bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and properties of xylanases from actinomycetes
Authors: BALL A.S. , MCCARTHY A.J.
Published: March 2008

The extracellular xylanase activity of 15 actinomycete strains, representing a range of taxa, was examined. Enzyme production was correlated with growth in all cases and product analysis demonstrated that degradation was the result of endoxylanase activity. This was subject to end‐product inhibition, probably by xylobiose, but was not inhibited by cellobiose or monomeric sugars. Gel electrophoresis showed that up to six separate endoxylanases were produced but only one was identified in strains that exhibited poor activity. Activity against xylan was found to be specific in that no cross‐reactions with endoglucanase activity were detected. The xylan‐degrading systems of actinomycetes are clearly complex and non‐uniform, although there is some evidence of conservation within Streptomyces.
Variation in nitrate metabolism in biovars of Pseudomonas solanacearum
Authors: Hayward A.C. , El‐Nashaar H.M. , Nvdegger Ursula , Lindo Liliam De
Published: March 2008

A collection of 327 strains of Pseudomonas solanacearum, representing five biovars, was divisible into three groups on the basis of differences in nitrate metabolism. Nine strains (2.8%), of which seven were biovar 2 from bacterial wilt of potato, were nitrate reduction‐deficient and failed to produce nitrite from nitrate by either of two methods of detection in five different media. A second group of 231 strains, comprising biovars 1 and 2 and a single biovar 3 strain, produced nitrite from nitrate and grew vigorously in the presence of nitrate under anaerobic conditions but were deficient in ability to denitrify. A third group comprising 57 strains of biovar 3, 28 of biovar 4 and one each of biovar 2 and 5 produced nitrite from nitrate and gave profuse growth and gas production from nitrate under anaerobic conditions. However, production of gas from nitrate (denitrification) was not a consistently reproducible property in some of the media tested. Gas production results were most reproducible when a semi‐solid succinate/nitrate or glycerol/nitrate medium was used. Serial passage of four nitrate reduction‐deficient isolates in nitrate medium did not restore ability to reduce nitrate.
Antibacterial activity of lactic acid bacteria isolated from vacuum‐packaged meats
Authors: Ahn C. , Stiles M.E.
Published: March 2008

Lactic acid bacteria isolated from vacuum‐packaged fresh meat stored at 4°C were shown to produce antagonistic substances active against closely related bacteria. Growth medium, pH and growth temperature all affected the production of the inhibitory substances. Ten strains including aciduric Lactobacillus‐type organisms, Carnobacterium spp. and Leuconostoc spp. were selected that produced protein‐aceous substances that caused inhibition of indicator strains. These were considered to be bacteriocins or bacteriocin‐like compounds based on their inactivation with protease, generally narrow spectra of antibacterial activity and bactericidal or bacte‐riostatic modes of action. Activity was not lost from supernatant fluids as a result of heat treatment at 62°C for 30 min, except for the Leuconostoc strains. Inhibitory spectra of some strains included Enterococcus spp. and Listeria monocytogenes. Some strains were of interest because their inhibitory substances were detected in the supernatant fluid early in the growth cycle. The inhibitory substances differed in characteristics between strains and there is evidence that more than one bacteriocin‐like substance may be produced by some strains.
Forces involved in adhesion of Bacillus cereus spores to solid surfaces under different environmental conditions
Authors: Husmark Ulrika , Rönner U.
Published: March 2008

Husmark, U. & Rönner, U. 1990. Forces involved in adhesion of Bacillus cereus spores to solid surfaces under different environmental conditions. Journal of Applied Bacteriology69, 557–562.

The adhesion of Bacillus cereus spores (NCTC 2599) to hydrophobic and hydro‐philic glass surfaces was studied when environmental conditions were varied. The spores were exposed in media of different polarities as well as different pH and ionic concentrations. With increasing ethanol concentrations, the polarity of the medium was decreased and the predominant force of attraction was found to be hydrophobic. The spore surface was uncharged at a pH around 3, at which value the spore was most adhesive to both hydrophobic and hydrophilic glass. This could be attributable to the absence of electrostatic repulsion. An increased ionic concentration of the bulk increased the degree of adhesion especially to the hydrophilic surfaces. This indicates the suppression of a solvation barrier at high ionic concentrations, when the polymers of the spore surface become dehydrated.
Cleanability in relation to bacterial retention on unused and abraded domestic sink materials
Authors: Holah J.T. , Thorpe R.H.
Published: March 2008

Holah, J.T. & Thorpe, R.H. 1990. Cleanability in relation to bacterial retention on unused and abraded domestic sink materials. Journal of Applied Bacteriology69, 599–608.

The relative Cleanability of stainless steel, enamelled steel, mineral resin and polycarbonate domestic sink materials was assessed by comparing the number of organisms remaining on surfaces after cleaning. In unused condition all materials, other than one enamelled steel, were equally cleanable. Stainless steel, abraded artificially or impact damaged to a similar degree as stainless steel subjected to domestic wear, retained approximately one log order less bacteria after cleaning than the other materials subjected to the same treatments. Little difference in Cleanability was recorded between the abraded surfaces of the other materials although enamelled steel surfaces were less cleanable than mineral resin or polycarbonate after impact damage, because of the greater susceptibility of enamelled steel to damage by this treatment. When cleaning time was extended beyond 10 s for the abraded and impact damaged materials, their Cleanability was not enhanced as compared with stainless steel. Changes in surface finish after abrasion were assessed by surface roughness measurement and scanning electron microscopy. Surfaces with poor Cleanability before and after abrasion were characterized by pitting, crevices or jags. These surfaces are likely to retain more bacteria because of increased numbers of attachment sites, a larger bacterial/material surface contact area and topographical areas in which applied cleaning shear forces are reduced. Materials that resist surface changes, e.g. stainless steel, will remain more hygienic when subjected to natural wear than materials which become more readily damaged.
Antimicrobial activity of Leuconostoc gelidum against closely related species and Listeria monocytogenes
Authors: Harding Charmaigne D. , Shaw E.G.
Published: March 2008

Harding, C.D. & Shaw, E.G. 1990. Antimicrobial activity of Leuconostoc gelidum against closely related species and Listeria monocytogenes. Journal of Applied Bacteriology69, 648–654.

A newly isolated strain of Leuconostoc gelidum was evaluated for its ability to inhibit a wide spectrum of lactic acid bacteria, meat spoilage bacteria and food‐related human pathogens, including Listeria monocytogenes. It was inhibitory to most of the lactobacilli, all the leuconostocs, and three strains of L. monocytogenes when tested both by direct and well diffusion methods. Cell‐free extract retained activity after 60 min at 100d̀C but was sensitive to protease. Dialysis suggested a molecular weight in excess of 104 daltons. The inhibitory effect was bactericidal and rapid.
Synthesis of collagenase by the phytopathogenic bacterium Corynebacterium rathayii
Authors: Labadie J.
Published: March 2008

Labadie, J. 1990. Synthesis of collagenase by the phytopathogenic bacterium Corynebacterium rathayii. Journal of Applied Bacteriology69, 828–833.

The collagenase‐producing bacterium tentatively called Empedobacter collagenolyti‐cum was recently identified as Corynebacterium rathayii. Production of collagenase was studied in different media containing peptones or peptides of known sequences. A hexapeptide, Pro‐Ala‐Gly‐Pro‐Pro‐Gly, is an inducer almost as good as collagen.
Optimization of cassava fermentation for fufu production: effects of single starter cultures
Authors: Oyewole O.B.
Published: March 2008

Single starter cultures were used to ferment cassava for fufu production in a process which involved steeping seeded cassava tubers in water for 96 h. The cultures used include Bacillus subtilis, Klebsiella sp., Lactobacillus plantarum and Candida krusei. Lactobacillus plantarum exhibited the highest acid producing ability, decreasing the pH of the cassava tubers from 6.0 to 3.62, with a corresponding increase in total titratable acidity (TTA) from 0.072% to 0.250% during the 96 h fermentation period. The effected changes in pH and TTA by other organisms ranged respectively from 5.03 and 0.125% for Klebsiella sp., 5.07 and 0.126% for C. krusei, to 5.20 and 0.128% for B. subtilis within the period. Lactobacillus plantarum grew better than other cultures singly inoculated. While all the cultures were found to contribute to the characteristic odour of fufu, C. krusei effected the highest perceived characteristic odour. Also, the cultures variably caused softening of the tubers, with B. subtilis showing the highest softening capability.
Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers
Authors: van Doorn W.G. , de Witte Y. , Perik R.R.J.
Published: March 2008

The presence of chlorine in solution (bleach), a slow release chlorine (DICA), a quaternary ammonium compound (benzalkonium chloride), a hydroxyquinoline compound (HQC), or aluminium sulphate in the vase water decreased the number of bacteria in stems of cut ‘Sonia’roses, with respect to untreated controls. However, when the concentration of the antimicrobial compound was high enough to reduce the number of bacteria in stems (measured after 7 d of vase life) to below the detection limit, the roses showed severe leaf chlorosis and leaf abscission. Benzalkonium chloride resulted in damage at a concentration just enough to reduce the number of bacteria in stems. Effects of HQC, aluminium sulphate, and silver nitrate on the number of bacteria were variable. In experiments in which HQC was relatively ineffective, only one bacterial strain was found in the stem. This strain grew on HQC concentrations as high as 400 mg/l, and was identified as Pseudomonas fluorescens. and accepted 8 June 1989
Antibiotic resistance of Salmonella strains isolated from natural polluted waters
Authors: Moriñigo M.A. , Cornax R. , Castro D. , Jimenez‐notaro M. , Romero P. , Borrego J.J.
Published: March 2008

Resistance to 14 antibiotics was tested in 270 Salmonella strains isolated from different aquatic environments. All the strains were sensitive to nalidixic acid (30 μg) and cephalothin (30 μg) but more than 90% were resistant to tetracycline (30 μg). The percentage of strains resistant to other antimicrobial substances depended on the antibiotic and on the isolation source. Twenty‐four resistance patterns were recorded in strains isolated from three environmental sources. The only multi‐resistance detected in the three ecosystems was that of sulphadiazine and tetracycline (about 20%). The serotypes most frequently detected with multi‐resistance to different antibiotics were Salmonella typhimurium and Salm. blockley.
The effects of microbial exopolysaccharides (EPS) in vase water on the water relations and the vase life of Rosa cv. Sonia
Authors: Put Henriëtte M.C. , Klop W.
Published: March 2008

Pure cultures of five microbial species were used to test the formation of exopolysaccharides (EPS) when grown in agitated sucrose (5% w/v) containing liquid cultures. These test species were isolated from stems of freshly harvested cut flowers (Chrysanthemum, Gerbera and Rosa) or from the vase water of these flower cultivars. The partial conversion of sucrose into other saccharides was demonstrated by HPLC and colorimetric analysis. The final polymeric character of the newly formed saccharides was investigated. SEM preparations of xylem vessels of Rosa maintained in EPS‐containing vase water showed blockage, disorganization and injury of the vessel structure. EPS were shown not to pass the xylem pit membranes. Recovery from the first symptoms of disturbed water flow (wilting) due to EPS was possible in young flowers by cutting off the blocked part of the stem (15–20 cm. The higher the microbial conversion rate of sucrose into polysaccharides, the more disturbed were the water relations of the roses placed in the EPS‐containing fluid, as was demonstrated by the decrease of: (1) water conductivity of Rosa stem segments (ml/30 min); (2) water uptake (ml/d); (3) Rosa vase life (d); and (4) flower bud development. Bacterial EPS (presumably levans and dextrans) could be concentrated in the retentate by molecular filtration with a cut‐off level of 10000 Da. Filtrates did not cause Rosa xylem blockage and ‘bent‐neck’of the flower stems, but still may be toxic to roses. Two simple methods were also used for diagnostic investigations: (1) the beetroot tissue cube test to detect microbial products causing injury of the plant cell membranes, (2) the acid fuchsin test, to show the extent and location of Rosa xylem vessel occlusion.
A rapid, semi‐automated SDS‐PAGE identification system for oral anaerobic bacteria
Authors: Slayne M.A. , Aldred M.J. , Wade W.G.
Published: March 2008

SDS‐polyacrylamide gel electrophoresis is a useful technique in bacterial differentiation and identification. A rapid, semi‐automated SDS‐PAGE system (Phast System) was assessed for identification of formate‐fumarate‐requiring, asaccharolytic, Gram‐negative oral anaerobes. The system permitted loading, separation and staining of gels within 2 h. Percentage similarities between strains were determined using correlation coefficients and cluster analysis. The protein profiles were sufficiently reproducible provided that distorted profiles were disregarded. Strains were successfully separated into their species, with the exception of Bacteroides ureolyticus NCTC 10939, which appeared to be distinct from other strains of that species. Twenty‐nine unidentified formate‐fumarate‐requiring, sub‐gingival plaque strains were suitably clustered with the standard strains as verified by a series of physiological and biochemical tests. and accepted 25 July 1989
A study of conventional formaldehyde fumigation methods
Authors: Lach V.H.
Published: March 2008

The currently recommended methods for the formaldehyde fumigation of rooms have been studied with the aid of an instrument designed to monitor the temperature, humidity and formaldehyde concentration. The results show that although the procedures are generally effective as measured by microbiological methods the conditions within the areas treated are not those expected from calculations based on the room volume and the amount of formaldehyde used. The measured formaldehyde levels in particular are much lower than predicted and indicate that formaldehyde vapour may be effective at lower concentrations than previously supposed.
The ineffectuality of potato protease inhibitor on the extracellular protease from Erwinia carotovora subsp. carotovora
Authors: Heilbronn Jacqueline , Lyon G. D.
Published: March 2008

Growth conditions are described for optimum production of extracellular protease in batch cultures of the soft rot pathogen Erwinia carotovora subsp. carotovora. This protease was inhibited by approximately 96% by 1 mmol/1 EDTA and by 55–6% by 10 mmol/l cysteine thereby classifying it as a metalloprotease. It was not inhibited by a chymotrypsin inhibitor extracted from potato tubers. This evidence suggests that the potato chymotrypsin inhibitor is not associated with resistance of potatoes to E. carotovora subsp. carotovora.
F‐specific RNA bacteriophages and sensitive host strains in faeces and wastewater of human and animal origin
Authors: Havelaar A. H. , Pot‐Hogeboom W. M. , Furuse K. , Pot R. , Hormann M. P.
Published: March 2008

Faeces of humans, pigs, cattle and chickens were investigated for the presence of somatic coliphages, F‐specific bacteriophages and Escherichia coli strains sensitive to infection by F‐specific phages. Attention was given to the possible effect of age and use of antibiotics on the prevalence of the FRNA phages and sensitive E. coli strains. Somatic coliphages were often detected in high numbers in all types of faeces. In contrast, FRNA phages were rarely detected in faeces from humans and cattle but more often in faeces from pigs and adult chickens. Samples from young chickens (with or without antibiotics) were consistently positive for FRNA phages (up to 3 × 106 pfu/g). F‐specific RNA phages were found in substantial numbers (> 103 pfu/ml) in a variety of wastewaters: domestic, hospital, slaughterhouses and occasionally in ‘grey water’. Their origin in wastewater was not clear. Strains from faeces usually belonged to serogroups I and IV. These types were also found in wastewater, as were group II and III strains. Serogroup II phages were abundant in wastewater of human origin but rare in faeces. Escherichia coli strains sensitive to infection by F‐specific phages were common in faeces (overall 290/1081: 27%). No strains with fully derepressed F‐pilus synthesis were detected among the sensitive strains. It is concluded that the occurrence of F‐specific RNA bacteriophages in water points to sewage pollution rather than faecal pollution; the mechanism of replication of these organisms in wastewater is not understood.
Instability of the morpholine‐degradative phenotype in mycobacteria isolated from activated sludge
Authors: Brown V. R. , Knapp J. S. , Heritage J.
Published: March 2008

The stability of the morpholine‐degradative phenotype was studied in a group of nine distinct strains of mycobacteria, all isolated from an activated sludge plant treating morpholine.

Variants incapable of morpholine degradation arose from all strains at high frequency following growth under non‐selective conditions. However, strains differed with respect to the frequency at which Mor− variants arose. No spontaneous reversion to wild type could be demonstrated. Six of the nine mycobacterial strains contained plasmids, each had a different plasmid profile. The plasmid profiles of wild type and Mor− variants were compared. In no case could loss of the ability to grow on morpholine be correlated with loss of a complete plasmid. However, evidence is presented which suggests that in two strains loss of the morpholine‐degradative phenotype may be correlated with a decrease in the size of a very large plasmid implying deletion of the DNA encoding morpholine degradation. The techniques employed to screen for plasmids in mycobacteria are discussed.
Comparative study of cell‐immunoenzymatic methods for the estimation of IgG and IgM anti‐brucella antibodies in the diagnosis of human brucellosis
Authors: Mongini Claudia , Fernandez Teresa , Turovetzky Arno , Hajos Silvia E.
Published: March 2008

Two methods which employ whole cells are described and compared for the detection of human IgG and IgM anti‐brucella antibodies. Dot ELISA and ELISA were shown to be suitable for a screening diagnosis of human brucellosis. Titres of antibodies obtained by dot ELISA showed 100% coincidence for IgG and 97% for IgM, compared with agglutination and complement fixation tests; when ELISA was used 11 % positive sera were not detected. The comparison of these two methods with the conventional serological test kit indicated that both dot ELISA and ELISA were sensitive, reproducible and specific for the quantification of IgG and IgM anti‐brucella antibodies.
A simplified key for identifying homofermentative Lactobacillus and Carnobacterium spp. from meat
Authors: Montel Marie‐Christine , Talon Regine , Fournaud Jeanne , Champomier Marie‐Christine
Published: March 2008

Species of Lactobacillus and Carnobacterium from meat and meat products could be separated by a few biochemical characteristics; presence of meso‐diaminopimelic acid in the cell wall, the isomers of lactic acid produced, production of citrulline from arginine and fermentation of some carbohydrates. This identification key was checked by DNA–DNA hybridizations studies.
The effect of various aquatic bacteria on the growth and senescence of duckweed (Lemna minor)
Authors: Underwood G.J.C. , Baker J.H.
Published: March 2008

Five different species of freshwater bacteria (Pseudomonas sp., Vibrio sp., Klebsiella sp., Enterobacter sp., Serratia sp.) and a mixed natural population were used separately to inoculate cultures of axenic duckweed (Lemna minor). Inoculation with Vibrio sp. caused the final population density of Lemna plants to be significantly greater after 52 d than that of either axenic controls or Lemna inoculated with a mixed bacterial community. Inoculation with Pseudomonas sp. caused the final population density of Lemna to be significantly higher than with the mixed bacterial treatment. Inoculation of Lemna with Klebsiella sp., Enterobacter sp. or Serratia sp. resulted in higher plant populations compared with controls, but these differences were not statistically significant. The presence of a mixed community of bacteria did not significantly affect the final population density of Lemna compared with the controls. However, Lemna plants inoculated with a natural population of bacteria showed significantly higher levels of senescence compared with the other five treatments and the controls. None of the five single bacterial taxa used appeared to have any significant effect of the sensescence of duckweed.
A DNA primer/probe system for the rapid and sensitive detection of Mycobacterium tuberculosis‐complex pathogens
Authors: Ralphs Nicola T. , Garrett S. , Morse R. , Cookson J.B. , Andrew P.W. , Boulnois G.J.
Published: March 2008

A 1·5 kb EcoRI–BamHI restriction fragment from Mycobacterium tuberculosis was found to hybridize specifically with genomic DNA from M. tuberculosis‐complex organisms. Primers were designed from the terminal sequences of this fragment and used to amplify uniquely M. tuberculosis‐group DNA in a polymerase chain reaction. It is suggested that a combination of these primers and probe will prove a useful tool for the early diagnosis of tuberculous infections.
Citrate metabolism by Lactobacillus plantarum isolated from orange juice
Authors: Kennes C. , Dubourguler H.C. , Albagnac G. , Nyns E.‐J.
Published: March 2008

The behaviour of Strains of Lactobacillus plantarum isolated from fermented orange juice and Lact. plantarum DSM 20174 was studied in the presence of citrate. When used as sole carbon source, citrate scarcely supported the growth of the bacteria. It was shown to enhance the growth of Lact. plantarum in glucose media. Under acid conditions (pH 4·0–5·0), 1 mol of citrate yielded 1·7 mol of acetate as sole major final metabolite with release of CO2 in the gas phase.
Characterization by plasmid profile analysis of acetic acid bacteria from wine, spirit and cider acetators for industrial vinegar production
Authors: Mariette Isabelle , Schwarz E. , Vogel R.F. , Hammes W.P.
Published: March 2008

The fermentation in industrial high acid submerged fermenters of wine, spirit or cider into vinegar was investigated by direct analysis of the plasmid patterns of the acetic acid bacteria involved. The strains were different in all samples. One strain from a red wine acetator was isolated by the double layer agar technique and proved to be the main fermenting organism. After inoculation of an acetator with this strain, the initiation of acidification was accelerated. Inoculation with spirit vinegar organisms led to immediate acidification. The spirit vinegar organisms were outnumbered after 12 d by fortuitously‐occurring, highly adapted red wine vinegar bacteria. Over‐oxidation was due to physiological regulation, a genetical change by plasmid loss or occurrence of new organisms was not observed.
Effect of chemical treatments on the micro‐organisms associated with malting of sorghum grains and sorghum malt
Authors: Ogundiwin J.O. , Ilori M.O. , Fessehatzion B. , Babalola G.O. , Olajuyigbe A.O.
Published: March 2008

The effect of five chemical preservatives on the micro‐organisms associated with sorghum grain and malts was investigated. Sorbic acid, sodium benzoate, nisin, formaldehyde and lime at concentrations up to 500, 100, 1000, 1500 and 2000 ppm, respectively did not adversely affect the malting properties of sorghum grain. Only HCHO and Ca(OH)2, each of which prevented bacteria and mould growth at 500 and 2000 ppm, respectively, were sufficiently effective at maximum practicable concentrations to control microbial contamination during malting.
Micro‐organisms at the cut surface and in xylem vessels of rose stems
Authors: van Doorn W.G. , de Stigter H.C.M. , de Witte Y. , Boekestein A.
Published: March 2008

Stems of cut rose flowers (Rosa hybrida L. cv. ‘Sonia’) were placed in water to study the development of a population of micro‐organisms at the cut surface and in the xylem vessels. The cut surface became covered with bacteria within 2 d of vase life. The bacteria were accompanied by an amorphous substance which was apparently bacterial slime. After 7 d of vase life many fungal hyphae were also found at the cut surface. Inside the xylem vessels the bacteria were often clustered at the inter‐vessel pits. After 4 d of vase life most of the vessels that had been opened by cutting contained bacteria. Only a few xylem elements, located several centimeters from the cut surface, contained an amorphous substance. A few fungal hyphae were observed inside the xylem vessels. No yeasts were found, either at the cut surface or inside the xylem. Pseudomonas species accounted for more than 70% of the total bacterial population of the cut surface and the xylem vessels, and Enterobacter species (mainly Ent. agglomerans) for less than 10%. Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Citrobacter and Flavobacterium were occasionally observed.
DNA‐DNA hybridization and analysis of restriction endonuclease and rRNA gene patterns of atypical (catalase‐weak/negative) Campylobacter jejuni from paediatric blood and faecal cultures
Authors: Hernandez J. , Owen R.J. , Costas M. , Lastovica A.
Published: March 2008

Sixteen strains of atypical (catalase‐weak or negative), hippurate‐hydrolysing campylobacters from paediatric blood and faecal cultures were identified by DNA–DNA slot hybridization. All were closely related ( 67%) to Campylobacter jejuni and representative strains had G + C contents of 30 ± 1 mol%. Numerical analysis of chromosomal DNA HaeIII digest patterns revealed two clusters of strains at the 55%S level corresponding to C. jejuni subsp. jejuni and C. jejuni subsp. doylei; most strains belonged to the latter subspecies. No two strains had identical patterns but within each subspecies two subgroups were identifiable, corresponding to Lior biotypes I and II. Southern blot hybridization analysis with a 16 + 23S rRNA cistron probe from Escherichia coli also showed differences between the various strains, and in a numerical analysis three groupings were formed at 70%S corresponding to C. jejuni subsp. jejuni Lior biotypes I and II, and C. jejuni subsp. doylei. Four of the subspecies doylei strains contained a 3·4‐MDa plasmid. These analyses showed that catalase‐negative C. jejuni subsp. jejuni were genomically distinguishable from C. jejuni subsp. doylei as were Lior biotypes within subsp. jejuni. Ability to produce catalase is not a feature common to all C. jejuni strains, and our results confirm that some strains of subspecies jejuni may be negative in that character although typical in other respects. DNA pattern heterogeneity was consistent with serological differences between strains.
Characteristics and identity of obligately aerobic spoilage yeasts from fish silage
Authors: Levin R. E. , Witkowski R.
Published: March 2008

R.E. LEVIN AND R. WITKOWSKI. 1991. Yarrowia (Canadida) lipolytica was the predominant organism isolated from the surface film of growth derived from ground hake gurry to which only phosphoric acid was added to give a pH of 4.0. The optimum pH for the crude extracellular protease activity of two distinguishable strains of Y. lipolytica, designated CL1 and CL2, with casin as substrate was 7.0. The optimum temperature of the crude extracellular protease activity from both strains was 50.C. The addition of 2.0% glucose to broth cultures resulted in a significant increase in final cell mass and extracellular protease activity but resulted in a reduction in the units of protease activity per mg of dry cell mass at initial pH values of 5.6 and 7.0 but not an initial pH of 8.0
Enumeration of Aeromonas hydrophila from domestic wastewater treatment plants and surface waters
Authors: Poffé R. , de Beeck E. Op
Published: March 2008

R. POFFÉ AND E. OP DE BEECK. 1991. Influents, effluents and sludges from sewage purification plants and surface water samples were examined quantitatively for Aeromonas hydrophila on the mA medium of Rippey and Cabelli. Between 104 and 106/ml A. hydrophila were found in domestic wastewaters. On the average 99.975% were removed by activated sludge and 98.25% by trickling filters. Only 20.9% of A. hydrophila end up in the primary sludge, which contained up to 107/g dry sludge. After 3 months, anaerobically (methane) fermented and partially dried sludge from trickling filters contained more than 106A. hydrophila/g dry sludge. Surface water receiving raw sewage contained several hundreds of A. hydrophila/ml, comparable with the numbers found in effluent waters, while surface water receiving no municipal wastewater and destined for the preparation of drinking water contained only small and negligible numbers. It was concluded that A. hydrophila was omnipresent in surface water.
Second serogroup of Legionella quinlivanii isolated from two unrelated sources in the United Kingdom
Authors: Birtles R.J. , Doshi Nivedita , Saunders N.A. , Harrison T.G.
Published: March 2008

R.J. BIRTLES, N. DOSHI, N.A. SAUNDERS AND T.G. HARRISON. 1991. A series of strains, presumptively identified as legionellas on the basis of their nutritional requirements and biochemical reactivity, were isolated from two unrelated environmental sources in the UK. Representatives of each of these series had a restriction endonuclease digest pattern indistinguishable from that of the Legionella quinlivanii type strain (1442‐AUS‐E) and the identity of these strains was confirmed by DNA homology studies. Serological examination of the two strains showed that they were distinct from the type strain 1442‐AUS‐E but indistinguishable from each other. A second serogroup, L. quinlivanii serogroup 2 (type strain LC870; NCTC 12434), is proposed to accommodate these strains.
A numerical taxonomic study of Propionibacterium strains from dairy sources
Authors: Britz T.J. , Riedel K‐H.J.
Published: March 2008

T.J. BRITZ AND K‐H.J. RIEDEL. 1991. Phenotypic results from 81 tests conducted on 73 propionibacteria, including five type strains, 22 reference strains, unidentified propionibacteria and strains isolated from dairy sources, were analysed by numerical taxonomy. Characters giving uniform results were excluded. With the simple matching coefficient and the single linkage cluster analysis, 61 cultures were recovered in five major clusters. Final linkage of all the Propionibacterium cultures examined was at the 77% S‐level. The results clearly showed that it was possible to distinguish between the ‘classical’ and ‘cutaneous’Propionibacterium spp., corresponding with the type habitat of each group. The major ‘classical’ clusters were equated with the P. freudenreichii, P. thoenii, P. jensenii and P. acidipropionici species, while the only major ‘cutaneous’ cluster was equated with the P. acnes species. The major clusters were identified by relating them to specific type strains and by comparing phenotypic characteristics. The differentiating characteristics of each cluster were determined. The largest cluster, representing 37% of the strains, was equated with P. jensenii but contained cultures that produced an atypical brown/red pigment. These strains, although positively identified as P. jensenii, could also be identified as the ‘old’‘P. rubrum’ species. Thus if pigmentation is used as differential characteristic two distinct groups of propionibacteria could be identified within the P. jensenii species.
Continued successful operation of open‐fronted microbiological safety cabinets in a force‐ventilated laboratory
Authors: Osborne R.W. , Durkin T.A.
Published: March 2008

R.W. OSBORNE AND T.A. DURKIN. 1991. The considerable refinements necessary to enable Class I and II microbiological safety cabinets to operate in a force‐ventilated laboratory and to meet appropriate safety criteria have been reported previously. The continued successful operation of such cabinets without a deterioration of operator protection is described. The performance of two Class II units, one meeting and one failing the current British Standard applied to four head KI‐Discus testing, is compared and discussed. In addition, some further potential difficulties within the environment, which could compromise cabinet containment, are highlighted.
Phosphotransferase‐dependent glucose transport in Corynebacterium glutamicum
Authors: Malin G.M. , Bourd G.I.
Published: March 2008

G.M. MALIN AND G.I. BOURD. 1991. The transport system for glucose and its non‐metabolizable analogue methyl‐α‐D‐glucoside (MG) has been described in Corynebacterium glutamicum. The initial product of the transport reaction was shown to be a phosphate ester of MG (MGP). Free MG appeared inside the cells as a result of MGP dephosphorylation. The bacteria transported MG with an apparent Km of 0.08 ± 0.017 mmol/l and Vmax of 21 ± 2.3 nmol/(min × mg dry wt). Toluenized cells and crude cell extracts catalysed phosphoenolpyruvate (PEP)‐dependent phosphorylation of MG and glucose. Both the membrane and the cytoplasmic fractions of bacterial extracts were required for phosphotransferase reaction. Most of the spontaneous mutants resistant to 2‐deoxyglucose (DG), xylitol and 5‐thioglucose were defective both in transport and in PEP‐dependent phosphorylation of MG. Some strains were defective only in glucose utilization and some were also unable to grow on a number of other sugars. The phosphotransferase activity in extracts from mutant cells was restored by the addition of either membrane or cytoplasmic fraction from wild type bacteria. It was concluded that Corynebacterium glutamicum accumulated glucose and MG by means of a PEP‐dependent phosphotransferase system (PTS).
Decreased biocide susceptibility of adherent Legionella pneumophila
Authors: Wright J.B. , Ruseska I. , Costerton J.W.
Published: March 2008

J.B. WRIGHT. I. RUSESKA AND J.W. COSTERTON. 1991. In a study of the in vitro effectiveness of biocides against Legionella pneumophila, some aspects of the cooling tower environment were replicated in the laboratory, paying particular attention to water hardness and pH. Pieces of Douglas fir and polyvinyl chloride were colonized in a recirculating system and the comparative efficacy of two biocides (Bronopol and Kathon) against the sessile and planktonic populations was examined. While the biocides were relatively effective against the planktonic L. pneumophila population over a short period of time (minimum 9‐12 h), substantially longer periods of time (maximum > 48 h) were required to reducc the number of cultivable bacteria to below detectable levels in the adherent population. The results indicate that failure to monitor the sessile population of L. pneumophila in laboratory studies of biocides may result in the use of incorrect dosages and/or contact times in field trials with apparently reduced in situ efficacy.
Production and characterization of the polysaccharide from Propionibacterium acidi‐propionici on whey‐based media
Authors: Racine Monique , Dumont Johanne , Champagne C.P. , Morin A.
Published: March 2008

M. RACINE, J. DUMONT, C.P. CHAMPAGNE AND A. MORIN. 1991. The effects of lactose, ammonium and phosphate on the production of extracellular polysaccharide from Propionibacterium acidi‐propionici VM‐25 were studied in whey‐based media. The polysaccharide was composed of a water‐soluble fraction (15% w/w), a water‐insoluble fraction (27% w/w) and ca 65% (w/w) of ash. Up to 15 g/l of polysaccharide was produced during growth on partially deproteinated whey, supplemented with lactose, NH4 Cl and KH2 PO4, after incubation at pH 7.0 and 25.C for 90 h. The final viscosity of the medium remained under 20 centipoises at the end of the fermentation (100–140 h). The fermentation of whey enabled a reduction of the lactose content up to 50%. The polysaccharide‐containing fractions were composed of glucose, galactose, mannose, rhamnose and fucose and had M, < 5800. The polysaccharide may have applications as a low viscosity stabilizing agent.
Methods for the establishment of intracellular associations of L‐forms with higher plants
Authors: Paton A.M. , Innes Carol M.J.
Published: March 2008

Procedures for inducing viable intracellular associations between the L‐forms of Pseudomonas syringae pv. phaseolicola and French dwarf bean, Phaseolus vulgaris, are described. It is suggested that this model system is a basis for more general application.
Modelling the effect of pH, acidulant and temperature on the growth rate of Yersinia enterocolitica
Authors: Adams M.R. , Little C.L. , Easter M.C.
Published: March 2008

Growth of two pathogenic and one environmental serotype of Yersinia enterocolitica under acidic conditions and at 4 and 25°C was investigated. At both temperatures the maximum growth inhibitory pH depended on the acidulant used and was in the order acetic > lactic > citric > sulphuric. At the lower temperature the maximum growth inhibitory pH was 0.3‐0.5 pH units higher than at 25°C. No difference was observed between the behaviour of pathogenic and environmental serotypes in this respect. Measurement of growth at a number of sub‐optimal temperatures and pH values showed that the variation of growth rate with temperature could be represented by a square root plot. The effect of different pH values could be incorporated into the model by replacing the regression coefficient b by its relationship with pH. Values of maximum growth inhibitory pH derived from the model were in good agreement with experimental values with the exception of acetic acid.
Studies on the lactoperoxidase system: reaction kinetics and antibacterial activity using two methods for hydrogen peroxide generation
Authors: Dionysius D.A. , Grieve P.A. , Vos A.C.
Published: March 2008

D.A. DIONYSIUS, P.A. GRIEVE AND A.C. VOS. 1992. Components of the lactoperoxidase system were measured during incubation in Isosensitest broth, with enzymatic (glucose oxidase, GO) or chemical (sodium carbonate peroxyhydrate, SCP) means to generate H2O2. When low levels of thiocyanate (SCN‐) were used in the GO system, H2O2 was detected and lactoperoxidase (LP) was inactivated when SCN‐ was depleted. With 10‐fold higher SCN‐, LP remained active and H2O2 was not detectable. The oxidation product of the LP reaction, most likely hypothiocyanite, was present in low concentrations. When SCP was used for the immediate generation of H2O2 in a system employing low SCN‐, half the LP activity was lost within minutes but thereafter it remained stable. Low concentrations of oxidation product were measured and H2O2 was not detected during the course of the experiment. At high SCN‐ levels, relatively high concentrations of oxidation product were produced immediately, with H2O2 undetectable. The results suggest that the final product of the LP reaction depends on the method of H2O2 generation and the relative proportions of the substrates. Antibacterial activity of the two LPS was tested against an enterotoxigenic strain of Escherichia coli. Both systems showed bactericidal activity within 4 h incubation at 37°C.
Antimicrobial properties of secretions from the metapleural glands of Myrmecia gulosa (the Australian bull ant)
Authors: Veal D.A. , Trimble Jane E. , Beattie A.J.
Published: March 2008

D.A. VEAL, J.E. TRIMBLE AND A.J. BEATTIE. 1992. Myrmecia gulose (Australian bull ant) produce secretions from their metapleural exocrine glands which have broad spectrum antimicrobial properties. Such secretions are probably of importance in disease control in bull ant communities. These antimicrobial secretions are stable at 100°C, resistant to proteolytic enzymes and are active over a wide pH range. Of the organisms tested only endospores of Bacillus cereus were found to be resistant. The antimicrobial agent(s) are absorbed by cells and result in cell lysis. The secretions do not interfere with any growth‐related processes. These observations demonstrate that insects may be a source of novel antimicrobial agent(s).
Effects of chlorhexidine diacetate on Candida albicans, C. glabrata and Saccharomyces cerevisiae
Authors: Hiom Sarah J. , Furr J.R. , Russell A.D. , Dickinson J.R.
Published: March 2008

S.J. HIOM, J.R. FURR, A.D. RUSSELL AND J.R. DICKINSON, 1992. The effects of chlorhexidine diacetate (CHA) on Candida albicans, C. glabrata and wild‐type and mannan, and permeability mutants of Saccharomyces cerevisiae have been studied. A CHA concentration of 10 μg/ml had little lethal activity against the Candida strains, but was more effective against S. cerevisiae. Concentrations of 100 and especially 1000 μg/ml brought about a much more rapid death of cells. 2‐Mercaptoethanol enhanced the activity of CHA to some extent. Some of the mutant strains of S. cerevisiae were rather more sensitive than the wild‐type strain. The age of cultures of C. albicans and C. glabrata influenced their response to CHA.
Conjugal transfer of R plasmids to and from Enterobacteriaceae isolated from sewage
Authors: Fernandez‐Astorga Aurora , de Aranguiz Agueda Fernandez , Pocino M. , Umaran Adelaida , Cisterna R.
Published: March 2008

A. FERNANDEZ‐ASTORGA, A. FERNANDEZ DE ARANGUIZ, M. POCINO, A. UMARAN AND R. CISTERNA. 1992. The potential of the transfer of natural plasmids between sewage strains has been studied. In vitro transfer was conducted at 37°C in tryptone soya broth and sterile raw sewage as mating media. In situ transfer was carried out in sterile raw sewage within membrane diffusion chambers at 10.6°C. When the recipient was a laboratory strain of Escherichia coli K‐12, the in situ frequency values were significantly lower (P < 0.001) than those obtained in vitro for the same mating pair. When the laboratory recipient was replaced with recipients from the same sewage source, frequency values decreased progressively from the optimum conditions to the most adverse. However, in situ frequency values were higher than those for the same donors mated with a laboratory recipient.
Detection of salmonellas by DNA hybridization with a fluorescent alkaline phosphatase substrate
Authors: Cano R. J. , Torres M.J. , Klem R.E. , Palomares J.C. , Casadesus J.
Published: March 2008

R. J. CANO, M.J. TORRES, R.E. KLEM, J.C. PALOMARES AND J. CASADESUS. 1992. This study evaluates a DNA hybridization assay for salmonella with AttoPhos™ (JBL Scientific, San Luis Obispo, CA), a fluorescent substrate for alkaline phosphatase. The probe used (50 ng/ml) was a biotinylated 600 bp fragment consisting of a tandem repeat of an insertion sequence (IS200) found in most Salmonella spp. evaluated. The hybridization was carried out at 65°C for 2 h without prior prehybridization and hybrids were detected by the addition of a streptavidin‐alkaline phosphatase conjugate. Circles (5 mm) were cut from the membrane and placed in a cuvette containing 1 ml of 1 mmol/1 AttoPhos™. The reaction was evaluated after 30 min at 37°C with a fluorometer with an excitation wavelength of 440 nm and an emission wavelength of 550 nm. The sensitivity of the probe was estimated to be 10 000 copies of target DNA or 5 times 10‐20 mol of DNA. All 74 salmonella strains tested reacted with the probe but none of the 98 heterologous species tested gave positive results. The results of this study indicate that our assay method, which employs a biotinylated tandem repeat of IS200 and AttoPhos™, is a specific and highly sensitive quantitative method for the detection of salmonellas.
Lack of colonization of 1 day old chicks by viable, non‐culturable Campylobacter jejuni
Authors: Mederma G.J. , Schets F.M. , van de Giessen A.W. , Havelaar A.H.
Published: March 2008

G.J. MEDEMA, F.M. SCHETS, A.W. VAN DE GIESSEN AND A.H. HAVELAAR. 1992. Seven strains of Campylobacter jejuni, isolated from various sources [human (n= 2), chicken (n= 3), water (n= 2)], were studied under starvation conditions in filter‐sterilized and pasteurized surface water by acridine orange direct count (AODC), viable count (DVC) and culture methods. Plate counts showed a rapid decline (2 log‐units/day) for all strains under these conditions. Only one of the seven strains (14%) showed a (prolonged) viable, non‐culturable ‘state’. The ability of these viable, non‐culturable cells to colonize the intestine was tested on day‐old chicks. The infectious oral dose of freshly cultured cells of this model was 26–260 cfu; 1.8×105 viable, non‐culturable C. jejuni were introduced to day‐old chicks orally. Campylobacter jejuni was not isolated from the caeca of the chicks after incubation for 7 d. Also, passage through the allantoic fluid of embryonated eggs did not recover viable, nonculturable C. jejuni. These findings cast serious doubts on the significance of the viable, non‐culturable ‘state’ in environmental transmission of C. jejuni.
Two β‐glucosidase activities in Fibrobacter succinogenes S85
Authors: Buchanan C.J. , Mitchell W.J.
Published: March 2008

Few bacteria are capable of degrading crystalline cellulose but there is considerable interest in the properties of enzyme systems with this capability. In the bovine and ovine rumen the principal cellulolytic bacterium is Fibrobacter (formerly Bacteroides) succinogenes. The cellulase system of this organism is composed of multiple enzyme components, including a constitutive and cell‐associated β‐glucosidase active against cellobiose. The properties of the β‐glucosidase activity have been investigated with the chromogenic substrate β‐nitrophenyl β‐D‐glucoside (pNPG). Hydrolytic activity against pNPG was located primarily in the cytoplasm and the cytoplasmic membrane but showed a gradual migration to the periplasm during growth on either glucose or cellobiose. Activity against cellobiose was found in the periplasm in significant amounts in all growth phases. Of the β‐glucosides tested, only cellobiose and pNPG were hydrolysed by crude cell extracts. In the presence of cellobiose, however, the rate of hydrolysis of pNPG was stimulated up to 10‐fold, and extracts hydrolysed methylumbelliferyl β‐D‐glucoside, 5‐bromo‐4‐chloro‐3‐indolyl β‐D‐glucoside, arbutin and aesculin. Activities against pNPG in the presence and absence of cellobiose displayed similar instability in the presence of oxygen; both were stabilized by dithiothreitol and the temperature and pH optima were identical. A significant proportion of the membrane‐associated β‐glucosidase was released by treatment with 0.3 mol/1 KCl, and fractionation by chromatography on CM‐cellulose showed the presence of two activities against pNPG, only one of which was stimulated by cellobiose.