bluuebunny/crossref_metadata_2025 huggingface dataset:
A note on antibiotic‐resistant Escherichia coli in adult man, raw sewage and sewage‐polluted River Tigris in Mosul, Nineva
Authors: Al‐Jebouri M. M. , Meshhadani Nariman S. Al ‐
Published: March 2008

A total of 600 isolates of Escherichia coli were isolated, over a 9 month period during 1984, from healthy human adults, raw sewage and the sewage‐polluted River Tigris in Nineva. Over 90% of these organisms were E. coli type 1, but only 8.3% could be serogrouped as enteropathogenic E. coli. Resistance of these organisms to 11 antimicrobial drugs was assessed. Over 40% were antibiotic‐resistant and of these 77.1% were resistant to more than one antibiotic. The minimal inhibitory concentration of ampicillin for 193 selected strains from the various sources was determined and ranged from <0.625‐ > 160 μg/ml. The high incidence of antibiotic‐resistant E. coli in this locality and the possible implications to human health are discussed.
Influence of temperature on the number of Legionella pneumophila in hot water systems
Authors: Groothuis D.G. , Veenendaal H.R. , Dijkstra H.L.
Published: March 2008

The occurrence of legionella in the hot water systems of two buildings (A and B) was investigated in relation to the water temperature. The peripheral parts of both hot water systems were found to be colonized by these organisms. A temperature of 60d̀C in the hot water mains returning from the building eliminated legionellas from the mains as well as from the peripheral taps and showers. Legionellas could be isolated from taps, showers and the mains when the temperature in the return mains was kept at 54d̀C. The hot water systems could not be completely decontaminated by raising the hot water temperature in the return mains to 70d̀C combined with flushing all the taps and showers. It is suggested that failure to decontaminate the systems is due to dead ends in the pipeline network, which are not reached by the hot water and that these dead ends are the source for recolonization of the systems.
The effect of plant alkaloids on in vitro rumen microbial fermentation
Authors: Silley P.
Published: March 2008

Crude alkaloid extracts from green Italian Ryegrass differed from those extracted from the ensiled grass with particular respect to the perloline moiety. Free perloline and crude alkaloid extracts from both silage and grass inhibited the production of volatile fatty acids in the fermentation of glucose by rumen microbes. With silage as fermentation substrate alkaloid extracts from silage and from grass (0.200 mg/l) caused a decrease in both substrate utilization (P< < 0.01) and proportion of methane in the gas phase (P< < 0.01). Molar proportions of acetate were also significantly decreased (P < 0.01) with a corresponding increase in the proportion of propionate (P < 0.01). These effects were not observed when grass nuts were used as the fermentation substrate. The results suggest that it is not the alkaloids per se that affect rumen microbial metabolism.
Sclerotium cepivorum Berk. in onion (Allium cepa L.) crops: isolation and characterization of bacteria antagonistic to the fungus in Queensland
Authors: Wong W. C. , Hughes I. K.
Published: March 2008

Bacteria antagonistic to the fungal pathogen Sclerotium cepivorum Berk., which causes onion white rot disease, were isolated and characterized. Eighty percent of the bacterial antagonists isolated from soil samples and sclerotia of S. cepivorum recovered from soil were identified as belonging to the genus Bacillus. The other antagonists were coryneforms and Pseudomonas spp. In contrast, 90% of the antagonists isolated from onion roots were mostly Pseudomonas spp. and the remainder were Erwinia spp. The significance of these antagonistic bacteria is discussed in relation to the control of white rot disease of onion.
A rapid method for identifying and quantifying soft rot erwinias directly from plant material based on their temperature tolerances and sensitivity to erythromycin
Authors: Perombelon M. C. M. , Hyman L. J.
Published: March 2008

A method is described for identifying and quantifying three soft rot erwinias directly from plant tissue and from other sources that is particularly useful in epidemiological studies. Colonies of these bacteria form characteristic deep cavities on selective‐diagnostic crystal violet pectate (CVP) medium. Bacteria from individual presumptive erwinia colonies on CVP plates spot inoculated on plates of CVP medium with or without erythromycin (35 μg/ml) added and incubated at 27, 33°5 and 37°C can be identified according to the pattern of cavity formation. Erwinia carotovora pv. atroseptica forms the characteristic cavities only at 27°C and E. carotovora pv. carotovora at 27 and 33.5°C but not at 37°C on CVP with or without erythromycin. Erwinia chrysanthemi forms cavities at all temperatures and can also be identified by failure to grow at 27°C on CVP with erythromycin. Similarly, erwinias in mixed populations can be quantified by dilution plating on CVP with or without erythromycin and incubating at the different temperatures. Using this method, ca 80% of 183 erwinia strains in a culture collection were correctly identified, the precision increasing to over 95% when recently isolated erwinia strains were examined.
Water relations and metabolism of propionate in two yeasts from hay
Authors: Magan N. , Lacey J.
Published: March 2008

Many yeasts and bacteria were isolated from moist hays (>30% water content) treated with up to 3% propionic acid‐based preservatives. Predominant yeasts were Candida guilliermondii var. guilliermondii and Hyphopichia burtonii. Growth of both species was decreased more than 50% in liquid medium containing 54 mmol/l ammonium propionate but some still occurred in 135 mmol/l propionate. Both metabolized between 80 and 85% of 27 mmol/l ammonium propionate in 1% malt broth within four weeks at 25°C. Growth on solid malt extract agar containing ammonium propionate was decreased by decreasing the water availability (water activity, aw) in the medium. Growth rates were slightly greater when glycerol rather than NaCl was used to alter aw in the range 0.995 to 0.93. At both 0.995 and 0.95 aw optimum growth was at pH 6. The significance of these findings with regard to the preservation of moist hay is discussed.
The effects of two ammonium propionate formulations on growth in vitro of Aspergillus species isolated from hay
Authors: Magan N. , Lacey J.
Published: March 2008

The efficacy of fully neutralized (AP) and half‐neutralized ammonium propionate (H‐AP) against growth of a number of Aspergillus spp. was determined in vitro on malt extract at different levels of water availability in the range 0.995–0.85 aw (water activity) (= 40–25% water content of hay). In general, Aspergillus flavus, A. fumigatus, A. nidulans, A. niger and A. versicolor were more sensitive to the H‐AP in the range 0.995–0.95 aw than to AP. At 0.90 and 0.85 aw growth of most species occurred in the absence of chemicals but only of a few species in 27 mmol/l AP. All three members of the A. glaucus group tested, A. amstelodami, A. repens and A. sejunctus, were similarly more sensitive to H‐AP over the aw range 0.95–0.85 than to AP. Aspergillus sejunctus was most tolerant, growing in 27 mmol/l H‐AP and 54 mmol/l AP at 0.85 aw. The number of days for growth initiation in 27 mmol/l H‐AP was greater than with AP at different levels of water availability and reflected the different effects of the two chemicals on growth rate.
Bacteriophages and indicator bacteria in human and animal faeces
Authors: Havelaar A. H. , Furuse K. , Hogeboom W. M.
Published: March 2008

In an attempt to explain the presence of F‐specific (RNA) bacteriophages in waste‐water, faecal material from humans and a variety of animals was examined. The phages were detected in appreciable numbers only in faeces from pigs, broiler chickens, sheep and calves but not from dogs, cows, horses and humans. Parallel examinations for somatic coliphages, thermotolerant coliforms, faecal streptococci and spores of sulphite‐reducing clostridia revealed the consistent presence of these organisms in all types of samples, albeit in variable numbers. The number of F‐specific bacteriophages was related to the total number of somatic coliphages, but phage counts were unrelated to bacterial counts. F‐specific RNA phages were grouped by serotyping and all animal isolates were found to belong to either group I (MS2 subtype) or IV (four different subtypes). Among the group IV isolates, most belonged to well‐known subtypes SP (24 isolates) or FI (18 isolates) but five isolates were related to phage ID2 and one isolate was a new subtype. In contrast with animal isolates, 19 isolates from hospital wastewater belonged to serogroups II or III.
Estimation of Gram‐negative bacteria in milk: A comparison of inhibitor systems for preventing Gram‐positive bacterial growth
Authors: Phillips J. D. , Griffiths M. W.
Published: March 2008

A number of inhibitor systems which have been reported to allow selection of Gram‐negative bacteria were tested against Gram‐positive and Gram‐negative isolates of dairy origin. No one system worked perfectly. A mixture of crystal violet‐penicillin‐nisin or monensin had least inhibitory effect on Gram‐negative isolates whereas Selectocult (a commercially available mixture of Benzalkon A 50% and crystal violet) and sodium deoxycholate were the most effective inhibitors of Gram‐positive bacteria. Cetrimide‐fucidin‐cephaloridine solutions, which have been reported as allowing selective growth of pseudomonads, were not so specific when applied to milk systems.
Survival and growth of Bacillus cereus in bread
Authors: Kaur P.
Published: March 2008

Bread doughs were artificially inoculated with spores of six Bacillus cereus strains at different inoculum levels and counts of survivors in bread determined during storage at 27·5°C. No B. cereus were isolated from the centre crumb of 400 g loaves when the dough contained less than 104 spores/g whereas with 800 g loaves survival occurred with doughs containing 5·0 times 103 spores/g. With all strains there was a period of at least 24 h before multiplication took place in the bread. The inclusion in dough of 0·2% of calcium propionate, based on flour, effectively delayed germination and subsequent multiplication of B. cereus spores. It is concluded that the risk of food poisoning due to the presence of B. cereus in bread is minimal.
Scanning electron microscopy preparation methods: their influence on the morphology and fibril formation in Pseudomonas fragi (ATCC 4973)
Authors: Fraser T. W. , Gilmour A.
Published: March 2008

The use of cryo‐scanning electron microscopy (cryo‐SEM) in the study of the morphology of Pseudomonas fragi (ATCC 4973) revealed gross differences when compared to material prepared using conventional chemical methods. Changes associated with each step of the chemical preparatory procedure were monitored by cryo‐SEM. It appeared that fibril formation was associated with the ethanol dehydration stage of the chemical preparation method and was not an attachment feature of these cells.
Cross‐point determination of Penicillium conidia—Characterization of closely related fungi
Authors: Ström G. B.
Published: March 2008

The cross‐points of conidia of Penicillium piceum were determined by partition in aqueous two‐phase systems. No differences in cross‐points or partition behaviour were registered for conidia subjected to u.v. radiation, 95°C dry heat or 120°C wet heat, compared with untreated conidia. The cultivation of fungi on various types of substrates affected the surface characteristics and thereby the cross‐points of the conidia. When the method was applied to three closely related and morphologically similar isolates in the P. viridicatum group, significant differences were observed between the range of cross‐points for conidia of P. crustosum, P. camembertii group II and P. camembertii group III grown on various media.
Growth and enterotoxin A production by Staphylococcus aureus S6 in Manchego type cheese
Authors: Gomez‐Lucia E. , Blanco J. L. , Goyache J. , Fuente R. de La , Vazquez J. A. , Ferri E. F. R. , Suarez G.
Published: March 2008

(from cow, goat and sheep) was inoculated with Staphylococcus aureus strain S6, which is generally considered to be a strong enterotoxin B producer and a weak enterotoxin A producer. It was then used to make Manchego type cheese as prepared industrially. Two concentrations of starter culture (1% and 0.1%) were tested. Staphylococcal growth was good in both but better in the more dilute culture. Staphylococcal enterotoxin B was not detected at any stage of the ripening process of any cheese tested. However enterotoxin A was detected in both starter concentrations, reaching as high as 769 ng/100 g of cheese in the 0.1% starter batches.
A tentative national reference procedure for isolation and enumeration of Escherichia coli from bivalve molluscan shellfish by most probable number method
Authors: West P. A. , Coleman Michelle R.
Published: March 2008

In the UK several quantitative methods exist for the examination of bivalve molluscan shellfish for sewage contamination. These methods include roll tubes, pour plates and most probable number (MPN) techniques, but there is no national standard method. A comparative study was made of the most commonly used methods for detection of Escherichia coli in bivalve shellfish. Schemes employing solid media, such as the roll tube and pour plate methods, underestimated faecal contamination in shellfish tissue compared with a liquid MPN multiple test‐tube method using minerals‐modified‐glutamate broth (MMGB) as primary enrichment medium. The composition of MMGB apparently permits repair of sublethally injured cells of E. coli. Incorporation of resuscitation stages into the pour plate technique did not yield higher counts. A standardized MPN technique for examination of bivalve molluscan shellfish for E. coli content is proposed as a possible national reference procedure pending further collaborative assessment.
The enumeration of thermotrophic types amongst the Enterobacteriaceae colonizing perishable foods
Authors: Mossel D. A. A. , Zee H. Vander , Haroon A. P. , Netten P. Van
Published: March 2008

A total of 41 pure cultures of Enterobacteriaceae, comprising 32 thermotrophic and nine psychrotrophic strains, pathogens or marker organisms, were examined for numbers of colony forming units obtained at 37° and 42°5°C (thermotrophs) and 30°C (psychrotrophs), when surface‐plated on a rich infusion agar and violet red bile agar. In addition 42 food and water samples, collected in a rural area of the Philippines, were examined by surface inoculating violet red bile AIPC (agar immersion plating and contact; ‘dip’) slides and incubating at 37° and 42°5°C. At 42°5°C there was almost total recovery of the thermotrophic Enterobacteriaceae, whereas the psychrotrophic strains were completely suppressed. At 37°C the psychrotrophs were only slightly inhibited. The Philippine foods, predominantly cooked meals, milk and drinking water, appeared to be significantly colonized by thermotrophic Enterobacteriaceae. It is concluded that incubation at 42°5°C satisfactorily selects enteropathogenic and other enteric Enterobacteriaceae while suppressing the psychrotrophic types which are mainly of vegetable origin. It is emphasized that, regardless of the temperature used, a resuscitation procedure for Enterobacteriaceae populations that have incurred sublethal injury in food has to precede counts on or in the usual selective media.
A note on symbiosis of Legionella pneumophila and Tatlockia micdadei with human respiratory flora
Authors: Stout Janet E. , Best Michele G. , Yu V. L. , Rihs J. D.
Published: March 2008

Sixteen micro‐organisms, representing clinically important respiratory microflora, were tested for their ability to stimulate the growth of Legionella pneumophila and Tatlockia micdadei in nutritionally‐deficient agar media. Nutritional symbiosis, indicated by the appearance of satellite colonies of L. pneumophila or T. micdadei, was observed for H. influenzae and N. meningitidis. This interaction between normal flora and pathogens of the respiratory tract may have clinical relevance in the pathogenesis of Legionnaires' disease and Pittsburgh pneumonia.
Inhibition of hyphal development and kill of Candida albicans blastospores by noxythiolin in vitro
Authors: Gorman S. P. , Mccafferty D. F. , Woolfson A. D. , Anderson L.
Published: March 2008

The cidal activity of the antimicrobial agent, noxythiolin, was investigated against a laboratory strain and a fresh isolate of Candida albicans. The order of resistance to noxythiolin was hyphal form (isolate) ≥ 25°C‐grown blastospores (isolate) ≥ 37°C‐grown blastospores (isolate) > laboratory strain blastospores. Noxythiolin activity was superior to that of ‘equivalent’ formaldehyde concentrations. Mycelial transformation in C. albicans was examined by light and scanning electron microscopy and measured in terms of percentage germination and hyphal extension. Noxythiolin, 2·5%, in contact for 30 min prevented germination of the blastospore population whereas the decomposition products, formaldehyde and N‐methylthiourea, showed no appreciable effect in the expected concentrations. The implications of these results are discussed in relation to the observed clinical efficacy of noxythiolin.
A note on survival of salmonellas during anaerobic digestion of cattle dung
Authors: Gadre R. V. , Ranade D. R. , Godbole S. H.
Published: March 2008

Anaerobic digestion of night soil with cattle dung slurry in biogas plants is advocated in Indian villages as a means of disposal of human excreta in the absence of conventional sanitary systems. Although intestinal pathogens are likely to be eliminated during anaerobic digestion, there is no conclusive evidence that this is so. Large numbers of saprophytic organisms in the fermenting mass make it impossible to detect the residual pathogens. Use of an antibiotic‐resistant strain of Salmonella typhimurium as a test organism to study its survival during anaerobic digestion showed that the organism is totally eliminated in nine days.
A comparative study of the rod and coccoid forms of Campylobacter jejuni ATCC 29428
Authors: Moran A. P. , Upton Mary E.
Published: March 2008

Coccoid forms in cultures of a strain of the enteric pathogen Campylobacter jejuni were investigated. A culture containing 100% coccoid forms was non‐viable. Coccoid forms had a lesser content of cytoplasmic components and nucleic acids than rods of C. jejuni. During the conversion to coccoid forms nucleotides leaked from the cells. The results of treatments with ionic and non‐ionic detergents, and lysozyme and ethylenediaminetetraacetic acid indicated a changed cell wall in coccoid forms compared with rods. Using rate‐zonal centrifugation coccoid forms were found to be less dense than rods. The results of this study indicate that the coccoid form of C. jejuni ATCC 29428 is a degenerate cell form which is undergoing cellular degradation.
Effects of dietary chlortetracycline on the antimicrobial resistance of porcine faecal streptococcaceae
Authors: Molitoris E. , Krichevsky M. I. , Fagerberg D. J. , Quarles C. L.
Published: March 2008

Breeding pigs and one‐half of their progeny were fed antimicrobial‐free rations; the other half of the progeny received rations supplemented with 100 g of chlortetracycline (Ctc)/ton. Effects of dietary Ctc with respect to the distribution of species and biotypes of faecal Gram‐positive cocci and their relative resistance to 12 antimicrobial agents were studied. Diversity of antimicrobial resistance (AMR) patterns and modal AMR patterns were determined for bacterial species common to all three groups. Numerical taxonomic analysis placed 1140 of 1150 isolates (99%) into 10 groups. Three of these were biotypes of Streptococcus faecium and contained the largest number of isolates (n= 934, 81%). Streptococcus faecalis, Strep. morbillorum, Pediococcus halophilus and Gemella haemolysans also were isolated. Generally, the proportion of tetracycline‐resistant strains for a species or biotype was greater from pigs fed Ctc, although differences were not significant (P > 0.05). There was a significant difference (P > 0.05) among all the groups for the percentage of penicillin‐resistant strains in a biotype of Strep. faecium. Overall, 57 and 43 different AMR patterns, including 2 to 11 and 1 to 11 resistance determinants, were demonstrated in isolates from control pigs and pigs fed Ctc, respectively. Modal AMR patterns in species and biotypes were the same from both progeny groups, except for Strep. faecium. AMR pattern diversity was decreased for strains from pigs fed Ctc. Similar proportions of resistant strains from each group of progeny pigs were accompanied by decreased AMR pattern diversity in strains from pigs fed Ctc. These results indicated a change in distribution of AMR phenotypical patterns, rather than a change in overall frequency of individual resistant phenotypes.
Comparison of Muller‐Kauffmann tetrathionate broth with Rappaport‐Vassiliadis (RV) medium for the isolation of salmonellas from sewage sludge
Authors: Rhodes P. , Quesnel L. B.
Published: March 2008

The Rappaport‐Vassiliadis (RV, modification of Rappaport's) medium was superior to Muller‐Kauffmann tetrathionate broth (MKT) for the enrichment and isolation of salmonellas from sewage sludge samples, either naturally contaminated or artificially inoculated with salmonella. Isolation rates for RV (42°C) were higher even when MKT (43°C) performance was improved by the use of brilliant green sulphamandelate agar. Kinetic results show that the suppression of the competing flora was poorer in MKT than in RV. The use of high inoculum to medium volume ratios (e.g. 1:5000) increased the isolation rates from RV and kinetic data explain why this was so.
Studies of symbiotic plasmids in Rhizobium trifolii and fast‐growing bacteria that nodulate soybeans
Authors: Buendia‐Claveria A. M. , Ruiz‐Sainz J. E. , Cubo‐Sanchez T. , Perez‐Silva J.
Published: March 2008

The Rhizobium trifolii symbiotic plasmid pRt5a was transferred to the fast‐growing soybean strain USDA 194. Transconjugants carrying pRt5a were not able to nodulate clovers and one of the transconjugants had lost its smallest resident plasmid and did not fix nitrogen in soybean. Transconjugants of USDA 194 carrying pRt5a were able to transfer pRt5a back to a non‐nodulating R. trifolii which inherited the symbiotic properties of the R. trifolii strain from which the plasmid was derived.
Numerical taxonomy of proteolytic psychrotrophs from Queensland raw milks
Authors: O'Connor R. E. , Ewings K. N. , Hayward A. C. , O'Rourke P. K.
Published: March 2008

Eighty‐seven proteolytic psychrotrophic micro‐organisms were isolated from 11 bulk milk supplies of two Queensland factories from different climatic regions, before and after storage at 4°C for 7 d. These isolates together with 15 reference strains formed the basis of a numerical taxonomic study involving 81 attributes. All but six isolates were pseudomonads. The strains clustered into nine groups, of which one group consisted of four yeasts. One group, containing 39 isolates, was designated asPseudomonas fluorescensbiovar 1; three groups, containing 27 isolates, asPs. fluorescensbiovar 5; and one group, containing 10 isolates, asPs. putidabiovar A. This study showed that the proteolytic psychrotrophic microflora of the 11 milks supplying the two factories was substantially different and that the proteolytic flora of 7 d refrigerated milk could not be estimated by examining the flora before storage.
Laboratory studies on salmonella‐contaminated cheese involved in a major outbreak of gastroenteritis
Authors: Ratnam S. , March Sandra B.
Published: March 2008

A major outbreak of gastroenteritis was traced to Cheddar cheese contaminated with Salmonella typhimurium. There were no significant differences in pH values of the contaminated (mean pH 5·31) and non‐contaminated (mean pH 5·39) cheese. The isolation rates of Salm. typhimurium were about the same when cheese samples were homogenized in lactose broth, lactose broth containing 1% Tween 80, or in aqueous 2% sodium citrate. Salmonella typhimurium was isolated regardless of preenrichment in lactose broth, but required selective enrichment in selenite cystine or tetrathionate brilliant green broth. There were no marked differences in the isolation rates obtained with different selective enrichment media, or after incubation at 36° and 43°C for 24 or 48 h. Contaminated samples of cheese failed to yield Salm. typhimurium consistently despite large and multiple samplings; samples from the interior of cheese blocks yielded positive results more frequently than the samples from the exterior. The number of Salm. typhimurium in factory sealed blocks as well as in samples obtained from the homes of known cases of salmonellosis was found to range from < 3/100 g to 9/100 g of cheese. The infective dose of Salm. typhimurium in contaminated cheese was probably no greater than 104 organisms, and a rapid decline in numbers of Salm. typhimurium must have occurred subsequent to the outbreak.
Partial purification, characterization and regulation of cellulolytic enzymes from Trichoderma longibrachiatum
Authors: Kalra M. K. , Sidhu M. S. , Sandhu D. K.
Published: March 2008

A net purification of 9·46‐, 18·6‐ and 16·7‐fold for filter paper (FP) hydrolytic activity, carboxymethyl (CM) cellulase and β‐glucosidase, respectively was achieved through ion exchange and gel chromatographies. The purified enzyme preparation showed an optimal pH of 5·0 for CM cellulase and 5·5 for the other two components. The enzyme activities increased up to 60°–65°C for the three enzyme components and they were stable at 30° or 40°C and pH 4·5 to 5·0 after 20–30 min treatment. The four enzyme components, that is, two FP activities (unadsorbed and adsorbed), a CM cellulase and a β‐glucosidase, had Km values of 47·6 mg, 33·3 mg, 4·0 mg and 0·18 mmol/l with Vmax of 4, 1·28, 66·5 and 1·28 units per mg protein. The molecular weights as determined with SDS‐PAGE were found to be 44000, 38000, 55000 and 63000 for the above four enzyme components in the same sequence. A distinct type of synergistic action was observed between these components by their action on dewaxed cotton. Glycerol at 1% strongly repressed the formation of all the cellulolytic enzymes. The role of proteolytic enzymes in in vitro inactivation of cellulases was not apparent.
Techniques for the optimum recovery of cold injured Campylobacter jejuni from milk or water
Authors: Humphrey T. J.
Published: March 2008

When broth was inoculated with cells of Campylobacter jejuni that had been injured by chilling there was a fall in the viable population of up to 90%. It was greater at 43° than 37°C and in the presence of certain antibiotics and in some cases resulted in a surviving population that was below the minimum inoculum for subsequent growth. A technique of pre‐enrichment in non‐selective culture broth at 37°C for 2 h before the addition of antibiotics and incubation at 43°C was found to significantly reduce the fall in numbers and to improve the detection of C. jejuni in samples of raw milk and water.
The toxicity of potassium tellurite to Staphylococcus aureus in rabbit plasma fibrinogen agar
Authors: Sawhney D.
Published: March 2008

The potassium tellurite concentration, 0.01% w/v, in Baird‐Parker agar has been recommended for plasma coagulase media such as pig or rabbit fibrinogen agar. Comparative tests have shown that with some strains of Staphylococcus aureus this level of potassium tellurite is too inhibitory and it should be reduced four‐fold to 0.0025% w/v to maximize the isolation rate. It is postulated that egg yolk in Baird‐Parker agar has a protective effect on staphylococci against the inhibitory action of tellurite.
Occurrence of fungal‐inhibiting Pseudomonas on caryopses of Tripsacum dactyloides L. and its implication for seed survival and agriculture application
Authors: Anderson R. C. , Liberta A. E.
Published: March 2008

Pseudomonas bacteria capable of inhibiting maize fungal pathogens were isolated from caryopses of three of 11 populations of eastern gamagrass (Tripsacum dactyloides) collected from eastern and central United States. The bacteria inhibited fungal pathogens in pure cultures and a zone of fungal inhibition 1–2 cm wide occurred around surface sterilized maize kernels that were treated with the bacteria and placed in culture dishes containing 2% maize meal agar. In cold‐soil germination tests, there were no significant (P < 0.05) differences in germination of scarified maize kernels that were treated with gum arabic (sticking agent) and one of the bacterial strains (98%) or the commercial fungicide, Captan (96%). Both of these treatments resulted in significantly higher germination than scarification (50%) or scarification and gum arabic alone (58%). Non‐scarified controls had 85% germination. The results indicate that Pseudomonas may be effective in preventing invasion of damaged seeds by pathogens capable of inhibiting germination and destroying seed embryos.
Rapid method for the detection of Group B streptococci from human sources
Authors: Jewes Linda A. , Jones Dorothy
Published: March 2008

A modification of the classical CAMP test has been devised for the rapid detection of streptococci of serological Group B from human sources. The method was compared with detection based on the development of orange pigmented colonies on a starch‐based medium and with detection by conventional methods. In a survey of vaginal carriage of Group B streptococci in parturient women, the modified CAMP test detected a carriage rate of 13.09%, the starch‐based, pigment enhancing medium, 5.76% and the conventional methods, 8.38%. It proved to be particularly useful for detecting the organisms in the presence of other bacteria.
Cellulase biosynthesis during degradation of cellulose derivatives by Thermomonospora curvata
Authors: Stutzenberger F. , Kahler G.
Published: March 2008

A variety of commercially used cellulose derivatives were compared with crystalline cellulose as substrates for induction of cellulase biosynthesis in the actinomycete Thermomonospora curvata. Cellulase induction during growth on uncoated cellophane was as rapid as that on crystalline cellulose, but on coated cellophanes, induction was delayed. Susceptibility to enzymatic attack determined the inductive potential of the substrate. Cellulose acetate was a poor substrate because of its extreme recalcitrance to attack. With other cellulose derivatives, soluble sugar accumulation caused a transient repression of cellulase biosynthesis, but the ratio of cellobiose (a cellulase inducer) to glucose (a cellulase repressor) was not a controlling factor. Crystalline cellulose yielded the lowest inducer/repressor sugar ratio (1.1:1 compared to 3.8–4.0:1 for cellulose derivatives), but supported the highest cellulase production. Glucose could not repress cellulase biosynthesis in the presence of cellobiose due to the strong preference for uptake of the disaccharide even by glucose‐grown cells.
Genetic factors in Rhizobium affecting the symbiotic carbon costs of N2 fixation and host plant biomass production
Authors: SKØT L. , Hirsch P. R. , Witty J. F.
Published: March 2008

The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different genomic backgrounds. The resulting strains were tested in symbiosis with plants of Pisum sativum using a flow‐through apparatus in which nodule nitrogenase activity and respiration were measured simultaneously under steady state conditions. Nodules formed by strains containing the background of JI6015 had the lowest carbon costs of N2 fixation (7.10–8.10 μmol C/μmol N2), but shoot dry weight of those plants was also smaller than that of plants nodulated by strains with the background of B151 or JI8400. Nodules formed by these two strain types had carbon costs of N2 fixation varying between 11.26 and 13.95 μmol C/μmol N2. The effect of symbiotic plasmids on the carbon costs was relatively small. A time‐course experiment demonstrated that nodules formed by a strain derived from JI6015 were delayed in the onset of nitrogenase activity and had a lower rate of activity compared to nodules induced by a strain with the background of B151. The relationship between nitrogenase activity, carbon costs of N2 fixation and host plant biomass production is discussed.
Immunodiffusion analysis shows that Mycobacterium paratuberculosis and other mycobactin‐dependent mycobacteria are variants of Mycobacterium avium
Authors: McIntyre G. , Stanford J. L.
Published: March 2008

Antigenic analysis by immunodiffusion has been applied to 74 strains of mycobactin‐dependent mycobacteria. Thirty‐eight strains were of Mycobacterium paratuberculosis from cases of Johne's disease of cattle or goats. The remaining cultures were obtained from a variety of animals and included the wood pigeon bacillus. Rabbit antisera were raised to some of the strains and these, together with antisera to M. avium and M. intracellulare, were used to examine sonicate preparations of all the cultures. All were found to be antigenically identical with M. avium and none were found to belong to M. intracellulare. A predominance of the cultures from Johne's disease belonged to the potential brunense subspecies of M. avium, and the remainder together with the majority of the other mycobactin‐dependent strains belonged to the type subspecies. In view of these findings the separate species status of M. paratuberculosis is refuted and some difficulty remains in the nomenclature of strains giving rise to Johne's disease.
The identification ofPseudomonas cepaciaand its occurrence in clinical material
Authors: Holmes B.
Published: March 2008

During the 19 year period ending December 1984, 4840 strains of Gram‐negative non‐fermentative bacteria were submitted to the National Collection of Type Cultures for identification. Of these, 195 strains (4·0% of the total) were identified asPseudomonas cepaciawhich demonstrates both that the species is regularly encountered in clinical material in the UK and that several laboratories have experienced difficulty in identifying the organism. The sources from which the 195 strains were isolated are reported and also the characteristics by which the species may be recognized. The clinical significance ofPs. cepaciais reviewed, and the resistance of this species to disinfectants and antimicrobial agents commonly used to treat pseudomonas infections is discussed to underline the necessity for the precise identification ofPs. cepacia.
A note on the use of cross‐linked starch in microbiology with special reference to detecting amylase production
Authors: Modi D. C. , Bhatt Y. B. , Shaikh M‐K. G. , Subramanyam V. R. , Dias F. F.
Published: March 2008

Anilogel‐E, a cross‐linked starch, can be used with distinct advantages where native starch or soluble starch are conventionally used, e.g. in scoring for amylolytic organisms, as an ingredient of fermentation media, and in enhancing protoplast regeneration. It is particularly useful for the direct visualization of amylase producing micro‐organisms on solid media, making prior replication of colonies unnecessary.
Effect of ascorbic, isoascorbic and dehydroascorbic acids on the growth and survival of Campylobacter jejuni
Authors: Juven B. J. , Kanner J.
Published: March 2008

Ascorbic acid (AsA), added to nutrient broth at a concentration of 5 mmol/l, was bactericidal towards Campylobacter jejuni grown at 42°C in a micro‐aerobic atmosphere. Specific enzymes, radical scavengers, metal chelators and reducing agents were tested as possible antagonists to the cytotoxicity of AsA. The addition of catalase or of the metal chelators ceruloplasmin or Desferal did not prevent the cytotoxic effect of AsA. The addition of the hydroxyl radical scavengers mannitol. formate, histidine or DMSO also failed to counteract the toxicity of AsA. On the other hand, thiourea or cysteamine and the reducing agents cysteine or dithionite significantly increased the recovery of C. jejuni in the presence of AsA. Although the possibility of the involvement of hydroxyl radicals in AsA cytotoxicity cannot be ruled out, it appears that the toxic effect of AsA is due mostly to the formation of products of oxidation of AsA and particularly to dehydroascorbic acid (DHA). Dehydroascorbic acid was also bactericidal to C. jejuni at a concentration of 5 mmol/l. Of all the compounds tested, only cysteamine was effective in preventing (partially) the toxic effect of DHA. The growth of C. jejuni was not inhibited by the addition of 5 mmol/l of isoascorbic acid or sodium isoascorbate.
The use of a model system to compare the efficiency of ultrasound and agitation in the recovery of Bacillus subtilis spores from polymer surfaces
Authors: Dewhurst E. , Rawson D. M. , Steele G. C.
Published: March 2008

The effectiveness of ultrasound and mechanical agitation for the recovery of Bacillus subtilis spores from pre‐inoculated glass, polystyrene, polypropylene, polyethylene and polycarbonate surfaces was tested in the presence and absence of surfactant. Recovery from polymers was improved by the use of surfactant. Simple agitation, as frequently used in bioburden determination, is shown to be a poor method for the recovery of spores from hard surfaces. The use of ultrasound achieves recoveries over 90% only with glass, recoveries from polymers ranging from 40%–75%. Recoveries from polypropylene and polycarbonate showed poor reproducibilities. Agitation with Ballotini beads improved the reproducibility of recoveries from polymers and also in the majority of cases improved recovery levels.
Isolation and characterization of aerobic heterotrophic bacteria from natural spring waters in the Lanjaron area (Spain)
Authors: Quevedo‐sarmiento Jorgina , Ramos‐cormenzana A. , Gonzalez‐lopez J.
Published: March 2008

Aerobic, heterotrophic bacteria were isolated from nine natural mineral water springs in the Lanjaron area of Spain over the period July 1980 to May 1981. The mineral waters contained few bacteria (mean counts 26–5275 cfu per 100 ml) and the bacterial flora of all nine springs was very similar. Most of the isolates were Gram‐negative rods (90%), and among these Pseudomonas spp. and members of the Flavobacterium‐Cytophaga‐Flexibacter group were numerically dominant. Aeromonas‐Vibrio and Enterobacteriaceae isolates were an important fraction of the total number, but isolates from remaining groups (Acinetobacter, Chromabacterium, Alcaligenes and Gram‐positive organisms) constituted only a small proportion of the flora. The comparatively small number of species isolated, and the occurrence of no more than three or four different bacterial types in spring water of different chemical and physical composition is discussed.
Growth of lipolytic psychrotrophic pseudomonads in raw and ultra‐heat‐treated milk
Authors: Shelley A. W. , Deeth H. C. , MacRae I. C.
Published: March 2008

The lipolytic floras of 36 raw milk samples showing lipolytic defects were dominated by pseudomonads. Representative lipolytic isolates were selected and tested for growth, lipase activity and lipolysis in ultra‐heat‐treated milk at temperatures ranging from 5° to 30°C. Pseudomonas fluorescens was the most frequently encountered species but Ps. fragi was found to cause more severe lipolytic defects in both single and mixed strain milk cultures. A representative strain of Ps. fragi multiplied faster in cold‐stored milk than did three representative strains of Ps. fluorescens. The lipases produced by Ps. fragi strains were more heat‐stable than those produced by Ps. fluorescens strains.
A note on the effect of nitrogen source on growth of and solvent production by Clostridium acetobutylicum
Authors: Welsh F. W. , Williams R. E. , Veliky I. A.
Published: March 2008

A number of mono‐ and dicarboxylic acid amino acids, amides and inorganic ammonium sources were tested to determine their effect on the growth of and solvent production by Clostridium acetobutylicum ATCC 824. Optimum cell growth (A650= 0.96) and solvent production (total solvents = 10.85 g/l) were obtained with the medium containing glutamic acid as the ammonium source. Similar results were obtained through three successive serial subcultures although changes in the fermentation were noted with the third subculture. Cell growth and solvent production fell after the second subculture when ammonium acetate was used as the ammonium source. Adaptation was shown to occur in a medium which contained asparagine.
The toxicity of a number of different bactericides to Clavibacter michiganense subsp. michiganense (Smith 1910) Jensen 1934 comb. nov. [basonym Corynebacterium michiganense pv. michiganense (AL)] and to the tomato plant, Lycopersicon esculentum
Authors: Thompson E. T.
Published: March 2008

Twenty‐seven proprietary products and pure chemicals were tested in vitro against cells of Clavibacter michiganense subsp. michiganense (Smith 1910) Jensen 1934 comb. nov. [basonym Corynebacterium michiganense pv. michiganense (AL)] (the cause of bacterial canker of tomato) and also for their phytotoxicity to tomato plants. The most bactericidal of these, with a minimum cidal concentration (MCC) range of > 10‐< 100 μg/ml, were a phenolic product called Applied 3–78, two quaternary ammonium compounds (benzalkonium chloride and cetrimide), and a silver colloid compound. Of these, only Applied 3–78 was not phytotoxic at values of 10 μg/ml or less, although it was phytotoxic at 10000 μg/ml. Copper oxychloride and sodium hypochlorite were amongst the group with a middle range of bactericidal properties, their MCC range being from > 1000 to < 10000 μg/ml. They were phytotoxic at 1000 μg/ml or less. When organic matter, a dead yeast suspension, was added to Applied 3–78, Kohrsolin and Panacide, only the activity of Applied 3–78 was relatively unchanged. The MCC ranges were: Applied 3–78, >80–< 100 μg/ml; Kohrsolin, > 800‐< 1000 μg/ml; and Panacide, > 1000 μg/ml. Phytotoxicity tests on 10 different tomato cultivars confirmed that Applied 3–78 was the least phytotoxic of these three products. Field trials on tomato crops showed that when Applied 3–78 was sprayed on the plants once, and Kohrsolin was either sprayed on or they were drenched with it once at 1000 μg/ml, no phytotoxicity symptoms developed.
The plasma membrane of Streptococcus cremoris: isolation and partial characterization
Authors: Rimpiläinen Marja A. , Niskasaari Kaarina , Juutinen Katri M. S. , Nurmiaho‐Lassila Eeva‐Liisa , Forsean Raili I.
Published: March 2008

Plasma membrane was isolated from Streptococcus cremoris using mutanolysin from a streptomycete as the cell wall‐degrading enzyme and phenylmethylsulfonyl fluoride as protease inhibitor. The specific activity of membrane‐bound enzyme, adenosine triphosphatase (ATPase), was 4 μmol/mg protein per min, which was 5–10 times higher than the activity found in other fractions obtained during the isolation procedure. The number of polypeptides in the plasma membrane was approximately 50 with molecular weights 13 500–100 000, minor changes in the polypeptide pattern were observed when the plasma membrane was isolated without a protease inhibitor. The chemical composition of the membrane preparation was 49.7% protein, 21.9% lipid, 5.1% aminosugars, 17.3% RNA and 0.03% DNA. Electron microscopic examination confirmed the membrane to be practically devoid of cell wall components. Our results indicate that the membrane integrity is well retained and therefore the membrane preparation is suitable for detailed studies on vectorial metabolism and its enzymes, e.g. ATPase.
Selection of pH buffers for use in conductimetric microbiological assays
Authors: Owens J. D. , Wacher‐Viveros M. C.
Published: March 2008

Many metabolic activities of micro‐organisms lead to changes in the pH value of cultures and consequently pH buffer compounds are potentially a major source of conductivity changes in cultures. To maximize changes in conductivity associated with microbial growth the pH buffer‐associated changes should occur in a direction that reinforces those due to other metabolic activities. In agreement with this, studies with Escherichia coli showed that fermentation of glucose and aerobic growth on L‐alanine yielded greater changes in the conductivity of media containing Tris(hydroxymethyl)aminomethane or L‐histidine buffers than in a medium containing phosphate buffer, whereas aerobic growth on glucose or succinate yielded greater changes with phosphate buffer than with Tris(hydroxymethyl)aminomethane or L‐histidine buffers. Criteria for the selection of appropriate pH buffer compounds are presented.
Germination of spores of Bacillus subtilis var. niger following exposure to gaseous ethylene oxide
Authors: Dadd A. H. , Rumbelow Janet E.
Published: March 2008

Spores of Bacillus subtilis var. niger exposed to a lethal dose of ethylene oxide (ETO) germinated freely under a variety of nutritional conditions. Outgrowth, however, did not occur. Good germinants for ETO‐exposed spores were (in order of decreasing effectiveness) alanine, valine, cysteine, isoleucine and histidine. Asparagine, while a germinant for unexposed spores, did not allow the germination of ETO‐exposed spores. Mixtures of amino acids were no more effective than alanine alone. Exposure to ETO lowered both the rate and amount of germination but the effect was much less than that on viability. A linear relationship was obtained by plotting germination in glucose alanine against survivors on a logarithmic scale. This relationship did not occur when valine was the germinant.
Seasonal distribution of facultatively enteropathogenic vibrios (Vibrio cholerae, Vibrio mimicus, Vibrio parahaemolyticus) in the freshwater of the Elbe River at Hamburg
Authors: Bockemühl J. , Roch K. , Wohlers B. , Aleksic V. , Aleksic S. , Wokatsch R.
Published: March 2008

Between June 1981 and December 1982 the incidence of Vibrio cholerae, V. mimicus and V. parahaemolyticus was determined at two sampling sites on the Elbe River at Hamburg. A total of 183 strains was isolated from 147 water samples. Of these, 107 belonged to non‐01 V. cholerae (ten strains producing a cholera‐like enterotoxin); 33 were identified as V. mimicus, including two enterotoxin producers; 42 strains were Kanagawa‐negative cultures of V. parahaemolyticus; and one was V. fluvialis. The highest incidence was observed from June to September with about 102 organisms/1. Halophilic vibrios, less than five organisms/1, were detectable during the period June/July to October. The vibrio incidence was not influenced by the numbers of aerobic heterotrophic bacteria, coliforms or faecal bacteria. In general water temperature correlated with the seasonal variation. Thus, a temperature rise over 10° to 20°C was followed by a distinct increase in vibrio numbers. Of 14 chemical parameters only chloride concentration might have had an influence on the seasonal variation. It is concluded that the three Vibrio species are indigenous organisms of the Elbe River.
Bactericidal effect of hydrogen peroxide on Salmonella typhimurium in liquid whole egg
Authors: ÜNlütürk A. , Turantasl F.
Published: March 2008

The effect of hydrogen peroxide on Salmonella typhimurium in whole egg was evaluated. The bactericidal effects observed on the test organism at 5° and 20°C were found to be similar. There was a 99% kill in the presence of 0°5% and 1°0% H2O2. Addition of the test organism and H2O2 after pre‐heating the egg material at 40°C for 15 min caused a rapid kill which was 10000‐fold greater than that produced by H2O2 alone.