxylate shunt via acetyl-CoA. Next, fructose 6-phosphate is generated from the intermediates of the TCA cycle through gluconeogenesis and enters into the hexosamine synthetic pathway to form UDP-N-acetylglucosamine, which is used as a direct precursor to extend the BF polysaccharide chain. We conducted the draft genome sequencing of IFO 13545 and identified all of the candidate genes corresponding to the enzymes in this pathway in the 5420-kb genome sequence. Disruption of the genes encoding acetyl-CoA synthetase and isocitrate lyase by homologous recombination resulted in little or no growth on acetate, indicating that the cell growth depends on acetate assimilation via the glyoxylate shunt. Disruption of the gene encoding glucosamine 6-phosphate synthase, a key enzyme for the hexosamine synthetic pathway, caused a significant decrease in flocculation activity, demonstrating that this pathway is primarily used for the BF biosynthesis. A gene cluster necessary for the polymerization and secretion of BF, named bfpABCD, was also identified for the first time. In addition, quantitative RT-PCR analysis of several key genes in the expected pathway was conducted to know their expression in acetate assimilation and BF biosynthesis. Based on the data obtained in this study, an overview of the BF synthetic pathway is discussed.

Identifikacija citrobacter youngae izolovanog iz hrane primenom MALDI-TOF metode

Salmonella-like bacteria, such as certain species of the Citrobacter genus are sometimes isolated from food and feed. By testing their biochemical and, partially, serological characteristics (according to the regulations given in the ISO 6579-1:2017 Standard) it is impossible to completely reject their affiliation to the Salmonella genus. In addition to this, the food microbiology laboratories usually lack diagnostic tools and procedures for precise identification of these isolates to the species level. Thus, it is considered useful to describe the identification of Citrobacter youngae species using MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry). Besides differential diagnostic criteria for distinguishing between Salmonella spp. and Citrobacter youngae, in this communication the relevant data on Citrobacter spp., the emerging opportunistic pathogenic member of Enterobacteriaceae family were presented.

Антиінтерферонова й антилактоферинова активність мікроорганізмів дистального відділу кишечника поросят за змішаної нематодозно-протозоозної інвазії

It was investigated the changes of anti infearonic and anti lactofearinic activity of microorganisms of distal part of the pigs intestine for mixed nonmatodozic – protozoozic invasion. Established that the organism invasion of the ascaris association, balantidium and eymeria does not cause changes of anti infearonic activity in microorganisms of genus Bacteroides spp., Prevotella spp., Propionibacterium spp., Peptostreptococcus spp. and Fusobacterium spp., but increases it in Bifidobacterium spp. at 9.09% and Clostridium spp. at 22.22%, and decreases to 7.69% in Eubacterium spp. Compared with controls, infearonic activity of microorganisms selected from animals intestine from the 2nd group was higher in Citrobacter spp., Staphylococcus spp., Klebsiella spp. and Streptococcus spp. accordingly in 4.6, 4.5, 2.9 and 2.3 times. In colilact. «-» gem «-» and Enterococcus spp. the growth of investigated rate was 1.2 to 1.4 times. Thanks to the result of investigation of anti infearonic activity of obligate anaerobes selected from the distal intestine of pigs infested by the association of intestinal parasites, was set its growth in microorganisms of genus Bifidobacterium spp. and Bacteroides spp. to 33.3%, Prevotella spp. – to 29.2%, Clostridium spр. – to 64.0%, Eubacterium spp. – to 26.7%, Propionibacterium spp. – to 84.6% and Peptostreptococcus spp. – to 15.4%, compared with microorganisms selected from the intestines of agility pigs. Among MAFAnM the most compared, to control, anti lactofearinic activity was grown in bacteria of genus Citrobacter spp., Klebsiella spp. and Staphylococcus spp. accordingly in 7.8, 3.7 and 3.5 times. Less expressed growth of the indicator was found in bacteria of genus Candidaspp. – into 1.5 times, E. coli.lact. «-» gem «+» and Enterobacter spp. – 1.4 times, Lactobacillusspp. and Enterococcus spp. – 1.3 times and Streptococcus spp. – 1.2 times.

Бактериофаги рода Citrobacter

Бактериофаги рода Citrobacter

Citrobacter portucalensis sp. nov., isolated from an aquatic sample.

A Gram-stain-negative strain, A60T, isolated from a water well sample in Portugal, was characterized phenotypically, genotypically and phylogenetically. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain A60T belonged to the genus Citrobacter, and recN gene phylogeny revealed one strongly supported clade encompassing strain A60T and 13 other strains from public databases, distinct from currently recognized species of the genus Citrobacter. Furthermore, multilocus sequence analysis (MLSA) based on concatenated partial fusA, leuS, pyrG and rpoB sequences confirmed the classification obtained with the recN sequence. In silico genomic comparisons, including average nucleotide identity (ANI) and the genome-to-genome distance calculator (GGDC), showed 94.6 % and 58.4 % identity to the closest relative Citrobacter freundii ATCC 8090T, respectively. The ability to metabolize different compounds further discriminated strain A60T from other species of the genus Citrobacter. The G+C content of strain A60T is 52.0 %. The results obtained support the description of a novel species within the genus Citrobacter, for which the name Citrobacter portucalensis sp. nov. is proposed, with the type strain A60T (=DSM 104542T=CECT 9236T).

A prospective microbiome-wide association study of food sensitization and food allergy in early childhood.

Alterations in the intestinal microbiome are prospectively associated with the development of asthma; less is known regarding the role of microbiome alterations in food allergy development. Intestinal microbiome samples were collected at age 3-6 months in children participating in the follow-up phase of an interventional trial of high-dose vitamin D given during pregnancy. At age 3, sensitization to foods (milk, egg, peanut, soy, wheat, walnut) was assessed. Food allergy was defined as caretaker report of healthcare provider-diagnosed allergy to the above foods prior to age 3 with evidence of IgE sensitization. Analysis was performed using Phyloseq and DESeq2; P-values were adjusted for multiple comparisons. Complete data were available for 225 children; there were 87 cases of food sensitization and 14 cases of food allergy. Microbial diversity measures did not differ between food sensitization and food allergy cases and controls. The genera Haemophilus (log2 fold change -2.15, P=.003), Dialister (log2 fold change -2.22, P=.009), Dorea (log2 fold change -1.65, P=.02), and Clostridium (log2 fold change -1.47, P=.002) were underrepresented among subjects with food sensitization. The genera Citrobacter (log2 fold change -3.41, P=.03), Oscillospira (log2 fold change -2.80, P=.03), Lactococcus (log2 fold change -3.19, P=.05), and Dorea (log2 fold change -3.00, P=.05) were underrepresented among subjects with food allergy. The temporal association between bacterial colonization and food sensitization and allergy suggests that the microbiome may have a causal role in the development of food allergy. Our findings have therapeutic implications for the prevention and treatment of food allergy.

Effects of Dietary Administration of Shewanella xiamenensis A-1, Aeromonas veronii A-7, and Bacillus subtilis, Single or Combined, on the Grass Carp (Ctenopharyngodon idella) Intestinal Microbiota.

Gut microbiota of grass carp plays an important role in host. However, detailed information regarding the changes of microbiota after probiotics administration in relation to the gastrointestinal microbiota is absent. In the present study, dietary administration of putative probiotics Shewanella xiamenensis A-1, Aeromonas veronii A-7, and Bacillus subtilisstrains was conducted in grass carp to investigate if there is a discernible alteration in intestinal microbiota and whether the alteration is associated with previous study about the immunity regulation in grass carp. Bacterial 16S rRNA gene sequence-based comparisons of the bacterial communities in the grass carp intestine were detected after 28days feeding by five diets, and results demonstrated the changes of microbial community composition at genus level. The abundance of Cetobacterium genus with potential immunity function increased. Potential pathogens and probiotics are important constitutions of the intestinal microbiota. Orally taken probiotics considerably reduced the abundance of the potential pathogenic bacteria (e.g., Pseudomonas and Flavobacterium genus) in the intestine. Meanwhile, putative probiotics used in this study were favorable to the reproduction of potential probiotics in THE intestine of grass carp (e.g., Vibrio, Streptococcus, and Enterococcus genus). Moreover, modulation of intestinal environment by the probiotics could impact the abundance of cellulose-degrading bacteria (e.g., Citrobacter genus). Those results suggested that oral probiotics administration can positively improve the composition of intestinal microbial community in grass carp, and this was associated with regulation of immunity in grass carp. Probiotics-induced alteration of microbiota may potentially lower the risk of disease outbreaks during cultivation stage of grass carp.

Citrobacter europaeus sp. nov., isolated from water and human faecal samples.

Strains 97/79T and A121, recovered respectively from human faeces and well water, were compared to currently known species of the genus Citrobacter using genotypic and phenotypic approaches. Multilocus sequence analysis based on housekeeping genes fusA, leuS, pyrG, rpoB and recN, showed that the two strains formed a distinct phylogenetic lineage within the genus Citrobacter. Average nucleotide identity (ANI) between strains 97/79T and A121 was 99.2 %, whereas ANI values of strain 97/79T with the type strains of closely related species of the genus Citrobacter, C. werkmanii, C. braakii, C. freundii, C. youngae and C. pasteurii, were all below 93.0 %. The ability to metabolize different compounds also discriminated strains 97/79T and A121 from other species of the genus Citrobacter. Based on these results, strains 97/79T and A121 represent a novel species of the genus Citrobacter, for which the name Citrobacter europaeus sp. nov. is proposed, with strain 97/79T (=CIP 106467T=DSM 103031T) as the type strain. The DNA G+C content of strain 97/79T is 52.0 %.

Functional analysis for gut microbes of the brown tree frog (Polypedates megacephalus) in artificial hibernation.

BackgroundAnnual hibernation is an adaptation that helps many animals conserve energy during food shortage in winter. This natural cycle is also accompanied by a remodeling of the intestinal immune system, which is an aspect of host biology that is both influenced by, and can itself influence, the microbiota. In amphibians, the bacteria in the intestinal tract show a drop in bacterial counts. The proportion of pathogenic bacteria is greater in hibernating frogs than that found in nonhibernating frogs. This suggests that some intestinal gut microbes in amphibians can be maintained and may contribute to the functions in this closed ecosystem during hibernation. However, these results were derived from culture-based approaches that only covered a small portion of bacteria in the intestinal tract.MethodsIn this study, we use a more comprehensive analysis, including bacterial appearance and functional prediction, to reveal the global changes in gut microbiota during artificial hibernation via high-throughput sequencing technology.ResultsOur results suggest that artificial hibernation in the brown tree frog (Polypedates megacephalus) could reduce microbial diversity, and artificially hibernating frogs tend to harbor core operational taxonomic units that are rarely distributed among nonhibernating frogs. In addition, artificial hibernation increased significantly the relative abundance of the red-leg syndrome-related pathogenic genus Citrobacter. Furthermore, functional predictions via PICRUSt and Tax4Fun suggested that artificial hibernation has effects on metabolism, disease, signal transduction, bacterial infection, and primary immunodeficiency.ConclusionsWe infer that artificial hibernation may impose potential effects on primary immunodeficiency and increase the risk of bacterial infections in the brown tree frog.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3318-6) contains supplementary material, which is available to authorized users.

Profile of Citrobacter freundii ST2, a Multi-acyl-homoserine Lactone Producer Associated with Marine Dinoflagellates.

Marine algae provide a unique niche termed the phycosphere for microorganism inhabitation. The phycosphere environment is an important niche for mutualistic and competitive interactions between algae and bacteria. Quorum sensing (QS) serves as a gene regulatory system in the microbial biosphere that allows bacteria to sense the population density with signaling molecules, such as acyl-homoserine lactone (AHL), and adapt their physiological activities to their surroundings. Understanding the QS system is important to elucidate the interactions between algal-associated microbial communities in the phycosphere condition. In this study, we isolated an epidermal bacterium (ST2) from the marine dinoflagellate Scrippsiella trochoidea and evaluated its AHL production profile. Strain ST2 was classified as a member of the genus Citrobacter closely related to Citrobacter freundii by 16S rRNA gene sequence analysis. Thin-layer chromatography revealed that C. freundii ST2 secreted three active AHL compounds into the culture supernatant. Specific compounds, such as N-butyryl-L-homoserine lactone (C4-AHL), N-octanoyl-DL-homoserine lactone (C8-AHL), and N-decanoyl-DL-homoserine lactone (C10-AHL), were identified by high-resolution tandem mass spectrometry. Carbon metabolic profiling with Biolog EcoPlate™ indicated that C. freundii ST2 was widely used as a carbon source and preferred carbohydrates, amino acids, and carboxylic acids as carbon substrates. Our results demonstrated that C. freundii ST2 is a multi-AHL producer that participates in the phycosphere carbon cycle.

Influence of Starvation on the Structure of Gut-Associated Bacterial Communities in the Chinese White Pine Beetle (Dendroctonus armandi)

This study investigated the influence of starvation on the structure of the gut bacterial community in the Chinese white pine beetle (Dendroctonus armandi). A total of 14 operational taxonomic units (OTUs0.03) clusters belonging to nine genera were identified. Denaturing gradient gel electrophoresis (DGGE) profiles of bacterial PCR-amplified 16S rRNA gene fragments from the guts of starved male and female adults revealed that the bacterial community diversity increased after starvation. The dominant genus Citrobacter decreased significantly, whereas the genus Serratia increased in both starved female and starved male adults. The most predominant bacterial genus in D. armandi adults was Citrobacter, except for starved male adults, in which Serratia was the most abundant genus (27%). Our findings reveal that starvation affects gut bacterial dynamics in D. armandi, as has been observed in other insect species.

Cultivation and characterization of symbiotic bacteria from the gut of Reticulitermes chinensis

The complex symbiotic relationship between wood-feeding termites and microorganisms inhabiting their intestinal tracts is a fascinating phenomenon in nature. To understand the physiological functions of symbiotic micro-organisms, bacteria were isolated from the gut homogenate of Reticulitermes chinensis with different media and culture conditions. Under aerobic conditions, 105 bacterial strains were isolated with 1/5 LB medium, 1/3 TSB medium and a modified basal mineral medium, MM-4. Most dominant isolates were bacteria in the genera Bacillus (27.6%) and Lactococcus (21.9%). Under anaerobic conditions, 60 bacterial strains were isolated with 1/5 LB medium, 1/3 TSB medium and a modified Peptone-Yeast medium. The predominant isolates were bacteria in the genus Enterobacter (41.7%) and Citrobacter (33.3%). Many of these bacterial isolates shared high sequence similarity (>98%) in 16S rRNA genes to bacterial clones obtained from the same termite and the other wood-feeding termites or cockroaches. Several bacterial species such as Deinococcus and Gryllotalpicola were isolated from termite gut for the first time. Characterization of these isolates showed that (i) most of Enterobacteriaceae and Lactococcus strains were able to hydrolyze uric acid; and (ii) many of the Bacillus and Streptomyces strains presented endo-β-1,4-glucanase activity. The preliminary results of this work gave us hints of possible functions of symbiotic bacteria in nitrogen recycling and cellulose degradation in the gut of wood-feeding termites

The significance of clean and dirty animals for bacterial dynamics along the beef chain

This study investigated the bacterial dynamics along the beef chain for clean and dirty cattle in the slaughter and processing lines, using classic quantitative methods and molecular analyses. In addition, the Norwegian national guidelines for Good Hygiene Practices in Norway were evaluated. In these guidelines, cattle presented for slaughter are categorised according to hide cleanliness, resulting in separate processing lines for meat from very dirty animals and reduced prices to farmers. The study was conducted in two commercial abattoirs in Norway. Two groups were compared; 40 visually clean cattle and 40 visually dirty cattle presented for slaughter, with 20 from each group at each abattoir. The same animals were sampled at five sampling sites: hides, carcass surfaces after dehiding, just before chilling, after chilling, and meat trimmings. Meat trimmings were sampled in only one abattoir. Three hundred and sixty samples were collected by swabbing 100cm2 of the brisket area at the first four sampling sites, and sampling 200g of meat trimmings at the fifth site. The results showed that the hides of dirty cattle had more Enterobacteriaceae and higher Aerobic Plate Counts (APC) than visually clean cattle (P<0.05), however there was no significant difference for Escherichia coli. For the other sampling sites, there were no differences between the dirty and the clean group. An effect of chilling/drying of the carcass surfaces was demonstrated by the significant reduction in the number of carcasses on which E. coli and Enterobacteriaceae were detected; from 11% and 39% before chilling to 1% and 16% after chilling, respectively. Enterobacteriaceae and E. coli were detected in only three and one of the meat trimming samples, respectively. Amplification and sequencing of the 16S rRNA gene from 643 Enterobacteriaceae colonies derived from 107 samples demonstrated that Escherichia/Shigella were dominant within this family on the hides. However, after dehiding, after grading, and after chilling, the genera Citrobacter and Enterobacter dominated. The meat trimmings were dominated by the genera Kluyvera, Hafnia, and unclassified Enterobacteriaceae. The relative proportions of Escherichia/Shigella were higher for dirty animals than for clean animals, and were higher on hides than from sampling sites further down the chain (P<0.05). The minor differences in contamination on carcass surfaces and meat trimmings between clean and dirty cattle indicate that separate processing lines in Norwegian abattoirs seem to be unnecessary.

SEAWATER QUALITY FOR SHRIMP MARICULTURE BASED ON MICROBIOLOGY PARAMETERS

&lt;p&gt;Seawater quality plays an important factor for the success of mariculture such as microbiology paramater. The research aimed to analize the waters quality for shrimp mariculture in Barru, Pangkep, and Maros based on bacteriology parameters. The research were carried out in June 2012. Bacteriology parameters analysed were total coliform, E.coli, pathogen, heterotrophic, halotolerant, and phosphate-nitrate-ammonia bacteria. Coliform and E.coli bacteria were analysed based on filtration. Pathogenic bacteria was identified using biochemical test. Heterotrophic, halotolerant, and phosphate-nitrate-ammonia bacteria were analysed using pour plate. The results from shrimp aquaculture showed the total abundance of coliform cell of &amp;gt;1000 colony forming unit (cfu)/100 ml, E.coli of 0-4 cfu/100ml, heterotrophic bacteria of about (31-176)x10&lt;sup&gt;3&lt;/sup&gt; cfu/ml, and halotolerant bacteria of about (31-375)x10&lt;sup&gt;3&lt;/sup&gt; cfu/ml. The results from sediment for heterotrophic bacteria was about (350-3920)x10&lt;sup&gt;3&lt;/sup&gt;&lt;sup&gt; &lt;/sup&gt;cfu/ml, halotolerant of about (350-4980)&lt;sup&gt;3&lt;/sup&gt;x10&lt;sup&gt; &lt;/sup&gt;cfu/ml, and phosphate-nitrate-ammonia bacteria of about 14-46 cfu/ml. The pathogen bacteria waere found such as genus Aeromonas, Pseudomonas, Proteus, Citrobacter, Shigella and Yersinia. The dominant pathogens in shrimp aquaculture water and sediment were Proteus and Citrobacter. The results indicated that seawaters in Barru, Pangkep, and Maros can be used for mariculture including shrimp Panaeid.&lt;/p&gt; &lt;p&gt;Keywords: bacteria, parameter, marineculture, shrimp.&lt;/p&gt;

SEAWATER QUALITY FOR SHRIMP MARICULTURE BASED ON MICROBIOLOGY PARAMETERS

Seawater quality plays an important factor for the success of mariculture such as microbiology paramater. The research aimed to analize the waters quality for shrimp mariculture in Barru, Pangkep, and Maros based on bacteriology parameters. The research were carried out in June 2012. Bacteriology parameters analysed were total coliform, E.coli, pathogen, heterotrophic, halotolerant, and phosphate-nitrate-ammonia bacteria. Coliform and E.coli bacteria were analysed based on filtration. Pathogenic bacteria was identified using biochemical test. Heterotrophic, halotolerant, and phosphate-nitrate-ammonia bacteria were analysed using pour plate. The results from shrimp aquaculture showed the total abundance of coliform cell of &gt;1000 colony forming unit (cfu)/100 ml, E.coli of 0-4 cfu/100ml, heterotrophic bacteria of about (31-176)x103 cfu/ml, and halotolerant bacteria of about (31-375)x103 cfu/ml. The results from sediment for heterotrophic bacteria was about (350-3920)x103 cfu/ml, halotolerant of about (350-4980)3x10 cfu/ml, and phosphate-nitrate-ammonia bacteria of about 14-46 cfu/ml. The pathogen bacteria waere found such as genus Aeromonas, Pseudomonas, Proteus, Citrobacter, Shigella and Yersinia. The dominant pathogens in shrimp aquaculture water and sediment were Proteus and Citrobacter. The results indicated that seawaters in Barru, Pangkep, and Maros can be used for mariculture including shrimp Panaeid. Keywords: bacteria, parameter, marineculture, shrimp.

Antimicrobial susceptibility pattern of urinary tract isolates of citrobacter species in a tertiary care hospital

Introduction: The genus Citrobacter is a distinct group of aerobic Gram-negative bacilli from the Enterobacteriaceae family. It is an opportunistic pathogen that can cause diarrhea, septicemia, meningitis, urinary tract and respiratory system infection. Its isolation in the hospital settings is increasing. It is a present challenge to the clinical microbiologist because of their increased occurrence in nosocomial infection. Objectives: The current study was done to find out the prevalence and antibiotic susceptibility pattern of Citrobacter species from urinary tract isolates. Materials and Methods: Urine samples received from January 2013 to December 2013 were considered. A total of 9186 urine samples were considered, out of which 6381 were sterile and 2805 plates had growth.65(2.312%)of the growth plates had Citrobacter species growth. Citrobacter species were identified by conventional biochemical method. Antibiotic sensitivity test was performed by Kirby-Bauer Disc diffusion method. Results: Out of 65 patients female: male ratio was 17:15.5.The age groups were 0-9years; 8 patients(12.3%),10-19years;3 patients(4.615%),20-29years;11patients (16.9%),30-39years;6patients(9.28%),40-49years;12 patients(18.46%),50-59years;5patients(7.69%),?60years;20 patients(30.76%).The effective agent against Citrobacter species was found to be Imipenem (90.76%) then Cefoperazone-Sulbactum (89.23%) followed by Piperacillin-Tazobactam and Amikacin (87.69%).6 Multidrug resistant strains and 8 were ESBL producers. Conclusion: From the study it was seen that multidrug resistant strains are emerging. Proper surveillance in the antimicrobial sensitivity of Citrobacter was required. The age group 60 and above was found in majority to have culture positive Citrobacter spp. Depending on antibiotic sensitivity pattern of Citrobacter isolates, the antibiotics should be used. Proper infection control measures should be taken to prevent the spread of the pathogen. Keywords: Antibiotic Susceptibility, Citrobacter Spp, Multi-Drug Resistant Bacteria, Urinary Tract Infections.

Optimization of treatment of Hp‐associated ulcers (898.2)

H.pylori eradication of existing treatment regimens do not lead to absolute efficiency. The purpose of the study. To study the efficacy of probiotics in the treatment of gastroduodenal ulcer.Materials. We observed 40 patients with gastroduodenal ulcer in the acute phase. Towards to integrated eradication therapy fertal to 1 capsule 2 times a day was added and bifiform in 2 capsules 3 times a day for a month.Results. In the period of acute ulcer decrease in the total number of E.coli was observed with normal enzymatic activity at 66.6%蠄107 CFU, Bifidobacterium Lactobacterbum and in 90.5% and 76.2% CFU蠄108 and 106, respectively. Increasing the number of E. coli with reduced enzyme activity in 47.6%蠅107 cfu, pathogenic Citrobacter 85.7%蠅106 cfu, fungi of the genus Candida in 42.8% of 蠅105 cfu .After treatment, scarring and ulceration H.pylori eradication was observed in 100% of patients , a normal level and Bifidobacterium Lactobacterbum at 100% at a concentration of蠅108 CFU , respectively, 106, E. coli with normal enzyme activity to 90% at a concentration of CFU蠅107i Citrobacter genus Candida fungi and 80% at a concentration of蠄105 CFU and 蠄 104, respectively.Conclusions: Probiotics in treatment of gastroduodenal ulcer increase Helicobacter pylori eradication rates, early relief of pain and dyspeptic syndromes, recovery of intestinal microflora and prevent the development of antibiotic‐associated diarrhea.

Identification of Three related genera salmonella citrobacter and proteus using API 20E, 16S-23S rDNA intergenic transcribed spacer fingerprinting, and 16S rDNA sequencing.

A total of 176 presumptive Salmonella strains isolated from different sources (food, environment, veterinary, and human) were analyzed by API 20E, serotyping, ITSF/ITSR-PCR and MINf/MINr-PCR. On the other hand, the 16S-23S rRNA intergenic transcribed spacer region was used to aid in their identification. Test results were confirmed by 16S rRNA sequencing. Of 176 suspected S. enterica isolates, API20E identified 105 (59.6%) as S. enterica, 42 (24%) as Citrobacter and 29 (16.4%) as Proteus. A total of 11 serotypes were found among 102 out of 105 Salmonella isolates. The remaining isolates were classified as untypeable by serotyping. When ITSF/ITSR-PCR and MINf/MINr-PCR were used, 101 out of 105 Salmonella isolates tested generated PCR products.Amplification of the spacer region between 16S-23S rRNA gene allowed discrimination of genera and facilitated species identification. Sequencing of 16S rRNA gene has identified 4 different species in proteus genus (P. mirabilis, P. penneri, P. vulgaris, and P. hausseri), 3 different species in Citrobacter genus (Citrobacter freundii, Citrobacter braakii, andCitrobacter youngae), and Salmonella enterica sub sp. enterica for all Salmonella isolates.The four suspect Salmonella isolates were definitively classified in Citrobacter genus. In conclusion, this study has demonstrated that API20E, serotyping associated toSalmonella specific PCR are accurate methods for S. enterica detection. In addition, PCR amplification of the 16S-23S spacer region was suitable tool for identification of bacteria at genera and species level. Key words: Salmonella, API 20E, serotyping, MINf/MINr-PCR, ITSF/ITSR-PCR, 16S-23S intergenic spacer regions (ITS)-PCR, 16S rRNA.

Distribution of chitin/chitosan-like bioflocculant-producing potential in the genus Citrobacter

Some strains belonging to the genera Citrobacter and Enterobacter have been reported to produce chitin/chitosan-like bioflocculants (BFs) from acetate. In this study, to investigate the distribution of the BF-producing potential in the genus Citrobacter and to screen stably and highly BF-producing strains, we obtained 36 Citrobacter strains from different culture collection centers, which were distributed among seven species in the genus, and tested for the flocculating activities of their culture supernatants using a kaolin suspension method. As a result, 21 strains belonging to C. freundii (17 strains in 23 strains tested), C. braakii (two in two), C. youngae (one in one), and C. werkmanii (one in two) showed flocculating activity, but this ability was limited to cells grown on acetate. Gas chromatography/mass spectrometry (GC/MS) analysis of the hydrolysates from the BFs of five selected strains indicated that they consisted of glucosamine and/or N-acetylglucosamine, such as the chitin/chitosan-like BF (BF04) produced by Citrobacter sp. TKF04 (Fujita et al. J Biosci Bioeng 89: 40-46, 2000). Gel filtration chromatography using a high-performance liquid chromatography system revealed that the molecular weight ranges of these BFs varied, but the average sizes were all above 1.66 × 10⁶Da.

Molecular characterization of phenanthrene-degrading methanogenic communities in leachate-contaminated aquifer sediment

The existence of polycyclic aromatic hydrocarbons in the various environments has aroused great environmental concerns due to their potential hazards to human health. The presence of polycyclic aromatic hydrocarbons in aquifer is particularly sensitive where groundwater is used as a source of potable water. Anaerobic biodegradation of polycyclic aromatic hydrocarbons is an attractive option for remediation of contaminated aquifer sediment. Bacterial and archaeal community structures of phenanthrene-degrading aquifer sediment under methanogenic condition were investigated using clone library analysis in combination with microcosm study. The bacterial members were all affiliated with γ-Proteobacteria. Phylum Euryarchaeota was the predominant archaeal group, represented by genera Methanosarcina, Methanobacterium and Thermogymnomonas. Both bacteria (genera Citrobacter and Pseudomonas) and archaea (genus Methanosarcina) might have links to phenanthrene degradation process. This work might provide some new insights into developing strategies for the isolation of the putative polycyclic aromatic hydrocarbons degraders under methanogenic condition and bioremediating polycyclic aromatic hydrocarbons in leachate-contaminated aquifer sediment.