共查询到20条相似文献,搜索用时 15 毫秒
1.
JENNIFER L. SCHMELDER ROBIN M. KALINOWSKI PETER W. BODNARUK 《Journal of Rapid Methods and Automation in Microbiology》2000,8(1):65-70
Aerobic plate counts (APC) are used by the food industry to help determine the sanitary state of equipment and bacterial load of finished product. Conventional aerobic count methods for processed meats require approximately 72 h incubation before results are available. Food processing plants with in-house analytical laboratories require methods that are simple, reliable and rapid. New test methods using PetrifilmTM (PF) and RedigelTM (RG) have been developed for determining APC. These methods are faster and easier than culturing in a standard agar medium. A variety of raw, cooked; cured and noncured meat products, cooling brine and environmental surface swabs were collected and analyzed for APC using PF, RG and plate count agar (PCA). Data analyses from over 200 samples indicated that the sensitivity of rapid testing methods for aerobic bacteria can vary depending on sample type. 相似文献
2.
EILEEN GARRY MEREDITH PESTA PATRICK WILLIAMS 《Journal of Rapid Methods and Automation in Microbiology》2004,12(2):149-153
In the food and dairy industries, aerobic plate counts are determined by a time-consuming and laborious hand-counting method. The PetriScan ® automated colony counter was developed to improve efficiency in the microbiology laboratory. In this study, colony counts of food, dairy, and milk products plated on 3MTM PetrifilmTM Aerobic Count Plates were compared using both automated and manual count plate methods. For sample variation, 16 different food, dairy, and milk products were used. Samples were prepared and serially diluted using Butterfield's diluent according to approved AOAC methods and APHA's Standard Methods. Plates were inoculated, incubated, and counted according to AOAC methods. For data collection, plates with counts between 5 and 300 colonies were included. A total of 55 low (5–30), 29 medium (31–100), and 23 high (101–300) count plates were used. Duplicate results were recorded for both methods; hand counts were tallied by two scientists. The duplicates of the mean log values for manual counts varied by 0.0005 and 0.0007, and the duplicates for the automated counts varied by 0.0011. The mean log value difference between the automated and manual counts for pooled data was 0.035. The correlation coefficient for the regression line comparing the automated and manual count methods for pooled data was 0.98. The regression equation was y = 0.9257x + 0.0781. These results demonstrate that the PetriScan® automated colony counter is a comparable and practical alternative to the standard method of manually counting plates. 相似文献
3.
M. VALLÉ P. EB R. TAILLIEZ P. MALLE 《Journal of Rapid Methods and Automation in Microbiology》1998,6(1):29-42
Abstract The total aerobic flora of seafish flesh is weakly halophilic, and requires on average 1.38% NaCl according to statistical studies. Enumeration is optimal on tryptone soya agar or on NaCl supplemented plate count agar (-H2 S), incubated at 20 and 25C, respectively. Plate count agar (-H2 S) was selected because it can also be used for enumeration of hydrogen sulfide-producing bacteria by degradation of sulfur-containing proteins, which are abundant in fish The models employed are sigmoidal. The initial bioburden is too great for there to be a lag phase during storage in ice at 0C. The models show that when the total aerobic microflora count exceeds 100,000 cfu/g, whole or filleted fish stored on ice at 0C are unfit for consumption. 相似文献
4.
The use of 4-methylumbelliferyl-β- D -glucuronide (MUG) in different solid media for the detection and enumeration of Escherichia coli in foods was evaluated by testing the effects of different substrate concentrations (50 or 100 μg ml−1 ), incubation temperatures (37 or 41·5°C) and incubation times (8, 12, 24 and 48 h). Different kinds of foods, both naturally and artificially contaminated, were analysed. The use of selective media without differential substances and an incubation time of 24 h seem to be worthy of recommendation. In this case an incubation temperature of 37°C would be preferred and the MUG concentration could be reduced to 50 μg ml−1 . Incubation times shorter than 24 h, which may cause a loss of sensitivity, require higher incubation temperatures (41·5°C) and MUG concentration (100 μg ml−1 ). 相似文献
5.
Impedimetric methods for evaluating post-pasteurization contamination and shelf-life of cream were assessed. Over 94% of the samples tested were in agreement, using selected cut-offs of 20 h for detection time measured at 21°C with creams containing inhibitors for the growth of Gram positive bacteria on standard plate count agar as growth media, and 3.2 × 107 cfu/g for plate counts obtained on cream which had been pre-incubated in the presence of inhibitors for the growth of Gram positive organisms, and on cream stored at 6°C for 7 d. Agreement between the impedimetric method and plate count was not as good if either Brain Heart Infusion or Milk Agar was used in place of Plate Count Agar in the former technique. A poor correlation was obtained between plate count methods for enumerating post-pasteurization contamination and keeping quality with impedimetric measurements on cream alone. It was possible, with a reasonable degree of certainty, to determine if cream had suffered post-pasteurization contamination within 20 h of production. 相似文献
6.
I. Gonzalez M. Lopez M. Mazas J. Gonzalez A. Bernardo 《Journal of applied microbiology》1995,78(5):548-554
The effect of recovery media and incubation temperature on the apparent heat resistance of three ATCC strains (4342, 7004 and 9818) of Bacillus cereus spores were studied. Nutrient Agar (NA), Tryptic Soy Agar (TSA), Plate Count Agar (PCA) and Milk Agar (MA) as the media and temperatures in the range of 15–40°C were used to recover heated spores. Higher counts of heat injured spores were obtained on PCA and NA. The optimum subculture temperature was about 5°C below the optimum temperature for unheated spores. No significant differences in heat resistance were observed with the different recovery conditions except for strains 4342 and 9818 when MA was used as plating medium.
Large differences in D -values were found among the strains ( D100 =0·28 min for 7004; D 100 =0·99 min for 4342; D 100 = 4·57 min for 9818). The 7004 strain showed a sub-population with a greater heat resistance. The z values obtained for the three strains studied under the different recovery conditions were similar (7·64°C 0·25). 相似文献
Large differences in D -values were found among the strains ( D
7.
MINIATURIZED TWO-FOLD DILUTION METHOD FOR ENUMERATING TOTAL MICROBIAL LOAD AND COLIFORMS IN RAW MILK
M. COSTELLO M.S. RHEE D.H. KANG 《Journal of Rapid Methods and Automation in Microbiology》2002,10(1):19-25
A rapid and simple method for enumerating total aerobic plate counts (APC) and coliforms in raw milk was developed and compared with conventional plating method. Following two-fold serial dilution of samples in a 96 well microtiter plate, double strength of two different modified media for APC or coliforms was added to each well. The final positive well (purple to yellow color) was determined and converted to dilution factors. The dilution factor of each sample was converted to Log10 DF (Dilution factors) and compared to actual microbial numbers Log10 CFU/mL. The results of 2-fold dilution method (Log10 DF) were strongly correlated to conventional plating method (Log10 CFU/mL) (P < 0.05). The correlation of the scatterplot of spread plating and 2-fold dilution method indicated a high level of agreement between two methods (R2 = 0.921 for total counts and R2 = 0.916 for forms from raw milk). This 2-fold dilution method is an easy, rapid, and economical method for enumeration of total microbial loads and coliforms in raw milk. 相似文献
8.
9.
The influence of environmental parameters on the bacterial populations of thermal springs in West Bengal, India 总被引:2,自引:0,他引:2
The physico-chemical characteristics and the bacterial populations of three thermal springs in West Bengal have been examined. The springs range in temperature from 42o C (Saubhagya Kund) to 65o C (Agni Kur.d). The levels of carbonate and bicarbonate alkalinity, total hardness and the ppm of chloride, phosphate and silicate as well of dissolved oxygen were measured at monthly intervals. Estimates of the bacterial populations were obtained from cultures. Water samples incubated at 37o C for enumeration of mesophilic microbes, at 50o C for thermo-tolerant bacteria and at 60o for strict thermophiles. Tests for coliform organisms were carried out at 37o C and at 50o C.
All three springs show seasonal variation in their physico-chemical characteristics and in their bacterial populations. The cooler springs have large populations of mesophilic and thermotolerant bacteria but fewer thermophilic types. In the two hot springs (Saubhagya Kund and Swetganga), the differences of mean bacterial populations observed between 37o and 50"C and between 50o and 60o C are highly significant ( P < 0.01), in the third (Agni Kund) the differences are also significant ( P < 0.01) but the population showed a rising trend with the temperature. Of the biotic and abiotic factors which could be involved in the observed seasonal variation in the bacterial populations, only the fluctuations in the phosphate levels were found to show a significant correlation (0.001 < P < 0.01). 相似文献
All three springs show seasonal variation in their physico-chemical characteristics and in their bacterial populations. The cooler springs have large populations of mesophilic and thermotolerant bacteria but fewer thermophilic types. In the two hot springs (Saubhagya Kund and Swetganga), the differences of mean bacterial populations observed between 37
10.
D.A. BAUTISTA G. KOZUB K.W.F. JERICHO M.W. GRIFFITHS 《Journal of Rapid Methods and Automation in Microbiology》1997,5(1):37-45
A rapid (<15 min), inexpensive and simple method has been developed to estimate the concentration of bacteria on surfaces of beef carcasses using adenosine triphosphate (ATP) bioluminescence. Surfaces (5x5 cm2 ) of beef carcasses (n= 159) were collected by excision. An ATP assay and aerobic plate count were performed on each sample. A significant (p < 0.001) positive linear relationship (r = 0.83) between plate count and ATP assay was obtained for 159 beef carcass samples. When thresholds levels were set at 1 × 104 , 1 × 105 and 1 × 106 CFU/cm2 , there was moderate to good agreement between the ATP bioluminescence assay and the aerobic plate count as determined by the k-statistic. The application of this ATP bioluminescence test to HACCP systems for beef slaughter processes is discussed. 相似文献
11.
María de los Angeles Mosso María del Carmen de la Rosa Carmen Vivar María del Rosario Medina 《Journal of applied microbiology》1994,77(4):370-381
The microbiological quality and heterotrophic bacterial populations of 26 thermal mineral water springs in Spain were studied. In most of the springs the number of viable aerobes was less than 103 cfu ml-1 and the number of sporulated bacteria less than 102 cfu ml-1 . No significant differences were foundin the counts obtained with Plate Count Agar (PCA) and PCA diluted 1 : 10 and incubated at 22°, 37° and 45°C. Total coliforms were found in 14 springs, faecal streptococci in three, spores of sulphite-reducing Clostridium and Pseudomonas aeruginosa in seven. Neither Escherichia coli nor Staphylococcus aureus were found. A total of 665 strains were isolated and 85·4% of these identified; 329 were Gram-positive and 239 were Gram-negative. The genera most prevalent present in the springs were Pseudomonas (in 92.3%), Bacillus (65.4%), Enterobacter, Micrococcus and Staphylococcus (50%), Acinetobacter (42.3%), Arthrobacter (38.4%), Clostridium (27%) and Xanthomonas (23%). Gram-negative bacteria predominated in the mesothermal springs and Gram-positive bacteria in the hyper- and hypothermal springs. The most common Gram-negative rod species isolated were Ps. fluorescens, Ps. aeruginosa, Ps. putida, Ent. agglomerans, Ent. sakazakii, Ac. calcoaceticus and Ent. amnigenus. 相似文献
12.
The production of acid phosphatases (E.C.3.1.3.2, ACPs) by Aspergillus niger N402A is regulated by specific growth rate, as well as phosphate availability and pH, as demonstrated by studies in continuous flow culture. Specific ACP activity was highest when A. niger was grown at pH 6.3 (64±8 U g−1 ) or pH 2.8 (99±11 U g−1 ), at a dilution rate of 0.07 h−1 and phosphate concentrations below 0.46 mM. ACP production was growth correlated for specific growth rates between 0.07 and 0.13 h−1 . Four different ACPs, including two phytases, were produced by A. niger N402A. The ACP and the phytase with maximal activities at pH 5.5 were differentially expressed at different culture pH values, with greater production at low pH. 相似文献
13.
A quantitative PCR-ELISA for the rapid enumeration of bacteria in refrigerated raw milk 总被引:1,自引:0,他引:1
R. Gutiérrez T. García I. González B. Sanz P.E. Hernández & R. Martín 《Journal of applied microbiology》1997,83(4):518-523
We have developed a quantitative PCR-ELISA for the rapid enumeration of bacteria inrefrigerated raw milk using primers designed from conserved regions in the 16S ribosomal RNAgene (rRNA). The designed primers permitted the amplification of a 147 bp DNA fragment froma wide selection of bacteria which may grow in milk at refrigeration temperatures. Amplified PCRproducts generated using a digoxigenin-labelled primer were heat-denatured before beingquantified by an enzyme-linked immunosorbent assay (ELISA). A biotinylated probe immobilizedonto streptavidin-coated microplates was used to capture the digoxigenin-labelled fragments thatwere detected with a peroxidase anti-digoxigenin conjugate. Subsequent enzymic conversion ofsubstrate gave distinct absorbence differences when assaying milk samples containing bacteria inthe range 103 –107 cfu ml−1 . The detection threshold for thePCR-ELISA assay developed in this work is 103 cfu ml−1 . 相似文献
14.
C. SCALICI S. SMALLS S. BLUMBERG D. ENGLISH L. JIMENEZ 《Journal of Rapid Methods and Automation in Microbiology》1998,6(3):199-209
A study was performed to compare the Millipore Digital Total Count System with a standard membrane filtration procedure in enumerating the number of microorganisms present in several types of water samples (e.g., Hot/Cold Deionized, Tap, and RO/Ultra Filtration). Water samples were collected over a 4 month period. Statistical data analysis demonstrated an overall correlation of greater than 82% between the two test methodologies. The linearity of the microbial counts between both test methods was compared by artificially contaminating sterile water samples with Pseudomonas aeruginosa. The linearity of the microbial counts between both methods was found to be greater than 96%. The Millipore Digital Total Count System was found to be comparable to the standard membrane filtration method in determining the number of microorganisms in a water sample. In conclusion, the Millipore Digital Total Count System was able to provide a 24 h enumeration of microorganisms present in a water sample. This rapid enumeration allows for a faster quality evaluation of water samples from an industrial water system that is used in the manufacture of cosmetic/pharmaceutical products. 相似文献
15.
Membrane filtration and epifluorescent microscopy were used for the rapid enumeration of bacteria in rinses of milking equipment. Rinse solution (10 ml) was filtered through a 0.6 µm pore size Nuclepore membrane filter and the bacteria retained stained with acridine orange. The clump count of orange fluorescing bacteria on the membrane correlated well with the corresponding plate count ( r =0.83). The technique is rapid, taking approximately 10 min, and is sufficiently sensitive to detect 1000 bacteria ml rinse (equivalent to 5 × 103 bacteria/m2 of milking equipment surfaces by the method currently in use). 相似文献
16.
SUMMARY. 1. The egg development of the widely distributed European stonefly. Nemoura cinerea Retzius. was investigated in the laboratory. There was a significant relationship between water temperature (T°C) and incubation period (Ydays), expressed by the regression equation: Y = 239 T−0.85 (r2 = 0.85. P<0.001).
2. The number of day-degrees above 0°C required for hatching showed a curvilinear relationship with water temperature, with a minimum requirement around 12°C.
3. Nemoura cinerea shows more variation in the rate of egg development than most other stoneflies. This, in part, explains the wide size range in nymphal populations and the species' extended emergence period. Flexibility in life cycle and asynchrony in egg development enable this species to colonize a wide range of freshwater habitats. 相似文献
2. The number of day-degrees above 0°C required for hatching showed a curvilinear relationship with water temperature, with a minimum requirement around 12°C.
3. Nemoura cinerea shows more variation in the rate of egg development than most other stoneflies. This, in part, explains the wide size range in nymphal populations and the species' extended emergence period. Flexibility in life cycle and asynchrony in egg development enable this species to colonize a wide range of freshwater habitats. 相似文献
17.
Ki-Seok Yoon Yukiko Sakai Natsuki Tsukada Kiyoshi Fujisawa & Hirofumi Nishihara 《FEMS microbiology letters》2009,290(1):114-120
Membrane-bound [NiFe]-hydrogenase from Hydrogenophaga sp. AH-24 was purified to homogeneity. The molecular weight was estimated as 100±10 kDa, consisting of two different subunits (62 and 37 kDa). The optimal pH values for H2 oxidation and evolution were 8.0 and 4.0, respectively, and the activity ratio (H2 oxidation/H2 evolution) was 1.61 × 102 at pH 7.0. The optimal temperature was 75 °C. The enzyme was quite stable under air atmosphere (the half-life of activity was c . 48 h at 4 °C), which should be important to function in the aerobic habitat of the strain. The enzyme showed high thermal stability under anaerobic conditions, which retained full activity for over 5 h at 50 °C. The activity increased up to 2.5-fold during incubation at 50 °C under H2 . Using methylene blue as an electron acceptor, the kinetic constants of the purified membrane-bound homogenase (MBH) were V max =336 U mg−1 , k cat =560 s−1 , and k cat / K m =2.24 × 107 M−1 s−1 . The MBH exhibited prominent electron paramagnetic resonance signals originating from [3Fe–4S]+ and [4Fe–4S]+ clusters. On the other hand, signals originating from Ni of the active center were very weak, as observed in other oxygen-stable hydrogenases from aerobic H2 -oxidizing bacteria. This is the first report of catalytic and biochemical characterization of the respiratory MBH from Hydrogenophaga . 相似文献
18.
G. Koumoundouros †† D. G. Sfakianakis P. Divanach † M. Kentouri † 《Journal of fish biology》2002,60(4):923-932
At four temperatures ( T= 15, 20, 25 and 28° C) swimming performance of Dicentrarchus labrax was significantly correlated with total length (23–43 mm L T ); r2 =0.623–0.829). The relative critical swimming speed ( RU crit = U crit L T −1 ), where U crit is the critical swimming speed, was constant throughout the L T range studied. The significant effect of temperature on the relative critical swimming speed was described binomially: RU crit =−0.0323T2 + 1.578 T −10.588 (r2 =1). The estimated maximum RU crit (8.69 L T s−1 ) was achieved at 24.4° C, and the 90% performance level was estimated between 19.3 and 29.6° C. 相似文献
19.
X. LIU R.K. PHEBUS D.Y.C. FUNG C.L. KASTNER 《Journal of Rapid Methods and Automation in Microbiology》1995,4(2):115-126
Growth of Arcobacter butzleri was evaluated in Brain Heart Infusion broth incubated aerobically, microaerobically, and with OxyraseTM supplementation (anaerobically). At initial concentrations of101 to 103 cells/mL, A. butzleri populations reached 7.5 to 8.0 log CFU/ml in 48h at 37C in OxyraseTM -supplemented broth. The organism quickly declined in the other two systems to undetectable levels during the initial 24h of incubation. Only moderate population levels (ca. 3 log CFU/ml) could be detected in aerobic and microaerobic systems after 56h incubation. Growth of five Arcobacter spp. strains was evaluated at 30C in Brucella-blood broth, modified Cary and Blair Transport Medium, and a biphase cultural system. Strains were inoculated at a level of ca. 103 cells/ml and incubated with and without OxyraseTM supplementation to the system for 36h. Both the Brucella-blood broth and the biphase system supported good growth of the strains, with counts reaching ca. 8 to 9 log CFU/ml. Modified Cary and Blair Transport Medium was the least effective cultural system. OxyraseTM provided slight to moderate stimulation of growth for most strains. 相似文献
20.
Abstract: The excitatory amino acid glutamate was previously shown to stimulate aerobic glycolysis in astrocytes by a mechanism involving its uptake through an Na+ -dependent transporter. Evidence had been provided that Na+ ,K+ -ATPase might be involved in this process. We have now measured the activity of Na+ ,K+ -ATPase in cultured astrocytes, using ouabain-sensitive 86 Rb uptake as an index. l -Glutamate increases glial Na+ ,K+ -ATPase activity in a concentration-dependent manner with an EC50 = 67 µ M . Both l - and d -aspartate, but not d -glutamate, produce a similar response, an observation that is consistent with an uptake-related effect rather than a receptor-mediated one. Under basal conditions, concentration-dependent inhibition of Na+ ,K+ -ATPase activity in astrocytes by ouabain indicates the presence of a single catalytic site with a low affinity for ouabain ( K 0.5 = 113 µ M ), compatible with the presence of an α1 isozyme. On stimulation with glutamate, however, most of the increased activity is inhibited by low concentrations of ouabain ( K 0.5 = 20 n M ), thus revealing a high-affinity site akin to the α2 isozyme. These results suggest that astrocytes possess a glutamate-sensitive isoform of Na+ ,K+ -ATPase that can be mobilized in response to increased neuronal activity. 相似文献