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1.
Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product
formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached
to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring.
Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including
HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K
M
values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K
cat/K
M
) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to
C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan
synthase 7-DMATS from Aspergillus fumigatus. 相似文献
2.
Lactic acid bacteria (LAB) are possessing ability to synthesize antimicrobial compounds (like bacteriocin) during their growth.
In this regard, novel bacteriocin compound secreting capability of LAB isolated from Tulum Cheese in Turkey was demonstrated.
The synthesized bacteriocin was purified by ammonium sulphate precipitation, dialysis and gel filtration. The molecular weight
(≈3.4 kDa) of obtained bacteriocin was confirmed by SDS-PAGE, which revealed single peptide band. Molecular identification
of LAB strain isolated from Tulum Cheese was conducted using 16S rDNA gene sequencing as Lactococcus lactis ssp. lactis LL171. The amino acid sequences (KKIDTRTGKTMEKTEKKIELSLKNMKTAT) of the bacteriocin from Lactococcus lactis ssp. lactis LL171 was found unique and novel than reported bacteriocins. Further, the bacteriocin was possessed the thermostable property
and active at wide range of pH values from 1 to 11. Thus, bacteriocin reported in this study has the potential applications
property as food preservative agent. 相似文献
3.
Fawzeia H. Elmhalli Katinka Pålsson Jan Örberg Thomas G. T. Jaenson 《Experimental & applied acarology》2009,48(3):251-262
The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A–E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs
at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate
increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results
obtained by methods A, C and E, the LC50 range was 0.035–0.037 mg PMD/cm2 and the LC95 range was 0.095–0.097 mg PMD/cm2 at 4 h of exposure; the LT50 range was 2.1–2.8 h and the LT95 range was 3.9–4.2 h at 0.1 mg PMD/cm2. To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm2) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed
that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic
to nymphs of I. ricinus and may be useful for tick control. 相似文献
4.
M. V. Zaicnikova Yu. Yu. Berestovskaya V. N. Akimov N. A. Kostrikina L. V. Vasilieva 《Microbiology》2011,80(1):101-107
Two novel strains of budding bacteria, Z-0071T and Z-0072, were isolated from dystrophic humified waters formed by xylotrophic fungi in the course of spruce wood degradation.
The cells of both strains are coccoid (0.95–1.80 μm), nonmotile, single or arranged in pairs. The cells have a complex system
of intracellular membranes and are covered with fimbriae and surrounded by a mucous capsule up to 0.3 μm thick. Both strains
are aerobic organoheterotrophic, mesophilic, and acid-tolerant microorganisms that are able to grow under microaerobic conditions.
They utilize N-acetyl-glucosamine, carbohydrates, and lactate as growth substrates. The strains grow in a pH range of 4.0–7.5
with an optimum at 6.0–6.5. The temperature range for growth is 4–30°C, with an optimum at 25–28°C. Strains Z-0071T and Z-0072, inhabitants of dystrophic low-mineral waters, are NaCl-sensitive: the NaCl content in the media above 0.5 g/l
inhibited growth. The main fatty acids of strains Z-0071T and Z-0072 are C16:0, C18:1ω9c, and C18:2ω9c, 12c. The DNA G + C base content is 51.2–51.7 mol %. The sequences of the 16S rRNA gene fragments (1310 bp) of strains Z-0071T and Z-0072 were found to be identical. The obtained sequences showed a 94.3% similarity with the sequences of the type strain
of the most closely related species Singulisphaera acidiphila MOB10≅T. The phenotypic and phylogenetic properties of strains Z-0071T and Z-0072 support classification of these strains within the genus Singulisphaera as a new species Singulisphaera mucilagenosa sp. nov., with the type strain Z-0071T (VKM B-2626). 相似文献
5.
Clare Annabel Bowen-O’Connor John Hubstenberger Cynthia Killough Dawn Marie VanLeeuwen Rolston St. Hilaire 《In vitro cellular & developmental biology. Plant》2007,43(1):40-50
Bigtooth maple (Acer grandidentatum) is a promising ornamental tree that is not widely used in managed landscapes. Tissue culture has not been used successfully
to propagate this taxon. We cultured single- and double-node explants from greenhouse-grown, 2-y old seedlings of bigtooth
maples, which are indigenous to New Mexico, Texas, and Utah, on Murashige–Skoog (MS), Linsmaier–Skoog (LS), Driver–Kuniyuki
Walnut (DKW), and Woody Plant (WPM) tissue culture media. Media affected shoot proliferation (P = 0.0242) but the zone of explant origin (P = 0.7594) did not. After four 30-d subcultures, explants on DKW media and WPM media produced 3.6 and 3.5 shoots per explant,
respectively. Sprouting rates were highest on DKW, making DKW the best overall media for shoot proliferation. Double-node
microshoots were rooted in vitro on DKW containing indole acetic acid (IAA). Microshoots represented six genotypes from three locations within Texas and New
Mexico. Rooting percentage increased up to 15% as IAA concentration increased (P = 0.0040). There was 100% survival of rooted microshoots in vented Phytatrays containing one perlite: one peat moss (v/v). We conclude that DKW can be used to proliferate microshoots, and IAA induces rooting in microshoots of bigtooth maple. 相似文献
6.
Jin Zhou Ju Chu Yong-Hong Wang Si-Liang Zhang Ying-Ping Zhuang Zhong-Yi Yuan 《World journal of microbiology & biotechnology》2008,24(6):789-796
An intracellular S-adenosylmethionine synthetase (SAM-s) was purified from the fermentation broth of Pichia pastoris GS115 by a sequence chromatography column. It was purified to apparent homogeneity by (NH4)2SO4 fractionation (30–60%), anion exchange, hydrophobic interaction, anion exchange and gel filtration chromatography. HPLC showed
the purity of purified SAM-s was 91.2%. The enzyme was purified up to 49.5-fold with a final yield of 20.3%. The molecular
weight of the homogeneous enzyme was 43.6 KDa, as determined by electro-spray ionization mass spectrometry (ESI-MS). Its isoelectric
point was approximately 4.7, indicating an acidic character. The optimum pH and temperature for the enzyme reaction were 8.5
and 35 °C, respectively. The enzyme was stable at pH 7.0–9.0 and was easy to inactivate in acid solution (pH ≤ 5.0). The temperature
stability was up to 45 °C. Metal ions, such as, Mn2+ and K+ at the concentration of 5 mM had a slight activation effect on the enzyme activity and the Mg2+ activated the enzyme significantly. The enzyme activity was strongly inhibited by heavy metal ions (Cu2+ and Ag2+) and EDTA. The purified enzyme from the transformed Pichia pastoris synthesized S-adenosylmethionine (SAM) from ATP and l-methionine in vitro with a K
m of 120 and 330 μM and V
max of 8.1 and 23.2 μmol/mg/min for l-methionine and ATP, respectively. 相似文献
7.
Bei Wu Yun-He Li Jian-Yong Wu Qi-Zhu Chen Xia Huang Yun-Feng Chen Xue-Lin Huang 《Molecular biology reports》2011,38(5):3189-3194
8.
A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum
temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range
of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis.
Received: July 22, 2002 / Accepted: January 21, 2003
Correspondence to:K. Hatai 相似文献
9.
Two experiments were performed to determine how application of the cytokinin benzyladenine (BA) influenced flowering in Doritaenopsis and Phalaenopsis orchid clones. In the first experiment, two vegetative orchid clones growing in 15-cm pots were transferred from a 28°C greenhouse
that inhibited flowering to a 23°C greenhouse for flower induction (day 0). A foliar spray (0.2 L m−2) containing BA at 100, 200, or 400 mg L−1 or 25, 50, or 100 mg L−1 each of BA and gibberellins A4 + A7 (BA+GA) was applied on days 0, 7, and 14. Plants treated with BA alone at 200 or 400 mg L−1 had a visible inflorescence 3–9 days earlier and had a mean of 0.7–3.5 more inflorescences and 3–8 more flowers per plant
than nontreated plants. The application of BA+GA had no effect on inflorescence number and total flower number at the rates
tested. In the second experiment, three orchid clones received a single foliar spray of BA at 200 mg L−1 at six time points relative to time of transfer from 29°C to 23°C (−1, 0, +1, +2, +4, or +6 weeks). A separate group of plants
received a BA application at week 0 but was maintained at 29°C. Inflorescence number was greatest in all three orchid clones
when plants were treated with BA 1 week after the temperature transfer. Plants that were sprayed with BA and maintained at
29°C did not initiate inflorescences. The promotion of flowering by the application of BA suggests that cytokinins at least
partially regulate inflorescence initiation of Doritaenopsis and Phalaenopsis, but its promotion is conditional and BA application cannot completely substitute for an inductive low temperature. 相似文献
10.
Two plant growth promoting rhizobacteria––Sinorhizobium meliloti RMP1 and Pseudomonas aeruginosa GRC2 were studied for integrated nutrient management to obtain improved yield of Brassica juncea. Low concentrations of urea and diammonium phosphate (DAP) stimulated the growth of both S. meliloti RMP1 and P. aeruginosa GRC2. 1 M of urea and 0.35 M of DAP was found lethal for RMP1, while 1.3 M and 0.37 M concentrations of urea and DAP proved to
be toxic for GRC2. Lc50 was observed as 0.49 M of urea and 0.15 M of DAP for RMP1, and 0.66 M urea and 0.18 M of DAP for GRC2. Urea and DAP adaptive variants of RMP1 and GRC2 was isolated. Adaptive bacterial variants had better growth rates at sub-lethal (Lc50) concentrations of urea and DAP as compared to non-adaptive variants. They also retained plant growth promoting attributes
similar to non adaptive variants. GRC2 and RMP1 did not affect the growth of each other and were chemotactically active for DAP, urea as well as root exudates of
B. juncea. Both the isolates colonized well in the rhizosphere of B. juncea, as their populations were recorded ≈5 log10 cfu g−1 after 120 days. Interestingly, the colonization ability was found even better when both strains were co-inoculated, as their
population was recorded in the range of ≈6 log10 cfu g−1 after 120 days. In field trials, application of RMP1 and GRC2 resulted in significant increase in biomass and yield of B. juncea as compared to control. However, yield was better with application of half dose and full dose of recommended fertilizers.
Interestingly, the biomass as well as yield improved further when both isolates were applied together along with half dose
of recommended fertilizers. 相似文献
11.
Runli He Zhijian Chang Zujun Yang Zongying Yuan Haixian Zhan Xiaojun Zhang Jianxia Liu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,118(6):1173-1180
Powdery mildew resistance from Thinopyrum intermedium was introgressed into common wheat (Triticum aestivum L.). Genetic analysis of the F1, F2, F3 and BC1 populations from powdery mildew resistant line CH5025 revealed that resistance was controlled by a single dominant allele.
The gene responsible for powdery mildew resistance was mapped by the linkage analysis of a segregating F2 population. The resistance gene was linked to five co-dominant genomic SSR markers (Xcfd233, Xwmc41, Xbarc11, Xgwm539 and Xwmc175) and their most likely order was Xcfd233–Xwmc41–Pm43–Xbarc11–Xgwm539–Xwmc175 at 2.6, 2.3, 4.2, 3.5 and 7.0 cM, respectively. Using the Chinese Spring nullisomic-tetrasomic and ditelosomic lines, the
polymorphic markers and the resistance gene were assigned to chromosome 2DL. As no powdery mildew resistance gene was previously
assigned to chromosome 2DL, this new resistance gene was designated Pm43. Pm43, together with the identified closely linked markers, could be useful in marker-assisted selection for pyramiding powdery
mildew resistance genes.
Runli He and Zhijian Chang contributed equally to this work. 相似文献
12.
Berbert-Molina MA Prata AM Pessanha LG Silveira MM 《Journal of industrial microbiology & biotechnology》2008,35(11):1397-1404
The kinetic and general growth features of Bacillus thuringiensis var. israelensis were evaluated. Initial glucose concentration (S
0) in fermentation media varied from 10 to 152 g/l. The results afforded to characterize four morphologically and physiologically
well-defined culture phases, independent of S
0 values: Phase I, vegetative growth; Phase II, transition to sporulation; Phase III, sporulation; and Phase IV, spores maturation
and cell lysis. Important process parameters were also determined. The maximum specific growth rates (μ
X,m) were not affected with S
0 up to 75 g/l (1.0–1.1 per hour), but higher glucose concentrations resulted in growth inhibition by substrate, revealed by
a reduction in μ
X,m values. These higher S
0 values led to longer Phases III and IV and delayed sporulation. Similar biomass concentrations (X
m = 15.2–15.9 g/l) were achieved with S
0 over 30.8 g/l, with increasing residual substrate, suggesting a limitation in some other nutrients and the use of glucose
to form other metabolites. In this case, with S
0 from 30.8 to 152 g/l, cell yield (Y
X/S
) decreased from 0.58 to 0.41 g/g. On the other hand, with S
0 = 10 g/l growth was limited by substrate, and Y
X/S
has shown its maximum value (0.83 g/g). 相似文献
13.
Mycobacterium tuberculosis, the causative agent of tuberculosis, has a lipid-rich cell wall that serves as an effective barrier against drugs and toxic
host cell products, which may contribute to the organism’s persistence in a host. M. tuberculosis contains four homologous operons called nice (mce1–4) that encode putative ABC transporters involved in lipid importation across the cell wall. Here, we analyzed the lipid composition
of M. tuberculosis disrupted in the mce2 operon. High resolution mass spectrometric and thin layer chromatographic analyses of the mutant’s cell wall lipid extracts
showed accumulation of SL-1 and SL1278 molecules. Radiographic quantitative analysis and densitometry revealed 2.9, 3.9 and 9.8-fold greater amount of [35S] SL-1 in the mce2 operon mutant compared to the wild type M. tuberculosis during the early/mid logarithmic, late logarithmic and stationary phase of growth in liquid broth, respectively. The amount
of [35S] SL1278 in the mutant also increased progressively over the same growth phases. The expression of the mce2 operon genes in the wild type strain progressively increased from the logarithmic to the stationary phase of bacterial growth
in vitro, which inversely correlated with the proportion of radiolabel incorporation into SL-1 and SL1278 at these phases. Since the mce2 operon is regulated in wild type M. tuberculosis, its cell wall may undergo changes in SL-1 and SL1278 contents during a natural course of infection and this may serve as an important adaptive strategy for M. tuberculosis to maintain persistence in a host. 相似文献
14.
Two oligosaccharides, a heptasaccharide (HS) and an octasaccharide (OS), isolated from Paris polyphylla var. yunnanensis, stimulated the growth and saponin accumulation of Panax ginseng hairy roots at 5–30 mg l−1. HS and OS at 30 mg l−1, fed separately to hairy root cultures at 10 days post-inoculation, increased the root biomass dry weight by more than 70%
to ∼20 g l−1 from 13 g l−1 and the total saponin content of roots by more than 1-fold to ∼3.5% from 1.6% (w/w). The results suggest that the two oligosaccharides
may have plant growth-regulatory activity in plant tissue cultures. 相似文献
15.
Nico Varo Andy J. Green Marta I. Sánchez Cristina Ramo Jesús Gómez Juan A. Amat 《Hydrobiologia》2011,664(1):163-171
Chemical communication may inform about the location of prey, predators, co-specifics, and mate partners in zooplankton. In
this study, we evaluated several life-history traits of the rotifer, Brachionus calyciflorus, exposed to conditioned media by a rotifer predator (Asplanchna brightwelli) and a cladocera competitor (Daphnia similis), quantifying population growth and life-table demography at two algal food levels (2.0 and 0.5 × 106 cells ml−1 of Chlorella pyrenoidosa). At both food levels, B. calyciflorus grown in predator-conditioned media had lower population abundance and slower population growth rate than controls. Conversely,
the competitor-conditioned media treatments produced both higher rotifer population abundance and faster population growth
rate than controls. Life-history parameters varied significantly depending on the presence of predator and competitor-conditioned
media. The Asplanchna-conditioned media significantly decreased gross reproductive rate (GRR): 8–9 offsprings per female; net reproductive rate
(R
0): 6–7 offsprings per female; population growth rate (r): 0.34–0.37 day−1; and increased generation time (T): 5.5–5.6 days. On the other hand, The Daphnia-conditioned media significantly increased the GRR (13–14 offsprings per female); net reproductive rate (8–9 offsprings per
female); population growth rate (0.42–0.43 day−1); and decreased generation time (4.9–5.0 days). However, the effects of food level on the life-history characteristic were
not significant in both treatments. Maximum values of the population abundance and the population growth rate are significantly
influenced by the predator densities and pre-culture time. This study suggests that rotifers use variable life-history strategies
(low reproduction and high survivorship versus high reproduction and low survivorship) based on the presence of predators
and competitors. 相似文献
16.
Park Y Zhang Z Laremore TN Li B Sim JS Im AR Ahn MY Kim YS Linhardt RJ 《Glycoconjugate journal》2008,25(9):863-877
Acharan sulfate content from African giant snail (Achatina fulica) was compared in eggs and snails of different ages. Acharan sulfate was not found in egg. Acharan sulfate disaccharide →4)-α-d-GlcNpAc (1→4)-α-l-IdoAp2S(1→, analyzed by SAX (strong-anion exchange)–HPLC was observed soon after hatching and increases as the snails grow.
Monosaccharide compositional analysis showed that mole % of glucosamine, a major monosaccharide of acharan sulfate, increased
with age while mole % of galactose decreased with age. These results suggest that galactans represent a major energy source
during development, while acharan sulfate appearing immediately after hatching, is essential for the snail growth. The structures
of neutral N-glycans released from eggs by peptide N-glycosidase F (PNGase F), were next elucidated using ESI-MS/MS, MALDI-MS/MS, enzyme digestion, and monosaccharide composition
analysis. Three types of neutral N-glycan structures were observed, truncated (Hex2–4-HexNAc2), high mannose (Hex5–9-HexNAc2), and complex (Hex3-HexNAc2–10) types. None showed core fucosylation. 相似文献
17.
Effect of temperature on the growth of the primary endosymbiont Buchnera aphidicola in the cowpea aphid Aphis craccivora was studied by measuring quantitatively the copy number of 16S rDNA of this endosymbiont. A 1.5 kb segment of eubacterial
16S rDNA amplified by PCR from total DNA of Aphis craccivora was confirmed by RFLP analysis and sequence BLAST as that of Buchnera aphidicola. No secondary endosymbiont was detected in the aphid population studied. The relative levels of Buchnera ratio, quantified by real-time PCR, were higher in old nymphs than in young ones at temperatures between 10–30˚C, and this
age-dependent difference was more pronounced at lower temperatures. Throughout the entire reproductive stage of Aphis craccivora, the relative levels of Buchnera ratio were higher at 10–25˚C than at 30˚C and 35˚C. A close relationship was found between these levels and the net reproductive
rate (R
0
) of aphid, which was suppressed not only at 35˚C but also at 10˚C. The decoupling of Aphis craccivora and Buchnera response at low temperatures suggests that the cowpea aphid was more sensitive to low temperatures, while Buchnera was more sensitive to high temperatures. 相似文献
18.
Pratiksha Bhadauriya Radha Gupta Surendra Singh Prakash Singh Bisen 《World journal of microbiology & biotechnology》2008,24(1):139-141
n-Alkanes pattern in response to NaCl stress has been studied in the cyanobacterium Anabaena cylindrica. Saturated hydrocarbons were separated and identified by gas chromatography-mass spectrometry (GC-MS) using serially coupled
capillary column. Light chain n-alkanes in the range of C9–C17 (43%) and heavy chain n-alkanes in range of C17–C23 (34%) and C23–C31 (23%) were identified as the major components of total hydrocarbons in the NaCl adapted cells of A. cylindrica. In contrast, NaCl-untreated cells of A. cylindrica had dominance of only long chain n-alkanes in the range of C23–C31 comprising about 94% of its total n-alkanes. The persistence of high level (43%) of short chain n-alkanes (C9–C17) in NaCl adapted cells of A. cylindrica as compared to its negligible level (0.2%) in NaCl untreated counterpart clearly indicates that NaCl stress causes the A. cylindrica to shift towards the synthesis of short chain n-alkanes. 相似文献
19.
20.
Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported
from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately
thermophilic mercury resistant bacteria were selected by growth at 62 °C on Luria agar containing HgCl2. Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl2 were 80 μg/ml and 30 μg/ml for these isolates, respectively, compared to 10 μg/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 μg/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium
by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H2S was detected in the headspace of cultures in the absence or presence of Hg2+, and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have
potential for decontamination of solutions containing Hg2+ without production of toxic volatile H2S. 相似文献