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1.
Requirements in terms of water activity (a(w)) for the growth, sporulation, and germination of Clostridium perfringens were determined. Strain A48 was used in all phases, and in addition either NCTC 8239 or NCTC 8797 was used for growth, sporulation, and germination studies. The desired a(w) of the test media was obtained by the addition of one of three solutes: glycerol, sucrose, or sodium chloride. The freezing point depression method was used to determine the a(w). The basal medium for growth and germination was Fluid Thioglycollate Medium. It had an a(w) of 0.995 and produced maximum growth and fastest growth rate among the six levels of a(w) tested. The lowest a(w) supporting growth and germination of C. perfringens was between 0.97 and 0.95 in the test media made with sucrose or sodium chloride and 0.93 or below in the test media adjusted with glycerol. Spore production by C. perfringens in Ellner's or modified medium required a higher a(w) than growth.  相似文献   

2.
Growth and sporulation of Clostridium perfringens type A in Duncan and Strong (DS) sporulation medium was investigated. A biphasic growth response was found to be dependent on starch concentration. Maximal levels of heat-resistant spores were formed at a starch concentration of 0.40%. Addition of glucose, maltose, or maltotriose to a sporulating culture resulted in an immediate turbidity increase, indicating that biphasic growth in DS medium may be due to such starch degradation products. Amylose and, to a lesser extent, amylopectin resulted in biphasic growth when each replaced starch in the sporulation medium. A levels of heat-resistant spores approximately equal to the control was produced with amylopectin but not amylose as the added carbohydrate. Addition of glucose or maltose to a DS medium without starch at stage II or III of sporulation did not alter the level of heat-resistant spores as compared with the level obtained in DS medium with starch. Omission of starch or glucose or maltose resulted in an approximately 100-fold decrease in the number of heat-resistant spores, although the percentage of sporulation (90%) was unaffected. The role of starch and amylopectin in the formation of heat-resistant spores probably involves the amyloytic production of utilizable short-chain glucose polymers that provide an energy source for the completion of sporulation.  相似文献   

3.
Regulation of Aspartokinase Activity in Clostridium perfringens   总被引:2,自引:2,他引:0       下载免费PDF全文
Cells of Clostridium perfringens type D apparently possess only a single species of aspartokinase. This enzyme has been partially purified and shown to be feedback inhibited by meso-diaminopimelate in an allosteric manner. The inhibitor exerts its action noncompetitively with respect to both substrates. The kinetic analysis further indicates that no homotropic cooperative interactions occur between either multiple substrate or inhibitor sites. Like aspartokinases from other bacteria, the clostridial enzyme is stimulated by the presence of either potassium or ammonium cations. A molecular weight of 102,000 was estimated for the enzyme following gel-filtration chromatography. Enzyme activity remains relatively constant throughout the growth cycle of the organism even well into the stationary growth phase. These results are discussed in terms of the role of the enzyme in the growth of the organism.  相似文献   

4.
Effect of Soy Proteins on the Growth of Clostridium perfringens   总被引:3,自引:2,他引:1  
Proteins that are used to fabricate imitation foods such as synthetic meats were evaluated for stimulative or inhibitory effects on the growth of Clostridium perfringens. Growth rate and extent were measured in thioglycolate medium without dextrose. This liquid medium contains Trypticase (BBL) which served as the protein control. For comparison, various soy proteins, synthetic meats, beef, turkey, sodium caseinate, and combinations of each were substituted for Trypticase. Meat loaf systems were also employed to determine the effects of protein additives to meat under actual meat loaf conditions. Growth of C. perfringens type A, strain S40, was measured in the respective media at 45 C at a pH of 7.0 and an E(h) of below -300 mv. Viable populations were enumerated by agar plate techniques on Trypticase-sulfite-yeast-citrate-agar incubated anaerobically (90% N(2)-10% CO(2)) for 18 hr at 35 C. When compared to Trypticase, some soy proteins had stimulative effects on the growth of C. perfringens, whereas sodium caseinate and some soy proteins were inhibitory. In liquid medium in which meat or soy meat was the source of protein, there was a marked stimulation by beef, chicken, and soy beef. Soy chicken supported growth at a rate less than observed with Trypticase. Under actual meat loaf conditions, the addition of soy meat or protein additives to beef did not affect the growth of C. perfringens. The addition of protein additives to turkey meat loaves significantly enhanced the rate of growth of C. perfringens. The stimulative effects of some soy proteins are significant in relation to control of foodborne disease.  相似文献   

5.
Chemically Defined Medium for the Growth of Clostridium perfringens   总被引:8,自引:8,他引:0  
A defined medium which supports growth of Clostridium perfringens at low inoculum levels was developed. Generation time for strain 8797 was 1.5 times greater than previously reported for growth in purged fluid thioglycolate medium.  相似文献   

6.
《Anaerobe》2000,6(4):233-240
The sensitivity of Clostridium perfringens strain 13 to oxygen and its toxic derivatives was investigated in a new, defined medium (MMP). Exponentially growing cells in MMP medium were very sensitive to exposure to air by vigorous shaking. When exposed to air, the cells survived only 1hour and then rapidly died. Addition of cysteine, ascorbic acid, or yeast extract to the medium significantly increased vegetative cell survival without inducing sporulation. The level of toxicity of peroxyl and hydroperoxyl radicals, generated by H2O2, t-butyl hydroperoxide or ethanol, was very similar with and without air exposure. By contrast, plumbagin or menadione, which generate superoxide radicals in the presence of oxygen, caused high levels of cell death only in aerobiosic culture. Growth-arrested cells were more resistant to H2O2and to redox-cycling agents than were exponentially growing cells, but the resistance required de novo synthesis of proteins. An adaptive response to oxidative stress was also suggested by the higher level of cell resistance to H2O2and to ethanol when cells were pretreated with sublethal doses of these oxidants.  相似文献   

7.
U.S. Department of Agriculture regulations require that brick chili be cooled from 48.9 degrees C to 4.4 degrees C within 2 h of cooking, but processors may not always be able to comply. Studies were conducted to evaluate the extent of bacterial multiplication resulting from outgrowth of germinated Clostridium perfringens spores experimentally inoculated into chili and incubated at various temperatures. Inoculated samples were heated (75 degrees C for 20 min) to activate spores, quickly equilibrated, and held at one of five desired temperatures for 6 h. No growth was observed for C. perfringens in samples held at 26.7 degrees C and below for 6 h, but growth was observed by 6 h in samples held at 32.2 degrees C and after 2 h in samples held at temperatures between 37.8 degrees C and 48.9 degrees C. Using isothermal growth data, we developed a simple model for predicting the growth of bacteria with time under exponential cooling conditions. The model predicts both the lag phase and the numbers of bacteria at specific times during the growth phase. It was developed by using isothermal growth data and tested by using temperature-varying growth data from experiments with spores of C. perfringens in chili. Actual data agreed closely with predicted results. The results should be useful for evaluating the hazard potential for growth of C. perfringens in chili.  相似文献   

8.
Two strains of Clostridium perfringens grew in a chemically defined medium consisting of L-tryptophan, L-arginine, L-glutamic acid, L-histidine HCl, L-leucine, DL-threonine, DL-phenylalanine, DL-tryrosine, DL-valine, L-cystine, ascorbic acid, Ca d -pantothenate, pyridoxine, biotin, adenine HCl, glucose, salts and mercaptoacetic acid. Alanine, aspartic acid and methionine were highly stimulatory but not essential for growth. Growth did not occur in the absence of glucose, but other fermentable carbohydrates were not tested. Acetone, isopropyl alcohol, succinic acid, acetic acid, butanol, butyric acid, lactic acid, pyruvic acid, oxaloacetic acid or acetaldehyde did not eliminate the requirement for glucose. Methionine was required for sporulation; one strain also required riboflavin, isoleucine, serine and lysine. Butanol increased the degree of sporulation in a complex thioglycolate medium. Failure of Cl. perfringens to sporulate in inadequately buffered media containing glucose was shown to be caused by the high H-ion concentration developing in the culture medium. In addition, some possible end-products of glucose metabolism such as lactic acid, oxaloacetic acid and acetaldehyde, reduced sporulation in one strain appreciably.  相似文献   

9.
10.
The beta-glucuronidase activity of intact cells of Clostridium perfringens was not influenced by the presence of either 0.09 or 0.19% lactic or butyric acids. In contrast, the enhanced enzyme activity of intact cells due to sodium deoxycholate was significantly decreased by the presence of these acids. These results suggest the possibility that the development of cancer due to the intake of a high fat diet may be inhibited by the presence of organic acids produced by intestinal bacteria.  相似文献   

11.
12.
Growth of Clostridium perfringens in cooked chili during cooling.   总被引:1,自引:1,他引:0       下载免费PDF全文
U.S. Department of Agriculture regulations require that brick chili be cooled from 48.9 degrees C to 4.4 degrees C within 2 h of cooking, but processors may not always be able to comply. Studies were conducted to evaluate the extent of bacterial multiplication resulting from outgrowth of germinated Clostridium perfringens spores experimentally inoculated into chili and incubated at various temperatures. Inoculated samples were heated (75 degrees C for 20 min) to activate spores, quickly equilibrated, and held at one of five desired temperatures for 6 h. No growth was observed for C. perfringens in samples held at 26.7 degrees C and below for 6 h, but growth was observed by 6 h in samples held at 32.2 degrees C and after 2 h in samples held at temperatures between 37.8 degrees C and 48.9 degrees C. Using isothermal growth data, we developed a simple model for predicting the growth of bacteria with time under exponential cooling conditions. The model predicts both the lag phase and the numbers of bacteria at specific times during the growth phase. It was developed by using isothermal growth data and tested by using temperature-varying growth data from experiments with spores of C. perfringens in chili. Actual data agreed closely with predicted results. The results should be useful for evaluating the hazard potential for growth of C. perfringens in chili.  相似文献   

13.
A chemically defined medium was developed that could support sporulation and growth of Clostridium perfringens strains ATCC 12916 and H9. This medium consisted of a modification of the basal medium of Boyd et al. plus 0.1% sodium thioglycolate and 0.5% monosodium glutamate. Five other strains grew, but did not sporulate, in this medium. With the addition of more vatamins into the medium, two more strains grew but did not sporulate. The effects of glucose, monosodium glutamate, ammonium glutamate, and sodium thioglycolate on growth and sporulation of C. perfringens ATCC 12916 in the defined medium was investigated.  相似文献   

14.
A new apparatus was developed for measuring changes in E(h), pH, and cell numbers. With this apparatus, the relationships of these parameters were studied at initial E(h) levels of 200 and 40 mv (pH 7.0), by using Clostridium perfringens and Pseudomonas fluorescens. One of the strains of C. perfringens grew more luxuriantly at the higher E(h), in the presence of small quantities of oxygen, than at the lower one in the absence of oxygen. P. fluorescens could grow at a relatively low E(h) (40 mv, pH 7.0) in pure culture but not in the presence of C. perfringens under the same conditions.  相似文献   

15.
The method by which sodium nitrite may act to prevent germination or outgrowth, or both, of heat-injured spores in canned cured meats was investigated by using Clostridium perfringens spores. Four possible mechanisms were tested: (i) prevention of germination of the heat-injured spores, (ii) prior combination with a component in a complex medium to prevent germination of heat-injured spores, (iii) inhibition of outgrowth of heat-injured spores, and (iv) induction of germination (which would render the spore susceptible to thermal inactivation). Only the third mechanism was effective with the entire spore population when levels of sodium nitrite commercially acceptable in canned cured meats were used. Concentrations of 0.02 and 0.01% prevented outgrowth of heat-sensitive and heat-resistant spores, respectively. Nitrite-induced germination occurred with higher sodium nitrite concentrations.  相似文献   

16.
Clostridium perfringens in the Environment   总被引:4,自引:2,他引:2       下载免费PDF全文
Clostridium perfringens was isolated from samples collected in Puget Sound in the state of Washington and areas considered as possible sources of these organisms to Puget Sound. The distribution of C. perfringens in the total Clostridium population was determined for fish gut contents and sediments collected in highly polluted and less polluted areas, sewage samples, freshwater sediments, and soils. The greatest numbers of C. perfringens were obtained from marine sediments collected near the sewage outfall at West Point. Fewer isolates were made from fish collected from less polluted stations, although the number of C. perfringens remained high in sediments from other Puget Sound stations. The proportion of C. perfringens in the total Clostridium populations varied between 56 and 71% for sewage samples and only 0.4 to 4.1% for freshwater sediments and soil samples. Only 25 C. perfringens isolates out of 137 from fish guts, or 18%, were identifiable serologically and these fell into 12 groups. C. perfringens were fed to fish and the fish were sacrificed after varying lengths of time. The number of C. perfringens increased slightly in the gut during the first 24 h and then the numbers decreased rapidly for the next 120 h.  相似文献   

17.
A mutant toxin (MT) that abolished almost 99% of the hemolytic activity of alpha-toxin was isolated by random polymerase chain reaction (PCR) mutagenesis of the gene for Clostridium perfringens alpha-toxin. In the mutant toxin, the amino acids at Tyr (Y)-62, Thr (T)-74 and Ile (I)-345 were substituted with His, Ile and Met, respectively. Replacement of T-74 with Ile by site-directed mutagenesis resulted in the loss of hemolytic, phospholipase C and sphingomyelinase activities by 1/250-fold of that of the wild-type. The replacement of Y-62 with Ile or I-345 with Met alone did not affect the activities of the toxin. T74I mutant bound to sheep erythrocyte membranes and specifically bound [65Zn]2+ in Tris-buffered saline, in the same manner as the wild-type, and contained 2 mol of zinc ions per mol of protein. These results suggest that the T-74 residue plays a key role in these biological activities of C. perfringens alpha-toxin.  相似文献   

18.
The minimal growth requirements for two strains of Clostridium perfringens were defined, and both synthetic and semisynthetic plating media were developed. Plate counts of the wild-type strains on both of these minimal media were equivalent to those on complex media. A number of auxotrophic mutants of each strain were isolated, and their phenotypes were defined.  相似文献   

19.
While the beta-glucuronidase activity of intact cells of Clostridium perfringens was higher in 0.95% sodium chloride (NaCl) than that in 0, 0.1 or 0.5%, that of Escherichia coli was higher in 0.1% NaCl than that in 0, 0.5 or 0.95% NaCl in 0.1 mol l-1 KH2PO4. However, the enzyme activity of both species of intact cells was higher in buffer containing 16 mEq sodium, 134 mEq potassium and 16 mEq chloride per litre than in that containing 146 mEq sodium, 13 mEq potassium and 146 mEq chloride. These findings suggest that bacterial cells are affected by the presence of NaCl and that the effect of NaCl on the activity of bacterial beta-glucuronidase may differ by location in the large intestine.  相似文献   

20.
The Clostridium perfringens alpha-toxin   总被引:3,自引:0,他引:3  
The gene encoding the alpha-(cpa) is present in all strains of Clostridium perfringens, and the purified alpha-toxin has been shown to be a zinc-containing phospholipase C enzyme, which is preferentially active towards phosphatidylcholine and sphingomyelin. The alpha-toxin is haemolytic as a result if its ability to hydrolyse cell membrane phospholipids and this activity distinguishes it from many other related zinc-metallophospholipases C. Recent studies have shown that the alpha-toxin is the major virulence determinant in cases of gas gangrene, and the toxin might play a role in several other diseases of animals and man as diverse as necrotic enteritis in chickens and Crohn's disease in man. In gas gangrene the toxin appears to have three major roles in the pathogenesis of disease. First, it is able to cause mistrafficking of neutrophils, such that they do not enter infected tissues. Second, the toxin is able to cause vasoconstriction and platelet aggregation which might reduce the blood supply to infected tissues. Finally, the toxin is able to detrimentally modulate host cell metabolism by activating the arachidonic acid cascade and protein kinase C. The molecular structure of the alpha-toxin reveals a two domain protein. The amino-terminal domain contains the phospholipase C active site which contains zinc ions. The carboxyterminal domain is a paralogue of lipid binding domains found in eukaryotes and appears to bind phospholipids in a calcium-dependent manner. Immunisation with the non-toxic carboxyterminal domain induces protection against the alpha-toxin and gas gangrene and this polypeptide might be exploited as a vaccine. Other workers have exploited the entire toxin as the basis of an anti-tumour system.  相似文献   

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