A modified conductance medium for the detection of Salmonella spp.

Selenite-Cystine/trimethylamine oxide/dulcitol medium has been used in conjunction with conductance instruments to detect the presence of Salmonella spp. in foods and faeces. However, a small but significant number of salmonella strains were missed by this method. The majority of these strains were detected when dulcitol was substituted by mannitol and tested on two separate Malthus conductance instruments. Some strains of Citrobacter freundii and Escherichia coli continued to give false positive results. Attempts are made to explain why the substitution of mannitol for dulcitol gives an improved medium.     

Some modification to the media for rapid automated detection of salmonellas by conductance measurement

A selenite medium for the automated detection of salmonellas by conductance measurements has been modified to eliminate the negative results given by some dulcitol-negative strains. The dulcitol is replaced with mannitol and pre-enrichment is best done in buffered peptone water containing mannitol and dimethylsulphoxide. It is suggested that both versions of the selenite medium be used initially.     

Effect of carbohydrate source in selenite cystine trimethylamine oxide broth on the detection of salmonellas using the Bactometer

Ninety-five salmonellas and 40 non-salmonellas were screened in the Bactometer using the standard formulation for Easter and Gibson's selenite cystine trimethylamine oxide dulcitol broth and versions in which dulcitol was replaced by mannitol or deoxyribose. More strains of salmonellas exceeded the current detection criteria (magnitude 250, rate 25) when dulcitol was replaced by either mannitol or deoxyribose as carbohydrate source. Using mannitol, more non-salmonella strains exceeded the detection criteria than with either dulcitol or deoxyribose.     

Detection of salmonellas in animal feeds by electrical conductance

A comparison was made between standard culture methods and electrical conductance using a Malthus AT Microbiological Analyser for the examination of animal feeds for salmonella. Conductance testing with a selenite cystine/trimethylamine-N-oxide/dulcitol medium resulted in the detection of salmonellas in 49 of 55 known positive animal feeds, 13 of 19 spiked feed samples and 36 of 47 salmonella cultures. Testing with a lysine decarboxylase/glucose medium gave significantly better results (P less than 0.05) than with selenite cystine medium but five lysine decarboxylase negative strains of salmonella were undetected. When both media were used in parallel all salmonella positive samples were detected. No difference was found between preenrichment in buffered peptone water containing trimethylamine/mannitol and that containing lysine/glucose. Positive detection criteria for selenite medium of conductance peak at greater than or equal to 500 microsiemens (microS) with a rate of change of greater than or equal to 60 microS/h or 400-499 microS with a rate of change of greater than or equal to 40 microS/h and for lysine medium with a peak of greater than or equal to 100 microS have been established. The method offers savings in media and operating costs over conventional standard culture methods, provides results within 48 h and is recommended for statutory feed monitoring purposes.     

Detection of salmonellas in confectionery products by conductance

A modified lysine decarboxylase broth has been developed which could be used with a Bactometer M123 to differentiate salmonellas from other bacteria by the characteristics of the conductance detection curve. The medium was used in combination with a selenite cystine trimethylamine oxide dulcitol medium to screen 50 strains of salmonellas and 42 strains of other organisms to establish detection curve magnitude and rate values which could be used to identify curves specific to salmonellas. The combination of media detected all salmonellas tested except Salmonella pullorum . The two media were used to screen 100 inoculated product samples with the Bactometer instrument, in parallel with traditional plating procedures, and using various combinations of pre-enrichment and selective enrichment incubation periods. After 24 h pre-enrichment, the Bactometer system detected more positive samples than the conventional plating procedures after pre-enrichment and selective enrichment. It is considered that these media used in parallel in the Bactometer after conventional pre-enrichment could provide a 48 h screening procedure for salmonellas with a sensitivity comparable to present plating procedures.     

Detection of salmonellas in confectionery products by conductance

A modified lysine decarboxylase broth has been developed which could be used with a Bactometer M123 to differentiate salmonellas from other bacteria by the characteristics of the conductance detection curve. The medium was used in combination with a selenite cystine trimethylamine oxide dulcitol medium to screen 50 strains of salmonellas and 42 strains of other organisms to establish detection curve magnitude and rate values which could be used to identify curves specific to salmonellas. The combination of media detected all salmonellas tested except Salmonella pullorum. The two media were used to screen 100 inoculated product samples with the Bactometer instrument, in parallel with traditional plating procedures, and using various combinations of pre-enrichment and selective enrichment incubation periods. After 24 h pre-enrichment, the Bactometer system detected more positive samples than the conventional plating procedures after pre-enrichment and selective enrichment. It is considered that these media used in parallel in the Bactometer after conventional pre-enrichment could provide a 48 h screening procedure for salmonellas with a sensitivity comparable to present plating procedures.     

Biochemical properties of Shigella flexneri and their practical significance

As the result of the study of 921 S. flexneri strains 1-6 and 4 (IV: 7,8), isolated in 31 regions of the USSR in 1975-1984, their biochemical characterization by 33 tests was made. All the strains under study proved to be typical in most of their constant signs, only some of strains 2a showed deviations in mannitol and some of strains 4a, in acetate. In strains of serovar 6, circulating in the USSR, specific features with respect to dulcitol and xylose were noted. The possibility of the biochemical subserovar typing of S. flexneri 1-5, X- and Y-var., with respect to maltose, arabinose, sorbitol and rhamnose was confirmed.     

Use of molybdenum media with glycerin and admixtures of unassimilated polyols for differentiating actinomycetes

Actinomycetes were cultivated in a medium containing from 0.15 to 0.2% of ammonium molybdate, glycerol and from 0.25 to 1% of polyol which was not assimilated by the cultures and inhibited the production of molybdenum blue in many actinomycetes. The cultures differed in their susceptibility to the inhibition by various polyols. There were not two polyols that would produce an identical effect on all of the cultures. Correlations were established in the action of polyols. The differences in the formation of molybdenum blue can be used for the differentiation and identification of actinomycetes to subdivide them into groups according to their sensitivity to inositol, mannitol, D-arabitol, xylitol, sorbitol, L-arabitol and dulcitol and according to their resistance to dulcitol (minimal, average and maximal resistance). The paper presents schemes for subdividing groups into subgroups and for establishing the properties.     

Improved biovar test for Ralstonia solanacearum

Race 3, biovar 2 strains of Ralstonia solanacearum are quarantined pathogens in Europe and Canada and Select Agent pathogens in the United States. The biovar classification of R. solanacearum strains is based on their biochemical abilities to utilize a carbohydrate panel. The standard biovar test uses bromothymol blue as a pH indicator in 15 ml culture tubes containing 3 to 5 ml of test media, and takes weeks to complete at 24 or 28 °C. We improved the biovar test by using phenol red as a pH indicator that changes color at a higher pH when a carbohydrate is utilized. We also conducted the test at 32 °C in 0.2 ml of 8-tube strips that reduced the medium needed by at least 20 fold. Using the improved test, biovars of R. solanacearum strains can be determined in 4 days when a panel of seven carbohydrates is used including glucose, trehalose, mannitol, sorbitol, dulcitol, maltose and cellobiose. To differentiate biovars 1, 2, 3 and 4, the test can be further simplified and completed in 3 days using a panel of four carbohydrates containing glucose, trehalose, maltose and dulcitol, significantly saving money, space and time.     

Production of erythritol and mannitol by Yarrowia lipolytica yeast in media containing glycerol

Glycerol is a by-product generated in large amounts during the production of biofuels. This study presents an alternative means of crude glycerol valorization through the production of erythritol and mannitol. In a shake-flasks experiment in a buffered medium, nine Yarrowia lipolytica strains were examined for polyols production. Three strains (A UV'1, A-15 and Wratislavia K1) were selected as promising producers of erythritol or/and mannitol and used in bioreactor batch cultures and fed-batch mode. Pure and biodiesel-derived crude glycerol media both supplemented (to 2.5 and 3.25?%) and not-supplemented with NaCl were applied. The best results for erythritol biosynthesis were achieved in medium with crude glycerol supplemented with 2.5?% NaCl. Wratislavia K1 strain produced up to 80.0?g?l(-1) erythritol with 0.49?g?g(-1) yield and productivity of 1.0?g?l(-1)?h(-1). Erythritol biosynthesis by A UV'1 and A-15 strains was accompanied by the simultaneous production of mannitol (up to 27.6?g?l(-1)). Extracellular as well as intracellular erythritol and mannitol ratios depended on the glycerol used and the presence of NaCl in the medium. The results from this study indicate that NaCl addition to the medium improves erythritol biosynthesis, and simultaneously inhibits mannitol formation.     

Osmoprotectors in some species of Japanese mangrove macroalgae

The macroalgae asSociated with the mangrove vegetation of the Japanese Islands Okinawa, Ishigaki and Iriomote were investigated. The flora includes members of the red algal genera Bostrychia, Caloglossa and Catenella, as well as the brown alga Dictyotopsis propagulifera Troll, which may be considered typical of mangrove forests. The distribution of the low molecular weight carbohydrates sorbitol, dulcitol, mannitol and floridoside was studied in the mangrove algae. Their physiological role as osmoprotectors was assessed by investigating the effect of salinity on the intracellular sorbitol and dulcitol concentration in Bostrychia pinnata J. Tanaka et Chihara and on the mannitol content in D. propagulifera. In both species the polyol values increased with increasing salinity.     

Aerobactin production and dulcitol fermentation in clonal groups of Escherichia coli O1: K1 strains from urinary tract infections

Abstract 70 urinary Escherichia coli O1:K1 strains were characterized for O1 antigen factors, mannose-resistant hemagglutination of human erythrocytes, flagellar and fimbrial antigens, dulcitol fermentation and aerobactin production. On the basis of their O1 and H antigens the strains could be assigned to 6 distinct groups. The most prevalent groups were: O1abcd: H⁻ :F9 (33 strains; pattern II), O1abc: H⁻ :F11 (9 strains; pattern IV), and O1abc: H7: F11 (19 strains; pattern V). Strains with patterns IV and V, both expressing fimbrial antigen F11, fermented dulcitol and produced aerobactin, whereas strains with pattern II were negative for both characteristics.     

Characterization of two major groups of diarrheagenic Escherichia coli O26 strains which are globally spread in human patients and domestic animals of different species

Twenty-three Escherichia coli O26 strains from humans, cattle, sheep, pigs and chicken were investigated for virulence markers and for genetic similarity by pulsed field gel electrophoresis and multi locus sequence typing. Two groups of genetically closely related O26 strains were defined. One group is formed by enteropathogenic (EPEC) and enterohemorrhagic (EHEC) E. coli strains, which do not ferment rhamnose and dulcitol and most of these carry a plasmid encoding enterohemolysin. The other group consists of rhamnose and dulcitol fermenting EPEC strains, which carry plasmids encoding alpha-hemolysin. Multiple species of domestic animals were shown to serve as a reservoir for human pathogenic O26 EPEC and EHEC strains.     

Production of d-Tagatose from Dulcitol by Arthrobacter globiformis

A process for the bacterial oxidation of dulcitol to d-tagatose has been developed. The strain Arthrobacter globiformis ST48 used in this fermentation was isolated from soil. The yield of d-tagatose accumulated in the medium from dulcitol was as high as 85%. About 14 g of d-tagatose crystals was isolated from 1 liter of 2% dulcitol medium.     

Mannitol is required for asexual sporulation in the wheat pathogen Stagonospora nodorum (glume blotch)

The physiological role of the mannitol cycle in the wheat pathogen Stagonospora nodorum (glume blotch) has been investigated by reverse genetics and metabolite profiling. A putative mannitol 2-dehydrogenase gene (Mdh1) was cloned by degenerate PCR and disrupted. The resulting mutated mdh1 strains lacked all detectable NADPH-dependent mannitol dehydrogenase activity. The mdh1 strains were unaffected for mannitol production but, surprisingly, were still able to utilize mannitol as a sole carbon source, suggesting a hitherto unknown mechanism for mannitol catabolism. The mutant strains were not compromised in their ability to cause disease or sporulate. To further our understanding of mannitol metabolism, a previously developed mannitol-1-phosphate dehydrogenase (gene mpd1) disruption construct [Solomon, Tan and Oliver (2005) Mol. Plant-Microbe Interact. 18, 110-115] was introduced into the mutated mdh1 background, resulting in a strain lacking both enzyme activities. The mpd1mdh1 strains were unable to grow on mannitol and produced only trace levels of mannitol. The double-mutant strains were unable to sporulate in vitro when grown on minimal medium for extended periods. Deficiency in sporulation was correlated with the depletion of intracellular mannitol pools. Significantly sporulation could be restored with the addition of mannitol. Pathogenicity of the double mutant was not compromised, although, like the previously characterized mpd1 mutants, the strains were unable to sporulate in planta. These findings not only question the currently hypothesized pathways of mannitol metabolism, but also identify for the first time that mannitol is required for sporulation of a filamentous fungus.     

Biosynthesis of D-mannitol from D-glucose by Aspergillus candidus

Mannitol has long been known as a product of glucose metabolism by some strains of Aspergillus. Apparently no concerted effort, has been made to develop a practical fermentation process to make mannitol. Work at the Northern Laboratory has shown that nearly all strains of white Aspergillus produce significant amounts of mannitol; many strains of black Aspergillus also have this characteristic. Aspergillus candidus NRRL 305 is an exceptionally good mannitol producer. Studies on a fermentation process were conducted in 20-1, stainless steel fermentors, without baffles. Czapek-Dox medium, modified by addition of corn meal, yeast extract, and enzymatically hydrolyzed casein was the most satisfactory medium tested. Suitable increments of glucose were fed daily to the fermentors. The duration of the fermentation was from 10 to 16 days. The effects of agitation, aeration, temperature, and pH of the medium were studied. Under optimal conditions yields of mannitol approached 50% of the glucose consumed.     

Chemoattractant effects of sugars and their related compounds on black abalone Haliotis discus

The chemoattractant properties of sugars and their related compounds were statistically estimated on the basis of an exploratory behavior of black abalone Haliotis discus. Six monosaccharides, three disaccharides, six sugar alcohols, six glycosides and two artificial sweeteners were tested. The active compounds were: glucose and galactose (monosaccharides), maltose (disaccharides), sorbitol, mannitol, maltitol, dulcitol and erythritol (sugar alcohols), all the glycosides, and saccharin (artificial sweeteners). Maltose, dulcitol and particularly phyllodukin showed the highest activity. The chemoattractant properties of maltose and phyllodukin increased as concentrations increased. The activity of phyllodulcin was higher at all concentrations tested than that of maltose.     

Formation of glucose from hexoses, pentoses, polyols and related substances in kidney cortex

1. Slices of rat kidney cortex, on incubation in a saline medium, formed d-glucose from the following substances: d-fructose, d-galactose, d-mannose, l-sorbose, l-arabinose, d-xylose, glycerol, myo-inositol, l-iditol, sorbitol, xylitol, ribitol, methylglyoxal, dihydroxyacetone, l-glyceraldehyde, d-glyceraldehyde, dl-glyceraldehyde, dl-glycerate. Values for the rates of glucose formation from these precursors are given. 2. No glucose was formed from l-rhamnose, d-arabitol, d-arabinose, d-ribose, l-fucose, d-lyxose, mannitol, dulcitol, d-glucuronate, propane-1,2-diol and propan-2-ol. 3. The pathways of glucose formation from the various precursors are discussed (Scheme 1). 4. l-Glyceraldehyde inhibited the formation of glucose from d-glyceraldehyde.     

Carbohydrate Utilization by the Soil Amoeba Hartmannella castellanii

SYNOPSIS. Carbohydrate utilization by 9 strains of Hartmannella castellanii has been studied by growing the amoebae in a chemically defined medium which did not support growth without an added energy source. Strains differed in the utilization of sucrose, raffinose, melibiose and mannitol. The strains which did not use sucrose for growth were shown to metabolize this sugar: ¹⁴CO₂ was produced and ¹⁴C incorporated into TCA isoluble compounds when the amoebae were grown in the presence of radioactive sucrose.     

A clinical,pathological, and mycological study of a fatal case of histoplasmosis in an infant

Summary The clinical history of a fatal case of acute disseminated Histoplasmosis in a 3-month-old infant is described. A liver biopsy performed ante mortem revealed numerous encapsulated organisms which were identified at H.capsulatum. This suggests the applicability of this technique as a diagnostic tool. An autopsy showed extensive involvement, the organisms being found in the lungs, thymus, mediastinal and retroperitoneal nodes, liver, adrenals, spleen, and kidneys.A portion of emulsified liver was inoculated into Swiss mice andH. capsulatum was recovered from the mouse tissues 4 weeks after inoculation.A study was made of the cultural characteristic of this culture and it conformed to those previously described for other strains. A study of its fermentation properties disclosed no acid or gas production in media containing glucose, sucrose, lactose, maltose, mannose, rhamnose, trehalose, dulcitol, sorbitol, mannitol, and xylose.