bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of transient temperatures on the growth of Salmonella typhimurium LT2. I: cycling within the growth region
Authors: Mitchell G.A. , Brocklehurst T.F. , Parker R. , Smith A.C.
Published: March 2008

The effect of fluctuating temperatures on microbial growth is important in the passage of foods through the food chain. Suspensions of Salmonella typhimurium were subjected to sinusoidally time‐varying temperatures of periods from 40 to 480 min within their growth temperature range. The change in the numbers of viable bacteria was measured with time and the experimental growth curves and average generation times compared with predictions based on isothermal growth data. The experimental average generation times exceeded the predictions by less than 30%, although the discrepancy increased with cycle frequency. Instantaneous growth rates obtained for the 480 min cycles were in agreement with those predicted from isothermal behaviour.
Antimicrobial activity of lactobacilli: preliminary characterization and optimization of production of acidocin B, a novel bacteriocin produced by Lactobacillus acidophilus M46
Authors: Brink B. ten , Minekus M. , van der Vossen J.M.B.M. , Leer R.J. , Veld J.H.J. Huis in't
Published: March 2008

Approximately 1000 lactobacillus strains were isolated and screened for the production of antimicrobial activity, using a target panel of spoilage organisms and pathogens. Only eight positive strains were found; two of these were studied in more detail. Lactobacillus salivarius M7 produces the new broad spectrum bacteriocin salivaricin B which inhibits the growth of Listeria monocytogenes, Bacillus cereus, Brochothrix thermosphacta, Enterococcus faecalis and many lactobacilli. A new atypical bacteriocin produced by Lact. acidophilus M46, acidocin B, combines the inhibition of Clostridium sporogenes with a very narrow activity spectrum within the genus Lactobacillus and was selected for further characterization. Acidocin B is sensitive to trypsin, heat‐stable (80°C for 20 min) and can be extracted from the culture supernatant fluid with butanol. Native acidocin B occurs as a large molecular weight complex (100 kDa), while with SDS‐PAGE the partly purified activity migrates as a peptide of 2·4 kDa. Optimization of the cultivation conditions resulted in an eightfold increase of the amount of acidocin B produced during growth. Growth is not necessary for acidocin B production; washed producer cells can synthesize the bacteriocin in a chemically defined production medium. The application potential of acidocin B is discussed.
Stability of plasmids in five strains of Salmonella maintained in stab culture at different temperatures
Authors: Olsen J.E. , Brown D.J. , Baggesen Dorte L. , Bisgaard M.
Published: March 2008

Four strains of Salmonella berta and one of Salm. enteritidis were stored as stab cultures in sugar‐free agar at 5°, 22° and 30°C and in 15% glycerol at—80°C. The stability of the plasmid profiles in each of the strains was monitored over a period of 2·5 years.

Plasmid profiles were stable in all strains stored at—80°C, and only six of 450 colonies examined from strains kept in sugar‐free agar at 5°C had lost plasmid molecules. Seventy of 440 colonies from stab cultures that were kept at 22°C, and 71 of 440 colonies at 30°C showed changed plasmid profiles. The total number of plasmids lost increased with time, and occasionally, more than one plasmid molecule was lost in the same strain.

The virulence associated plasmid of Salm. enteritidis was remarkably stable as it was maintained in all colonies examined at all temperatures investigated. Likewise, no change in SmaI restriction profile was observed in this plasmid molecule at any temperature.
RAPD typing for distinguishing species and strains in the genus Listeria
Authors: Farber J.M. , Addison C.J.
Published: March 2008

The randomly amplified polymorphic DNA (RAPD) technique was employed in the development of a typing protocol for Listeria isolates, particularly Listeria monocytogenes strains. A single strain of L. monocytogenes was used and 200 random decamer primers were screened for their discriminatory abilities by visualizing the amplification products electrophoretically. Three candidate primers displaying potentially useful banding patterns were selected and tested against 52 L. monocytogenes strains, encompassing 11 serotypes, and 12 other strains representing five other Listeria spp. Thirty‐four banding profiles were obtained with one particular primer. RAPD analysis allowed differentiation between Listeria spp. and was found to further subdivide strains of the same serotype. Where only one primer was used strains from different serotypes were occasionally found to produce identical banding profiles. RAPD analysis, which in our hands proved to be reproducible, shows much promise as a molecular alternative to traditional L. monocytogenes typing protocols.
Production and viability of coccoid forms of Campylobacter jejuni
Authors: Boucher S.N. , Slater E.R. , Chamberlain A.H.L. , Adams M.R.
Published: March 2008

Studies were conducted into the formation and physiological state of coccoid cells of a strain of the human and animal pathogen Campylobacter jejuni. It was found that growth phase and the presence of chloramphenicol did not affect the rate of shape transformation from spiral to coccoid, while nutrient limitation, aeration of the medium and the presence of free‐radical scavengers had profound effects. Coccoid cells were found to reduce the tetrazolium salts INT (2‐(p‐iodophenyl)‐3‐(p‐nitrophenyl)‐5‐phenyl tetrazolium chloride) and CTC (5‐cyano‐2,3‐ditolyl tetrazolium chloride) to their respective formazans and this was linked to cellular respiration. However, respiring coccoid cells could not sustain their existence in prolonged adverse conditions, and it was concluded that they represent a degenerative stage rather than a dormant state of the organism.
Bacterial whole cell protein profiles of the rRNA group II pseudomonads
Authors: Li Xlang , Hayward A.C.
Published: March 2008

Studies on bacterial whole cell protein profiles showed that members of the rRNA group II pseudomonads were distinct from other non‐fluorescent and fluorescent pseudomonads, including Pseudomonas aeruginosa, the type species of the genus Pseudomonas. Strains of Ps. andropogonis, Ps. caryophylli, Ps. gladioli pv. gladioli, Ps. pickettii, Ps. pseudomallei and Ps. rubrisubalbicans showed uniform and distinct protein patterns, while strains of Ps. solanacearum and Ps. cepacia displayed differences within species. Numerical analysis of their protein profiles with GelManager and Taxan programs generated dendrograms comprising 16 clusters at 89% similarity. Each cluster included strains belonging to the same species with the exception of Ps. solanacearum, which fragmented into three clusters. Pseudomonas solanacearum showed different protein patterns correlating with different biovars and the two divisions of Cook et al. (1989), as well as the results of 16S rRNA gene sequencing. The whole cell protein profiles of a total of 83 strains belonging to 14 bacterial species were numerically analysed.
Survival of allochthonous bacteria in still mineral water bottled in polyvinyl chloride (PVC) and glass
Authors: Moreira Leonilde , Agostinho Paula , Morals Paula Vasconcellos , da Costa M. S.
Published: March 2008

The mortality of Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae and Pseudomonas aeruginosa, based on the culturability of these bacteria, was assessed in non‐carbonated mineral water, bottled in polyvinyl chloride (PVC) containing the indigenous flora, sterile mineral water bottled in PVC, sterile mineral water in glass containers, and sterile tap water in glass containers. There was a general decrease in the culturability of these organisms in the four test waters, except that Ps. aeruginosa grew in sterile tap water. Escherichia coli and Kl. pneumoniae had the highest mortality rates under the conditions tested, while Ent. cloacae had a very low and constant mortality rate that would have resulted in the persistence of this organism in mineral water for a long period of time. After a sharp initial decrease in culturability, Ps. aeruginosa also had a very low mortality rate in mineral water bottled in PVC.
Enhancement of β‐galactosidase productivity of Aspergillus niger NCIM‐616
Authors: Rasouli I.R. , Ulkarni P.R.K
Published: March 2008

A series of mutations was carried out with Aspergillus niger NCIM‐616 as the parent strain. A mutant strain NG‐4 with 28% increased β‐galactosidase productivity was produced with N‐methyl‐N‐nitro‐N‐nitrosoguanidine (NTG) at 1500µg ml‐1 concentration and exposure timeof 60 min. This mutant yielded a third generation u.v.‐treated strain, UV—5 with a 117·6% increase in β‐galactosidase productivity with respect to the parent strain.
Heterotrophic bacterial populations in the mineral waters of thermal springs in Spain
Authors: Mosso María de los Angeles , de la Rosa María del Carmen , Vivar Carmen , Medina María del Rosario
Published: March 2008

The microbiological quality and heterotrophic bacterial populations of 26 thermal mineral water springs in Spain were studied. In most of the springs the number of viable aerobes was less than 103 cfu ml‐1 and the number of sporulated bacteria less than 102 cfu ml‐1. No significant differences were foundin the counts obtained with Plate Count Agar (PCA) and PCA diluted 1 : 10 and incubated at 22°, 37° and 45°C. Total coliforms were found in 14 springs, faecal streptococci in three, spores of sulphite‐reducing Clostridium and Pseudomonas aeruginosa in seven. Neither Escherichia coli nor Staphylococcus aureus were found. A total of 665 strains were isolated and 85·4% of these identified; 329 were Gram‐positive and 239 were Gram‐negative. The genera most prevalent present in the springs were Pseudomonas (in 92.3%), Bacillus (65.4%), Enterobacter, Micrococcus and Staphylococcus (50%), Acinetobacter (42.3%), Arthrobacter (38.4%), Clostridium (27%) and Xanthomonas (23%). Gram‐negative bacteria predominated in the mesothermal springs and Gram‐positive bacteria in the hyper‐ and hypothermal springs. The most common Gram‐negative rod species isolated were Ps. fluorescens, Ps. aeruginosa, Ps. putida, Ent. agglomerans, Ent. sakazakii, Ac. calcoaceticus and Ent. amnigenus.
Effect of environmental pH on the fermentation balance of Lactobacillus reuteri
Authors: Ragout Alicia , Siñeriz Faustino , Diekmann H. , de Valdez Graciela Font
Published: March 2008

The influence of environmental pH on the regulation of glucose catabolism by Lactobacillus reuteri was examined in anaerobic batch cultures. Under acidic conditions both glucose consumption and end‐products formation were low. Maximum biomass was reached at pH 5·0, with a specific growth rate of µ= 0·78 h‐1. The shift in pH values from 4.3 to 6.5 reflected an increase in glucose uptake as well as in the yield (Yp/x) of acetate, lactate and ethanol after 12 h of incubation. Ethanol was the major metabolite produced at all pH values assayed.
Biochemical properties and whole‐cell protein profiles of group G streptococci isolated from dogs
Authors: Vieira V.V. , Castro A.C.D.
Published: March 2008

Whole‐cell protein profiles obtained by SDS‐PAGE were used in conjuction with physiological tests to differentiate strains of Streptococcus canis isolated from dogs. Fermentation of trehalose and lactose, aesculin hydrolysis together with production of β–D–glucuronidase and α–D–galactosidase allowed the demonstration of nine different biotypes. However, visual analysis of the protein patterns andcomparison by the coefficient of Dice showed minor differences in band patterns among strains. Only two different profiles were observed. Although a correlation between biotypingand protein profile has been found, this kind of analysis did not provide the basis for a typing method.
An enzyme‐linked immunosorbent assay (ELISA) for detection of Clostridium aldrichii in anaerobi ligesters*
Authors: Brigmon R.L. , Chynoweth D.P. , Yang J.C. , Zam S.G.
Published: March 2008

Monoclonal antibodies (Mabs) against Clostridium aldrichii were prepared by in vivo and in vitro immunization with whole cells and produced after fusion as ascites in BALB/c mice. Anenzyme‐linked immunosorbent assay (ELISA) was used to test for specificity and sensitivity of the Mabs to detect Cl. aldrichii. The lower limit for Cl. aldrichii detection in pure and mixed culture with ELISA was 105 cells ml‐1. Twentyother species of bacteria, including 12 celluloytic species, were tested for cross‐reactivity with the ELISA, but none was detected. The ELISA was used for detection of Cl. aldrichii over a 16‐month period in five mesophilic continuously‐stirred tank reactors((CSTR) with wood, glucose, sludge or sorghum as substrates. The population of Cl. aldrichii in the poplar wood anaerobic digester effluentwas 106‐107 cells ml‐1 over that time. These numbers were confirmed by anaerobic microbiological methods. Results from the ELISA technique were obtained in 36 h vs 3 weeks for culture methods. It is concluded that the ELISA is a useful, time‐saving method for identification, detection and quantification of Cl. aldrichii in axenic, mixed culture, and in complex undefined cultures such as those found in anaerobic digesters.
Modeling growth and off‐flavours production of spoiled beer bacteria, Pectinatus frisingensis
Authors: Membré J.M. , Tholozan J.L.
Published: March 2008

The genus Pectinatus includes strictly anaerobic Gram‐negative non‐spore‐forming mesophilic bacteria often referred to as beer‐spoilage bacteria. Pectinatus frisingensis was chosen as the reference strain. The organisms were grown in batch cultures under stringent anaerobic conditions in a synthetic medium and with pH regulation. Various glucose and lactate concentrations were used, and a low inoculum reproduced spoilage conditions in bottled beer. Propionate and acetate are the major compounds responsible for the off‐flavour of beer. Gompertz curves were fitted to acid‐biomass production and glucose consumption; thereby the lag‐phase, production rate and final concentrations were derived. Volatile fatty acids production began 19 h after biomass growth. There was no lineareffect of substrate on final concentration of propionate, acetate and biomass. An additive model is proposed for the prediction of bacterial growth and acid production on both glucose and lactate.
Characterization of β‐glucosidase activity in yeasts of oenological origin
Authors: Rosi Iolanda , Vinella M. , Domizio P.
Published: March 2008

I. ROSI, M. VINELLA AND P. DOMIZIO. 1994. Three hundred and seventeen strains representing 20 species of yeasts were screened for the presence of β‐glucosidase activity. All of the strains of the species Debaryomyces castellii, Deb. hansenii, Deb. polymorphus, Kloeckera apiculata and Hansenula anomala showed β‐glucosidase activity, but only one of 153 strains of Saccharomyces cerevisiae. The other species behaved differently, depending upon the strain. The strains that hydrolysed arbutin were checked to localize the β‐glucosidase activity. A strain of Deb. hansenii exhibited the highest exocellular activity and some wall‐bound and intracellular activity. The β‐glucosidase synthesis from this yeast was enhanced by aerobic conditions of growth, was repressed by high glucose concentration (9%) and occurred during exponential growth. The optimum conditions for enzymatic preparations of Deb. hansenii were between pH 4.0 and 5.0 and 40d̀C. A high concentration of ethanol and glucose did not reduce the ezymatic activity. The enzymatic preparations of Deb. hansenii released monoterpenols and other alcohols from a grape glycoside extract.
Pulsed‐field gel electrophoresis‐fingerprinting, genome size estimation and rrn loci number of Rhizobium galegae
Authors: Huber Ingrid , Selenska‐Pobell Sonja
Published: March 2008

I. HUBER AND S. SELENSKA‐POBELL. 1994. The genomes of several Rhizobium galegae (of.) strains, which effectively nodulate Galega officinalis host, were analysed by pulsed‐field gel electrophoresis (PFGE). Individual PFGE‐fingerprints were obtained for every particular strain when the rarely cutting restriction endonucleases SpeI and AsnI were applied. In hybridization experiments, where a DNA fragment carrying the rrnB ribosomal RNA operon of Escherichia coli was used as a probe, the number of the resulting strain‐specific SpeI and AsnI bands was reduced to three for all of the strains studied. This suggests that in Rh. galegae (of.) there are at least three rrn loci. On the basis of the lengths of the SpeI fragments, separated by PFGE, the genome size of five Rh. galegae (of.) strains was estimated to be 5852 ± 198 kbp.
Degradation and utilization of forage hemicellulose by rumen bacteria, singly in coculture or added sequentially
Authors: Fondevila M. , Dehority B. A.
Published: March 2008

M. FONDEVILA AND B.A. DEHORITY 1994. Procedures for sequential addition experiments were developed to study the mechanisms involved in the synergistic and inhibitory interactions observed in forage hemicellulose digestion by rumen bacterial cocultures. One organism was allowed to ferment a forage substrate, the culture tube was sterilized and then inoculated with a second organism. No differences were found in the extent of degradation or utilization between fermentations sterilized by oxidation or heat, and based on ease of handling, heat was used in all subsequent experiments. Studies were conducted with Fibrobacter succinogenes A3c, Ruminococcus flavefaciens B34b and Prevotella ruminicola H2b, singly and in all possible combinations. Results from the sequential addition studies substantiated earlier suggestions that the increase observed in hemicellulose utilization results from initial solubilization of the hemicellulose from the forage by the non‐utilizer and subsequent utilization of this solubilized polysaccharide by the utilizing, but non‐degrading organism.
Staphylococcal growth and enterotoxins (A—D) and thermonuclease synthesis in the presence of dehydrated garlic
Authors: González‐Fandos E. , García‐López M.L. , Sierra M.L. , Otero A.
Published: March 2008

E. GONZÁLEZ‐FANDOS, M.L. GARCÍA‐LÓPEZ, M.L. SIERRA AND A. OTERO. 1994. The inhibition of Staphylococcus aureus growth and enterotoxin and thermonuclease production by various concentrations of garlic (Allium sativum) was studied in BHI broth. The growth of Staph. aureus was inhibited by dehydrated garlic at levels of 1.5% (w/v) and over. Enterotoxins A, B and C1 were only detectable in broth containing < 1% of garlic while enterotoxin D was produced at a level of 2%. Garlic also inhibited thermonuclease (TNAse) production, complete inhibition being observed at levels ≥ 1.5%. TNAse was not always detected when enterotoxin was present.
A red pigment synthesized by an Aspergillus parasiticus mutant as a possible new intermediate in the aflatoxin biosynthetic pathway
Authors: García M.‐E. , Herce M.D. , Blanco J.L. , Suárez G.
Published: March 2008

M.‐E. GARCÍA, M.D. HERCE, J.L. BLANCO AND G. SUÁREZ. 1994. The isolation of a red pigment from an Aspergillus parasiticus mutant obtained by 366 nm u.v. light treatment of A. parasiticus NRRL 2999 is described. Studies of conversion in aflatoxin B1 and G1 suggest that the red pigment could be a possible new intermediate in the aflatoxin biosynthetic pathway not described to date, and this has been verified by studies in gas chromatography/mass spectrometry. The solubility and stability characteristics under refrigeration storage, and the influence of the temperature and the pH on its production by the A. parasiticus mutant were also studied. It grew best at 30d̀C and pH 6. The red pigment was most soluble in ethyl acetate. The results obtained in water are emphasized where there was high stability.
Random amplification of polymorphic bacterial DNA: evaluation of 11 oligonucleotides and application to food contaminated with Listeria monocytogenes
Authors: Niederhauser Ch. , Höfelein Ch. , Allmann M. , Burkhalter P. , Lüthy J. , Candrian U.
Published: March 2008

CH. NIEDERHAUSER, CH. HÖFELEIN, M. ALLMANN, P. BURKHALTER, J. LÜTHY AND U. CANDRIAN. 1994. The polymerase chain reaction was used to obtain randomly‐amplified polymorphic DNA (RAPD) profiles from Listeria spp. and enterobacteria. Eleven different oligonucleotides were evaluated. Only one, HR4 (19mer), generated reproducible and specific profiles for Listeria spp., while results for enterobacteria were controversial. A total of 57 different Listeria strains were subjected to the RAPD analysis and 27 different profiles were recognized. RAPD typing allowed strains of the same serotype to be distinguished but the same profile was obtained from different serotypes of L. monocytogenes in three cases and in one case two different serotypes of L. innocua yielded the same profile. RAPD‐typing with HR4 allowed L. monocytogenes contamination in several food outlets to be traced back to a food processing plant. In additional experiments, the general utility of this RAPD system in typing Yersinia enterocolitica, verotoxigenic Escherichia coli and Salmonella enteritidis was evaluated.
The microaerophily and photosensitivity of Propionibacterium acnes
Authors: Gribbon Enda Martin , Shoesmith J.G. , Cunliffe W.J. , Holland K.T.
Published: March 2008

E. MARTIN GRIBBON, J.G. SHOESMITH, W.J. CUNLIFFE AND K.T. HOLLAND. 1994. The effect of oxygen on the in vitro propagation of Propionibacterium acnes was investigated under defined culture conditions. This micro‐organism is the predominant bacterial resident within the pilosebaceous follicles of sebum‐rich areas of human skin. The organism was grown in continuous culture in defined synthetic medium with glucose as the main carbon‐energy source at various air saturation concentrations and in the presence and absence of light. Steady state continuous cultures were achieved at very low oxygen tensions in the presence of light, and at higher levels of oxygen when non‐illuminated. Culture biomass yields were higher than those of anaerobic cultures. Bacterial cells were inactivated in the presence of light at high oxygen concentrations because of photosensitization reactions involving excess oxygen and microbial porphyrin species.
Interaction of the bacteriocin pediocin SJ‐1 with the cytoplasmic membrane of sensitive bacterial cells as detected by ANS fluorescence
Authors: Schved F. , Lindner P. , Juven B.J.
Published: March 2008

The l‐anilino‐8‐naphthalenesulphonic acid (ANS) fluorescent probe was used to monitor alterations in the cytoplasmic membrane of sensitive Lactobacillus plantarurm cells, caused by pediocin SJ‐1, a bacteriocin produced by Pediococcus acidilactici. The addition of pediocin SJ‐1 to the sensitive cells caused an increase in fluorescence intensity of ANS and a blue shift in its emission maximum from 520 to 475 nm. None of these spectral changes could be detected when pediocin SJ‐1 was added to cells of a Lact. plantarum variant resistant to pediocin SJ‐1. Upon the addition of pediocin SJ‐1, dose‐dependent energy transfer took place between tryptophanyl residues in the cytoplasmic membrane of sensitive cells and ANS. Similar ANS‐fluorescence changes were observed with the bacteriocin nisin. The concentrations of pediocin SJ‐1 needed to effect changes in the fluorescence spectrum of ANS were of the same magnitude as those required for a bactericidal effect and the release of u.v.‐absorbing material. A hypothesis on the mode of action of pediocin SJ‐1 is proposed.
Bactericidal activity in the pig roundworm Ascaris suum
Authors: Wardlaw A.C. , Forsyth L.M.G. , Crompton D.W.T.
Published: March 2008

A potent, humoral, bactericidal activity against Micrococcus luteus was discovered in pseudocoelomic fluid of the pig roundworm, Ascaris suum. The activity, which was not bacteriolytic, was not due to lysozyme or to a dietary antibiotic. It was not inactivated by exposure to 100°C, to low or high pH, or to ethanol. Dialysis, electrophoresis and agar‐diffusion experiments suggested that the main antibacterial activity in the fluid was associated with a basic substance of molecular weight somewhat less than 14000 Da. Two other Gram‐positive organisms, Bacillus megaterium and Staphylococcus aureus, were also killed by the Ascaris fluid, but the Gram‐negative Escherichia coli, Proteus vulgaris and Bordetella bronchiseptica were insensitive.
An evaluation of the repeatability and reproducibility of a surface test for the activity of disinfectants
Authors: Bloomfield Sally F. , Arthur M. , Van Klingeren B. , Pullen W. , Holah J.T. , Elton Rebecca
Published: March 2008

A collaborative study was carried out to determine the precision of a disinfectant surface test method which is currently under consideration for development as a harmonized European standard surface test. Results indicate that significant variation in microbicidal effect occurs both within and between test laboratories despite careful standardization of test conditions, but that the variability may be less than that associated with suspension tests. Indications are that much of this variability derives from random variations in the resistance of the test strains from day to day and, most particularly, from test period to test period both within as well as between laboratories. It is concluded that although the test may be sufficiently reliable to be used as a standard method, adequate replication must be specified to distinguish borderline pass from borderline fail concentrations.
The interaction of trimethoprim and quinolones against Gram‐negative fish pathogens
Authors: Inglis V. , Cafini M. , Yoshida T.
Published: March 2008

The effect of combination of trimethoprim with other non‐sulphonamide antibacterial agents, in particular oxolinic acid and nalidixic acid, was evaluated against Gram‐negative fish pathogens. The species included Aeromonas salmonicida, Yersinia ruckeri, some Vibrio spp. and Escherichia coli as a reference. The extent of synergy found by other workers with these substances against human Gram‐negative bacteria was not apparent here. Some positive interaction between trimethoprim and oxolinic acid was found with Aer. salmonicida, Y. ruckeri and E. coli and between trimethoprim and nalidixic acid with Y. ruckeri in double disc diffusion tests but was not supported by fractional inhibitory concentration indices. The combinations were not effective in preventing emergence of resistance in passage on a drug gradient. Trimethoprim‐resistant isolates of Aer. salmonicida were inhibited by low levels of oxolinic acid but the converse did not apply.
The effects of glucosinolates and their hydrolysis products on microbial growth
Authors: Brabban A.D. , Edwards C.
Published: March 2008

Rapemeal, which contains potentially toxic compounds such as glucosinolates, was assessed as a substrate for the growth of micro‐organisms. The effects of glucosinolates and their degradation products were tested on a range of industrially important microbial species. Sinigrin (2‐propenyl glucosinolate) was found to be relatively innocuous to all of the organisms tested but its hydrolysis to yield isothiocyanates, thiocyanates and nitriles resulted in inhibition of growth. The initial inhibitory sinigrin concentration before its hydrolysis was found to be species‐dependent with Bacillus subtilis being the most resistant (80 μg ml‐1) and Saccharomyces cerevisiae (40 μg ml‐1) the most sensitive. Three Gram‐positive organisms tested were found to be more resistant to hydrolysis products than other micro‐organisms. Similar results were observed with phenylisothiocyanate for which inhibition was found to be inhibitor and cell concentration‐dependent. Addition of thioglucoside glucohydrolase during active growth of Escherichia coli in a sinigrin‐containing liquid medium reduced the number of viable cells. Similar effects were also observed in rapemeal media in which growth inhibition was dependent on the glucosinolate content of the rapemeal.
Identification of enterohaemorrhagic Escherichia coli by means of their production of enterohaemolysin
Authors: Bettelheim K.A.
Published: March 2008

With increasing interest in verocytotoxigenic Escherichia coli (VTEC) being associated with both human and animal infection, a simple system of rapidly identifying the majority of VTEC has been devised. This depends on the fact that most VTEC produce enterohaemolysin, which is rarely produced by non‐VTEC. By employing two media, traditional sheep blood agar (SBA) and washed sheep blood agar supplemented with calcium (WSBA‐Ca), enterohaemolysin‐producing strains can be easily differentiated from other E. coli enabling most VTEC types, including ones belonging to serogroups other than O157, to be isolated.
Thermostable dextranases: screening, detection and preliminary characterization
Authors: Wynter C.V.A. , Galea C.F. , Cox L.M. , Dawson M.W. , Patel B.K. , Hamilton S. , Jersey J. De , Inkerman P.A.
Published: March 2008

Screening methods have been developed for detection of micro‐organisms producing thermostable dextranases. They utilize the incorporation of Blue Dextran into agar or liquid culture media for isolation of active dextranase producers growing at temperatures above 55°C. A variety of high temperature environments in sugar factories and naturally occurring thermal water samples were excellent sources of dextranase producers. A number of aerobic and anaerobic thermophilic bacteria, isolated from these sources, were found to produce thermostable dextranases. Dextranases with the greatest thermostability were found in cultures of anaerobic bacteria grown above 65°C. Temperature optima were determined for several crude enzyme preparations, four of which exhibited temperature optima in the range 65–85°C.
Factors affecting the electroporation of Bacillus subtilis
Authors: McDonald I.R. , Riley P.W. , Sharp R.J. , McCarthy A.J.
Published: March 2008

Bacillus subtilis 168 trp ‐ was found to be transformable with the tetracycline resistance plasmid pAB124 by electroporation of whole cells, inconsistently and at very low frequencies. Supplementation of the growth medium with glycine, or particularly DL‐threonine, produced cells that could be electrotransformed much more efficiently at frequencies up to 2.5 X 103 transformants per μg plasmid DNA. Transformation was optimal with cells grown in medium containing a racemic mixture of the D‐ and L‐isomers of threonine, and no transformants were obtained when pure forms of the D‐ and L‐threonine isomers were used. The cell walls of B. subtilis grown in the presence or absence of D‐, L‐ and DL‐threonine had a similar amino acid composition which did not include threonine. A more complex biochemical explanation of the enhancement of electroporation by growth in DL‐threonine is likely, and this is discussed. Lysozyme treatments to weaken the cell wall and possibly mimic the effect of DL‐threonine did not yield any transformants. The effects of buffer composition and culture incubation time were also determined and the electroporation protocol optimized accordingly. The response of a range of other B. subtilis strains to electroporation by the method produced was found to be variable. In all cases, transformation was verified by recovery of the plasmid DNA from putative transformants.
Polar lipids ofStaphylococcusstrains analysed by fast atom bombardment mass spectrometry
Authors: Drucker D.B. , Abdullah N.
Published: March 2008

This study used fast atom bombardment mass spectrometry (FAB MS) to obtain detailed information on polar lipids ofStaphylococcusby examining 23 isolates. Eighteen major anions were found in the range m/z 199–297, consistent with the presence of carboxylate anions. A further 21 major anions were found in the higher mass regions of m/z 609–805, consistent with the presence of phospholipid anions. InStaph. aureus, Staph. epidermidis, Staph. haemolyticusandStaph. hominis, the most intense peaks putatively assigned as carboxylate ions were consistent with presence of C15:0, followed by C17:0except in the case ofStaph. epidermidis.The major phospholipid anions were consistent with the presence of PG(30 : 0), PG(32 : 0) and PG(33 : 0). It is concluded thatStaphylococcushas a characteristic polar lipid profile and that qualitative and quantitative differences may be seen betweenStaph. aureusandStaph. epidermidis.
Degradation activity of adhered and suspended Pseudomonas cells cultured on 2,4,6‐trichlorophenol, measured by indirect conductimetry
Authors: Ascón‐Cabrera M.A. , Ascón‐Reyes D.B. , Lebeault J.M.
Published: March 2008

The degradation activity (expressed as specific CO2 production rates) of adhered and suspended Pseudomonas cells, strains SP1 and SP2, during the degradation of 2,4,6‐trichlorophenol (2,4,6‐TCP), was compared using indirect conductimetry technique. This technique is defined as the measurement of CO2 ionization in an alkaline solution and expressed as the negative conductance change values of such solution. The attachment surfaces were porous glass and silicone rubber. The 2,4,6‐TCP concentrations ranged from 10 to 500 mg 1−1. Specific respiration rates were determined from CO2 evolution rates and biomass yields of both suspended and adhered cell cultures. CO2 evolution rates were determined after conversion of conductance change values into CO2 produced values. Results indicate that glass‐adhered cells reached a higher maximum specific CO2 evolution rate (QCO2max) than both suspended and silicone rubber‐adhered cells. However, suspended cells showed a lower saturation constant (Ks) than the adhered cells. These results suggest that depending on support nature the respiration activity of adhered cells could be higher than of suspended cells. Moreover, the indirect conductimetry technique could efficiently be used by measurements of respiration activities of both attached or suspended xenobiotic‐degrading micro‐organisms.
Genetic and functional analysis of novobiocin non‐producing mutants of Streptomyces niveus
Authors: Hoggarth J. H. , Cushing K. E. , Ritchie D. A.
Published: March 2008

Analysis of a series of 10 novobiocin non‐producing (Nov−) mutants of Streptomyces niveus failed to detect the production of novobiocin in all pairwise combinations in cosynthesis tests. Novobiocin production was restored in nine mutants when the growth medium was supplemented with the pathway intermediates, novobiocic acid and descarbamylnovobiocin, indicating that the mutants are blocked in the synthesis of the amino coumarin moiety (Ring B). Thin layer chromatographic analysis confirmed this by showing that each mutant was able to synthesize the benzoic acid component (Ring A) but not novobiocic acid (the fusion product of Rings A and B) or descarbamylnovobiocin. A study of the novobiocin resistance characteristics of the 10 mutants showed resistance levels considerably lower than for wild type. The Nov− mutants could be classified into four phenotypic groupings (Ib+ Is+, Ib+ Is−, Ib− Is+ and Ib− Is−) on the basis of their ability to be induced to high level resistance (Ib) by an inducing factor produced by wild‐type mycelium and their ability to induce high level resistance (Is) in wild type.
Production of feruloyl/ρ‐coumaroyl esterase activity by Penicillium expansum, Penicillium brevicompactum and Aspergillus niger
Authors: Donaghy J. A. , McKay A. M.
Published: March 2008

Extracellular esterase production by Penicillium expansum, Penicillium brevicompactum and Aspergillus niger was determined in both liquid and solid‐state culture. Methyl ferulate was used as the main carbon source in liquid culture whereas wheat bran and sugar beet pulp were used in solid‐state culture. Extracted enzyme for each fungus showed activity in the presence of ONP butyrate, methyl ferulate, methyl coumarate and two ‘natural’feruloylated carbohydrate esters. Higher enzyme recoveries were obtained using wheat bran in solid‐state culture. Higher levels of feruloyl esterase activity were recovered from P. expansum on all feruloylated substrates than from P. brevicompactum or A. niger. Using ONP butyrate as substrate the pH and temperature optima for the esterases of both Penicillium spp. were 6.0 and 25–30°C. Aspergillus niger esterase activity showed a broader temperature range with an optimum at 40°C.
Characterization of two virulent Lactobacillus fermentum bacteriophages isolated from sour dough
Authors: Foschino R. , Perrone F. , Galli A.
Published: March 2008

Two different bacteriophages, FE5‐B1 and Z63‐B1, active against strains of Lactobacillus fermentum were isolated from a sample of sour dough of a regional wheat bread. They showed different host specificities when tested against 58 strains of obligately heterofermentative lactic acid bacteria, as well as differences in adsorption and one‐step growth kinetics. The burst size of FE5‐B1 was about 100 pfu cell−1. This phage belonged to the A1 morphotype of Myoviridae family, having an icosahedral head (83 nm diam.) and a sheathed contractile tail (170 nm in length). The phage consisted of five major structural proteins and had a genome of 86 kbp. Z63‐B1 showed a burst size of 10 pfu cell−1 and belonged to the B1 morphotype or Siphoviridae family. Z63‐B1 had an isometric head (60 nm diam.) and a non‐contractile tail (160 nm in length), with eight major different structural proteins and a genome of 32 kbp.
Non‐culturable Legionella pneumophila associated with Acanthamoeba castellanii: detection of the bacterium using DNA amplification and hybridization
Authors: Hay J. , Seal D.V. , Billcliffe B. , Freer J.H.
Published: March 2008

J. HAY. D.V. SEAL, B.BILLCLIFFE AND J.H. FREER. 1995. The intracellular localization of Legionella pneumophila serogroup 1 within Acanthamoeba castellanii rendered the bacteria non‐culturable on supplemented BCYE agar. DNA amplification, using two 19‐mer primers, and hybridization using a 25‐mer oligonucleotide probe, permitted detection of Leg. pneumophila in approximately 81% (29/36) of samples where the bacteria could not be detected using culture. A combination of co‐cultivation of samples with Leg. pneumophila‐naive A. polyphaga or Hartmannella vermiformis, incubation in a defined liquid medium or use of catalase indicated that approximately 31% (9/29) of the samples contained Leg. pneumophila which were viable although not culturable.
Antibiotic production and biocontrol activity by Bacillus subtilis CL27 and Bacillus pumilus CL45
Authors: Leifert C. , Li H. , Chidburee Siripun , Hampson S. , Workman Suzanne , Sigee D. , Epton H.A.S. , Harbour Agnes
Published: March 2008

C. LEIFERT, H. LI, S. CHIDBUREE, S. HAMPSON, S. WORKMAN, D. SIGEE, H.A.S. EPTON AND A. HARBOUR. 1995. Bacillus subtilis CL27 and B. pumilus CL45 showed similar activity against Botrytis cinerea in in vitro plate assays. In a seedling bioassay, however, B. subtilis CL27 had activity similar to a commercial fungicide while B. pumilus CL45 failed completely to prevent seedling damping‐off caused by Bot. cinerea.

Antibiotic production by the two Bacillus strains was found to depend on the growth substrate and highest antibiotic production was found on media based on homogenized cabbage tissue. Antibiotic activity was found to depend on the pH and nutrient concentration in the assay medium. Antifungal antibiotics produced by B. subtilis CL27 and B. pumilus CL45 in different fermentation media were separated by thin layer chromatography. As suspected from the activity spectrum, three antibiotics (one with activity against Alternaria brassicicola, one with activity against Botrytis cinerea and one with activity against both fungi) could be detected in the fermentation broth of CL27, but only one in the fermentation broth of CL45. The two antibiotics produced by strain CL27 with activity against A. brassicicola were identified as peptides since their bands on the TLC plates developed a green to blue/green colour after treatment with 4,4'‐tetramethyldiamino‐diphenylmethane (TDM) reagent. The third antibiotics produced by strain CL27 and antibiotic produced by CL45 had a similar Rf‐value and appeared not to be peptides based on the reaction with TDM. However, they showed a slightly different activity spectrum when tested against a range of different fungi.

Antibiotic production was clearly indicated as the mode of action of in vivo biocontrol by strain CL27 against damping off caused by Bot. cinerea of Astilbe micro‐plants, because a u.v.‐induced antibiotic negative mutant strain CL27b showed no activity in seedling bioassays in vivo. Also the mutant strain CL27a which produced the two peptide antibiotics but had lost the ability to produce the non‐peptide antibiotic, showed greatly reduced in vivo activity.
Isolation of nisin‐producing Lactococcus lactis strains from dry fermented sausages
Authors: Rodriguez J.M. , Cintas L.M. , Casaus P. , Horn N. , Dodd H.M. , Hernández P.E. , Gasson M.J.
Published: March 2008

J.M. RODRÍGUEZ, L.M. CINTAS, P. CASAUS, N. HORN, H.M. DODD, P.E. HERNÁNDEZ AND M.J. GASSON. 1995. A total of 4608 lactic acid bacteria (LAB) were isolated from 24 Spanish fermented sausages and screened for bacteriocin production. Two strains, BB24 and G18, produced bacteriocins that inhibited a broad spectrum of Gram‐positive bacteria. BB24 and G18 were tentatively identified as Lactococcus lactis by carbohydrate fermentation patterns and other biochemical characteristics. The characterization of their bacteriocins suggested that both could be the well‐known lantibiotic nisin. This was confirmed by PCR analysis of their genomic DNA. Nucleotide sequencing revealed that they produced nisin A. The fact that BB24 and G18 were isolated from sausages produced in two different regions of Spain suggests that nisin‐producing L. lactis strains may be more widespread in meat products than previously thought. Nisin produced by L. lactis BB24 has been purified to homogeneity by a procedure that included ammonium sulphate precipitation and cation‐exchange, hydrophobic‐interaction and reverse‐phase chromatography. The purification procedure was simple, rapid and reproducible.
Degradation of methoxylated aromatic acids by Pseudomonas putida
Authors: Turner J.E. , Allison N.
Published: March 2008

J.E. TURNER AND N. ALLISON. 1995. A newly‐isolated strain of Pseudomonas putida (HVA‐1) utilized homovanillic acid as sole carbon and energy source. Homovanillate‐grown bacteria oxidized homovanillate and homoprotocatechuate but monohydroxylated and other methoxylated phenylacetic acids were oxidized poorly; methoxy‐substituted benzoates were not oxidized. Extracts of homovanillate‐grown cells contained homoprotocatechuate 2,3‐dioxygenase but the primary homovanillate‐degrading enzyme could not be detected. No other methoxylated phenylacetic acid supported growth of the organism but vanillate was utilized as a carbon and energy source. When homovanillate‐grown cells were used to inoculate media containing vanillate a 26 h lag period occurred before growth commenced. Vanillate‐grown bacteria oxidized vanillate and protocatechuate but no significant oxygen uptake was obtained with homovanillate and other phenylacetic acid derivatives. Analysis of pathway intermediates revealed that homovanillate‐grown bacteria produced homoprotocatechuate, formaldehyde and the ring‐cleavage product 5‐carboxymethyl 2‐hydroxymuconic semialdehyde (CHMS) when incubated with homovanillate but monohydroxylated or monomethoxylated phenylacetic acids were not detected. These results suggest that homovanillate is degraded directly to the ring‐cleavage substrate homoprotocatechuate by an unstable but highly specific demethylase and then undergoes extradiol cleavage to CHMS. It would also appear that the uptake/degradatory pathways for homovanillate and vanillate in this organism are entirely separate and independently controlled. If stabilization of the homovanillate demethylase can be achieved, there is potential for exploiting the substrate specificity of this enzyme in both medical diagnosis and in the paper industry.
Establishment of oil‐degrading bacteria associated with cyanobacteria in oil‐polluted soil
Authors: Sorkhoh N.A. , Al‐Hasan R.H. , Khanafer Majeda , Radwan S.S.
Published: March 2008

N.A. SORKHOH, R.H. AL‐HASAN, M. KHANAFER AND S.S. RADWAN. 1995. A unique natural microbial cocktail with promising potential for remediating oil‐polluted desert in the Gulf region is reported. Oil‐degrading micro‐organisms immobilized within dense cyanobacterial mats on oily coasts of the Arabian Gulf were successfully established in oil‐contaminated sand. Those micro‐organisms biodegraded 50% of the oil within 10–20 weeks. Nocardioforms belonging to the genus Rhodcoccus predominated in the first few weeks, but after 22 weeks Pseudomonas spp. increased, sharing Rhodococcus in the predominance. Other oil‐utilizing bacterial genera included Bacillus and Arthrobacter. Filamentous actinomycetes belonging to the genera Streptomyces and probably Thermoactinomyces, as well as fungi belonging mainly to Aspergillus and Penicillium increased in the contaminated sand during the experiment but declined later. Representative strains grew on spectra of the tested n‐alkanes with chain lengths between C10 and C40, as sole sources of carbon and energy.
Biodegradation of linear alkylbenzenesulphonates (LAS) by mixed methanotrophic‐heterotrophic cultures
Authors: Hršak Dubravka , Grbić‐Galić Dunja
Published: March 2008

The biodegradation of undecylbenzenesulphonate (C11LAS) was studied in shake flasks at 21°C using two mixed bacterial cultures. The first culture, MM1, contained a type II methanotroph and four heterotrophs, and was enriched from a groundwater aquifer. The second culture, MC, consisted of five heterotrophic strains, most of them belonging to the genus Pseudomonas, and was isolated from the wastewater of a detergent plant. Methane, carbon dioxide and oxygen concentrations were determined by gas chromatography. Concentrations of C11LAS and the aromatic intermediates were determined by reversed‐phase HPLC. In spite of faster transformation of the alkyl side‐chain by the culture MC, the culture MM1 containing type II methanotroph was capable of further degradation of C11LAS aromatic intermediates (sulphophenylalkanoates). The most probable mechanism for the degradation of the alkyl part of the C11LAS molecule by both cultures was β‐oxidation of the terminal methyl group followed by β‐oxidation. Studies of methane utilization demonstrated an approximately three times higher second‐order rate coefficient for methane consumption (kmax/Ks) in the absence of C11LAS. This indicates a possible metabolic activity of methanotrophs in the transformation of the complex LAS molecule due to the methane monooxygenase enzyme system.
Mixed culture of Lactobacillus hilgardii and Leuconostoc oenos isolated from Argentine wine
Authors: Rodriguez Ana V. , de Nadra María C. Manca
Published: March 2008

Growth, sugar and organic acid metabolism of Lactobacillus hilgardii X1B and Leuconostoc oenos X2L isolated from Argentinian wine were examined in pure and mixed cultures. In mixed culture Leuc. oenos X2L did not grow, no viable cells were detected after 24 h, but the consumption of glucose and fructose by Lact. hilgardii was higher. An increase of mannitol and acetic acid production was detected during the early stages of growth. Over 12 h, higher levels of d(‐) lactic acid and slightly increased levels of l(+) lactic acid were observed. Citric and malic acid were simultaneously metabolized, but a slight increase in citric acid consumption was observed in mixed culture.