bluuebunny/crossref_metadata_2025 huggingface dataset:
Scanning electron micrograph study of Bacillus licheniformis during bioleaching of silica from magnesite ore
Authors: Mohanty B.K. , Mishra A.K.
Published: March 2008

We report a scanning electron micrographical study of morphological characteristics of Bacillus licheniformis during bioleaching of silica from magnesite ore and its effect on the ore surface. When grown in the presence of magnesite ore the bacteria were pleomorphic and developed protrusions on the cell surface by which they adhered to the ore surface. A significant amount of soluble silica was released into the leaching solution during incubation for 96 h and was followed by a heavy corrosion of the ore surface. This observation was supported by a petrographic thin‐section analysis which showed the absence of silica veins in magnesite ore exposed to the organism.
Molecular characterization of Lactobacillus curvatus and Lact. sake isolated from sauerkraut and their application in sausage fermentations
Authors: Vogelxy R.F. , Lohmann M. , Nguyen Margarethe , Weller Andrea N. , Hammes W.P.
Published: March 2008

Lactobacillus curvatus and Lact. sake are best adapted to meat fermentations and dominate the flora during the whole process. In fermenting sauerkraut, Leuconostoc mesenteroides subsp. mesenteroides is the major organism only during the early phase. In this environment Lact. curvatus and Lact. sake provide up to 50% of the microbial flora especially of the later phase, depending on the process conditions. Strains of Lact. curvatus and Lact. sake isolated from fermenting sauerkraut were identified by hybridization with species specific 23S rRNA‐targeted oligonucleotide probes and further characterized. In 59 of 72 strains, plasmid DNA was detected. Small cryptic plasmids of 20 strains were found to be homologous with pLc2, a 2·6 kb plasmid from Lact. curvatus LTH683, which was originally isolated from meat. The ability to compete was investigated in fermenting sausages of two strains each of Lact. curvatus and Lact. sake isolated from sauerkraut. One strain each of Lact. curvatus and Lact sake was found to outnumber the meat‐borne flora and govern the process.
Numerical taxonomy of Lactobacillus spp. associated with healthy and diseased mucosa of the human intestines
Authors: Molin G. , Jeppsson B. , Johansson M.‐L. , Ahrné S. , Nobaek S. , Ståhl M. , Bengmark S.
Published: March 2008

Two‐hundred and fifty Lactobacillus strains isolated from healthy and diseased mucosa of human intestines of 75 individuals and 49 reference strains were phenotypically classified using 49 unit characters. Data were processed by the Jaccard (Sj) and Simple Matching (SSM) coefficients, and unweighted pair group algorithm with arithmetic averages. Seventeen major clusters were defined at the 76%Sj‐similarity level which approximately correspond to the SSM‐level of 91%. Seven clusters could be identified: Lactobacillus plantarum (isolates recovered from 5% of the patients), Lact. casei subsp. rhamnosus (17% of the patients), Lact. casei subsp. pseudoplantarum (5% of the patients), Leuconostoc mesenteroides subsp. mesenteroides (3% of the patients), Lact. buchneri (4% of patients), Lact. reuteri (4% of the patients) and Lact. salivarius subsp. salivarius (9% of the patients). Unassigned clusters 1 and 3 both contained homofermentative Lactobacillus strains. Cluster 1 included the type strains of Lact. crispatus, Lact. acidophilus, Lact. jensenii and Lact. gasseri, and cluster 3, the type strains of Lact. delbrueckii subsp. lactis, Lact. agilis and Lact. casei subsp. tolerans. Clusters 1 and 3 were found in 15% and 25% of the patients, respectively. Unassigned clusters 2, 6, 7, 8 and 10 contained homofermentative Lactobacillus strains but no reference strains. Clusters 11, 12, 15 and 17 were made up of heterofermentative Lactobacillus strains but no reference strains. Phenotypical characteristics of the clusters are given. No obvious trends in species (cluster) composition between different intestinal locations could be noted. Most clusters contained isolates from both diseased and healthy mucosa. Exceptions were cluster 15 and cluster 17 which only included isolates from healthy mucosa, and cluster 11 which only included isolates from diseased mucosa. Cluster 15 was isolated in 12% of the patients, and cluster 11 in 8%.
Interrelationships between strains of Salmonella enteritidis belonging to phage types 4, 7, 7a, 8, 13, 13a, 23, 24 and 30
Authors: Threlfall E.J. , Chart H. , Ward L.R. , de Sa J.D.H. , Rowe B.
Published: March 2008

Salmonella enteritidis strain P278849 expressed long‐chain lipopolysaccharide (LPS, termed ‘smooth’), carried plasmids of 38, 34 (pDEP 44, incompatibility group N, R‐type AS), 2.0 and 1 MDa, and belonged to phage type (PT) 23. Introduction of pDEP 44 into a smooth strain of Salm. enteritidis PT 4 produced a smooth strain of Salm. enteritidis of PT 24. Transfer of this plasmid into a strain of PT 8 also resulted in formation of a smooth strain of Salm. enteritidis of PT 24. Moving pDEP 44 into strains of Salm. enteritidis of PTs 7 or 7a which did not express LPS (termed ‘rough’) resulted in rough strains of PT 23. In contrast, transfer of this plasmid into a smooth strain of Salm. enteritidis PT 7a resulted in a smooth strain of PT 23. Introduction of pDEP 44 into strains of Salm. enteritidis of PT 13 or PT 13a did not change the phage type, whereas transferring the plasmid into strains of PT 30 caused strains to become resistant to lysis by the typing phages and therefore untypable. The possibility of strains of Salm. enteritidis of PT 8 being the progenitors of strains of Salm. enteritidis of PT 24 must now be considered when investigating the epidemiology of Salm. enteritidis of PT 24 infections in areas where Salm. enteritidis PT 8 is common.
Development of a 24 h screen to detect viable salmonellas in faeces
Authors: Cherrington Christina A. , Huis in't Veld J.H.J.
Published: March 2008

A 24 h screen to detect viable salmonellas in faeces was developed by studying growth dynamics of salmonellas and competing flora in combinations of enrichment media and artificially‐inoculated pig faeces. Muller‐Kauffmann tetrathionate (MK) broth, incubated overnight at 42°C, maintained the lowest ratio of salmonella: competing flora and identified all inoculated samples. A 4 h postenrichment in M broth plus novobiocin reduced the number of false‐positive results in subsequent ELISAs. Adjusting the negative cut‐off values and incubation time of the chromogenic substrate from that recommended in the ELISA instructions reduced the rate of false‐positive results further and allowed the detection of 103 salmonellas per ml in the presence of up to 107 ml−1 aerobic‐competing cells. Suspension of faeces diluted 1 in 2 and 1 in 5, rather than 1 in 10 in MK broth did not necessitate further adjustments to the ELISA baseline values. The proposed screen protocol is an overnight incubation of faeces suspended 1 in 10 in MK broth, a 1 in 100 subculture into M broth plus 10 μg ml−1 novobiocin (MbN) for 4 h, steam inactivation of MbN cultures and testing by ELISA, and can detect three salmonella cells per g faeces.
Revival of Bacillus subtilis spores from biocide‐induced injury in the germination process
Authors: Williams Nicola D. , Russell A.D.
Published: March 2008

Spores of Bacillus subtilis NCTC 8236 were treated with glutaraldehyde, Lugol's iodine, polyvinylpyrrolidone‐iodine (PVP‐I), sodium hypochlorite or sodium dichloroisocyanurate (NaDCC). After exposure survivors were enumerated on nutrient agar containing potential revival agents (subtilisin, lysozyme, calcium dipicolinate, calcium lactate). Of these, only calcium lactate had any significant enhancing effect and then only with iodine‐treated spores. Calcium lactate (9 mmol 1−1) in nutrient broth enhanced the rate and extent of germination of iodine‐treated spores but not of spores previously subjected to glutaraldehyde, hypochlorite or NaDCC.
Culture media for the differentiation of isolates of Yersinia ruckeri, based on detection of a virulence factor
Authors: Furones M.D. , Gilpin M.L. , Munn C.B.
Published: March 2008

M.D. FURONES, M.L. GILPIN AND C.B. MUNN. 1993. Strains of the bacterial fish pathogen Yersinia ruckeri were identified with the API 20E system and distinguished on the basis of whole cell agglutination with antisera, sorbitol fermentation and polymyxin B sensitivity. Strains which were shown to possess the virulence‐associated heat‐sensitive factor (HSF) were shown to grow preferentially on culture media containing sodium dodecyl sulphate (SDS) and to produce a creamy deposit around the colonies. By contrast, strains lacking this factor (HSF‐) grew poorly and without forming a deposit. Enhancement of the differentiation between the two types was shown by the incorporation of Coomassie brilliant blue dye into agar containing 1% SDS, and the uptake of Coomassie blue and Congo red was shown to be temperature‐dependent. Most strains tested were shown to belong to serotype I, and were sensitive to polymyxin and did not ferment sorbitol. With the medium developed most serotype I strains but not those of other serotypes were shown to possess HSF. It is suggested that the medium is used in epidemiological studies of Y. ruckeri.
Factors affecting the selection and use of tetrazolium salts as cytochemical indicators of microbial viability and activity
Authors: Thom Susan M. , Horobin R.W. , Seidler E. , Barer M.R.
Published: March 2008

S.M. THOM, R.W. HOROBIN, E. SEIDLER AND M.R. BARER. 1993. The reduction of four tetrazolium cations (TCs), nitroblue tetrazolium (NBT), neotetrazolium (NT), methylthiazolyldiphenyltetrazolium (MTT) and iodonitrophenyltetrazolium (INT), by viable micro‐organisms, immobilized on glass cover slips, was examined by light microscopy with a view to determining a systematic basis for applying these reagents as cytochemical indicators of microbial viability and activity. The potential value of histochemical information about TC reactions for developing their microbiological applications was also assessed. INT and MTT detected viable cells more readily than NBT and NT. In order to obtain cell‐localized formazan, MTT required cobalt ions in the reaction mixture and INT reactions had to be assessed soon after mounting. In general, formazan deposition could be accelerated by the addition of glucose and an intermediate electron carrier (IEC) to the reaction mixture, although inhibitory effects of IECs were also detected. Cultures in exponential phase, in stationary phase and inhibited by chloramphenicol could be differentiated with MTT but not with INT. For some organisms, notably Candida albicans, Pseudomonas aeruginosa and Enterococcus faecalis. TC reactions proved to be a relatively insensitive means of demonstrating viability. Two parameters used in selecting TCs for histochemical reactions, lipophilicity and reducibility appeared to be predictive for the relative sensitivity of these reagents as indicators of cell viability. The concepts of substantivity, a measure of non‐specific interactions between reagents and staining substrates, and TC oxygen sensitivity, the effect of competition between oxygen and TCs for electrons, were found to be relevant to formazan deposition in live microbes. These findings support the use of TCs as cytochemical probes of microbial activity in defined settings and the use of histochemical knowledge to support further development of these techniques.
Isolation and characterization of a Bacillus strain capable of degrading the extracellular glucan from Cellulomonas flavigena strain KU
Authors: Bertram P.A. , Buller C.S. , Stewart G.C. , Akagi J.M.
Published: March 2008

P.A. BERTRAM, C.S. BULLER, G.C. STEWART AND J.M. AKAGI. 1993. Bacteria capable of utilizing the water‐insoluble purified extracellular (1 → 3)‐β‐D‐glucan (curdlan) from Cellulomonas flavigena strain KU by extracellular enzymes, were insolated and characterized. Enrichment cultures from a Winogradsky column were incubated anaerobically at 55d̀C with curdlan as the sole source of carbon. Colonies surrounded by zones of clearing were selected from subcultures on solid curdlan media. One of the isolates was chosen for further study and identified by conventional methods, API‐tests with calculation of similarity coefficients and ID‐scores, estimation of mol% (G + C) and DNA‐DNA liquid hybridization. The isolate is a facultatively anaerobic, facultatively thermophilic Bacillus sp. Identification at the species‐level was not achieved. The isolate was characterized by some rare traits among bacilli, but it remains unresolved whether it defines a new taxon.
Purification and properties of the endocellular β‐glucosidase of Candida cacaoi Buckley and Van Uden CBS 2020
Authors: Drider D. , Pommares P. , Chemardin P. , Arnaud A. , Galzy P.
Published: March 2008

D. DRIDER, P. POMMARES, P. CHEMARDIN, A. ARNAUD AND P. GALZY. 1993. The endocellular enzyme β‐glucosidase of Candida cacaoi was purified by ion‐exchange chromatography and gel filtration. The molecular weight was 220 ± 10 kDa; its optimum pH was between 4 and 5.5 and its optimum temperature was 60d̀C. This enzyme was active against soluble glucosides tested with β(1–2), β(1–3), β(1–4) and even α(1–4) and α(1–6) and was inhibited by D‐glucono‐δ‐lactone. The enzyme was constitutive but its synthesis was repressed by glucose.
Preliminary characterization of bacteriophages of Serratia entomophila
Authors: Wilson C.R. , Jackson T.A. , Mahanty H.K.
Published: March 2008

C.R. WILSON, T.A. JACKSON AND H.K. MAHANTY. 1993. Bacteriophage was found for the first time associated with the bacterium Serratia entomophila, a pathogen of the New Zealand grass grub (Costelytra zealandica). Phage was isolated from the homogenized guts of field‐collected grass grubs from sites throughout New Zealand. The main phage type, φCW1, produced opaque plaques in sensitive bacterial lawn and had a lamboid structure consisting of an icosahedral head (55 nm) and a long non‐contractile tail (175 times 17 nm) with a bar across the base of the tail. Nucleic acid from φCW1 was digested to nucleotides by DNAse, suggesting double stranded DNA. On further examination of the homogenates, five phage types, φCW1‐5, could be distinguished on the basis of plaque morphology. Bacterial host range was determined by testing against a selection of Serratia spp. and other bacteria. All five phage types lysed Ser. entomophila only. Differences in susceptibility to the phage types were found within this species. Lysogeny was demonstrated in φCW1 by immunity to superinfection and induction of free bacteriophage from suspected lysogens. A restriction map for φCW1 was determined with BamHI, EcoRI and HindIII and a postulated origin of replication (ori) and cohesive site (cos) was suggested. The possible implications of bacteriophage on the use of Ser. entomophila as a biological control agent are discussed.
A simple, rapid and sensitive presence/absence detection test for bacteriophage in drinking water
Authors: Armon R. , Kott Y.
Published: March 2008

R. ARMON AND Y. KOTT. 1993. A rapid, simple and sensitive direct bacteriophage presence detection method for 500 ml drinking water samples has been developed. The method includes a glass device consisting of a jar containing the water sample and an immersible probe filled with solidified soft agar containing bacterial host cells. Host bacteria in logarithmic phase were added to the experimental volume and the probe was submerged. The entire device was incubated in a water bath at 36d̀C.

Plaques of somatic bacteriophage infecting Escherichia coli strain CN13, could be detected within 3 h. Male‐specific bacteriophages infecting E. coli F+ amp were detected within 6 h. Bacteriophage infecting the anaerobe Bacteroides fragilis subsp. fragilis HSP40 were detected after 8 h. Application of this device and the associated technique, enabled a one‐step detection of 1 pfu of E. coli or Bact. fragilis specific bacteriophage in 500 ml drinking water samples.
External quality assessment in water microbiology: statistical analysis of performance
Authors: Tillett Hilary E. , Lightfoot N.F. , Eaton Sheila
Published: March 2008

H.E. TILLETT, N.F. LIGHTFOOT AND S. EATON. 1993. A UK‐based scheme of water microbiology assessment requires participants to record counts of relevant organisms. Not every sample will contain the target number of organisms because of natural variation and therefore a range of results is acceptable. Results which are tail‐end (i.e. at the extreme low or high end of this range) could occasionally be reported by any individual laboratory by chance. Several tail‐end results might imply a laboratory problem. Statistical assessment is done in two stages. A non‐parametric test of the distribution of tail‐end counts amongst laboratories is performed (Cochran's Q) and, if they are not random, then observed and expected frequencies of tail‐end counts are compared to identify participants who may have reported excessive numbers of low or high results.

Analyses so far have shown that laboratories find high counts no more frequently than would be expected by chance, but that significant clusters of low counts can be detected among participants. These findings have been observed both in short‐term and in long‐term assessments, thus allowing detection of new episodes of poor performance and intermittent problems.

The analysis relies on an objective definition of tail‐end results. Working definitions are presented which should identify poor performance in terms of microbiological significance, and which allow fair comparison between membrane‐filtration and multiple‐tube techniques. Smaller differences between laboratories, which may be statistically significant, will not be detected. Different definitions of poor performance could be incorporated into future assessments.
Production of histamine and tyramine by lactic acid bacteria isolated from vacuum‐packed sugar‐salted fish
Authors: Leisner J.J. , Millan J.C. , Huss H.H. , Larsen L.M.
Published: March 2008

The incidence of histamine‐ or tyramine‐producing lactic acid bacteria was examined in several products of vacuum‐packed sugar‐salted fish (salmon, halibut, mackerel). No histamine‐producing isolates were observed, whereas the majority of tyramine‐producing isolates were identified as Carnobacterium spp. These organisms were shown to be important members of the microbial flora during storage of vacuum‐packed sugar‐salted salmon at 5°C. The amount of tyramine produced was reduced by lowering the temperature from 9°C to 4°C for all of five strains of carnobacteria or lactobacilli. The majority of tyramine was produced during the exponential growth phase for Carnobacterium piscicola N 5 and Lactobacillus viridescens N 69. The ability of these bacteria to produce tyramine may be used as an index of microbial quality/acceptability of stored vacuum‐packed sugar‐salted fish.
Continuous culture studies on the synthesis of capsular polysaccharide by Klebsiella pneumoniae K1
Authors: Mengistu Y. , Edwards C. , Saunders J.R.
Published: March 2008

The synthesis of capsular polysaccharide by Klebsiella pneumoniae K1 was investigated in a minimal salts medium by continuous culture. The organism produced larger amounts of polysaccharide under nitrogen‐limited conditions than under carbon‐limited conditions. The synthesis of polysaccharide was dependent not only on the availability of excess carbon, but also on growth rate. The rate of polysaccharide synthesis was greatest at low dilutions, low temperature (30°C) and at neutral pH. Prolonged growth in nitrogen‐limited culture resulted in the development of non‐mucoid variants, possibly due to a selective growth advantage over mucoid cells. The non‐mucoid isolate was more susceptible to some bacteriophages, possibly due to the reduction or absence of capsular polysaccharide.
Exopolysaccharide and storage polymer production in Enterobacter aerogenes type 8 strains
Authors: de Souza Angelita M. , Sutherland I.W.
Published: March 2008

Many exopolysaccharide (EPS)‐producing bacterial strains also synthesize storage polymers. The production of slime EPS and of the storage polymer glycogen was compared in batch cultures of EPS+ and EPS‐ isogenic strains of Enterobacter aerogenes type 8. Conditions of nutrient imbalance with high C: N ratios favoured both EPS and storage polymer synthesis and resulted in little subsequent degradation of glycogen. In the EPS+ strain, glycogen synthesis was consistently lower than in the EPS‐ strain, indicating that substrate was preferentially used for EPS production. Reduced levels of carbon substrate in the growth medium resulted in lower storage polymer synthesis and in the degradation of the glycogen formed in EPS‐producing bacteria. Considerable differences in the synthesis and breakdown of intracellular carbohydrate were observed between bacteria grown in synthetic media with ammonium salts and the same bacteria grown in medium with casein hydrolysate as the nitrogen source. Growth in media depleted in magnesium was slower than in complete media but high yields of glycogen were obtained in both the EPS+ and EPS‐ strains.
Characteristics of ‘atypical’, cytochrome oxidase‐negative Aeromonas salmonicida isolated from ulcerated flounders (Platichthys flesus (L.))
Authors: Wiklund T. , Dalsgaard I. , Eerola E. , Olivier G.
Published: March 2008

‘Atypical’, cytochrome oxidase‐negative variants of the fish pathogen Aeromonas salmonicida, isolated from ulcerated flounder (Platichthys flesus), were studied using different methods. Two of the strains possessed a protein that corresponded to the A‐layer protein of Aer. salmonicida. The strains reacted with antibodies against the A‐layer and monoclonal antibodies against the O‐antigen of typical Aer. salmonicida. These tests confirm that the isolates from flounder should be classified as Aer. salmonicida. Analysis of the fatty acids showed that the isolates were rather homogenous but the values of the guanine plus cytosine content of the DNA of the bacteria varied too much for any conclusion to be drawn on their taxonomic location. The strains examined exhibited several biochemical characters that differed from those of the type strains of Aer. salmonicida subsp. salmonicida and Aer. salmonicida, subsp. achromogenes. The results suggest that these ‘atypical’, cytochrome oxidase‐negative variants may form a new subspecies of Aer. salmonicida.
Microflora on explanted silicone rubber voice prostheses: taxonomy, hydrophobicity and electrophoretic mobility
Authors: Neu T.R. , Verkerke G.J. , Herrmann I.F. , Schutte H.K. , Mei H.C. Vander , Busscher H.J.
Published: March 2008

Silicone rubber voice prostheses are implants which are inserted in a non‐sterile environment and therefore become quickly colonized by micro‐organisms. The micro‐organisms exist on the medical grade silicone rubber as mixed biofilms of bacteria and yeasts. A total of 79 bacterial and 39 yeast strains were isolated from these biofilms by soft ultrasonic treatment. Gram‐positive/catalase‐negative and Gram‐positive/catalase‐positive cocci represented the dominant bacterial strains. The yeasts were mainly Candida species. Further characterization of cell surface properties such as hydrophobicity by microbial adhesion to hexadecane and electrophoretic mobility showed a distinct difference when the bacterial strains were compared with the yeasts. The bacterial hydrophobicities ranged from 0 to 100% adhesion to hexadecane, whereas the yeast strains, especially the Candida albicans strains, all had markedly hydrophilic cell surfaces. A comparison of the electrophoretic mobilities showed also differences between bacteria and yeast. The values for the bacteria were found to be between ‐2.5 to ‐0.5 (10‐8 m2 V‐1 s‐1), whereas for the yeasts electrophoretic mobilities were more positive. Based on the adhesive properties of the isolated micro‐organisms, strategies can now be developed to modify the properties of the silicone rubber to reduce biofilm formation on such prostheses.
Effect of sub‐MIC antibiotics on the cell surface and extracellular virulence determinants of Pseudomonas cepacia
Authors: McKenney D. , Willcock L. , Trueman P.A. , Allison D.G.
Published: March 2008

The effects of sub‐MICs of ciprofloxacin and tobramycin on the cell surface characteristics and extracellular virulence factors of Pseudomonas cepacia were evaluated. Cells were grown in batch culture under iron‐deficient and iron‐replete conditions. At sub‐MIC levels that did not affect bacterial growth cell surface hydrophobicity decreased under both iron‐replete and iron‐depleted conditions with ciprofloxacin, but increased with tobramycin under iron‐sufficient conditions. Exopolysaccharide synthesis, lipase production and siderophore production were all significantly increased by the presence of ciprofloxacin under both growth conditions. Outer membrane protein and lipopolysaccharide profiles were not affected by exposure to the two antibiotics.
Newspaper as a substrate for cellulolytic landfill bacteria
Authors: Cummings S.P. , Stewart C.S.
Published: March 2008

Five cellulolytic bacterial isolates (Clostridium and Eubacterium spp.) from a methane‐producing landfill were examined to determine their ability to utilize newspaper as a substrate for growth. Solubilization was poor with even the most actively cellulolytic bacteria. The major factor causing the low activity seemed to be that as much as 24% of the newspaper was composed of the high molecular weight polymer lignin, which exerts a protective effect on the attack of otherwise susceptible polymers. The presence of ink on heavily printed paper also reduced the rate of cellulose solubilization. Although the ink did not appear directly toxic to the bacteria it masked the surface of the paper, covering the cellulose fibres and preventing bacterial adhesion to the substrate. The action of the cellulolytic isolates was also strongly inhibited below the optimum growth temperature of 37°C.
Isolation and characterization of mutants of Bacillus thuringiensis var. israelensis
Authors: Kim H.‐S. , Côté J.‐C. , Fréchette S. , Chung Y.S.
Published: March 2008

Several mutants of Bacillus thuringiensis var. israelensis HD‐500 (Bti) were obtained after treatment with N‐methyl‐n'‐nitro‐N‐nitrosoguanidine. On the basis of the production (+) or absence (‐) of spore (Spo) and crystal (Cry) the strains were grouped into three categories: Spo + Cry +, Spo + Cry ‐ and Spo ‐ Cry + . NGI‐22, a Spo + Cry ‐ mutant lacked all crystal proteins. Both NGI‐23 and NGI‐23‐1 were Spo ‐ Cry + . NGI‐23‐1, however, produced multiple crystals per cell. These mutants could prove useful not only for analysing sporulation and crystal formation as well as the linkage between the two genetic processes but also for improving the potential of Bti as a microbial insecticide.
Ferric iron reduction‐linked growth yields of Shewanella putrefaciens MR‐1
Authors: Myers C.R. , Myers J.M.
Published: March 2008

The anaerobic reduction of ferric citrate by Shewanella putrefaciens MR‐1 cells was inhibited markedly by p‐chloromercuriphenylsulphonate, moderately by potassium cyanide, and to a small extent by 2‐heptyl‐4‐hydroxyquinolone‐N‐oxide. Iron reduction was accompanied by increases in total cellular protein, with values of 0.33‐7.54 g cell protein produced per mol Fe(III) reduced. The growth yields were dependent upon the growth conditions of the inoculum and the initial concentration of Fe(III) citrate in the medium. Specifically, maximum growth yields were obtained when the inoculum was pregrown anaerobically and when the initial Fe(III) citrate concentrations were 5–10 mmol l‐1. Lower growth yields were obtained with initial Fe(III) citrate concentrations of 20–30 mmol l‐1, suggesting that cell growth was partially inhibited by higher concentrations of Fe(III) or Fe(II). Maximal growth yields were also observed early (6–24 h), after which continued increases in cell protein were minimal.
Presence of Carnobacterium spp. in French surface mould‐ripened soft‐cheese
Authors: Millière J.B. , Michel M. , Mathieu F. , Lefebvre G.
Published: March 2008

Thirty‐six ‘atypical lactobacilli’, randomly picked from five surface mould‐ripened soft‐cheeses, were characterized by physiological and chemical, including DNA, analyses. This homofermentative, non‐aciduric and psychrotrophic group represented the major bacterial flora with counts between 108 and 109 cfu g‐1. Common characteristics were the production of L‐(+)‐lactic acid enantiomer, the presence of meso‐diaminopimelic acid in the peptidoglycan, the hydrolysis of arginine and the failure to produce acid from sorbitol. On the basis of the description of the genus Carnobacterium (Collins et al. 1987), 33 isolates were assigned to C. piscicola and three to C. divergens. Antibacterial substance production was observed for 16 isolates, with a narrow spectrum of activity. To our knowledge, this is the first report of Carnobacterium spp. in mould‐ripened soft‐cheese.
Chitinolytic properties of Bacillus pabuli K1
Authors: Frändberg Emma , Schnürer J.
Published: March 2008

The chitinolytic properties of Bacillus pabuli K1 isolated from mouldy grain was studied. Chitinase activity was measured as the release of p‐nitrophenol from p‐nitrophenyl‐N, N'‐diacetylchitobiose. Influences of substrate concentration and different environmental variables on growth and chitinase activity were determined. The optimum environmental conditions for chitinase production were: 30°C, initial pH 8, initial oxygen 10% and aw > 0.99. Chitinase production was induced when B. pabuli K1 was grown on colloidal chitin. The smallest chito‐oligosaccharide able to induce chitinase production was N, N'‐diacetylchitobiose, (GlcNAc)2. Production was also induced by (GlcNAc)3 and (GlcNAc)4. When the bacterium was grown on glucose or N‐acetylglucosamine, no chitinases were formed. The highest chitinase production observed was obtained with colloidal chitin as substrate. The production of chitinases by B. pabuli K1 growing on chitin was repressed by high levels (0.6%) of glucose. The production was also repressed by 0.6% starch, laminarin and β‐glucan from barley and by glycerol. The addition of pectin and carboxymethyl cellulose increased chitinase production.
Effect of substrate on the production of antifungal volatiles from Bacillus subtilis
Authors: Fiddaman P.J. , Rossall S.
Published: March 2008

An antibiotic‐producing strain of Bacillus subtilis has been shown to produce potent antifungal volatiles (AFV). These volatiles are active against a range of fungal species and are produced on a range of growth media and in loam‐based compost. In vitro antifungal volatile activity on nutrient agar is enhanced with the addition of D‐glucose, complex carbohydrates and peptones. The addition of L‐glucose led to significantly less AFV activity than comparable levels of D‐glucose. Growth studies in liquid culture revealed that B. subtilis failed to grow in response to L‐glucose. Further growth studies on solid media showed no clear correlation between enhanced bacterial growth and increases in in vitro AFV activity in response to supply of substrates. Low level AFV activity was also detected from oilseed rape roots inoculated with B. subtilis. Gas chromatography mass spectrometry headspace analysis of B. subtilis cultures grown on various substrates revealed common similarities between substrates promoting AFV activity, although it was not possible to isolate individual antifungal compounds.
Plasmid and pathogenicity in Xanthomonas oryzae pathovar oryzae, the bacterial blight pathogen of Oryza sativa
Authors: Amuthan G. , Mahadevan A.
Published: March 2008

Xanthomonas oryzae pv. oryzae, the causative agent for bacterial leaf blight of rice, comprises diverse groups of strains differing in biochemical and pathological characteristics. A collection of X.o. pv. oryzae strains differing in geographical origin was screened for the presence of plasmids. Out of 17 isolates of X.o. pv. oryzae, 14 harboured plasmids of which two isolates (XoP5, XoC26) had two plasmids each and one isolate (XoR20) had three. The remaining isolates contained a single plasmid of identical mobility. Finger print analysis of plasmids was carried out using Eco RI for 10 isolates. The restriction fragment pattern was distinct for each isolate. They were classified under three groups based on cluster analysis using the unweighted pair group method with averages (UPGMA). Of the 18 plasmids, the plasmid pMA36 (X.o. pv. oryzae XoC36) was further characterized. This plasmid was cured by acridine orange at the frequency rate of 10%. The cured strain was transformed with pMA36 at a frequency of 2.3 times 102 transformants μg‐1 of plasmid DNA. The plasmid‐cured strain was virulent on rice but symptom development was delayed when compared to wild and transformed strains. The wild type strain (X.o. pv. oryzae XoC36) was resistant to ampicillin, carbenicillin and rifampicin whereas the cured strain was resistant to carbenicillin and rifampicin but sensitive to ampicillin. The transformant was resistant to the three antibiotics indicating that the plasmid pMA36 codes for ampicillin resistance. The plasmid influenced the pathogenicity of X.o. pv. oryzae.
Carbofuran‐degrading bacteria from previously treated field soils
Authors: Parekh N.R. , Suett D.L. , Roberts S.J. , McKeown T. , Shaw E.D. , Jukes A.A.
Published: March 2008

Laboratory incubation studies were made on soils collected from five field sites with different histories of treatment with carbofuran. All soils treated earlier with carbofuran degraded the compound more rapidly than untreated samples of the same soils. Reduced rates of degradation in the presence of chloramphenicol imply that soil bacteria are primarily responsible for the breakdown of carbofuran in these soils. Sixty‐eight bacteria, capable of degrading carbofuran as the sole source of carbon and nitrogen, were isolated from liquid cultures of treated soils. The concentration of carbofuran in the liquid medium used for isolation and subsequent culture of carbofuran‐degrading isolates appeared to affect the stability of their ability to degrade. Similar types of carbofuran‐degrading bacteria were isolated from different soils and several different types were isolated from one soil. All carbofuran‐degrading isolates were Gram‐negative, aerobic rods which hydrolysed the insecticide to carbofuran phenol. They were separated into four groups on the basis of a limited number of phenotypic characters. There was a good correlation between the phenotype of carbofuran‐degrading isolates and the stability of their ability to degrade. Fourteen isolates were placed in phenotypic group I and 13 of these did not degrade carbofuran after one subculture in liquid medium. Phenotypic groups II, III and IV consisted of 54 isolates in total (3, 46 and 5 isolates respectively) and 52 of these retained their ability to degrade carbofuran when subcultured.
Molecular cloning and expression in Escherichia coli of genes encoding pectate lyase and pectin methylesterase activities from Bacteroides thetaiotaomicron
Authors: Tierny Y. , Béchet M. , Joncquiert J.‐C. , Dubourguier H.‐C. , Guillaume J.‐B.
Published: March 2008

Bacteroides thetaiotaomicron strain 217 can use pectins as a sole carbon source. Preliminary characterization of the pectinolytic enzymes revealed three complementary activities in this strain: a pectin methylesterase (PME), a pectate lyase (PL) and a polygalacturonase (PG), which were all inducible by pectin or polygalacturonate. Use of the lambdoid phage replacement vector ΛEMBL3 allowed a 13.2 kb insert mediating both PL and PME activities to be isolated. Subcloning of two Eco RI fragments in pBR325 led to the separate isolation of the pel and pme genes. They were expressed constitutively in Escherichia coli HB101, as proved by the activities observed even in mineral medium supplemented only with glucose. In addition, the pme gene was expressed in both orientations. These results suggest that each gene represents an individual transcriptional unit. Several properties of the cloned PL were different from those of the original strain: it was mainly associated to the outer membrane, its optimum pH was higher, and its stability at 50°C was lost but partially preserved by CaCl2. In addition, the apparent specific PL activity in the E. coli membrane fraction was about 30‐fold higher. On the other hand, most of the properties of the cloned PME were similar to those of the original. Despite an enhanced thermostability, the apparent specific activity of the cloned PME was about 6‐fold lower, and was independent of the insert orientation.
The degradation of malic acid by high density cell suspensions of Leuconostoc oenos
Authors: Gao Chongxiao , Fleet G.H.
Published: March 2008

Washed cell suspensions of Leuconostoc oenos catalysed the degradation of L‐malic acid to L‐lactic acid. Cell suspensions of 1010 cfu ml‐1 degraded 90–95% of the malic acid in a buffer assay system and in wine within 30 min. A reaction time of 6 h was needed to obtain the same extent of degradation with suspensions of 109 cfu ml‐1. With a reaction period of 6 h and an initial malic acid concentration of 3 g 1‐1, reaction variables of pH 2.5‐4.0, temperature 10–30°C, ethanol up to 15%, and L‐lactic acid up to 4 g 1‐1 did not decrease the degradation of malic acid to below 90–95%. Total SO2 at 100 mg 1‐1 decreased the degradation of malic acid to 80%. The degradation (%) of malic acid was decreased when the concentration of malic acid was decreased below 2 g 1‐1. The results indicate the prospect of using high densities of Leuc. oenos cells in membrane bioreactor systems for the rapid, continuous, deacidification of wine.
Metabolic activities of pseudomonads in batch cultures in extract of minced lamb
Authors: Drosinos E.H. , Board R.G.
Published: March 2008

E.H. DROSINOS AND R.G. BOARD. 1994. Pseudomonas fragi, Ps. lundensis and Ps. fluorescens were studied in axenic batch cultures growing in a lamb juice (pH 6.0) aerobically or in an atmosphere (Ps. fragi only) enriched with carbon dioxide at 4d̀C. With all but a glucose dehydrogenase‐deficient strain of Ps. fluorescens there was a sequential catabolism of glucose and lactate. Diauxic growth was observed in a nutrient‐deficient meat juice supplemented with glucose and lactate. A transient peak in the concentration of gluconate and pyruvate was associated with the catabolism of glucose and lactate respectively. With Ps. fluorescens deficient in glucose dehydrogenase there was simultaneous catabolism of glucose and lactate. The stereoisomers of lactate were catabolized simultaneously in a laboratory medium. Glucose‐6‐phosphate was oxidized to 6‐phosphogluconate by Ps. fragi and Ps. lundensis under aerobic conditions only. Creatine and creatinine were catabolized by Ps. fragi under aerobic conditions only. There was a slight decrease in the concentration of total amino acids (ninhydrin‐reactive material) during the exponential phase of growth. The results suggest that the dominance of Ps. fragi in the climax populations in meat is due to catabolism of amino acid related substrates, creatine and creatinine.
Isolation of a 43 kDa protein from Mycobacterium tuberculosis H37Rv and its identification as a pyridine nucleotide transhydrogenase
Authors: Deshpande R.G. , Khan M.B. , Bhat D.A. , Navalkar R.G.
Published: March 2008

R.G. DESHPANDE, M.B. KHAN, D.A. BHAT AND R.G. NAVALKAR. 1994. A 43 kDa protein (TB43) was isolated from the cell sonicate (CS) of Mycobacterium tuberculosis H37Rv with immobilized metal affinity chromatography (IMAC) on a Ni‐nitrilotriacetic acid column. Two‐dimensional electrophoresis of the IMAC fraction showed a major spot with an Mr of 43000 and a pI of ˜6.0. The N‐terminal amino acid sequence of TB43 was met‐arg‐val‐gly‐ile‐pro‐asn‐glu‐thr‐lys‐asn‐asn‐glu‐phe‐arg‐val‐ala‐ile‐thr‐pro‐ala. It showed 86% homology with the N‐terminal end of the alanine dehydrogenase of Myco. tuberculosis and 65% homology with the N‐terminal end of the alpha‐subunit of the Escherichia coli pyridine nucleotide transhydrogenase (Tsh). TB43 did not show any alanine dehydrogenase activity and did not react with monoclonal antibody (MAb) HBT10, which is known to recognize the 40 kDa alanine dehydrogenase of Myco. tuberculosis. It was also not recognized by MAb F29–29 which is known to react with a 43 kDa protein of Myco. tuberculosis complex. This protein exhibited strong Tsh activity. A similar 43 kDa protein showing Tsh activity was also isolated by IMAC from Myco. bovis CS. However, the pI of the protein was ˜7.0. A similar protein could not be isolated from the CS or culture filtrate of Myco. bovis BCG and Myco. tuberculosis H37Ra. TB43 is a cell‐associated pyridine nucleotide transhydrogenase and is distinct from the 40/44 kDa secreted alanine dehydrogenase of Myco. tuberculosis.
Microbial succession and intestinal enzyme activities in the developing rat
Authors: Chang Jerjang , Chadwick R.W. , Allison Joycelyn C. , Hayes Yumiko O. , Talley Detra L. , Autry Cari E.
Published: March 2008

J. CHANG, R.W. CHADWICK, J.C. ALLISON, Y.O. HAYES, D.L. TALLEY AND C.E. AUTRY. 1994. The succession of gut bacteria and selected intestinal enzyme activities in developing 7–35‐d‐old rats was studied. Aerobes and anaerobes were identified as members of four broad major bacterial groups, i.e. Gram‐positive rods, Gram‐positive cocci, Gram‐negative rods and obligate anaerobes. The enzyme activities of nitro and azo reductases, β‐glucuronidase, dechlorinase and dehydrochlorinase were determined by anaerobic incubation of intestinal homogenates with 3,4‐dichloronitrobenzene, methyl orange, ***p‐nitrophenyl‐β‐D‐glucuronide, and ***p, p‐DDT respectively. Nitroreductase and azo reductase activities increased significantly with the appearance of anaerobes in the large intestine. No increase in either nitroreductase or azo reductase activities in the small intestine was found. The early and high level of β‐glucuronidase activity in the small and large intestines coincided with high numbers of coliforms recovered in 7 and 14 d animals. Dehydrochlorinase activity appeared early but was undetectable at both 21 and 28 d. Its activity increased at 35 d. Dechlorinase activity was variable in development. The rapid changes in the microbial flora and intestinal enzyme activities may influence the susceptibility of pre‐pubescent rats to a variety of toxicants. Therefore, age‐dependent toxicity may be important in the risk assessment of some environmental chemicals.
Improvement and update of a set of keys for biochemical identification of Vibrio species
Authors: Alsina Mercedes , Blanch Anicet R.
Published: March 2008

M. ALSINA AND A.R. BLANCH. 1994. Two biochemical keys for fast and presumptive identification of certain Vibrio species are presented. They constitute a new improved version of a set of keys previously described, which were specially designed for environmental and clinical isolates. They may be used for Gram‐negative, oxidase‐positive, facultative anaerobes that grow on TCBS agar. The revised set of biochemical keys consists of 29 tests and a maximum of 10 tests is still sufficient for the most complicated identification. The new keys maintain the same criteria and characteristics of the original set of keys.
Mathematical model of the interactions between Micrococcus spp. and Pseudomonas aeruginosa on agar surface
Authors: Chapuis Catherine , Flandrois J.‐P.
Published: March 2008

C. CHAPUIS AND J.‐P. FLANDROIS. 1994. The interactions between six differentMicrococcusspecies and two strains ofPseudomonas aeruginosawere studied on an agar surface. This type of interaction on solid surface could act as a model of situations occurring either in the environment, in food or in man. The hypothesis of an amensalistic relationship between aMicrococcusspp. andPseudomonas aeruginosa, due essentially toPs. aeruginosabacteriolytic enzymes, is retained as the basis for a mathematical model of the variations of the colony surface ofMicrococcusspp. (S) with respect to the distance (d) fromPs. aeruginosacells. The diffusion of the bacteriolytic substance in agar explains the limitation of the growth of theMicrococcusspp. This modelS=Smax(1 ‐ e‐md***2) is shown to be adapted to all the interactions studied.
A mathematical analysis of microbial inactivation at linearly rising temperatures: calculation of the temperature rise needed to kill Listeria monocytogenes in different foods and methods for dynamic measurements of D and z values
Authors: Miles C.A. , Mackey B.M.
Published: March 2008

From a theoretical analysis of the inactivation of microbes heated at linearly rising temperatures an equation was derived for predicting the linear temperature rise needed to reduce viable numbers of microbes by any chosen factor. This equation is used to predict the temperatures needed to inactivate Listeria monocytogenes in different foods based on published D and z values. Two novel mathematical methods for deriving D and z values from viable counts obtained at linearly rising temperatures are also presented.
Sugar and organic acid metabolism in mixed cultures of Pediococcus pentosaceus and Leuconostoc oenos isolated from wine
Authors: Rodriguez Ana V. , Manca de Nadra Maria C.
Published: March 2008

Pediococcus pentosaceus 12p and Leuconostoc oenos X2L isolated from Argentinian wine were examined for growth and changes in the concentrations of glucose, fructose, sucrose and mannitol and malic, citric, acetic and lactic acids in pure and mixed cultures. In mixed cultures a mutualistic growth response and a change in the balance of end‐products of sugar and organic acid metabolism were observed. The production of mannitol and acetic acid was lower while D(‐) and L(+) lactic acids were detected in higher levels than in pure cultures. Malic and citric acids were metabolized simultaneously, but the amount of citric acid consumed was lower than in pure culture of Leuc. oenos.
Effect of stress treatments on the detection of Listeria monocytogenes and enterotoxigenic Escherichia coli by the polymerase chain reaction
Authors: Masters C.I. , Shallcross J.A. , Mackey B.M.
Published: March 2008

The relationship between viability assessed by plate counts and detectability by gene probe‐polymerase chain reaction (PCR) techniques was examined with cells of Escherichia coli and Listeria monocytogenes previously exposed to a range of stress treatments. In all cases the organisms were detectable by PCR after plate counts had declined to zero. Treatment with acid or hydrogen peroxide caused loss of PCR soon after viability was lost, but strong PCR signals were obtained from starved or desiccated cells long after cells became non‐viable. Exposure to temperatures up to 100°C had little effect on detection by PCR and even autoclaving cells at 121°C for 15 min failed to abolish PCR detection completely. There is thus no simple relationship between viability and detectability by PCR. Detection of pathogens by PCR in environmental monitoring requires additional evidence of viability before risk can be properly assessed.
Selection and biochemical studies of pyrimidine‐requiring mutants of Lactobacillus plantarum
Authors: Masson A. , Kammerer B. , Hubert J.‐C.
Published: March 2008

Mutagenesis and mutant enrichment in Lactobacillus plantarum, a lactic acid bacterium used in silage, sauerkraut and sausage fabrication, were studied. In optimal conditions, auxotrophic mutants were obtained that permitted investigation of the de novo pyrimidine biosynthesis. Uracil‐requiring mutants were characterized for their enzymatic defect, in aspartate transcarbamylase (ATCase), dihydro‐orotase (DHOase), dihydro‐orotate dehydrogenase (DHOdehase), orotidine monophosphate pyrophosphorylase (OMPppase) or in orotidine monophosphate decarboxylase (OMPdecase). The five enzymatic activities are totally repressed by uracil in the growth medium.