Showing papers in "Letters in Applied Microbiology in 1997"
TL;DR: The results imply that interaction of Ag+ with thiol groups plays an essential role in bacterial inactivation.
Abstract: Microbiologically it was demonstrated that amino acids, e.g. cysteine (CySH), and other compounds, e.g. sodium thioglycollate, containing thiol groups neutralized the activity of silver nitrate against Pseudomonas aeruginosa PAO1. Amino acids with disulphide bonds were inactive, with the exception of L-cystine dimethyl ester, as were all amino acids with no sulphur groups. Iodoacetamide reacted with CySH to produce a CyS-acetamide complex that was unable to quench the activity of Ag+. Chemical analyses using cyclic voltammetry demonstrated that high coordination numbers (3.1) were obtained with thiol-containing amino acids and low numbers (0.28-0.4) with other amino acids. Both microbiologically and chemically, the results imply that interaction of Ag+ with thiol groups plays an essential role in bacterial inactivation.
800 citations
TL;DR: The medium AUM solidified with agar enabled the recovery of a wide range of urease‐positive and ‐negative urinary pathogens and was capable of forming crystals and encrustations resembling those found in natural urinary tract infections.
Abstract: A simple artificial urine medium (AUM) has been developed which provides conditions similar to that found in human urine. AUM solidified with agar enabled the recovery of a wide range of urease-positive and -negative urinary pathogens. Liquid AUM supported growth at concentrations of up to 10(8) cfu ml-1, as found in normal urine. Reproducible, steady-state growth also occurred over many generations in continuous culture. AUM was capable of forming crystals and encrustations resembling those found in natural urinary tract infections. The medium is a suitable replacement for normal urine for use in a wide range of experiments modelling the growth and attachment of urinary pathogens in the clinical environment.
423 citations
TL;DR: Important oils extracted from plants of known origin showed antimicrobial activity against three bacteria and four yeasts using the drop diffusion method, and it was found that 50‐fold higher activity was found when no dispersing solvent was used.
Abstract: Fifty-one essential oils extracted from plants of known origin were tested for their antimicrobial activity against three bacteria, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and four yeasts, Torulopsis utilis, Schizosaccharomyces pombe, Candida albicans and Saccharomyces cerevisiae using the drop diffusion method. All showed antimicrobial activity against at least one of the micro-organisms. Following this preliminary screening, 13 essential oils showing antimicrobial activity against at least five of the micro-organisms were tested in the range 50 micrograms ml-1 to 500 micrograms ml-1 using broth micro dilution techniques with dimethylsulphoxide (DMSO) as a dispersing solvent. The concentration of most of the oils required for total inhibition of growth was > 500 micrograms ml-1. Further studies on the antimicrobial action of cinnamon oil in the range 10-150 micrograms ml-1 showed that 50-fold higher activity was found when no dispersing solvent was used.
294 citations
TL;DR: A pH and dye‐based fast procedure for screening l‐asparaginase‐producing micro‐organisms is reported and results correlate with quantitative estimations in culture broths.
Abstract: A pH and dye-based fast procedure for screening L-asparaginase producing micro-organisms is reported. The procedure is suitable for bacterial and fungal screening. The results are obtained within 24 and 48 h for bacteria and fungi, respectively. The results correlate with quantitative estimations in culture broths.
293 citations
TL;DR: Methods for the detection of Alicyclobacillus acidoterrestris at a level of 1 cell per 100 ml and enumeration with a sensitivity of 5 cells ml−1 were developed and outgrew and multiplied at a similar rate to vegetative cells in both orange juice and apple juice.
Abstract: Methods for the detection of Alicyclobacillus acidoterrestris at a level of 1 cell per 100 ml and enumeration with a sensitivity of 5 cells ml-1 were developed. Spores of A. acidoterrestris survived pasteurization and outgrew and multiplied at a similar rate to vegetative cells in both orange juice and apple juice. Alicyclobacillus acidoterrestris grew readily in orange juice, apple juice and a non-carbonated fruit juice-containing drink at temperatures of 25-44 degrees C producing a taint and elevated levels (1-100 ppb) of guaiacol. Isolates of A. acidoterrestris can be identified using the DuPont RiboPrinter. It was isolated from apple drinks, apple juice concentrate and freshly squeezed orange juice.
212 citations
TL;DR: In a comparison of the D‐values of several members of the Enterobacteriaceae in dairy products, Ent.
Abstract: Enterobacter sakazakii, designated a unique species in 1980, has been implicated in a rare but severe form of neonatal meningitis, with dried-infant formula being implicated as the mode of transmission The high mortality rate (40-80%) and the lack of information about this organism led to a study of the heat resistance of Ent sakazakii in reconstituted dried-infant formula Ten Canadian Ent sakazakii strains (5 clinical and 5 food isolates) were used to determine the heat resistance of this organism at 52, 54, 56, 58 and 60 degrees C in reconstituted dried-infant formula D-values of 548, 237, 103, 42 and 25 min were obtained for each temperature, respectively The overall calculated z-value was 582 degrees C In a comparison of the D-values of several members of the Enterobacteriaceae in dairy products, Ent sakazakii appeared to be one of the most thermotolerant organisms The importance of process control during manufacture and the use of aseptic procedures during the preparation, use and storage of dried-infant formula is discussed
189 citations
TL;DR: Application of B. cereus 65 directly to soil significantly protected cotton seedlings from root rot disease caused by Rhizoctonia solani.
Abstract: Bacillus cereus strain 65, previously isolated as an endophyte of Sinapis, was shown to produce and excrete a chitinase with an apparent molecular mass of 36 kDa. The enzyme was classified as a chitobiosidase because it was able to cleave diacetylchitobiose (GlcNAc)2 from the non-reducing end of trimeric chitin derivatives. The chitinase exhibited activity over the pH range 4.5-7.5 and was stable between pH 4.0 and 8.5. The enzyme had an isoelectric point of 6.4. Application of B. cereus 65 directly to soil significantly protected cotton seedlings from root rot disease caused by Rhizoctonia solani.
182 citations
TL;DR: Shelf‐life analysis demonstrated that incorporation of nisin at a level of 2·5 mg l−1 could effectively inhibit the growth of L. monocytogenes for a period of 8 weeks or more (dependent on cheese type).
Abstract: The efficacy of nisin to control the food-borne pathogen Listeria monocytogenes in ricotta-type cheeses over long storage (70 d) at 6-8 degrees C was determined. Cheeses were prepared from unpasteurized milk by direct acidification with acetic acid (final pH 5.9) and/or calcium chloride addition during heat treatment. Nisin was added in the commercial form of Nisaplin pre-production to the milk. Each batch of cheese was inoculated with 10(2)-10(3) cfu g-1 of a five-strain cocktail of L. monocytogenes before storage. Shelf-life analysis demonstrated that incorporation of nisin at a level of 2.5 mg l-1 could effectively inhibit the growth of L. monocytogenes for a period of 8 weeks or more (dependent on cheese type). Cheese made without the addition of nisin contained unsafe levels of the organism within 1-2 weeks of incubation. Measurement of initial and residual nisin indicated a high level of retention over the 10-week incubation period at 6-8 degrees C, with only 10-32% nisin loss.
180 citations
TL;DR: The colonization of Lactobacillus rhamnosus GG (ATCC 53103, henceforth L.GG) in five human colonoscopy patients was studied and suggests that L. GG is able to adhere in vivo to the colon.
Abstract: The colonization of Lactobacillus rhamnosus GG (ATCC 53103, henceforth L.GG) in five human colonoscopy patients was studied. The test subjects consumed whey drink fermented with the bacterium for 12 d before the colonoscopy. The presence of L.GG was subsequently checked both in the faecal samples and in the colonic biopsies obtained from various locations in the large intestine. In all patients L.GG was the dominant faecal lactic acid bacterium as a result of the administration. In four patients L.GG could also be recovered from the biopsies, while with one patient (suffering from ulcerative colitis diagnosed during the colonoscopy) no L.GG was detected in the biopsy samples. The results suggest that L.GG is able to adhere in vivo to the colon. Study of the faecal samples alone is apparently not sufficient for elucidation of the gastrointestinal ecology of probiotic bacteria.
164 citations
TL;DR: Some microbiological methods recommended for control of fish products by national and international authorities are inappropriate for detection of psychrotolerant and heat‐labile micro‐organisms like P. phosphoreum, which was not detected previously in spoiled MAP fish.
Abstract: Occurrence and growth of Photobacterium phosphoreum were studied in 20 experiments with fresh fish from Denmark, Iceland and Greece. The organism was detected in all marine fish species but not in fish from fresh water. Growth of P. phosphoreum to high levels (> 10 7 cfu g -1 ) was observed in most products and the organism is likely to be of importance for spoilage of several modified atmosphere-packed (MAP) marine fish species when stored at chill temperatures. Some microbiological methods recommended for control of fish products by national and international authorities are inappropriate for detection of psychrotolerant and heat-labile micro-organisms like P. phosphoreum. These methods have been used in many previous studies of MAP fish and this could explain why, contrary to the findings in the present study, P. phosphoreum in general was not detected previously in spoiled MAP fish.
149 citations
TL;DR: The demonstration of an oxygen requirement for the inactivation of faecal bacteria in sunlight indicates that solar‐based water disinfection systems are likely to require fully aerobic conditions in order to function effectively.
Abstract: Suspensions of the faecal indicator bacteria Escherichia coli and Enterococcus faecalis were incubated in full sunlight in plastic bottles containing either (i) air-equilibrated (oxygenated) water or (ii) anaerobic (deoxygenated) water. A rapid decrease in cfu ml−1 was observed for actively growing and stationary phase cells of both types of faecal bacteria when illuminated under aerobic conditions, with Ent. faecalis showing the greater enhancement in the rate of inactivation in air-equilibrated water. The demonstration of an oxygen requirement for the inactivation of faecal bacteria in sunlight indicates that solar-based water disinfection systems are likely to require fully aerobic conditions in order to function effectively.
TL;DR: Both the plasmid and the associated antimicrobial resistance could be transferred to an Escherichia coli recipient by single‐step conjugation at a frequency of 4·3×10−3 transconjugants per donor cell.
Abstract: Strains of Aeromonas hydrophila isolates from skin lesions of the common freshwater fish, Telapia mossambica, were screened for the presence of plasmid DNA by agarose gel electrophoresis and tested for susceptibility to 10 antimicrobial agents. Of the 21 fish isolates examined, all were resistant to ampicillin and sensitive to gentamycin. Most isolates were resistant to streptomycin (57%), tetracycline (48%) and erythromycin (43%). While seven of 21 isolates harboured plasmids, with sizes ranging from 3 to 63·4 kilobase pair (kb), it was only possible to associate the presence of a plasmid with antibiotic resistance (ampicillin and tetracycline) in strain AH11. Both the plasmid and the associated antimicrobial resistance could be transferred to an Escherichia coli recipient by single-step conjugation at a frequency of 4·3×10−3 transconjugants per donor cell.
TL;DR: These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes.
Abstract: Pseudomonas aeruginosa GS3 produces rhamnolipid biosurfactants during growth on molasses and cornsteep liquor as the primary carbon and nitrogen sources, respectively. After 96 h of growth the culture supernatant fluid had a rhamnose concentration of 0.24 g 1 -1 and reduced the interfacial tension against crude oil from 21 mN m- -1 to 0.47 mN m -1 . The rhamnolipids were able to form stable emulsions with n-alkanes, aromatics, crude oil and olive oil. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes.
TL;DR: The results strongly suggest that the amylase produced by the intestinal microflora play an important role in the digestion of starch in freshwater fish to some extent.
Abstract: The amylase-producing ability of the intestinal microflora in cultured specimens of ayu, carp, channel catfish, Japanese eel and tilapia was determined. Mean viable counts of aerobes and anaerobes ranged from 1.1 x 10 6 to 3.7 x 10 8 cfu g -1 and from 1.3 x 10 3 to 1.6 x 10 8 cfu g -1 , respectively. piermufias spp. and Bacteroidaceae were predominant in four to five fish species. Of 206 strains examined, 65 (31.6%) produced > 0.01 U amylase ml -1 . The percentage of producers differed among families and genera of bacteria and fish species. While 56% of the anaerobes produced amylase, only. 20% of the aerobes did. More than 50% of Aeromonas, Bacteroidaceae and Clostridium strains produced amylase efficiently while Acinetobacter, coryneforms, Enterobacteriaceae, Moraxella, Plesiomonas and Streptococcus strains did not. High amylase production (> 0.05 U ml -1 ) was found in 12 strains, 11 from Aeromonoas and one Pseudomonas. The percentage of high amylase producers in Japanese eel was lower than the other four fish (2-30%). These results strongly suggest that the amylase produced by the intestinal microflora play an important role in the digestion of starch in freshwater fish to some extent.
TL;DR: The effect of combinations of temperature, pH, NaCl and incubation time on growth from spores of non‐proteolytic Clostridium botulinum types B, E and F was determined using a strictly anaerobic medium.
Abstract: The effect of combinations of temperature (2°, 3°, 4°, 5°, 8° and 10°C), pH (5·0–7·2) and NaCl (0·1–5·0% w/w) on growth from spores of non-proteolytic Clostridium botulinum types B, E and F was determined using a strictly anaerobic medium. Inoculated media were observed weekly for turbidity, and tests were made for the presence of toxin in conditions that approached the limits of growth. Growth and toxin production were detected at 3°C in 5 weeks, at 4°C in 3/4 weeks and at 5°C in 2/3 weeks. The resulting data define growth/no growth boundaries with respect to low temperature, pH, NaCl and incubation time. This is important in assessment of the risk of growth and toxin production by non-proteolytic Cl. botulinum in minimally processed chilled foods.
TL;DR: It was concluded that ERIC‐PCR does not necessarily direct amplification from genuine ERIC sequences, with the exception being a subset of bands from enterobacterial targets.
Abstract: We examined the use of enterobacterial repetitive intergenic consensus (ERIC) sequences in PCR on the DNAs of various bacteria, bacteriophage, invertebrates, fungi, plants and vertebrates and have shown that complex ERIC-PCR patterns can be readily produced from all of these target organisms. A range of annealing temperatures was tested, from 52 degrees C (the commonly used annealing temperature) to 66 degrees C (the approximate Tm of ERIC primers). At the higher temperatures, most bands failed to amplify, the exception being a subset of bands from enterobacterial targets. It was concluded that ERIC-PCR does not necessarily direct amplification from genuine ERIC sequences.
TL;DR: A rapid, inexpensive, large‐scale DNA extraction method involving minimal purification has been developed that is applicable to various soil types and could be used in PCR directed at high‐copy number (bacterialsmall subunit rRNA) and single‐copy genes.
Abstract: A rapid, inexpensive, large-scale DNA extraction method involving minimal purification has been developed that is applicable to various soil types. DNA was extracted from 100 g of soil using direct lysis with glass beads and sodium dodecyl sulphate (SDS) followed by polyethylene glycol precipitation, potassium acetate precipitation, phenol extraction and isopropanol precipitation. The crude extract could be used in PCR directed at high-copy number (bacterial small subunit rRNA) and single-copy (fungal beta-tubulin) genes.
TL;DR: A multiplex PCR assay specifically detecting Escherichia coli O157 : H7 was developed by employing primers amplifying a DNA sequence upstream of E. coli O156 eaeA gene and genes encoding Shiga‐like toxins (SLT) I and II.
Abstract: A multiplex PCR assay specifically detecting Escherichia coli O157 : H7 was developed by employing primers amplifying a DNA sequence upstream of E. coli O157 : H7 eaeA gene and genes encoding Shiga-like toxins (SLT) I and II. Analysis of 151 bacterial strains revealed that all E. coli O157 : H7 strains were identified simultaneously with the SLT types and could be distinguished from E. coli O55 : H7 and E. coli 055 : NM, and other non-0157 SLT-producing E. coli strains. Primer design, reaction composition (in particular, primer quantity and ratios), and amplification profile were most important in development of this multiplex PCR. This assay can serve not only as a confirmation test but also potentially can be applied to detect the pathogen in food.
Journal Article•
TL;DR: The baroprotective effect of reduced a w on microbial inhibition by HHP was described by a linear relationship between the water activity depression factor (1-a w ) and the log of the survival fraction.
Abstract: Zygosaccharomyces bailii inhibition was evaluated in model systems with initial water activity (a w ) ranging from 0.998 to 0.900 and exposed to a high hydrostatic pressure (HHP) treatment of 345 MPa at 21°C for 5 min. The yeast was completely inhibited (<10 cfu ml -1 ) after the HHP treatment when the a w was higher than 0.98. As the a w of the model system decreased, the number of surviving Z. bailii increased. For a w 0.92, 0.91 and 0.90, the HHP treatment reduced the initial inocula less than 1 log-cycle. The baroprotective effect of reduced a w on microbial inhibition by HHP was described by a linear relationship between the water activity depression factor (1-a w ) and the log of the survival fraction.
TL;DR: The development of communities of the thermophilic microflora of natural whey culture for Parmigiano Reggiano cheese production was studied by means of molecular techniques and RAPD analysis facilitates the identification of the Lactobacillus strains involved in this microbial association.
Abstract: The development of communities of the thermophilic microflora of natural whey culture for Parmigiano Reggiano cheese production was studied by means of molecular techniques. RAPD analysis facilitates the identification of the Lactobacillus strains involved in this microbial association and permitted the study of population dynamics during two cycles of whey fermentation. Analysis of RAPD fingerprints revealed the presence of four biotypes that dominate the whey fermentation process. Sequence analysis of 16S rDNA demonstrated that the strains isolated from whey belong to Lact. helveticus and Lact. delbrueckii ssp. lactis species.
TL;DR: Significant identity was found between the N‐terminal parts of the LO18 protein and the Hsp18 from Clostridium acetobutylicum suggesting that LO18protein belongs to the family of small heat shock proteins conserved in prokaryotic and eukaryotic cells.
Abstract: In Leuconostoc oenos, a malolactic bacterium, the synthesis of a stress protein called LO18 with an apparent molecular mass of 18 kDa was greatly induced after heat (42 degrees C), acid (pH 3) or ethanolic (12% (v/v)) shocks. Moreover, the LO18 protein synthesis was induced in stationary growth phase and was detected for a long time (30 h) during this growth phase. Significant identity was found between the N-terminal parts of the LO18 protein and the Hsp18 from Clostridium acetobutylicum suggesting that LO18 protein belongs to the family of small heat shock proteins conserved in prokaryotic and eukaryotic cells.
TL;DR: Cow’s milk was inoculated with E. coli O157 and ‘bifido’ yoghurt, made with the two starter cultures plus Bifidobacterium bifidum for low and high pathogen inocula, respectively.
Abstract: Cow's milk was inoculated with ca 10(3) and 10(7) cfu ml-1 Escherichia coli O157:H7 After fermentation at 42 degrees C for 0-5 h, the yoghurt was stored at 4 degrees C Two kinds of yoghurt were used: traditional yoghurt (TY), made with Streptococcus thermophilus and Lactobacillus bulgaricus starter cultures, and 'bifido' yoghurt (BY), made with the two starter cultures plus Bifidobacterium bifidum After 7 d E coli O157:H7 decreased from 352 to 272 log10 cfu ml-1 and from 708 to 532 log10 cfu ml-1 in TY, and from 349 to 273 log10 cfu ml-1 and from 738 to 541 log10 cfu ml-1 in BY The pH values of yoghurt dropped from 66 to 45 and 44 in TY (for low and high pathogen inocula, respectively), and from 66 to 46 and 45 in BY (for low and high pathogen inocula, respectively)
TL;DR: While the decrease of LA utilization index was accompanied with growth of delipidized biomass and with reduction of lipid accumulation within the cells, high lipid yield was as a consequence of the direct oil source incorporation into intracellular lipid.
Abstract: Lipid formation and γ-linolenic acid (GLA) production by 48 species of Mucorales fungi grown on sunflower oil (which consists of 70% linoleic acid; LA) were studied. The strains accumulated 42.7-65.8% lipid in biomass (7.66-13.39 g I -1 ). Eight cultures produced more than 200 mg GLA 1 -1 . Highest GLA yields exhibited Mucor mucedo CCF-1384 and Cunninghamella echinulata CCF-103 (379 and 373 mg 1 -1 , respectively). Mortierella alpina CCF-185 synthesized 465 mg 1 -1 arachidonic acid. While the decrease of LA utilization index (ratio of LA content of cell lipid/LA content of oil source) was accompanied with growth of delipidized biomass and with reduction of lipid accumulation within the cells, high lipid yield was as a consequence of the direct oil source incorporation into intracellular lipid.
TL;DR: The effect of high hydrostatic pressure on the activity of 13 metabolic enzymes produced by all three strains of Listeria monocytogenes was examined using gel electrophoresis and it appears that these enzymes were not a determining factor in relation to previously observed differences in the overall pressure resistance of the three strains.
Abstract: R.K. SIMPSON AND A. GILMOUR. 1997. The effect of high hydrostatic pressure (100-550 MPa, 15 min, ambient temperature) on the activity of 13 metabolic enzymes produced by all three strains of Listeria monocitogenes (NCTC 11994, a poultry isolate and Scott A) was examined using gel electrophoresis. The enzymes assayed exhibited a wide variation in barotolerance. The pressure resistance of each particular enzyme was not dependent on the strain from which it was derived. This would seem to indicate that these enzymes were not a determining factor in relation to previously observed differences in the overall pressure resistance of the three strains.
TL;DR: A psychrotrophic bacterium producing a protease active at low temperatures was isolated from fish intestine and identified as a Pseudomonas species and its maximum temperature was 25°C, an unusually low temperature.
Abstract: A psychrotrophic bacterium producing a protease active at low temperatures was isolated from fish intestine and identified as a Pseudomonas species. Optimum growth and protease-producing temperatures of this strain were 15 degrees C and 10 degrees C, respectively. The maximum temperature for proteolytic activity was 25 degrees C, an unusually low temperature.
TL;DR: The MAR indexes of hospital isolates of Pseudomonas aeruginosa were determined with reference to nine different cephalosporins suggesting their origin from a high risk source of contamination where antibiotics are often used.
Abstract: The MAR indexes of hospital isolates of Pseudomonas aeruginosa were determined with reference to nine different cephalosporins. The values for all the strains were higher than 0.2 suggesting their origin from a high risk source of contamination where antibiotics are often used. Emergence of MAR pathogenic strains of Ps. aeruginosa indicated possible nosocomial infection in the hospital environment. beta-Lactamases produced by these organisms were tested and their inhibition by clavulanic acid was studied. beta-Lactamase produced by one of these strains (Ps-1) could not be inhibited by clavulanic acid whereas beta-lactamases of three other strains (Ps-2, Ps-3 and Ps-4) could be inhibited by clavulanic acid in the presence of cephalosporins, suggesting a possible use of clavulanic acid in combination with cephalosporins, to combat beta-lactamase induced resistance in Ps. aeruginosa.
TL;DR: Flow cytometry in combination with fluorescent molecular markers 5‐ (and 6‐)carboxyfluorescein succinimidylester and propidium iodide and double‐labelling with CFSE and PI provided additional information about damage levels and distributions within populations.
Abstract: Flow cytometry in combination with fluorescent molecular markers 5- (and 6-) carboxyfluorescein succinimidylester (CFSE) and propidium iodide (PI) have been applied to determine lag times, numbers of cell divisions and injury after mild heat (50 degrees C, 5 min) and nisin treatments (0.1 and 1.0 microgram ml-1) of Lactobacillus plantarum. Initial labelling with covalently bound dye CFSE (20 and 100 micrograms ml-1) allowed determination of lag times and cell proliferation for up to eight generations. Double-labelling with CFSE and PI (5 micrograms ml-1) provided additional information about damage levels and distributions within populations. Subpopulations surviving treatment could be identified easily and selectively sorted.
TL;DR: The content of QS did not decline when incubated for 24 h in the medium containing autoclavedrumen liquor, suggesting that rumen microbes have enzyme(s) capable of degrading QS, and its beneficial effects mediated by binding to ammonia is studied.
Abstract: Quillaja saponin (QS) was incubated at 39 degrees C in an in vitro medium containing rumen liquor from a cow fed a roughage diet. No degradation of QS was observed up to 6 h of fermentation. Incubation for 9, 12 and 24 h decreased the content of QS by 16%, 45% and 100%. The content of QS did not decrease when incubated for 24 h in the medium containing autoclaved rumen liquor, suggesting that rumen microbes have enzyme(s) capable fo degrading QS. The fate of QS will help gain a better understanding of mechanisms of action of QS on rumen fermentation, and its beneficial effects mediated by binding to ammonia.
TL;DR: Random amplification of polymorphic DNA (RAPD) is proving to be a useful technique in studying the epidemiology of micro‐organisms and a technique to obtain reproducible RAPD fingerprints of Salmonella isolates without the need to purify genomic DNA is described.
Abstract: Random amplification of polymorphic DNA (RAPD) is proving to be a useful technique in studying the epidemiology of micro-organisms. The technique can be troublesome and time consuming to establish due to the essentially empirical approach to optimization. By standardization of certain parameters and use of a commercially available PCR buffer optimization kit, a particularly promising primer was identified and RAPD conditions for a highly discriminatory and reproducible characterization of Salmonella isolates was achieved. In addition, a technique to obtain reproducible RAPD fingerprints of Salmonella isolates without the need to purify genomic DNA is described.
TL;DR: To detect Cryptosporidium in environmental specimens in the Republic of Ireland, grab samples of river water were prepared by calcium carbonate flocculation, and marine mussel tissue homogenated prior to testing with a fluorescently labelled monoclonal antibody and fluorescence microscopy.
Abstract: To detect Cryptosporidium in environmental specimens in the Republic of Ireland, grab samples of river water were prepared by calcium carbonate flocculation, and marine mussel tissue homogenated prior to testing with a fluorescently labelled monoclonal antibody and fluorescence microscopy. The parasite was detected in both river waters and marine mussels (Mytilus edulis). Filter feeders such as Mytilus edulis may be of value as biological monitors for the presence of cryptosporidial oocysts in sea water. The presence of Cryptosporidium in river and marine waters and, in particular, contaminating mussels used for human consumption, has obvious health implications.