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1.
For the first time, growth curves are shown for the phytopathogen Xylella fastidiosa on traditional growth media such as PW (periwinkle wilt), BCYE (buffered charcoal yeast extract), and on new ones such as GYE (glutamate yeast extract) and PYE (phosphate yeast extract) that were developed in this work. The optimal growth conditions on solid and liquid media as well as their measurements are presented, by using total protein content and turbidity determinations. The results demonstrated that yeast extract provided sufficient nutrients for X. fastidiosa, since the cells grew well on PYE medium. 相似文献
2.
Xylella fastidiosa causes diseases on a growing list of economically important plants. An understanding of how xylellae diseases originated
and evolved is important for disease prevention and management. In this study, we evaluated the phylogenetic relationships
of X. fastidiosa strains from citrus, grapevine, and mulberry through the analyses of random amplified polymorphic DNAs (RAPDs) and conserved
16S rDNA genes. RAPD analysis emphasized the vigorous genome-wide divergence of X. fastidiosa and detected three clonal groups of strains that cause Pierce's disease (PD) of grapevine, citrus variegated chlorosis (CVC),
and mulberry leaf scorch (MLS). Analysis of 16S rDNA sequences also identified the PD and CVC groups, but with a less stable
evolutionary tree. MLS strains were included in the PD group by the 16S rDNA analysis. The Asiatic origins of the major commercial
grape and citrus cultivars suggest the recent evolution of both PD and CVC disease in North and South America, respectively,
since X. fastidiosa is a New World organism. In order to prevent the development of new diseases caused by X. fastidiosa, it is important to understand the diversity of X. fastidiosa strains, how strains of X. fastidiosa select their hosts, and their ecological roles in the native vegetation.
Received: 7 February 2002 / Accepted: 7 March 2002 相似文献
3.
Buffered charcoal–yeast extract medium (BCYE) has been used for isolation of Xylella fastidiosa from citrus ( Citrus sinensis) and coffee ( Coffea arabica) plants affected by citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS). BCYE is composed of ACES (2-[2-amino-2oxoethyl)
amino]-ethanesulfonic acid) buffer, activated charcoal, yeast extract, L-cysteine, ferric pyrophosphate, and agar. ACES buffer
is costly and not always commercially available in Brazil, and the L-cysteine and ferric pyrophosphate need to be filter sterilized
in 0.22-μm pore membranes before inclusion in the medium. Omission of L-cysteine, addition of magnesium sulfate, and replacements
of ACES and ferric pyrophosphate for potassium phosphate and ferrous sulfate resulted in an effective, less expensive, and
entirely autoclavable medium, named phosphate buffered charcoal-yeast extract medium (PCYE). The final cost of PCYE was approximately
one tenth that of BCYE. Its effectiveness was tested for the isolation of X. fastidiosa from symptomatic leaves collected from 52 citrus plants affected by CVC and 43 coffee plants affected by CLS. PCYE was as
effective as BCYE and has been used routinely in our and other laboratories for isolation, growth, and quantification of X. fastidiosa from plant tissues. 相似文献
4.
Nitrite served as an energy-conserving electron acceptor for the acetogenic bacterium Moorella thermoacetica. Growth occurred in an undefined (0.1% yeast extract) medium containing 20 m M glyoxylate and 5 m M nitrite and was essentially equivalent to that observed in the absence of nitrite. In the presence of nitrite, acetate (the
normal product of glyoxylate-derived acetogenesis) was not detected during growth. Instead, growth was coupled to nitrite
dissimilation to ammonium, and acetogenesis was limited to the stationary phase. Furthermore, membranes from glyoxylate-grown
cells under nitrite-dissimilating conditions were deficient in the b-type cytochrome that is typically found in the membranes of acetogenic cells. Unlike glyoxylate, other acetogenic substrates
(fructose, oxalate, glycolate, vanillin, and hydrogen) were not growth supportive in the undefined medium containing nitrite,
and glyoxylate-dependent growth did not occur in a nitrite-supplemented, basal (without yeast extract) medium. Glyoxylate-dependent
growth by Moorella thermoautotrophica was not observed in the undefined medium containing nitrite.
Received: 1 April 2002 / Accepted: 9 July 2002 相似文献
5.
Xylella fastidiosa has been reported as responsible for a devastating disease on olive trees in Apulia region (south‐eastern Italy), characterized by a quick decline syndrome. In Lebanon, the pathogen was recently associated with leaf scorch symptoms on oleander, and reports on leaf scorch and dieback of olive trees branches by technicians and farmers have shown an increasing trend in the main agricultural areas. To assess the occurrence and distribution of the pathogen in Lebanon, samples of twigs from olive trees (82), olive seedlings (26), grapevine (30), oleander (32) and ornamentals imported from Italy (48) were analysed by isolation on four agarized media, serological techniques (ELISA and DTBIA) using Xylella fastidiosa‐specific antibodies and by PCR, using three specific sets of primers. Results unequivocally demonstrated that all the collected samples were free from the pathogen. As well, both detection protocols and attempts at isolating the pathogen on agarized media demonstrated that oleander samples gathered from American University campus in Beirut, where X. fastidiosa was previously reported, were not infected. Nevertheless, continuous monitoring and rigorous control measures of propagative materials are necessary to prevent the introduction of Xylella fastidiosa in Lebanon. 相似文献
7.
The effect of p-nitrophenol (PNP) concentration with or without glucose and yeast extract on the growth and biodegradative capacity of Ralstonia eutropha was examined. The chemical constituents of the culture medium were modeled using a response surface methodology. The experiments
were performed according to the central composite design arrangement considering PNP, glucose and yeast extract as the selected
variables whose influences on the degradation was evaluated (shaking in reciprocal mode, temperature of 30°C, pH 7 and test
time of about 9 h). Quadratic polynomial regression equations were used to quantitatively explain variations between and within
the models (responses: the biodegradation capacity and the biomass formation). The coefficient of determination was high ( R
adjusted2 = 0.9783), indicating the constructed polynomial model for PNP biodegradative capacity explains the variation between the
regressors fairly well. A PNP removal efficiency of 74.5% occurred within 9 h (15 mg/L as the initial concentration of PNP
with use of yeast extract at 0.5 g/L). 相似文献
8.
In this research, ethanol production from carob pod extract (extract) using Zymomonas mobilis with medium optimized by Plackett–Burman (P–B) and response surface methodologies (RSM) was studied. Z. mobilis was recognized as useful for ethanol production from carob pod extract. The effects of initial concentrations of sugar, peptone,
and yeast extract as well as agitation rate (rpm), pH, and culture time in nonhydrolyzed carob pod extract were investigated.
Significantly affecting variables ( P = 0.05) in the model obtained from RSM studies were: weights of bacterial inoculum, initial sugar, peptone, and yeast extract.
Acid hydrolysis was useful to complete conversion of sugars to glucose and fructose. Nonhydrolyzed extract showed higher ethanol
yield and residual sugar compared with hydrolyzed extract. Ethanol produced (g g −1 initial sugar, as the response) was not significantly different ( P = 0.05) when Z. mobilis performance was compared in hydrolyzed and nonhydrolyzed extract. The maximum ethanol of 0.34 ± 0.02 g g −1 initial sugar was obtained at 30°C, initial pH 5.2, and 80 rpm, using concentrations (g per 50 mL culture media) of: inoculum
bacterial dry weight, 0.017; initial sugar, 5.78; peptone, 0.43; yeast extract, 0.43; and culture time of 36 h. 相似文献
9.
Mycelium of Beauveria bassiana can be grown in liquid culture, filtered, and the mycelium dried. After rehydration the mycelium sporulates.
Two carbohydrate sources (sucrose and maltose), and one nitrogen/vitamin source (yeast extract) were tested for mycelium growth
and subsequent conidial production. Maximum mycelium growth (12.31 mg/ml), in liquid culture, was in the sucrose (3.5%)/yeast
extract (3.5%) medium, but mycelium from a maltose (2%)/yeast extract (0.75%) medium produced the maximum of 4.62×10 6 conidia/mg dry mycelium after incubation in moist Petri dishes.
Using the data on mycelium yield (in liquid culture) and conidial production (by dry mycelium) it is calculated that the sucrose
(3.5%)/yeast extract (3.5%) and the maltose (2%)/yeast extract (0.75%) media produce most conidia per media volume (an equivalent
of 3.52–3.72×10 7 conidia/ml).
相似文献
10.
Thermoanaerobacter thermohydrosulfuricus strain YM3 and Clostridium thermocellum strain YM4, obtained originally as a stable coculture, required yeast extract to grow separately. Cell-free broths of T. thermohydrosulfuricus strain YM3 and C. thermocellum strain YM4 monocultures replaced yeast extract in supporting the growth of strains YM4 and YM3, respectively. T. thermohydrosulfuricus strain YM3 produced vitamin B 6, B 12 analog(s), p-aminobenzoic acid and folic acid, which were required by C. thermocellum strain YM4. Likewise, strain YM4 produced niacin-active compound(s), thiamine, and methionine required by strain YM3.
Received: 17 March 1995 / Accepted: 27 March 1995 相似文献
11.
A xylem-limited bacterium resembling Xylella fastidiosa has been shown previously by electron mmcroscopy to be associated with citrus variegated chlorosis (CVC), a new disease of sweet organe tress in Brazil. A bacterium was consistently cultured from plant tissues from CVC twigs of sweet orange trees but not from tissues of healthy trees on several cell-free media known to support the growth of Xylella fastidiosa. Bacterial colonies typical of X. fastidiosa became visible on PW, CS20, and PD2 agar media after 5 and 7–10 days of incubation, respectively. The cells of the CVC bacterium were rod-shaped, 1.4–3 m in length, and 0.2–0.4 m in diameter, with rippled walls. An antiserum against an isolate (8.1.b) of the bacterium gave strong positive reactions to double-antibody-sandwich (DAS), enzyme-linked immunosorbent assay (ELISA) with other cultured isolates from CVC citrus, as well as with several type strains of X. fastidiosa. This result indicates that the CVC bacterium is a strain of X. fastidiosa. ELISA was also highly positive with all leaves tested from CVC-affected shoots. Leaves from symptomless tress reacted negatively. Sweet organe seedlings inoculated with a pure culture of the CVC bacterium supported multiplication of the bacterium, which became systemic with 6 months after inoculation and could be reisolated from the inoculated seedlings. Symptoms characteristic of CVC developed 9 months post inoculation. 相似文献
12.
In this paper, we described the development of a potassium-chloride-based-salt formulation containing low sodium concentrations
(5.0 to 11 mM) to support the growth of Salinispora tropica strain NPS21184 and its production of salinosporamide A (NPI-0052). The sodium present in the media was essentially derived
from the complex nitrogen sources Hy Soy, yeast extract, and peptone used in the media. We demonstrated that good growth rate
and yield of S. tropica strain NPS21184 were detected in both agar and liquid media containing the potassium-chloride-based-salt formulation with
sodium concentration as low as 5.0 mM, significantly less than the critical seawater-growth requirement concentration of 50 mM
sodium for a marine microorganism. We also observed good production of NPI-0052 (176 to 243 mg/l) by S. tropica strain NPS21184 grown in production media containing the potassium chloride-based-salt formulation. The production of deschloro
analog, salinosporamide B (NPI-0047), was significantly lower in the low-sodium-salt-formulation medium than in the high-sodium-salt-formulation
media. We demonstrated that while S. tropica strain NPS21184 is a novel marine actinomycete that requires high salt content for growth, it does not require sodium-chloride-based
seawater-type media for growth and production of NPI-0052. 相似文献
13.
The nutritional conditions supporting growth and maximum dye removal by Aspergillus lentulus have been investigated. Initially a composite media containing yeast extract, glucose and mineral components was used and
the effect of various components on dye removal was studied. For maximum dye removal (≈100%), ≥0.5% (w/v) glucose and ≥0.25%
(w/v) yeast extract were essential. While glucose played an important role in pellet formation, which in turn was important
for dye removal, yeast extract contributed towards higher biomass production. Mineral components (except NH 4NO 3) did not affect dye removal significantly. Next the alternate sources of carbon (molasses, jaggery, starch and sodium acetate)
and nitrogen (peptone, urea, ammonium nitrate, sodium nitrate and ammonium chloride) were tested. Among carbon sources, all
the sources produced almost complete dye removal in 48 h (more than 97% in 24 h), except sodium acetate (64% in 48 h). All
the tested nitrogen sources resulted in >90% dye removal in 48 h. Yeast extract and peptone gave best results with high dye
removal rate (9.8 and 8.1 mg/l/h, respectively). However, among the low cost alternates, urea and NH 4Cl came out to be suitable sources due to the high uptake capacity of the biomass produced coupled with high dye removal rate
in case of NH 4Cl. Therefore, a combination of urea and NH 4Cl was tested, which produced complete dye removal with a high dye removal rate (10 mg/l/h). Finally the modified composite
media containing urea and NH 4Cl as nitrogen sources and glucose as carbon source was utilized for effluent treatment. Results indicated that performance
of modified composite media was at par with composite media for supporting growth of A. lentulus and dye removal from the textile effluent. 相似文献
14.
Xylella fastidiosa is a xylem-limited bacterium that causes citrus variegated chlorosis (CVC), Pierce’s disease of grapevine, and leaf scald
of coffee and plum and many other plant species. This pathogen is vectored by sharpshooter leafhoppers (Hemiptera: Cicadellidae:
Cicadellinae) and resides in the insect foregut. Scanning electron microscopy was used to determine the retention sites of
X. fastidiosa for the most common vector species in Brazilian citrus groves, Acrogonia citrina, Bucephalogonia xanthophis, Dilobopterus costalimai, and Oncometopia facialis. After a 48-h acquisition access period on infected citrus or plum, adult sharpshooters were kept on healthy citrus seedlings
for an incubation period of 2 weeks to allow for bacterial multiplication. Then the vector heads were incubated for 24 h in
a fixative and transferred into a cryoprotector liquid. Bacterial rod cells exhibiting similar X. fastidiosa morphology were found laterally attached to different regions inside the cibarial pump chamber (longitudinal groove, lateral
surface, cibarial diaphragm and apodemal groove) of A. citrina, O. facialis, and D. costalimai, and polarly attached to the precibarium channel of O. facialis. Polymerase chain reactions of vector’s heads were positive for the presence of X. fastidiosa. No X. fastidiosa-like cells were detected in B. xanthophis. A different type of rod-shaped bacterium was found on B. xanthophis cibarium chamber and images suggest that the cibarium wall was degraded/digested by these bacteria. Colonization patterns
of X. fastidiosa in their vectors are fundamental aspects to be explored toward understanding acquisition, adhesion, and transmission mechanisms
for development of X. fastidiosa control strategies. 相似文献
15.
An inexpensive culture medium based on sunflower seed extract (SSE) for production of Leptolegnia chapmanii was developed. Vegetative growth on solid and liquid SSE was compared with two culture media used routinely (peptone, yeast and glucose (PYG) and Emerson YPss). Results indicate that the oomycete is able to grow on SSE medium, producing more zoospores at a faster rate as well as inducing higher mortality rates in Aedes aegypti larvae. 相似文献
16.
The efficacy of brain heart infusion (BHI)-egg albumen agar, yeast extract phosphate agar and several modified peptone glucose agar media was evaluated for isolation of Blastomyces dermatitidis from sputum concomitantly seeded with the yeast form of the pathogen and Candida albicans. Based upon high per cent culture positivity of sputum, improved recovery (CFU/ml) of the seeded inoculum, faster growth rate of B. dermatitidis and low level of contamination, BHI-egg albumen agar, followed by yeast extract phosphate agar are recommended as the media of choice for the isolation of B. dermatitidis from contaminated clinical specimens. 相似文献
17.
Heavy metal tolerance of two marine strains of Yarrowia lipolytica was tested on solid yeast extract peptone dextrose agar plates. Based on minimum inhibitory concentration esteems, it is inferred that the two strains of Y. lipolytica were tolerant to heavy metals such as Pb(II), Cr(III), Zn(II), Cu(II), As(V), and Ni(II) ions. The impact of various heavy metal concentrations on the growth kinetics of Y. lipolytica was likewise assessed. With increased heavy metal concentration, the specific growth rate was reduced with delayed doubling time. Furthermore, biofilm development of both yeasts on the glass surfaces and in microtitre plates was assessed in presence of different heavy metals. In microtitre plates, a short lag phase of biofilm formation was noticed without the addition of heavy metals in yeast nitrogen base liquid media. A lag phase was extended over increasing metal concentrations of media. Heavy metals like Cr(VI), Cd(II), and As(V) are contrastingly influenced on biofilms’ formation of microtitre plates. Other heavy metals did not much influence on biofilms development. Thus, biofilm formation is a strategy of Y. lipolytica under stress of heavy metals has significance in bioremediation process for recovery of heavy metals from contaminated environment. 相似文献
18.
The ability to produce several antibacterial agents greatly increases the chance of producer’s survival. In this study, red-pigmented
Vibrio sp. DSM 14379 and Bacillus sp., both isolated from the same sampling volume from estuarine waters of the Northern Adriatic Sea, were grown in a co-culture.
The antibacterial activity of the red pigment extract was tested on Bacillus sp. in microtiter plates. The MIC 50 for Bacillus sp. was estimated to be around 10 −5 mg/L. The extract prepared form the nonpigmented mutant of Vibrio sp. had no antibacterial effect. The pigment production of Vibrio sp. was studied under different physicochemical conditions. There was no pigment production at high or low temperatures,
high or low salt concentrations in peptone yeast extract (PYE) medium, low glucose concentration in mineral growth medium
or high glucose concentration in PYE medium. This indicates that the red pigment production is a luxurious good that Vibrio sp. makes only under favorable conditions. The Malthusian fitness of Bacillus sp. in a co-culture with Vibrio sp. under optimal environmental conditions dropped from 4.0 to −7.6, which corresponds to three orders of magnitude decrease
in the number of CFU relative to the monoculture. The nonpigmented mutant of Vibrio sp. in a co-culture with Bacillus sp. had a significant antibacterial activity. This result shows that studying antibacterial properties in isolation (i.e.
pigment extract only) may not reveal full antibacterial potential of the bacterial strain. The red pigment is a redundant
antibacterial agent of Vibrio sp. 相似文献
19.
Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen
Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe
improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the
cryptococcal strain. A high CO 2 atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli
are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions
for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted
Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated
with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans.
Published: March 3, 2004 相似文献
20.
In the present work, statistical experimental methodology was used to enhance the production of amidase from Rhodococcus erythropolis MTCC 1526. R.
erythropolis MTCC 1526 was selected through screening of seven strains of Rhodococcus species. The Placket–Burman screening experiments suggested that sorbitol as carbon source, yeast extract and meat peptone
as nitrogen sources, and acetamide as amidase inducer are the most influential media components. The concentrations of these
four media components were optimised using a face-centred design of response surface methodology (RSM). The optimum medium
composition for amidase production was found to contain sorbitol (5 g/L), yeast extract (4 g/L), meat peptone (2.5 g/L), and
acetamide (12.25 mM). Amidase activities before and after optimisation were 157.85 units/g dry cells and 1,086.57 units/g
dry cells, respectively. Thus, use of RSM increased production of amidase from R.
erythropolis MTCC 1526 by 6.88-fold. 相似文献
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