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1.
Mark A. Jackson Selim Erhan Tadeusz J. Poprawski 《Biocontrol Science and Technology》2006,16(1):61-75
Blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus were formulated with 10% lactose/1% bovine serum albumin (BSA) or various compositions of Fantesk™, a starch-oil composite prepared by jet-cooking an aqueous dispersion of starch and oil. Storage stability studies with wet blastospore formulations showed that maximum blastospore survival was achieved during low-temperature storage at -20°C with lactose/BSA formulations or starch-oil formulations supplemented with sucrose, zein protein, and whole milk. Under conditions of wet storage at -20°C, the addition of whole milk to starch-oil formulations significantly improved blastospore stability while the addition of sucrose or zein protein had no effect. In freeze-drying studies, no significant differences were seen in blastospore desiccation tolerance or in stability during storage at either 4 or -20°C when blastospores of P. fumosoroseus were formulated with lactose/BSA or starch-oil formulations with sucrose, zein protein, and whole milk. Freeze-dried blastospore formulations stored at 4°C showed no loss in blastospore viability after 3 months storage and blastospore formulations stored at -20°C showed no loss in viability during the entire 12-month study. For freeze-dried, starch-oil formulations, sucrose was shown to improve blastospore survival during the freeze-drying process. The addition of whole milk to starch-oil formulations significantly improved the stability of freeze-dried blastospores stored at 4°C. Compared to unformulated blastospore suspensions that showed blastospore settling after 30 min, suspensions of blastospores formulated with lactose/BSA or starch-oil composites remained stable for up to 2 h after mixing. 相似文献
2.
AIMS: To test the effects of C : N : P ratio modification of a well-known nutrient medium formulation, the Endo formulation on biofilm formation by Enterobacter cloacae Ecl and Citrobacter freundii Cf1 in both single-species and binary species biofilms. METHODS AND RESULTS: The C : N : P atom : atom ratio of a well-known nutrient medium formulation, the Endo formulation, that has been applied in fermentative biohydrogen studies, was modified to include two different C concentrations, one containing 17.65 g l(-1) and the other 8.84 g l(-1) sucrose, each containing four different C : N : P ratios, two at higher C : N : P ratios (334 : 84 : 16.8 and 334 : 84 : 3) and two at lower C : N : P ratios (334 : 28 : 5.6 and 334 : 28 : 1). Attached cells were enumerated after dislodging the biofilms that had formed on granular activated carbon (GAC). The modified medium containing 17.65 g l(-1) sucrose and having a C : N : P ratio of 334 : 28 : 5.6 resulted in significantly (P < 0.05) higher counts of attached cells for both single-species biofilms at 7.73 log(10) CFU g(-1) GAC and 9.3 log(10)CFU g(-1) GAC for Ent. cloacae Ecl and Cit. freundii Cf1, respectively, and binary species biofilms at 8.2 log(10) CFU g(-1) GAC and 6.34 log(10) CFU g(-1) GAC for Ent. cloacae Ecl and Cit. freundii Cf1, respectively. Scanning electron micrographs showed qualitative evidence that the 334 : 28 : 5.6 ratio encouraged more complex and extensive biofilm growth for both single-species and binary species biofilms. CONCLUSIONS: The differences in the attachment numbers between the different ratios were found not to be a result of the individual actions of the bacterial isolates involved but rather because of the effects of the various C : N : P ratios. The 334 : 28 : 5.6 ratio showed significantly (P < 0.05) higher counts of attached cells for both single-species and binary species biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates that C : N : P ratios should be a key consideration with regard to maximizing biofilm formation in shake flask and fluidized bed bioreactor studies as well as understanding fundamental factors affecting biofilm growth in natural environments. 相似文献
3.
Amino acid sequence of bacterial microbe-associated molecular pattern flg22 is required for virulence 总被引:3,自引:0,他引:3
Naito K Taguchi F Suzuki T Inagaki Y Toyoda K Shiraishi T Ichinose Y 《Molecular plant-microbe interactions : MPMI》2008,21(9):1165-1174
Flagellin proteins derived from Pseudomonas syringae pv. tabaci 6605 and flg22Pa (QRLSTGSRINSAKDDAAGLQIA), one of the microbe-associated molecular patterns (MAMP) in bacterial flagellin, induce cell death and growth inhibition in Arabidopsis thaliana. To examine the importance of aspartic acid (D) at position 43 from the N-terminus of a flagellin in its elicitor activity, D43 was replaced with valine (V) and alanine (A) in P. syringae pv. tabaci flagellin and flg22Pta. The abilities of flagellins from P. syringae pv. tabaci D43V and D43A to induce cell death and growth inhibition were reduced, whereas the abilities of flg22PtaD43V and flg22PtaD43A were abolished. These results indicate that D43 is important for elicitor activity in P. syringae pv. tabaci. When tobacco plants were inoculated with each bacterium by the spray method, both P. syringae pv. tabaci D43V and D43A mutants had remarkably reduced ability to cause disease symptoms. Both mutants had reduced or no swimming and swarming motilities and adhesion ability. In P. syringae pv. tabaci D43V, little flagellin protein was detected and few flagella were observed by electron microscopy. These results indicate that mutant flagella are unstable and that flagellar motility is impaired. Thus, the amino acid residue required for MAMP activity is important for the intrinsic flagellar function. 相似文献
4.
Type VI secretion systems (T6SS) of Gram-negative bacteria form injectisomes that have the potential to translocate effector proteins into eukaryotic host cells. In silico analysis of the genomes in six Pseudomonas syringae pathovars revealed that P. syringae pv. tomato DC3000, pv. tabaci ATCC 11528, pv. tomato T1 and pv. oryzae 1-6 each carry two putative T6SS gene clusters (HSI-I and HSI-II; HSI: Hcp secretion island), whereas pv. phaseolicola 1448A and pv. syringae B728 each carry one. The pv. tomato DC3000 HSI-I and pv. tomato T1 HSI-II possess a highly similar organization and nucleotide sequence, whereas the pv. tomato DC3000, pv. oryzae 1-6 and pv. tabaci 11528 HSI-II are more divergent. Putative effector orthologues vary in number among the strains examined. The Clp-ATPases and IcmF orthologues form distinct phylogenetic groups: the proteins from pv. tomato DC3000, pv. tomato T1, pv. oryzae and pv. tabaci 11528 from HSI-II group together with most orthologues from other fluorescent pseudomonads, whereas those from pv. phaseolicola, pv. syringae, pv. tabaci, pv. tomato T1 and pv. oryzae from HSI-I group closer to the Ralstonia solanacearum and Xanthomonas orthologues. Our analysis suggests multiple independent acquisitions and possible gene attrition/loss of putative T6SS genes by members of P. syringae. 相似文献
5.
PATRIZIA FERRANTE CHRISTOPHER R. CLARKE KERI A. CAVANAUGH RICHARD W. MICHELMORE ROBERTO BUONAURIO BORIS A. VINATZER 《Molecular Plant Pathology》2009,10(6):837-842
To study the role of type III-secreted effectors in the host adaptation of the tobacco ( Nicotiana sp.) pathogen Pseudomonas syringae pv. tabaci , a selection of seven strains was first characterized by multilocus sequence typing (MLST) to determine their phylogenetic affinity. MLST revealed that all strains represented a tight phylogenetic group and that the most closely related strain with a completely sequenced genome was the bean ( Phaseolus vulgaris ) pathogen P. syringae pv. phaseolicola 1448A. Using primers designed to 21 P. syringae pv. phaseolicola 1448A effector genes, it was determined that P. syringae pv. phaseolicola 1448A shared at least 10 effectors with all tested P. syringae pv. tabaci strains. Six of the 11 effectors that failed to amplify from P. syringae pv. tabaci strains were individually expressed in one P. syringae pv. tabaci strain. Although five effectors had no effect on phenotype, growth in planta and disease severity of the transgenic P. syringae pv. tabaci expressing hopQ1-1 Pph1448A were significantly increased in bean, but reduced in tobacco. We conclude that hopQ1-1 has been retained in P. syringae pv. phaseolicola 1448A, as this effector suppresses immunity in bean, whereas hopQ1-1 is missing from P. syringae pv. tabaci strains because it triggers defences in Nicotiana spp. This provides evidence that fine-tuning effector repertoires during host adaptation lead to a concomitant reduction in virulence in non-host species. 相似文献
6.
AIMS: To compare agar plate and real-time PCR methods on enumeration of total anaerobic bacteria, Lactobacillus and Clostridium perfringens in dog faeces. METHODS AND RESULTS: Thirty-two faecal specimens from Labrador retriever dogs were used to compare agar plate and real-time PCR enumeration methods for Lactobacillus, C. perfringens and total anaerobic bacteria. Total anaerobic bacteria, C. perfringens and Lactobacillus of faeces were counted (as CFU g(-1) faeces) for 48-h incubation at 37 degrees C in an anaerobic gas chamber on genus-selective media. Total genomic DNA from samples was extracted by the QIAamp DNA stool mini kit. The quantification of DNA (as DNA copy per gram faeces) by real-time PCR was performed with a LightCycler system with the QuantiTect SYBR green PCR kit for PCR amplification. The results indicated that there was a significant correlation between CFU and DNA copy of Lactobacillus (R2 = 0.78, P < 0.01) and total anaerobic bacteria (R2 = 0.21, P < 0.05); but no correlation was found between CFU and DNA copy of C. perfringens. The regression equations for Lactobacillus and total anaerobic bacteria were log(DNA copy) = 0.83 x log(CFU) + 1.43 and log(DNA copy) = 1.62 x log(CFU) - 6.32 respectively. CONCLUSIONS: The real-time PCR method could be used to enumerate Lactobacillus within 2 days when compared with plating method which requires 5-6 days. SIGNIFICANCE AND IMPACT OF THE STUDY: The real-time PCR method and the primer set for Lactobacillus spp. harboured in the dog intestine can be used for rapid enumeration of lactobacilli and monitoring of the faecal Lactobacillus community. 相似文献
7.
A xyloglucan-specific endo-β-1,4-glucanase inhibitor cDNA, NbXEGIP1 , was amplified from diseased leaves of Nicotiana benthamiana . The sequence was similar to the tomato xyloglucan-specific endo-β-1,4-glucanase inhibitor (XEGIP) and tobacco nectarin IV genes that have been described as binding and inactivating fungal Family 12 xyloglucan-specific endo-β-1,4-glucanases. Expression of NbXEGIP1 was not detected in healthy leaves, but the gene was induced during the later stages of infection by the fungi Colletotrichum destructivum and C. orbiculare . Induction of NbXEGIP1 also occurred during disease development by the bacterium Pseudomonas syringae pv. tabaci and during the hypersensitive response produced by P. syringae pv. tabaci expressing avrPto . A portion of NbXEGIP1 was cloned into a tobacco rattle virus vector for virus-induced gene silencing in N. benthamiana . Silencing NbXEGIP1 did not affect the interactions with either Colletotrichum species but did significantly reduce population levels of P. syringae pv. tabaci in the compatible interaction and P. syringae pv. tabaci expressing avrPto in the incompatible interaction. In the susceptible response to P. syringae pv. tabaci , silencing of NbXEGIP1 also resulted in visibly wilted leaves several hours prior to necrosis, which was not observed in control plants. This was related to a significantly higher level of electrolyte leakage and higher expression of a defensin gene from infected NbXEGIP1 -silenced leaves compared with control leaves. Silencing appeared to be specific as it did not affect expression of a related gene, NbXEGIP2 . NbXEGIP1 may act as an inhibitor of a bacterial enzyme that degrades the xyloglucan–cellulose plant cell-wall network, and degradation of the cell wall results in host membrane disruption and signalling of defence responses. 相似文献
8.
Yang SL Bu DP Wang JQ Hu ZY Li D Wei HY Zhou LY Loor JJ 《Animal : an international journal of animal bioscience》2009,3(11):1562-1569
The objective of this study was to evaluate changes in ruminal microorganisms and fermentation parameters due to dietary supplementation of soybean and linseed oil alone or in combination. Four dietary treatments were tested in a Latin square designed experiment using four primiparous rumen-cannulated dairy cows. Treatments were control (C, 60 : 40 forage to concentrate) or C with 4% soybean oil (S), 4% linseed oil (L) or 2% soybean oil plus 2% linseed oil (SL) in a 4 × 4 Latin square with four periods of 21 days. Forage and concentrate mixtures were fed at 0800 and 2000 h daily. Ruminal fluid was collected every 2 h over a 12-h period on day 19 of each experimental period and pH was measured immediately. Samples were prepared for analyses of concentrations of volatile fatty acids (VFA) by GLC and ammonia. Counts of total and individual bacterial groups (cellulolytic, proteolytic, amylolytic bacteria and total viable bacteria) were performed using the roll-tube technique, and protozoa counts were measured via microscopy in ruminal fluid collected at 0, 4 and 8 h after the morning feeding. Content of ruminal digesta was obtained via the rumen cannula before the morning feeding and used immediately for DNA extraction and quantity of specific bacterial species was obtained using real- time PCR. Ruminal pH did not differ but total VFA (110 v. 105 mmol/l) were lower (P < 0.05) with oil supplementation compared with C. Concentration of ruminal NH3-N (4.4 v. 5.6 mmol/l) was greater (P < 0.05) due to oil compared with C. Compared with C, oil supplementation resulted in lower (P < 0.05) cellulolytic bacteria (3.25 × 108 v. 4.66 × 108 colony-forming units (CFU)/ml) and protozoa (9.04 × 104 v. 12.92 × 104 cell/ml) colony counts. Proteolytic bacteria (7.01 × 108 v. 6.08 × 108 CFU/ml) counts, however, were greater in response to oil compared with C (P < 0.05). Among oil treatments, the amount of Butyrivibrio fibrisolvens, Fibrobacter succinogenes and Ruminococcus flavefaciens in ruminal fluid was substantially lower (P < 0.05) when L was included. Compared to C, the amount of Ruminococcus albus decreased by an average of 40% regardless of oil level or type. Overall, the results indicate that some ruminal microorganisms, except proteolytic bacteria, are highly susceptible to dietary unsaturated fatty acids supplementation, particularly when linolenic acid rich oils were fed. Dietary oil effects on ruminal fermentation parameters seemed associated with the profile of ruminal microorganisms. 相似文献
9.
Campylobacter jejuni is prevalent in poultry, but the effect of combined refrigerated and frozen storage on its survival, conditions relevant to poultry processing and storage, has not been evaluated. Therefore, the effects of refrigeration at 4 degrees C, freezing at -20 degrees C, and a combination of refrigeration and freezing on the survival of C. jejuni in ground chicken and on chicken skin were examined. Samples were enumerated using tryptic soy agar containing sheep's blood and modified cefoperazone charcoal deoxycholate agar. Refrigerated storage alone for 3 to 7 days produced a reduction in cell counts of 0.34 to 0.81 log10 CFU/g in ground chicken and a reduction in cell counts of 0.31 to 0.63 log10 CFU/g on chicken skin. Declines were comparable for each sample type using either plating medium. Frozen storage, alone and with prerefrigeration, produced a reduction in cell counts of 0.56 to 1.57 log10 CFU/g in ground chicken and a reduction in cell counts of 1.38 to 3.39 log10 CFU/g on chicken skin over a 2-week period. The recovery of C. jejuni following freezing was similar on both plating media. The survival following frozen storage was greater in ground chicken than on chicken skin with or without prerefrigeration. Cell counts after freezing were lower on chicken skin samples that had been prerefrigerated for 7 days than in those that had been prerefrigerated for 0, 1, or 3 days. This was not observed for ground chicken samples, possibly due to their composition. C. jejuni survived storage at 4 and -20 degrees C with either sample type. This study indicates that, individually or in combination, refrigeration and freezing are not a substitute for safe handling and proper cooking of poultry. 相似文献
10.
Solid Substrate Formulations of the Mycoherbicide Colletotrichum truncatum for Hemp Sesbania ( Sesbania exaltata ) Control 总被引:1,自引:0,他引:1
Colletotrichum truncatum was grown on kernels of eight different grains for 3 or 4 weeks at room temperature (22-24°C). Fresh preparations of conidia as well as fungus-infested corn and rice suspensions resulted in 100% mortality of hemp sesbania seedlings when sprayed postemergence with a 14 h dew period. Fresh preparations of mycelia and fungus-infested sorghum suspensions resulted in 90 and 65% mortality of hemp sesbania seedlings, respectively. Lower mortality ( ≤15%) occurred with the other ground fungus-infested grain suspensions. Fresh preparations of conidia, fungus-infested corn, rice and sorghum, and mycelia, when applied to soil pre-emergence, resulted in 100, 94, 100, 83 and 71% mortality of hemp sesbania seedlings 14 days after application, respectively. Lower mortality ( ≤23%) occurred with the other ground fungus-infested grain preparations. Freshly-prepared C. truncatum at 6.25, 12.5, 25 and 50 mg fungus-formulated rice cm -2 of soil surface, applied pre-emergence or at the time of planting, killed 97, 100, 100 and 100% of hemp sesbania, respectively. After storage at 22-24°C for 6 to 24 months, the rice formulation caused 67 to 93% mortality after 6 months, 39 to 81% after 12 months, and ≤2% after 24 months, respectively. When C. truncatum was refrigerated at 4-6°C, the rice formulation retained good efficacy through 24 months, and when frozen, for up to 8 years. C. truncatum formulated on rice stored under all the above conditions contained mainly sclerotia at 2.4 x 10 5 sclerotia g -1 . C. truncatum killed hemp sesbania seedlings with a single soil application through 4 plantings on the same soil. These results indicate that rice and possibly corn are excellent solid substrates for the formulation of C. truncatum . This is a simple and effective method for enhancing the activity of C. truncatum against hemp sesbania. 相似文献
11.
It has been demonstrated that for a nonpathogenic, leaf-associated bacterium, effectiveness in the control of bacterial speck of tomato is correlated with the similarity in the nutritional needs of the nonpathogenic bacterium and the pathogen Pseudomonas syringae pv. tomato. This relationship was investigated further in this study by using the pathogen Xanthomonas campestris pv. vesicatoria, the causal agent of bacterial spot of tomato, and a collection of nonpathogenic bacteria isolated from tomato foliage. The effects of inoculation of tomato plants with one of 34 nonpathogenic bacteria prior to inoculation with the pathogen X. campestris pv. vesicatoria were quantified by determining (i) the reduction in disease severity (number of lesions per square centimeter) in greenhouse assays and (ii) the reduction in leaf surface pathogen population size (log(10) of the number of CFU per leaflet) in growth chamber assays. Nutritional similarity between the nonpathogenic bacteria and X. campestris pv. vesicatoria was quantified by using either niche overlap indices (NOI) or relatedness in cluster analyses based upon in vitro utilization of carbon or nitrogen sources reported to be present in tomato tissues or in Biolog GN plates. In contrast to studies with P. syringae pv. tomato, nutritional similarity between the nonpathogenic bacteria and the pathogen X. campestris pv. vesicatoria was not correlated with reductions in disease severity. Nutritional similarity was also not correlated with reductions in pathogen population size. Further, the percentage of reduction in leaf surface pathogen population size was not correlated with the percentage of reduction in disease severity, suggesting that the epiphytic population size of X. campestris pv. vesicatoria is not related to disease severity and that X. campestris pv. vesicatoria exhibits behavior in the phyllosphere prior to lesion formation that is different from that of P. syringae pv. tomato. 相似文献
12.
M E McBride 《Applied and environmental microbiology》1984,48(2):338-341
A comparison has been made of the in-use bacterial load of two bar soaps with and without antibacterials and two liquid soaps in five different locations over a 1-week period. Of the 25 samples taken from each soap, 92 to 96% of samples from bar soaps were culture positive as compared to 8% of those from liquid soaps. Bacterial populations ranged from 0 to 3.8 log CFU per sample for bar soaps and from 0 to 2.0 log CFU per sample for liquid soaps. The mean bacterial populations per sample were 1.96 and 2.47 log CFU for the two bar soaps, and 0.08 and 0.12 log CFU for the two liquid soaps. The difference in bacterial population between bar soaps and liquid soaps was statistically significant (P = 0.005). Staphylococcus aureus was isolated on three occasions from bar soaps but not from liquid soaps. S. aureus was isolated twice from the exterior of the plastic dispensers of liquid soap but not from the soap itself. Gram-negative bacteria were cultured only from soaps containing antibacterials. Bacterial populations on bar soaps were not high compared with bacterial populations on hands, and the flora was continually changing without evidence of a carrier state. 相似文献
13.
M E McBride 《Applied microbiology》1984,48(2):338-341
A comparison has been made of the in-use bacterial load of two bar soaps with and without antibacterials and two liquid soaps in five different locations over a 1-week period. Of the 25 samples taken from each soap, 92 to 96% of samples from bar soaps were culture positive as compared to 8% of those from liquid soaps. Bacterial populations ranged from 0 to 3.8 log CFU per sample for bar soaps and from 0 to 2.0 log CFU per sample for liquid soaps. The mean bacterial populations per sample were 1.96 and 2.47 log CFU for the two bar soaps, and 0.08 and 0.12 log CFU for the two liquid soaps. The difference in bacterial population between bar soaps and liquid soaps was statistically significant (P = 0.005). Staphylococcus aureus was isolated on three occasions from bar soaps but not from liquid soaps. S. aureus was isolated twice from the exterior of the plastic dispensers of liquid soap but not from the soap itself. Gram-negative bacteria were cultured only from soaps containing antibacterials. Bacterial populations on bar soaps were not high compared with bacterial populations on hands, and the flora was continually changing without evidence of a carrier state. 相似文献
14.
Laser photoacoustic detection allows in planta detection of nitric oxide in tobacco following challenge with avirulent and virulent Pseudomonas syringae Pathovars
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We demonstrate the use of laser photoacoustic detection (LPAD) as a highly sensitive method to detect in planta nitric oxide ((*)NO) production from tobacco (Nicotiana tabacum). LPAD calibration against (*)NO gas demonstrated a linear relationship over 2 orders of magnitude with a detection threshold of <20 pmol h(-1) (1 part per billion volume [ppbv]). The specificity of the photoacoustic signal for (*)NO when adding gas or the (*)NO donor, sodium nitroprusside, on injection into plant leaves, was demonstrated by its abolition with O(3) ((*)NO + O(3) --> NO(2) + O(2)). The utility of the LPAD method was shown by examination of a nonhost hypersensitive response and a disease induced by Pseudomonas syringae (P. s.) pv phaseolicola and P. s. pv tabaci in tobacco. (*)NO was detected within 40 min of challenge with P. s. pv phaseolicola, some 5 h before the initiation of visible tissue collapse. The wildfire tobacco pathogen P. s. pv tabaci initiated (*)NO generation at 2 h postinfection. The use of (*)NO donors, the scavenger CPTIO ([4-carboxyphenyl]-4,5-dihydro-4,4,5,5-tetramethyl-3-oxide), and the mammalian nitric oxide synthase inhibitor l-NMMA (N(G)-monomethyl-l-arginine) indicated that (*)NO influenced the kinetics of cell death and resistance to both avirulent and virulent bacteria in tobacco. These observations suggest that (*)NO is integral to the elicitation of cell death associated with these two bacterial pathogens in tobacco. 相似文献
15.
The pathogenicity of Trematophoma lignicola on Amaranthus retroflexus was increased when its conidia were formulated in oilseed rape emulsion. However, this formulation did not reduce the dew period required to allow conidial germination and infection of the host, nor did it protect the conidia from desiccation before the onset of dew. The fungus gave effective control of A. retroflexus plants up to the 4-true-leaf stage. Plants with 5 to 6-true-leaves were infected and their dry weight reduced, but plants with more than 6-true-leaves were unaffected. Plants grown in warm conditions (18-21°C/12-15°C, day/night) were more likely to be successfully controlled than those grown in the cold (10-12°C/7-8°C; day/night). Significant dry weight loss of A. retroflexus plants were achieved at application volumes down to 100 l ha -1 at 5 ×10 6 conidia ml -1 . More effective control was achieved by application of conidia of T. lignicola than mycelial or pycnidial applications. 相似文献
16.
Shimizu R Taguchi F Marutani M Mukaihara T Inagaki Y Toyoda K Shiraishi T Ichinose Y 《Molecular genetics and genomics : MGG》2003,269(1):21-30
To investigate the role of flagella and monomer flagellin in the interaction between Pseudomonas syringae pv. tabaci and plants, non-polar fliC and fliD mutants were produced. The ORFs for fliC and fliD are deleted in the DeltafliC and DeltafliD mutants, respectively. Both mutants lost all flagella and were non-motile. The DeltafliC mutant did not produce flagellin, whereas the DeltafliD mutant, which lacks the HAP2 protein, secreted large amounts of monomer flagellin into the culture medium. Inoculation of non-host tomato leaves with wild-type P. syringae pv. tabaci or the DeltafliD mutant induced a hypersensitive reaction (HR), whereas the DeltafliC mutant propagated and caused characteristic symptom-like changes. In tomato cells in suspension culture, wild-type P. syringae pv. tabaci induced slight, visible HR-like changes. The DeltafliC mutant did not induce HR, but the DeltafliD mutant induced a remarkably strong HR. Expression of the hsr203J gene was rapidly and strongly induced by inoculation with the DeltafliD mutant, compared to inoculation with wild-type P. syringae pv. tabaci. Furthermore, introduction of the fliC gene into the DeltafliC mutant restored motility and HR-inducing ability in tomato. These results, together with our previous study, suggest that the flagellin monomer of pv. tabaci acts as a strong elicitor to induce HR-associated cell death in non-host tomato cells. 相似文献
17.
Survival of cultured cells in the cold : A kinetic study with special reference to the effect of serum in culture media 总被引:1,自引:0,他引:1
The survival at 4 °C of mouse fibroblasts (strain L-929) and rat liver cells (strain JTC-25·P5) was kinetically analysed after they had been pre-incubated at 37 °C in medium with or without supplement of serum. Both the composition of medium used for preincubation at 37 °C and that employed for storage at 4 °C had influence on the survival period.When the cells had been grown at 37 °C in Eagle minimal essential medium (MEM) alone, they rapidly lost their viability at 4 °C from the beginning. However, when grown at 37 °C in MEM supplemented with calf serum, they maintained viability at 4 °C for about 16 days and 8 days for L cells and JTC-25·P5 cells respectively, before the initiation of rapid loss of viability. The presence of macromolecular fraction of calf serum in the medium during preincubation was found to be responsible for the prolongation of survival at 4 °C. 相似文献
18.
Ivić-Kolevska S Miljković-Selimović B Kocić B 《Acta microbiologica et immunologica Hungarica》2012,59(2):185-198
The aim of this study was to determine the survival of Campylobacter jejuni in chicken meat samples at frozen temperatures and given length of incubation and to determine the impact of aerobic bacteria on the survival of C. jejuni. The chicken meat samples were inoculated with C. jejuni NCTC 11351 suspensions and stored in bags at temperatures of -20°C and -70°C. The mean value of C. jejuni from meat samples decreased from 7.52 log10 CFU/g after 30 minutes of incubation at ambient temperature, to 3.87 log10 CFU/g on the eighth week of incubation at -20°C, and to 3.78 log10 CFU/g at incubation at -70°C after the same incubation period. Both freezing temperatures, -20°C and -70°C, decreased the number of campylobacters. The presence of aerobic mesophilic bacteria did not influence the survival of C. jejuni in chicken meet samples. Keeping poultry meat at freezing temperatures is important for the reduction of C. jejuni, which has a strong influence on the prevention of occurrence of campylobacteriosis in humans. 相似文献
19.
Atterbury RJ Dillon E Swift C Connerton PL Frost JA Dodd CE Rees CE Connerton IF 《Applied and environmental microbiology》2005,71(8):4885-4887
Campylobacter jejuni and Campylobacter-specific bacteriophage were enumerated from broiler chicken ceca selected from 90 United Kingdom flocks (n = 205). C. jejuni counts in the presence of bacteriophage (mean log(10) 5.1 CFU/g) were associated with a significant (P < 0.001) reduction compared to samples with Campylobacter alone (mean log(10) 6.9 CFU/g). 相似文献
20.
Zapka CA Campbell EJ Maxwell SL Gerba CP Dolan MJ Arbogast JW Macinga DR 《Applied and environmental microbiology》2011,77(9):2898-2904
Bulk-soap-refillable dispensers are prone to extrinsic bacterial contamination, and recent studies demonstrated that approximately one in four dispensers in public restrooms are contaminated. The purpose of this study was to quantify bacterial hand contamination and transfer after use of contaminated soap under controlled laboratory and in-use conditions in a community setting. Under laboratory conditions using liquid soap experimentally contaminated with 7.51 log(10) CFU/ml of Serratia marcescens, an average of 5.28 log(10) CFU remained on each hand after washing, and 2.23 log(10) CFU was transferred to an agar surface. In an elementary-school-based field study, Gram-negative bacteria on the hands of students and staff increased by 1.42 log(10) CFU per hand (26-fold) after washing with soap from contaminated bulk-soap-refillable dispensers. In contrast, washing with soap from dispensers with sealed refills significantly reduced bacteria on hands by 0.30 log(10) CFU per hand (2-fold). Additionally, the mean number of Gram-negative bacteria transferred to surfaces after washing with soap from dispensers with sealed-soap refills (0.06 log(10) CFU) was significantly lower than the mean number after washing with contaminated bulk-soap-refillable dispensers (0.74 log(10) CFU; P < 0.01). Finally, significantly higher levels of Gram-negative bacteria were recovered from students (2.82 log(10) CFU per hand) than were recovered from staff (2.22 log(10) CFU per hand) after washing with contaminated bulk soap (P < 0.01). These results demonstrate that washing with contaminated soap from bulk-soap-refillable dispensers can increase the number of opportunistic pathogens on the hands and may play a role in the transmission of bacteria in public settings. 相似文献