bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutralization efficacy of Dey‐Engley medium in testing of contact lens disinfecting solutions
Authors: Sutton S. V. W. , Wrzosek T. , Proud D. W.
Published: March 2008

A quantitative assay for the demonstration of neutralizer efficacy was developed to monitor contact lens disinfecting solutions. Adequate neutralization of disinfecting agents is essential to the accurate determination of disinfecting activity with time. This method employed the recovery of small numbers of micro‐organisms from neutralizing medium containing a disinfectant. A statistical estimation of significance between treatments demonstrated that Dey‐Engley medium (DE; Difco) was generally effective when tested as an agar growth medium with several bacterial test organisms. DE medium from another vendor was less effective, underscoring the need for laboratory quality control and monitoring. DE agar (Difco) adequately neutralized all solutions tested at a 1:20 dilution. The solutions included those containing DymedTM (polyaminopropyl biguanide, 0·00005%), chlorhexidine (0·005%), Polyquad® (0·001%), chlorhexidine (0·005%) and thimerosal (BP, 0·001%), thimerosal (BP, 0·002%) and Tris(2‐hydroxyethyl) tallow ammonium chloride (0·013%), and a solution preserved with 115 ppm benzalkonium chloride (BAK). A modification of this medium was developed which retained virtually all of the neutralizing efficacy for the solutions tested while allowing the use of automated testing procedures.
Detection and identification of Listeria monocytogenes in cooked sausage products and in milk by in vitro amplification of haemolysin gene fragments
Authors: Furrer B. , Candrian U. , Hoefelein Ch. , Luethy J.
Published: March 2008

Recent outbreaks of listeriosis have emphasized the urgent need for rapid and reliable detection methods for Listeria spp., especially in food. Haemolysin production is a major factor in the pathogenesis of listeriosis and the polymerase chain reaction (PCR) was used to amplify two specific DNA fragments of the α‐ and the β‐haemolysin genes. The amplification system specifically recognized L. monocytogenes strains. The detection limit determined with pure cultures was 10 bacteria when estimated with α‐haemolysin primers. In the analysis of 50 samples of cooked sausage products, bacterial colonies suspected to be Listeria spp. were isolated by conventional methods from six samples. PCR analysis identified three of six as L. monocytogenes. Subsequent serotyping showed perfect agreement with the PCR results. Since enrichment is the most time consuming step in conventional methods a PCR procedure which allows the direct detection of L. monocytogenes in milk was developed. Pasteurized milk was artificially contaminated with various levels of L. monocytogenes. The detection limit was determined to be 10 bacteria/10 ml milk and direct detection and identification of L. monocytogenes took less than two working days. These results show that this haemolysin gene amplification system is very rapid and reliable and therefore avoids cumbersome and lengthy cultivation steps.
The influence of agricultural run‐off on bacterial populations in a river
Authors: Fernández‐Alvarez Rosa M. , Carballo‐Cuervo S. , de la Rosa‐Jorge M. Carmen , Lecea Josefina Rodríguez‐de
Published: March 2008

The microbiological quality of the River Riato (Spain) was evaluated. The influence of cattle that roam free in the warm season was marked. The degree of faecal pollution in the river was higher than predicted from the river basin geographical characteristics. The counts of faecal indicators greatly increased when the cattle were allowed to roam free. Counts of enterobacteria and faecal coliforms ranged from 103 to 106/100 ml. Faecal streptococci counts were smaller (< 10/100 ml). Escherichia coli and Pseudomonas aeruginosa were isolated from all samples. Streptococcus bovis was also isolated but not Strep. faecalis.
In vitro susceptibility of Erwinia amylovora (Burrill) Winslow et al. to geraniol and citronellol
Authors: Scortichini M. , Rossi Maria Pia
Published: March 2008

The in vitro antimicrobial activity of geraniol and citronellol towards seven strains of Erwinia amylovora, the causal agent of ‘fire blight’of Rosaceous plants, was assessed in tube cultures. All of the strains tested at 1 × 105 cfu/ml were inhibited for 24 h by geraniol in the range 600–1500 mg/1, whereas its minimum bactericidal concentration was 800–1700 mg/1. Citronellol was less effective, being bactericidal for only two of seven strains. RIF‐NY, isolated from apple orchards, was relatively resistant to geraniol; 1700 mg/1 of the chemical only reduced the growth of an inoculum of 1 × 107 cfu/ml. In general, such terpenoids commenced exerting a bactericidal effect 6 h after addition to the suspensions, even if geraniol added at 1700 mg/1 to 1 × 103 cfu/ml of five strains, commenced its bactericidal activity earlier than 6 h.
Bacteria in food packaging paper and board
Authors: Välsänen O.M. , Mentu J. , Salkinoja‐Salonen M.S.
Published: March 2008

The bacteria of food packaging paper and board were studied. Most of the aerobic strains were spore‐formers; members of the genus Bacillus with B. cereus group (B. cereus, B. mycoides, B. thuringiensis), B. polymyxa group (B. polymyxa, B. circulans, B. macerans, B. pabuli), B. brevis and B. licheniformis predominated. The main source of spore‐forming bacteria in paper and board was the broke (rejected paper of board, which is repulped and recycled into the process). Gram‐negative bacteria were rare in paper and board in spite of their abundance in the stock. A strain of B. pumilus forming clumping, hairy spores may be of significance in aseptic packaging.
Purification and characterization of glucoamylase of Aspergillus terreus NA‐170 mutant
Authors: Ghosh Anuradha , Chatterjee Banhisikha , Das Arati
Published: March 2008

A catabolite‐derepressed mutant strain of Aspergillus terreus NA‐170 was isolated by multi‐step mutagenesis. The mutant produced an appreciable yield of glucoamylase in the culture medium. The enzyme was purified and was shown to be homogeneous. It hydrolysed successive glucose residues from the non‐reducing end of starch molecules. The purified enzyme had an optimum pH of 5·0 and was stable over the pH range 3·0–7·0. It was highly active over a broad temperature range, 30–75°C, with optimal activity at 60°C. The molecular weight was 70 000 as determined by Sephadex G‐200 filtration. The enzyme showed a decrease in Km values with increasing chain length of the substrate molecule.
Distribution of Aeromonas species in waters with different levels of pollution
Authors: Araujo Rosa M. , Arribas Rosa M. , Pares Ramón
Published: March 2008

Strains of Aeromonas spp. (883) were isolated from 10 stations in the north‐west of Spain. Biotyping of the strains gave: 55%Aeromonas caviae, 34%A. hydrophila, 6%A. sobria and 5%Aeromonas spp. Phenotypic characters that have been claimed to be related to virulence such as haemolysis and the Voges‐Proskauer reaction were detected mostly in A. hydrophila and A. sobria. The distribution of the species was significantly related to levels of faecal pollution in waters. Aeromonas caviae predominated in sewage and waters with a high degree of faecal pollution. In less polluted waters, either fresh or marine, A. caviae and A. hydrophila were almost equally distributed. In waters with low or no faecal pollution, the proportion of A. sobria to other species increased considerably.
Habituation to acid inEscherichia coli: conditions for habituation and its effects on plasmid transfer
Authors: Raja N. , Goodson M. , Chui W.C.M. , Smith D.G. , Rowbury R.J.
Published: March 2008

Induction of acid resistance (habituation) inEscherichia coliat pH 5·0 tookca5 min in broth at 37°C and 30–60 min in minimal medium. Induction occurred at a range of pH values from 4·0 to 6·0; it was dependent on continuing protein and RNA synthesis but substantial acid resistance appeared in the presence of nalidixic acid. Acid resistance was long‐lasting; organisms grown at pH 5·0 retained most of their resistance after 2 h growth at pH 7·0. Organisms grown at pH 5·0 showed increased synthesis of a number of cytoplasmic proteins compared with the level in cells grown at pH 7·0. DNA repair‐deficient strains carryingrecA, uvrAorpolAlmutations were more acid‐sensitive than the repair‐proficient parents but were able to habituate at pH 5·0. Organisms grown at pH 5·0 transferred the ColV plasmid much more effectively at acid pH than did those grown at pH 7·0 and habituated recipients appeared better able to repair incoming acid‐damaged plasmid DNA than did those that were non‐habituated. Induction of acid resistance at pH 5·0 may be significant for the survival of organisms exposed to periodic discharges of acid effluent in the aquatic environment and habituation may also allow plasmid transfer and repair of acid‐damaged plasmid DNA during or after such exposure.
Use of DNA probes in the study of silage colonization by Lactobacillus and Pediococcus strains
Authors: Cocconcelli P.S. , Triban Elisetta , Basso M. , Bottazzl V.
Published: March 2008

P.S. COCCONCELLI, E. TRIBAN, M. BASSO AND V. BOTTAZZI. 1991. A technique to monitor lactic acid bacteria inoculants in silage, based on specific DNA probes, was developed and used to evaluate the colonization properties of two strains of Lactobacillus plantarum and one strain of Pediococcus pentosaceus which were used as maize silage inoculants in farm conditions. The results indicated that these three strains were able to dominate the natural microflora of the silage, representing more than the 95% of the bacterial biomass of the maize silage. These studies indicate that the colony hybridization with specific DNA probes may be an effective method for monitoring bacteria and evaluating the colonization properties of inoculants in maize silage.
A selective medium for Fusobacterium spp.
Authors: Brazier J.S. , Citron Diane M. , Goldstein E.J.C.
Published: March 2008

J.S. BRAZIER, D.M. CITRON AND E.J.C. GOLDSTEIN, 1991. A new selective medium (JVN) for the isolation of Fusobacterium spp. from clinical material is described. The medium incorporates josamycin, vancomycin and norfloxacin (at 3, 4 and 1 μg/ml, respectively) as the selective agents, plus 5% defibrinated horse blood in Fastidious Anaerobe Agar Base (Lab M). This formula allowed luxuriant growth of all 82 strains (eight recognized species) of fusobacteria tested, while significantly inhibiting 51/51 (100%) strains of facultative anaerobes and 45/51 (88%) strains of other obligate anaerobes. JVN medium allowed the successful isolation of strains of Fusobacterium naviforme, F. nucleatum and F. necrophorum from the gingivae of 9/16 healthy volunteers, and strains of F. varium and F. mortiferum from faecal suspensions seeded with these organisms.
A new dynamic method for the rapid determination of the biodegradable dissolved organic carbon in drinking water
Authors: Ribas F. , Frias J. , Lucena F.
Published: March 2008

F. RIBAS, J. FRIAS AND F. LUCENA. 1991. A new method for the determination of biodegradable dissolved organic carbon (BDOC), which may be useful to the water industry, is proposed. It is a dynamic method that measures the BDOC of circulating water continuously pumped across a biofilm attached to a special support that fills a system of two glass columns. The BDOC value corresponds to the difference in DOC between inlet and outlet water samples. The sampling may be intermittent or continuous, but the process is continuous. The biofilms give good performances over periods of at least 1 year. The analytical results are not significantly different from those of other bioassays based on the use of indigenous bacteria and the total duration of analysis is between 2 and 3 h.
High frequency transformation of Streptomyces niveus protoplasts by plasmid DNA
Authors: Hussain H.A. , Ritchie D.A.
Published: March 2008

H.A. HUSSAIN AND D.A. RITCHIE. 1991. A procedure has been developed for transforming protoplasts of the novobiocin producing strain Streptomyces niveus at high frequency. This required the isolation of strains LH13 and LH20 defective in DNA restriction from the wild type (ATCC 19793) which is transformed at very low frequencies. The LH13 and LH20 derivatives were obtained by curing pIJ702 DNA from the few S. niveus transformed protoplasts obtained by transformation of the wild type with high concentrations of pIJ702 DNA. Protoplasts of S. niveus strains LH13 and LH20 produced about 106 transformants/μg DNA with modified pIJ702 DNA derived by replication in S. niveus. Unmodified DNA (derived from replication in S. lividans) from a series of pIJ101, SCP2 and pSN2‐based derivatives, gave transformation frequencies in the range of 102‐103 transformants/μg DNA. Optimal conditions for the formation and transformation of S. niveus protoplasts are described.
Specific enumeration of lactic acid bacteria in fermenting grape must and wine by colony hybridization with non‐isotopic DNA probes
Authors: Lonvaud‐Funel Aline , Joyeux Annick , Ledoux O.
Published: March 2008

A. LONVAUD‐FUNEL, A. JOYEUX AND O. LEDOUX. 1991. Total DNA extracted from lactic acid bacteria commonly found in musts and wines was randomly labelled with digoxigenin. It was assayed for the detection of several species by dot‐blot hybridization. The method proved to be specific as there was no cross‐hybridization between most of the species belonging to the genera Leuconostoc, Pediococcus and Lactobacillus, homofermentative and heterofermentative (Lact. plantarum, Lact. casei, Leuc. mesenteroides, Leuc. oenos, Ped. damnosus, Ped. pentosaceus). However, it failed for some Lact. brevis strains which strongly hybridized with Lact. hilgardii.

Colony hybridization was performed directly on plates soon after enumeration. Eight probes of the most common species were used; it was possible to follow the evolution of each species during the vinification of two red wines. According to the phase of alcoholic fermentation, then malolactic fermentation, the predominance or regression of bacilli and cocci could be established.
Specific and intraspecific molecular typing of lactococci based on polymorphism of DNA encoding rRNA
Authors: Rodrigues U.M. , Aguirre M. , Facklam R.R. , Collins M.D.
Published: March 2008

U.M. RODRIGUES, M. AGUIRRE, R.R. FACKLAM AND M.D. COLLINS. 1991. The rRNA gene restriction patterns or species of the genus Lactococcus were determined. Chromosomal DNA was digested with endonucleases and probed with radiolabelled DNA complementary to rRNA synthesized by random oligonucleotide priming using reverse transcriptase. Highly discriminatory restriction patterns were obtained which served to distinguish the five currently recognized lactococcal species. In addition the observed variations in the patterns at intra‐specific level indicate that rRNA gene restriction fingerprinting may be of value in distinguishing the individual strains for epidemiological studies, and monitoring and checking authenticity of starter strains.
Role of siderophores in the biocontrol of Pseudomonas tolaasii by fluorescent pseudomonad antagonists
Authors: Henry M.B. , Lynch J.M. , Fermor T.R.
Published: March 2008

A number of pseudomonad bacteria were investigated for their in vitro antagonism on agar against Pseudomonas tolaasii, the causative agent of bacterial blotch of the cultivated mushroom. Addition of FeCl3 to the culture medium suppressed the antagonism in 14 of the 20 bacteria tested and the production of a substance with an absorption peak at 400 nm by all antagonists was eliminated by the presence of Fe3+. Both observations indicated that siderophores could be involved in the mode of action of some antagonists. The addition of the iron chelators EDTA and bipyridyl to the medium used for culture of antagonists and pathogens did not generally prevent growth. Siderophore production is not essential for the in vivo activity of antagonists.
The protective activity of tea against infection by Vibrio cholerae O1
Authors: Toda Masako , Okubo Sachie , Ikigai H. , Suzuki T. , Suzuki Yumiko , Shimamura T.
Published: March 2008

Extracts of black tea exhibited bactericidal activity against Vibrio cholerae O1. The tea extract inhibited the haemolysin activity of V. cholerae O1, El Tor and the morphological changes of Chinese hamster ovary cells induced by cholera toxin. Tea extract also reduced fluid accumulation induced by cholera toxin in sealed adult mice and by V. cholerae O1 in ligated intestinal loops of rabbits. These findings suggest that tea has protective activity against V. cholerae O1.
The production of bioluminescent lactic acid bacteria suitable for the rapid assessment of starter culture activity in milk
Authors: Ahmad K.A. , Stewart G.S.A.B.
Published: March 2008

Promoter elements from Lactobacillus casei were isolated with an Escherichia coli promoter probe vehicle and inserted 5′ to the luxA/B genes from Vibrio fischeri located within a pCK1‐based shuttle vector. Three independent promoter‐lux constructs were each used to transform Lactobacillus casei, Lactococcus lactis and Lactococcus lactis subsp. diacetylactis by electroporation. Transformants of all three bacteria which expressed a bioluminescent phenotype in the presence of exogenous dodecanal were obtained. By virtue of monitoring changes in light production, these recombinant micro‐organisms could form the basis of a rapid monitoring system for antimicrobial substances in milk active against starter culture bacteria. In addition, the research potential of in vivo bioluminescence for monitoring gene expression in lactic acid bacteria in situ within fermentation systems can now be addressed.
Selective enumeration of spores of Clostridium species in dried foods
Authors: Weenk G. , Fitzmaurice E. , Mossel D.A.A.
Published: March 2008

The suitability of a variety of media and procedures for the enumeration of sulphite‐reducing clostridia in food was investigated. The most suitable procedure was pasteurization of the 1/10 macerate for at least 1 min at 80°C; followed by culture at 30°C for up to 3 d in a sulphite‐based, differential reinforced clostridium medium, without bicarbonate or lactate but with an increased iron concentration, and sulphite and iron added after sterilization. Black sulphite‐reducing colonies were finally tested for sensitivity to metronidazole and confirmation of their failure to grow on agar slopes under aerobic conditions.
Effect of ciliate protozoa on the activity of polysaccharide‐degrading enzymes and fibre breakdown in the rumen ecosystem
Authors: Williams A.G. , Withers Susan E.
Published: March 2008

The effect of ciliate protozoa on the activity of polysaccharide‐degrading enzymes in microbial populations from the digesta solids and liquor fractions of rumen contents was examined after the refaunation of ciliate‐free sheep with an A‐type rumen protozoal population. Although the culturable rumen bacterial population was reduced after refaunation the number of fibrolytic micro‐organisms detected was higher; the xylanolytic bacterial population and numbers of fungal zoospores were increased after refaunation. The proportion of propionic acid was lower in the refaunated animals, whereas the concentration of ammonia and the acidic metabolites acetate, butyrate and valerate were all increased. The range of enzyme activities present in the digesta subpopulations were the same in defaunated and refaunated animals. The activities of the polysaccharide‐degrading enzymes, however, were increased in the microbial populations associated with the digesta solids after refaunation, and at 16 h after feeding the activities were 4–8 times (β‐d‐xylosidase 20 times) higher than the levels detected in the adherent population from defaunated sheep. The protozoa, either directly through their own enzymes or indirectly as a consequence of their effects on the population size and activity of the other fibrolytic micro‐organisms present, have an important role in determining the level of activity of polysaccharide‐degrading enzymes in the rumen ecosystem. Although the extent of ryegrass (Lolium perenne) hay digestion was similar after 24 h in the absence or presence of protozoa, the initial ruminal degradation was higher in refaunated sheep.
Short‐chain organic acids at pH 5.0 kill Escherichia coli and Salmonella spp. without causing membrane perturbation
Authors: Cherrington Christina A. , Hinton M. , Pearson G.R. , Chopra I.
Published: March 2008

When strains of Escherichia coli K12 and Salmonella spp. were incubated with 0.5–0.7 mol/l formic or propionic acid at pH 5.0, propionic acid was more active than formic acid. It killed 90% of the cell population within 60 min compared with over 3 h for formic acid. Cell death was not associated with a reduction in culture turbidity or a loss of membrane integrity since morphologically normal membranes were observed by electron microscopy and only a small proportion of the cytoplasmic enzyme β‐galactosidase leaked into the supernatant fluid of acid‐treated E. coli K12 cultures.
Effect of some antibiotics and biocides on plasmid transfer in Staphylococcus aureus
Authors: Al‐Masaudi Saad B. , Day M.J. , Russell A.D.
Published: March 2008

S.B. AL‐MASAUDI, M.J. DAY AND A.D. RUSSELL. 1991. The effects of some antibiotics and biocides on the conjugative transfer of the Staphylococcus aureus gentamicin resistance plasmid pWG613 were investigated. Gentamicin and vancomycin were found to stimulate plasmid transfer frequency by 10‐ to 20‐fold whereas methicillin and three inhibitors of protein synthesis each reduced it by various degrees. Most significantly, mupirocin inhibited plasmid transfer frequency by more than 1000‐fold. All the biocides tested (cationic agents, sodium dodecyl sulphate and an organomercurial) reduced plasmid transfer.
Monitoring of a Vibrio natriegens and Desulfovibrio vulgaris marine aerobic biofilm on a stainless steel surface in a laboratory tubular flow system
Authors: Benbouzid‐Rollet Nadia D. , Conte M. , Guezennec J. , Prieur D.
Published: March 2008

N.D. BENBOUZID‐ROLLET, M. CONTE, J. GUEZENNEC AND D. PRIEUR. 1991. In an aerobic bulk environment sulphate‐reducing bacteria (SRB) can find suitable growth conditions on surfaces where other micro‐organisms have developed an extensive biofilm. On metal surfaces they may induce or enhance corrosion. A laboratory tubular flow system was designed to study this phenomenon by creating a biofilm on stainless steel under dynamic conditions with Vibrio natriegens and Desulfovibrio vulgaris. The sulphate reducer colonized the surface, constituting approximately 5% of the total population. Its in situ growth rate, calculated by a simplified mathematical model, showed that the attached SRB multiplied at their settling locations. No significant difference with respect to corrosion enhancement was found in the electrochemical reactions of the metal betwen the control and the reactor, where D. vulgaris was present in the biofilm.
A nitrate reductase‐based colorimetric assay for the study of bacterial adherence
Authors: Shoeb H.A. , Tawfik A.F. , Shibl A.M.
Published: March 2008

H.A. SHOEB, A.F. TAWFIK AND A.M. SHIBL. 1991. Washed intact cells of Escherichia coli and Streptococcus aureus, grown under partial anaerobic conditions in nitrate media, reduced nitrate quantitatively when formate was used as a reducing substrate. Nitrate reductase was applied as an index for bacterial adherence to different target surfaces including uroepithelial cells, HeLa cells and fibrin clots. Nitrate reduction by adhered as well as control cells was determined by quantitative diazotization reaction for nitrite. Variations in the conditions which affect adherence gave rise to corresponding variations in the nitrate reduction index from which bacterial adherence can be conveniently determined under these conditions. This method is simple, reproducible and easy to perform in a short time.
Encapsulation of coagulase‐negative staphylococci of bovine origin
Authors: Matthews K.R. , Oliver S.P. , Guidry A.J.
Published: March 2008

Capsule expression was assessed in six coagulase‐negative staphylococcal strains in serum‐soft agar and by india ink and electron microscopy. Classification of strains as encapsulated by serum‐soft agar and india ink methods differed. Staphylococcus chromogenes, Staph. hyicus, and Staph. simulans grew as diffuse colonies in serum‐soft agar and unstained halos were detected in india ink preparations. Staphylococcus hominis and Staph. simulans grew as diffuse colonies in serum‐soft agar but no unstained halo was seen in india ink preparations. Staphylococcus hyicus was the only strain that gave negative results with serum‐soft agar and india ink assays. Conventional electron microscopy revealed the presence of capsular polysaccharides on the cell surface of Staph. chromogenes, Staph. hominis and Staph. hyicus. Conventional electron microscopic technique used to examine the surface of cells was detrimental to capsule structure. During dehydration the capsule collapsed and appeared as electron dense aggregates at the surface of cells. To confirm results of conventional electron microscopy and to visualize clearly the cell surface, encapsulated Staph. hyicus and unencapsulated Staph. simulans were observed after freeze‐fracture and etching by scanning electron microscopy. The fibrous nature of capsular polysaccharides surrounding cells of Staph. hyicus were distinct and confirmed observation by conventional electron microscopy. A rapid transmission electron microscopic technique is described also for observation of capsule. Results of the rapid TEM method agreed with conventional TEM and SEM. The finding that coagulase‐negative staphylococci isolated from bovine milk are capable of capsule production may be important when investigating pathogenicity of these micro‐organisms.
Composition of the enterococcal and streptococcal intestinal flora of poultry
Authors: Devriese L.A. , Hommez J. , Wijfels R. , Haesebrouck F.
Published: March 2008

Identification to species level showed that Enterococcus faecalis and Ent. faecium largely dominated the enterococcal and streptococcal gut flora of 1‐d‐old chicks. Enterococcus faecalis was rare in 3‐ to 5‐week‐old broilers. Two species, Ent. faecium and Streptococcus alactolyticus, were isolated from nearly all broilers examined. Enterococcus hirae and Ent. durans were found in the small intestines of this category of poultry.

In layers and parent stock of over 12 weeks of age, Ent. cecorum dominated with Strep. alactolyticus ranking next. Other species were isolated irregularly. Enterococcus avium and Ent. gallinarum, originally described from chickens, were rarely found. These species did not appear to belong to the normal intestinal flora of poultry.
The differential fluorescence of bacteria stained with acridine orange and the effects of heat
Authors: Back J.P. , Kroll R.G.
Published: March 2008

Some factors affecting the fluorescence of bacteria stained with acridine orange and the direct epifluorescent filter technique (DEFT) were studied. When bacterial cells from a chemostat operated at dilution rates between 0.1 and 0.7/h were used the differential fluorescence observed in the DEFT related to cell ‘activity’ and the orange fluorescence, which was predominant at high growth rates, may be related to an increase in the RNA content of the cells. Heat affected the colour of cell fluorescence and this was dependent on the cell type and, in particular, age. Uptake of acridine orange into the cells was also found to be an important factor determining the colour of fluorescence. However, with heat‐treated cells there was no correlation between the amount of uptake and colour of fluorescence. The relative amounts and degree of denaturation of the different types of nucleic acids remaining in the cells after heat treatment appeared primarily to determine the colour of fluorescence.
Using dBASE to write PENNAME, a computer key to common Penicillium species
Authors: Pitt J.I.
Published: March 2008

dBASE III Plus™ computer software includes a high level computer language as well as a database management program. dBASE possesses advantages for key construction, including simple entry of raw data, effective user interaction in the selection of outputs, and ready comparison of included species with unknowns. This paper describes the use of dBASE in the construction of PENNAME, a new computer key to common Penicillium species.
Characterization of Erwinia chrysanthemi biovars in alpine water sources by biochemical properties, GLC fatty acid analysis and genomic DNA fingerprinting
Authors: Cother E.J. , Bradley J.K. , Gillings M.R. , Fahy P.C.
Published: March 2008

E.J. COTHER, J.K. BRADLEY, M.R. GILLINGS AND P.C. FAHY. 1992. Erwinia chrysanthemi isolated from the headwaters of the Murrumbidgee River was shown to be different from strains isolated from the source of the Murray River only 140 km away. Biovar 5 (sensu Samson) was found consistently in the upper reaches of the Murrumbidgee River but was not detected in the Murray River where the majority of strains isolated were characterized biochemically as biovar 3. Fatty acid methyl ester analysis of 56 water strains by gas‐liquid chromatography and the Hewlett‐Packard Microbial Identification System confirmed the existence of a distinct biotype at the source of each river system. All Erw. chrysanthemi strains contained cis 9 hexadecanoic (16 : cis9), hexadecanoic (16 : 0), and tetradecanoic (12 : 0) acids. The majority of strains contained dodecanoic acid (12 : 0) in small amounts. Twenty‐six isolates (18 from water, six from potato, and two type cultures) selected for DNA digestion with Hae III or Hinf I were placed in 10 clonal lines based on restriction patterns. No clone was common to both river systems. Restriction patterns obtained by analysis of strains from soft‐rotting potatoes were identical to those obtained from cultures from the headwaters or upper reaches of both rivers. Biochemical, fatty acid and DNA characterization methods all supported the hypothesis that Erw. chrysanthemi is a natural component of the alpine aquatic microflora which could infect potatoes via irrigation water.
Higher alcohol and acetic acid production by apiculate wine yeasts
Authors: Romano Patrizia , Suzzi Giovanna , Comi G. , Zironi R.
Published: March 2008

P. ROMANO, G. SUZZI, G. COMI AND R. ZIRONI. 1992. Ninety‐six strains of apiculate wine yeasts were investigated for their ability to produce higher alcohols and acetic acid in synthetic medium. Less isoamyl alcohol and more n‐propanol and isobutanol were formed by Hanseniaspora guilliermondii than by Kloeckera apiculata. The latter produced twice as much acetic acid as H. guilliermondii. The production of higher alcohols and acetic acid was found to be a characteristic of individual strains and was statistically significant. In a multivariate analysis of higher alcohol production two main groupings were formed at 86%S, corresponding to the taxa H. guilliermondii and K. apiculata. Strains that produced low amounts (50 mg/1) of acetic acid, comparable with that of Saccharomyces cerevisiae, were found in both species of apiculate yeasts.
Microbiological quality of bottled water sold in retail outlets in Nigeria
Authors: Ogan M.T.
Published: March 2008

M.T. OGAN. 1992. The microbiological quality of four brands of bottled water sold in retail outlets in Nigeria were assessed by routine methods in 90 samples. Samples of two brands were acidic in the pH range 3.5–5.9. Faecal coliforms and streptococci were not recovered from any sample. Heterotrophic plate counts (HPC) numbered 50–800 cfu/ml in two brands, A and B, and 100–87000 cfu/ml in C and D. Component colony types among the HPC bacteria in brands C and D produced water‐soluble, fluorescent pigments on colony count and other agar media, and occurred in 11 of 16 batches: their numbers varied from 60 to 82000 cfu/ml. Presumptive antibiotic‐resistant proportions of the HPC bacteria were also recovered from brands C and D on agar amended with ampicillin, penicillin or streptomycin. Five isolates from the green pigmented colonies, representing five batches of brands C and D were satisfactorily identified as strains of Pseudomonas aeruginosa. These strains resisted between four and nine of 14 antibiotics tested. Resistance to tetracycline was eliminated in one isolate when it was cured by incubation at 42d̀C for 100 h, but gel electrophoretic resolution of the DNA did not reveal presence of a plasmid. Strains of Bacillus were the second most commonly isolated bacteria; they were the only colony types in most samples with low HPC counts.
Generalized transduction in Bacillus thuringiensis var. aizawai
Authors: Inal J.R.M. , Karunakaran V. , Burges H.D.
Published: March 2008

J.R.M. INAL. V. KARUNAKARAN AND H.D. BURGES. 1992. Four temperate phages, ØHD67, ØHD130, ØHD228 and ØHD248, which were isolated from Bacillus thuringiensis H‐serotype 7 strains, were tested for their ability to mediate transduction within H‐serotype 7 and also between H‐serotype 7 and 3a3b. The optimum conditions to facilitate transduction were determined. The four phages successfully mediated transduction within serotype 7 of all five auxotrophic markers tested and thus seem to have the ability to mediate generalized transduction. The phages also mediated transduction between H‐serotype 7 and H‐serotype 3a3b of 10 of 11 auxotrophic markers tested.
Use of gene probes based on the insertion sequence IS986 to differentiate between BCG vaccine strains
Authors: Fomukong N.G. , Dale J.W. , Osborn T.W. , Grange J.M.
Published: March 2008

N.G. FOMUKONG, J.W. DALE, T.W. OSBORN AND J.M. GRANGE. 1992. Gene probes derived from the insertion sequence IS986, which have previously been shown to differentiate isolates of Mycobacterium tuberculosis for epidemiological analysis, are also capable of distinguishing two groups of BCG vaccine strains. Most BCG strains have a single copy of IS986, at the same chromosomal site, while the Brazilian, Japanese and USSR strains have an additional copy at a different, common location. These results correlate with the results of previous antigenic analysis and may reflect a different clonal origin of the two groups of BCG strains.
Comparison of definitions of the lag phase and the exponential phase in bacterial growth
Authors: Zwietering M.H. , Rombouts F.M. , Riet K. van 't
Published: March 2008

M.H. ZWIETERING, F.M. ROMBOUTS AND K. VAN 'T RIET. 1992. Different definitions of the lag time and of the duration of the exponential phase can be used to calculate these quantities from growth models. The conventional definitions were compared with newly proposed definitions. It appeared to be possible to derive values for the lag time and the duration of the exponential phase from the growth models, and differences between the various definitions could be quantified. All the different values can be calculated from the growth parameters μm, and a. Therefore, it appeared to be unnecessary to use complicated mathematical equations: simple equations were adequate. For the Gompertz model the conventional definition of the lag time did not differ appreciably from the newly proposed definition. The end‐point of the exponential phase and thus the duration of the exponential phase differed considerably for the two definitions. For the logistic model the two definitions lead to considerable differences for all quantities. It is recommended that the conventional definition is used for calculating the lag time. For the duration of the exponential phase it is recommended that the new definition is used. The value can be calculated, however, directly from the conventional growth parameters.
Repair and calcium dipicolinate release of bioindicators in propylene glycol and propylene glycol—water mixtures
Authors: Philipp Brigitte , Sucker H.
Published: March 2008

B. PHILIPP AND H. SUCKER. 1992. The heat sterilization of spores of Bacillus stearothermophilus ATCC 7953 in propylene glycol (PG) and PG—water mixtures was investigated. Unusual non‐logarithmic survival curves with a marked long shoulder, designated as the lag‐time, were observed at the maximum of resistance. When the number of colony‐forming units were determined after intervals of incubation, the growth curves of spores previously treated at 121°C in PG or PG‐4% water varied considerably. Spores receiving a heat treatment that was longer than the lag‐time showed no growth. When the heat treatment was shorter than the lag‐time, spores showed a delayed growth phase. When spores received heat treatment that was long but which fell within the lag‐time, there was a greater decrease in spore counts before the exponential growth phase began. In PG and PG with low water concentrations, a suppressed release of the specific spore substance calcium dipicolinate was observed during sterilization at 121°C of B. stearothermophilus ATCC 7953 and B. subtilis var. niger ATCC 9372. Calcium dipicolinate release, however, was observed in water.
Effects of bacteria isolated from a saprophagous rhabditid nematode Caenorhabditis elegans on the mycelial growth of Agaricus bisporus
Authors: Grewal P. S. , Hand P.
Published: March 2008

P. S. GREWAL AND P. HAND. 1992. The effects of 10 species of bacteria isolated from a saprophagous rhabditid nematode Caenorhabditis elegans on mycelial growth of the cultivated mushroom Agaricus bisporus were studied in agar cultures. Bacterial species showed differential effects on the mycelial growth of A. bisporus and the effects also depended upon the mushroom strain (C43, C54 and U3). Bacillus cereus, Bacillus sp. and Enterobacter amnigenus caused significant inhibition in mycelial growth of all three strains of A. bisporus. Pseudomonas aeruginosa, Ps. fluorescens biovar reactans and Ps. maltophilia resulted in a significant increase in mycelial growth of C54 strain. Enterobacter cloacae caused a mean inhibition of about 83% in the linear mycelial extension of the most commonly cultivated mushroom strain U3. Bacillus cereus, Ent. amnigenus and Ent. cloacae produced volatile inhibitory substance(s). This is believed to be the first report about the inhibitory effects of specific bacteria isolated from a saprophagous nematode on the mycelial growth of A. bisporus.
Purification and partial characterization of an intracellular aminopeptidase from Streptococcus salivarius subsp. thermophilus strain ACA‐DC 114
Authors: Tsakalidou Efthimia , Kalantzopoulos G.
Published: March 2008

E. TSAKALIDOU AND G. KALANTZOPOULOS. 1992. An intracellular aminopeptidase from Streptococcus salivarius subsp. thermophilus strain ACA‐DC 114, isolated from traditional Greek yoghurt, was purified by chromatography on DEAE‐cellulose and Sephadex G‐100. The enzyme had a molecular weight of 89 000. It was active over a pH range 4.5‐9.5 and had optimum activity on L‐lysyl‐4‐nitroanilide at pH 6.5 and 35°C with Km= 1.80 mmol/l; above 55°C the enzyme activity declined rapidly. The aminopeptidase was capable of degrading substrates by hydrolysis of the N‐terminal amino acid; it had very low endopeptidase and no carboxypeptidase activity. The enzyme was strongly inactivated by EDTA. Serine and sulphydryl group reagents had no effect on enzyme activity.
Rapid detection and identification of Erwinia carotovora subsp. atroseptica by a conjugated Staphylococcus aureus slide agglutination test
Authors: McLeod A. , Pérombelon M.C.M.
Published: March 2008

A. MCLEOD AND M.C.M. PEROMBELON. 1992. A conjugated Staphylococcus aureus slide agglutination test was used to detect and identify the potato blackleg pathogen, Erwinia carotovora subsp. atroseptica. Agglutination was obtained with > 108 cfu/ml of the homologous strain with a polyclonal antiserum (171) against E.c. atroseptica serogroup I which is the predominant E.c. atroseptica serogroup on potatoes in Scotland. The titre of antiserum 171 against live cells of E.c. atroseptica groups I and XXII was 2000 whereas that of other serogroups was considerably less; only 1 and 4 out of 22 serogroups of E. carotovora subsp. carotovora reacted at 1:1500 and 1:1000 antiserum dilutions, respectively and one of the three less common other E.c. atroseptica serogroups reacted at 1:1000. When tested against 24 different bacterial species including E. chrysanthemi and saprophytic bacteria present in potato tuber rots, negative results were obtained with 1:1000 antiserum dilution. The titre against heat‐treated (1 h, 70°C) cells of E.c. atroseptica serogroups I and XXII was1700–2000 whereas it was < 10 against other bacteria including E.c. carotovora. Detection of E.c. atroseptica serogroups I and XXII in diseased potato tissues was achieved directly by the slide agglutination test, but lower antiserum dilutions (1:700–1000) were needed. Still lower antiserum dilutions were needed with heat‐treated test material for E.c. atroseptica identification.
A study of the incidence of different fluorescent Pseudomonas species and biovars in the microflora of fresh and spoiled meat and fish, raw milk, cheese, soil and water
Authors: Gennari M. , Dragotto F.
Published: March 2008

M. GENNARI AND F. DRAGOTTO. 1992. Of 182 various foodstuffs and environmental samples examined, 86% had microflora containing fluorescent Pseudomonas in differing proportions. A computer‐aided technique was used to identify most of the 445 fluorescent strains. Pseudomonas fluorescens biovar V‐1 was most frequently isolated (24%); it either predominated or was present in all types of samples. Other strains, belonging to the other subgroups of biovar V (V‐2, V‐4, V‐5, V‐6 and V‐7), together represented 14.3%. We also identified Ps. fluorescens biovars I‐1 and I‐2 (13.9%), II‐1 and II‐3 (3.6%), III‐1 and III‐2 (8.7%), IV‐2 (0.7%); Ps. putida A and B (11%); Ps. lundensis (10.3%); group B3 (2%) and Ps. aeruginosa (0.7%). Unidentified strains accounted for 10.6% of the flora, many resembling Ps. fluorescens biovar V. Although the presence of Ps. fluorescens V‐1 was often marked, other taxa predominated or were present in large quantities in some particular samples, such as Ps. fluorescens I‐1 in raw milk and cheese, Ps. lundensis in spoiled meat and Ps. fluorescens III‐1 in spoiled fish. Pseudomonas putida A and B were evident in environmental rather than in food samples.
Diagnostic application of monoclonal antibodies to outer membrane protein for rapid detection of salmonella
Authors: Kerr S. , Ball H.J. , Mackie D.P. , Pollock D.A. , Finlay D.A.
Published: March 2008

S. KERR. H.J. BALL, D.P. MACKIE, D.A. POLLOCK AND D.A. FINLAY. 1992. Monoclonal antibodies produced to Salmonella enteritidis outer membrane proteins were screened against 57 Salmonella serovars and several related enterobacteria. Those detecting all Salmonella serovars and none of the related enterobacteria were used in a microtitre plate antigen capture ELISA to screen clinical samples. Sixty‐one of 2100 samples yielded salmonellas after incubation for 24 h in selective media by conventional culture. Of these 58 were detected by the ELISA. Sixty‐five false positives by ELISA were found to be Enterobacter spp. The results show the potential of this ELISA to eliminate a large proportion of the salmonella‐negative cultures at an early stage.
Evaluation of a commercial microbial identification system based on fatty acid profiles for rapid, accurate identification of plant pathogenic bacteria
Authors: Stead D.E. , Sellwood J.E. , Wilson J. , Viney I.
Published: March 2008

D.E. STEAD, J.E. SELLWOOD, J. WILSON AND I. VINEY, 1992. Fatty acid profiles of 773 strains representing 25 taxa of plant pathogenic and related saprophytic bacteria were compared with two commercially available broad‐spectrum libraries and one self‐generated library based primarily on cultures from the National Collection of Plant Pathogenic Bacteria. The accuracy of identification at specific level was often 100%, although for some closely related species and infraspecific taxa accuracy was sometimes significantly less than this. The accuracy of identification of Xanthomonas campestris pathovars was much better than for Pseudomonas syringae pathovars. Almost all identifications were made within24–48 h. Standardization of cultural conditions was essential. Hydroxy fatty acids were of great taxonomic value in classification of Gram‐negative bacteria. Improved library development and standardization of cultural and analytical techniques will further increase the accuracy of identification. Fatty acid profiling offers a valuable rapid, accurate method for identification of many bacteria.
Diversity of yeasts in selected dairy products
Authors: Rohm H. , Eliskases‐Lechner Frieda , Bräuer Martina
Published: March 2008

H. ROHM, F. ELISKASES‐LECHNER AND M. BRÄUER. 1992. The biochemical properties of 1013 yeasts isolated from various milk products (yoghurt, kefir and cheese environment) were compared. The differences in percentage positive reactions described as variable in the standard descriptions indicate environmental selection mechanisms and the existence of yeast‐product associations. The effects of the results on three simplified identification methods are discussed.
Synthetic DNA probes for detection of genes for enterotoxins A, B, C, D, E and for TSST‐1 in staphylococcal strains
Authors: Jaulhac B. , Bes M. , Bornsteint N. , Plémont Y. , Brun Y. , Fleurette J.
Published: March 2008

B. JAULHAC, M. BES, N. BORNSTEIN, Y. PIÉMONTY. BRUN AND J. FLEURETTE. 1992. A dot blot hybridization technique with oligonucleotide probes was developed for the specific detection of the TSST‐1 gene and the staphylococcal enterotoxin (SE) genes A, B, C, D and E. For each toxin gene a probe sequence was chosen from the previously determined sequence. A total of 145 staphylococcal strains (133 Staphylococcus aureus and 12 coagulase‐negative staphylococci (CNS)) were studied by this genotypic method and by two phenotypic assays (gel immunodiffusion and ELISA). An excellent correlation (96%) was observed between the genotypic and phenotypic assays. DNA from two CNS strains hybridized with a probe without detection of the corresponding toxin (SEB for one strain and SEC for the other strain). One Staph. aureus strain was shown to be an SEC producer, but was not detected by the corresponding probe. Gene probe and immunological assays seem to be complementary methods for studies of staphylococcal strains producing (or potentially producing) TSST‐1 or enterotoxins.
Rapid assessment of bacterial viability and vitality by rhodamine 123 and flow cytometry
Authors: Kaprelyants A.S. , Kell D.B.
Published: March 2008

A.S. KAPRELYANTS AND D.B. KELL. 1992. The fluorescent dye rhodamine 123 (Rh 123) is concentrated by microbial cells in an uncoupler‐sensitive fashion. Steady‐state fluorescence measurements with Micrococcus luteus indicated that provided the added dye concentration is below approximately 1 mmol/1, uptake is fully uncoupler‐sensitive and is not accompanied by significant self‐quenching of the fluorescence of accumulated dye molecules. ‘Viable’ and ‘non‐viable’ cells are easily and quantitatively distinguished in a flow cytometer by the extent to which they accumulate the dye. The viability of a very slowly growing chemostat culture of Mic. luteus is apparently only about40–50%, as judged by plate counts, but most of the ‘non‐viable’ cells can be resuscitated by incubation of the culture in nutrient medium before plating. The extent to which individual cells accumulate rhodamine 123 can be rapidly assessed by flow cytometry, and reflects the three distinguishable physiological states exhibited by the culture (‘non‐viable’, ‘viable’ and ‘non‐viable‐but‐resuscitable’). Gram‐negative bacteria do not accumulate rhodamine 123 significantly because their outer membrane is not permeable to it; a simple treatment overcomes this. Flow cytometry using rhodamine 123 should prove of general utility for the rapid assessment of microbial viability and vitality.