共查询到20条相似文献,搜索用时 15 毫秒
1.
Ingo Schmidt 《Current microbiology》2009,59(2):130-138
The ammonia oxidizers Nitrosomonas europaea and Nitrosomonas eutropha are able to grow chemoorganotrophically under anoxic conditions with pyruvate, lactate, acetate, serine, succinate, α-ketoglutarate,
or fructose as substrate and nitrite as terminal electron acceptor. The growth yield of both bacteria is about 3.5 mg protein
(mmol pyruvate)−1 and the maximum growth rates of N. europaea and N. eutropha are 0.094 d−1 and 0.175 d−1, respectively. In the presence of pyruvate and CO2 about 80% of the incorporated carbon derives from pyruvate and about 20% from CO2. Pyruvate is used as energy and only carbon source in the absence of CO2 (chemoorganoheterotrophic growth). CO2 stimulates the chemoorganotrophic growth of both ammonia oxidizers and the expression of ribulose bisphosphate carboxylase/oxygenase
is down-regulated at increasing CO2 concentration. Ammonium, although required as nitrogen source, is inhibitory for the chemoorganotrophic metabolism of N. europaea and N. eutropha. In the presence of ammonium pyruvate consumption and the expression of the genes aceE, ppc, gltA, odhA, and ppsA (energy conservation) as well as nirK, norB, and nsc (denitrification) are reduced. 相似文献
2.
Mario Esparza Juan Pablo Cárdenas Botho Bowien Eugenia Jedlicki David S Holmes 《BMC microbiology》2010,10(1):229
Background
Acidithiobacillus ferrooxidans is chemolithoautotrophic γ-proteobacterium that thrives at extremely low pH (pH 1-2). Although a substantial amount of information is available regarding CO2 uptake and fixation in a variety of facultative autotrophs, less is known about the processes in obligate autotrophs, especially those living in extremely acidic conditions, prompting the present study. 相似文献3.
To develop an integrated process of CO2-fixation and H2 photoproduction by marine green microalga Platymonas subcordiformis, the impact of algal cells grown in CO2-supplemented air bubble column bioreactor was investigated on H2 photoproduction regulated by carbonylcyanide m-chlorophenylhrazone. Highest cell growth (3.85 × 106 cells ml−1), starch content (0.25 ± 0.08 mg per 106 cells) and hydrogen production (50 ± 3 ml l−1) were achieved at 3% CO2-supplemented culture, which are respectively 1.4, 2.1, 1.5-fold of the air-supplemented culture. Improved H2 production correlated well with the increase in starch accumulation. In this process, the algal cells have been recycled
for stable H2 production of 40–50 ml l−1 over five cycles. 相似文献
4.
Iron–sulfur clusters are one of the most common types of redox center in nature. Three proteins of IscS (a cysteine desulfurase),
IscU (a scaffold protein) and IscA (an iron chaperon) encoded by the operon iscSUA are involved in the iron–sulfur cluster assembly in Acidithiobacillus ferrooxidans. In this study the gene of IscS from A. ferrooxidans ATCC 23270 was cloned and expressed in Escherichia coli, the protein was purified by one-step affinity chromatography to homogeneity. The molecular mass of recombinant IscS was
46 kDa by SDS-PAGE. The IscS was a pyridoxal phosphate-containing protein, that catalyzed the elimination of S from l-cysteine to yield l-alanine and elemental sulfur or H2S, depending on whether or not a reducing agent was added to the reaction mixture.
Jia Zeng and Yanfei Zhang contributed equally to this work. 相似文献
5.
Summary
Lilium Asiatic hybrid ‘Mona’ bulblets were cultured in vitro for 100 d under photoautotrophic (CO2-enriched conditions and without sucrose in the medium) and heterotrophic (non-enriched CO2 conditions and sucrose-supplemented medium) methods and under various levels of photosynthetic photon flux (PPF). Bulblet
growth and net photosynthetic rate (NPR) were analyzed. CO2− and PPF-enriched conditions enhanced the overall growth of bulblets, scale leaves, and roots. Heterotrophic conditions enhanced
bulblet growth but higher PPF levels were inhibitory to the development of scale leaves. These results indicate the CO2− and PPF-enriched conditions (photoautotrophic conditions) are beneficial for the production of high-quality bulblets of Asiatic
hybrid lilies in vitro 相似文献
6.
Lima FL de Carvalho MA Apolônio AC Bemquerer MP Santoro MM Oliveira JS Alviano CS Farias Lde M 《Journal of industrial microbiology & biotechnology》2008,35(2):103-110
Aggregatibacter (Actinobacillus) actinomycetemcomitans P7–20 strain isolated from a periodontally diseased patient has produced a bacteriocin (named as actinomycetemcomitin) that is
active against Peptostreptococcus anaerobius ATCC 27337. Actinomycetemcomitin was produced during exponential and stationary growth phases, and its amount decreased until
it disappeared during the decline growth phase. It was purified by ammonium sulphate precipitation (30–60% saturation), and
further by FPLC (mono-Q ionic exchange and Phenyl Superose hydrophobic interaction) and HPLC (C-18 reversed-phase). This bacteriocin
loses its activity after incubation at a pH below 7.0 or above 8.0, following heating for 30 min at 45°C, and after treatment
with proteolytic enzymes such as trypsin, α-chymotrypsin, and papain. Actinomycetemcomitin has a molecular mass of 20.3 KDa
and it represents a new bacteriocin from A. actinomycetemcomitans. 相似文献
7.
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
8.
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
9.
Sipma J Osuna MB Parshina SN Lettinga G Stams AJ Lens PN 《Applied microbiology and biotechnology》2007,76(2):339-347
Desulfotomaculum carboxydivorans, recently isolated from a full-scale anaerobic wastewater treatment facility, is a sulfate reducer capable of hydrogenogenic
growth on carbon monoxide (CO). In the presence of sulfate, the hydrogen formed is used for sulfate reduction. The organism
grows rapidly at 200 kPa CO, pH 7.0, and 55°C, with a generation time of 100 min, producing nearly equimolar amounts of H2 and CO2 from CO and H2O. The high specific CO conversion rates, exceeding 0.8 mol CO (g protein)−1 h−1, makes this bacterium an interesting candidate for a biological alternative of the currently employed chemical catalytic
water–gas shift reaction to purify synthesis gas (contains mainly H2, CO, and CO2). Furthermore, as D. carboxydivorans is capable of hydrogenotrophic sulfate reduction at partial CO pressures exceeding 100 kPa, it is also a good candidate for
biodesulfurization processes using synthesis gas as electron donor at elevated temperatures, e.g., in biological flue gas
desulfurization. Although high maximal specific sulfate reduction rates (32 mmol (g protein)−1 h−1) can be obtained, its sulfide tolerance is rather low and pH dependent, i.e., maximally 9 and 5 mM sulfide at pH 7.2 and
pH 6.5, respectively. 相似文献
10.
Y. Kitaya L. Xiao A. Masuda T. Ozawa M. Tsuda K. Omasa 《Journal of applied phycology》2008,20(5):737-742
Symbiotic dinoflagellates of the species Amphidinium are expected to be pharmaceutically useful microalgae because they produce antitumor macrolides. A microalgae production
system with a large number of cells at a high density has been developed for the efficient production of macrolide compounds.
In the present study, the effects of culture conditions on the cellular growth rate of dinoflagellates were investigated to
determine the optimum culture conditions for obtaining high yields of microalgae. Amphidinium species was cultured under conditions with six temperature levels (21–35°C), six levels of photosynthetic photon flux density
(15–70 μmol photons m−2 s−1), three levels of CO2 concentration (0.02–0.1%), and three levels of O2 concentration (0.2–21%). The number of cells cultured in a certain volume of solution was monitored microscopically and the
cellular growth rate was expressed as the specific growth rate. The maximum specific growth rate was 0.022 h−1 at a temperature of 26°C and O2 concentration of 5%, and the specific growth rate was saturated at a CO2 concentration of 0.05%, a photosynthetic photon flux density of 35 μmol photons m−2 s−1 and a photoperiod of 12 h day−1 upon increasing each environmental parameter. The results demonstrate that Amphidinium species can multiply efficiently under conditions of relatively low light intensity and low O2 concentration. 相似文献
11.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
12.
Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Salt stress caused a marked decrease in osmotic potential and a significant accumulation of
Na+ and Cl− in leaves of both species. Moderate salinity had a stimulating effect on growth rate, net CO2 assimilation, transpiration and stomatal conductance for the xero-halophytic species. At higher salinities, these physiological
parameters decreased significantly, and their percentages of reduction were higher in A. halimus than in N. retusa whereas, in M. arborea they decreased linearly with salinity. Nitraria retusa PSII photochemistry and carotenoid content were unaffected by salinity, but a reduction in chlorophyll content was observed
at 800 mM NaCl. Similar results were found in A. halimus, but with a decrease in the efficiency of PSII (F′v/F′m) occurred at 800 mM. Conversely, in M. arborea plants we observed a significant reduction in pigment concentrations and chlorophyll fluorescence parameters. The marked
toxic effect of Na+ and/or Cl− observed in M. arborea indicates that salt damage effect could be attributed to ions’ toxicity, and that the reduction in photosynthesis is most
probably due to damages in the photosynthetic apparatus rather than factors affecting stomatal closure. For the two halophyte
species, it appears that there is occurrence of co-limitation of photosynthesis by stomatal and non-stomatal factors. Our
results suggest that both N. retusa and A. halimus show high tolerance to both high salinity and photoinhibition while M. arborea was considered as a slightly salt tolerant species. 相似文献
13.
Four temperature treatments were studied in the climate controlled growth chambers of the Georgia Envirotron: 25/20, 30/25,
35/30, and 40/35 °C during 14/10 h light/dark cycle. For the first growth stage (V3-5), the highest net photosynthetic rate
(P
N) of sweet corn was found for the lowest temperature of 28–34 μmol m−2 s−1 while the P
N for the highest temperature treatment was 50–60 % lower. We detected a gradual decline of about 1 P
N unit per 1 °C increase in temperature. Maximum transpiration rate (E) fluctuated between 0.36 and 0.54 mm h−1 (≈5.0–6.5 mm d−1) for the high temperature treatment and the minimum E fluctuated between 0.25 and 0.36 mm h−1 (≈3.5–5.0 mm d−1) for the low temperature treatment. Cumulative CO2 fixation of the 40/35 °C treatment was 33.7 g m−2 d−1 and it increased by about 50 % as temperature declined. The corresponding water use efficiency (WUE) decreased from 14 to
5 g(CO2) kg−1(H2O) for the lowest and highest temperature treatments, respectively. Three main factors affected WUE, P
N, and E of Zea: the high temperature which reduced P
N, vapor pressure deficit (VPD) that was directly related to E but did not affect P
N, and quasi stem conductance (QC) that was directly related to P
N but did not affect E. As a result, WUE of the 25/20 °C temperature treatment was almost three times larger than that of 40/35 °C temperature treatment. 相似文献
14.
J. A. Bunce 《Photosynthetica》2008,46(4):517-524
Plants differ in how much the response of net photosynthetic rate (P
N) to temperature (T) changes with the T during leaf development, and also in the biochemical basis of such changes in response. The amount of photosynthetic acclimation
to T and the components of the photosynthetic system involved were compared in Arabidopsis thaliana and Brassica oleracea to determine how well A. thaliana might serve as a model organism to study the process of photosynthetic acclimation to T. Responses of single-leaf gas exchange and chlorophyll fluorescence to CO2 concentration measured over the range of 10–35 °C for both species grown at 15, 21, and 27 °C were used to determine the
T dependencies of maximum rates of carboxylation (VCmax), photosynthetic electron transport (Jmax), triose phosphate utilization rate (TPU), and mesophyll conductance to carbon dioxide (g’m). In A. thaliana, the optimum T of P
N at air concentrations of CO2 was unaffected by this range of growth T, and the T dependencies of VCmax, Jmax, and g’m were also unaffected by growth T. There was no evidence of TPU limitation of P
N in this species over the range of measurement conditions. In contrast, the optimum T of P
N increased with growth T in B. oleracea, and the T dependencies of VCmax, Jmax, and g’m, as well as the T at which TPU limited P
N all varied significantly with growth T. Thus B. oleracea had much a larger capacity to acclimate photosynthetically to moderate T than did A. thaliana. 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.
Luis Arigita Ma Jesús Cañal Ricardo Sánchez Tamés Aida González 《In vitro cellular & developmental biology. Plant》2010,46(3):312-322
In traditional in vitro culture, the low CO2 concentration inside the vessels restricts photosynthesis and necessitates the addition of sucrose to the culture medium
as the main energy source, thus bringing about changes in the absorption of mineral elements from the culture medium. In this
study, we investigated macronutrient absorption and sugar consumption in Actinidia deliciosa Chevalier Liang and Ferguson cv. Hayward (kiwi), cultured on medium supplemented with varying amounts of sucrose (0, 10,
and 20 g l−1) under both heterotrophy and autotrophy, flushed with different concentrations of CO2 (non-ventilation, 300, 600, and 2,000 μl l−1). In ventilated systems with 20 g l−1 of sucrose, sucrose absorption was less than under non-ventilation. The lowest rate of sucrose absorption was recorded when
the explants were cultured on medium supplemented with 20 g l−1 of sucrose and flushed with 600 μl l−1 CO2. Absorption of NO3
−, PO4
3−, and Mg2+ were high (maximum) at the end of the culture period (40 d) in explants flushed with 600 μl l−1 CO2 that have been cultured 20 d in the presence of sucrose and then transferred to a sucrose-free medium. These autotrophic
conditions promoted maximum plant growth in terms of both fresh and dry mass as well as the length and number of shoots and
leaves. The study shows that to maintain an optimum regime of mineral nutrition for prolonged culture of kiwi in vitro, an increased amount of these three ions should be supplemented in Murashige and Skoog’s medium. 相似文献
17.
Claudia Ruta Irene Morone-Fortunato 《In vitro cellular & developmental biology. Plant》2010,46(2):172-179
Shoot tips and nodes from a genotype of Cistus clusii were cultured on a medium containing Murashige and Skoog macronutrients, Nitsch and Nitsch micronutrients, sucrose, iron,
thiamine, myoinositol, and agar. This establishment medium, enriched with growth regulators and the biocide substances Plant
Preservative Mixture and Thiabendazole lactate, improved explant survival by 14–16% and reduced contamination late in culture.
For the proliferation stage, the explants rapidly formed axillary buds on a culture medium containing 6-benzylaminopurine
(0.5 mg l−1). The best response for rooting was obtained on a culture medium with a 0.1 mg l−1 indolebutyric acid supplement. Rooted plantlets were acclimatized to greenhouse conditions and then transferred to the field
in order to evaluate their phenotypic homogeneity. Karyotyping showed that the in vitro propagated plantlets have the same chromosome numbers as the mother plants. The success of this work indicates that micropropagation
can be a useful tool for the conservation of C. clusii Dunal, an endangered plant in Italy. 相似文献
18.
We experimentally demonstrate that elevated CO2 can modify herbivory-induced plant chemical responses in terms of both total and individual glucosinolate concentrations.
Overall, herbivory by larvae of diamondback moths (Plutella xylostella) resulted in no change in glucosinolate levels of the annual plant Arabidopsis thaliana under ambient CO2 conditions. However, herbivory induced a significant 28–62% increase in glucosinolate contents at elevated CO2. These inducible chemical responses were both genotype-specific and dependent on the individual glucosinolate considered.
Elevated CO2 can also affect structural defenses such as trichomes and insect-glucosinolate interactions. Insect performance was significantly
influenced by specific glucosinolates, although only under CO2 enrichment. This study can have implications for the evolution of inducible defenses and coevolutionary adaptations between
plants and their associated herbivores in future changing environments. 相似文献
19.
Kate V. Everett Barry A. Chioza Christina Georgoula Ashley Reece R. Mark Gardiner Eddie M. K. Chung 《Human genetics》2009,126(6):819-831
Infantile hypertrophic pyloric stenosis (IHPS) is the most common inherited form of gastrointestinal obstruction in infancy
with a striking male preponderance. Infants present with vomiting due to gastric outlet obstruction caused by hypertrophy
of the smooth muscle of the pylorus. Two loci specific to extended pedigrees displaying autosomal dominant inheritance have
been identified. A genome scan identified loci on chromosomes 11q14–q22 and Xq23–q24 which are predicted to be responsible
for a subset of smaller families with IHPS demonstrating non-Mendelian inheritance. The two linked chromosomal regions both
harbour functional candidate genes which are members of the canonical transient receptor potential (TRPC) family of ion channels.
Both TRPC5 (Xq23–q24) and TRPC6 (11q14–q22) have a potential role in smooth muscle control and hypertrophy. Here, we report suggestive evidence for a third
locus on chromosome 3q12–q25 (Z
max = 2.7, p < 0.004), a region which harbours a third TRPC gene, TRPC1. Fine mapping of all three genes using a tagSNP approach and re-sequencing identified a SNP in the promoter region of TRPC6 and a missense variant in exon 4 of TRPC6 which may be putative causal variants. 相似文献
20.
Thompson LJ Gray VM Kalala B Lindsay D Reynolds K von Holy A 《Biotechnology letters》2008,30(2):271-274
Carrier induced granular particles comprising Enterobacter cloacae and Citrobacter freundii were used to generate H2 from sucrose in an anaerobic fluidized bed bioreactor. At a hydraulic retention time of 4.5 h, 95.8% of the sucrose was consumed
and the rate of H2 production reached 180 mmol H2 l h−1. Biogas composition for H2 and CO2 was 42 and 55%, respectively.
Alex von Holy—Deceased 相似文献