共查询到20条相似文献,搜索用时 31 毫秒
1.
Tengfei Yu Qi Feng Jianhua Si Xiaoyou Zhang Downey Alec Chunyan Zhao 《Journal of Plant Biology》2016,59(6):648-657
Extensive research has found that nighttime transpiration (E n) is positively correlated to the vapour pressure deficit (VPD), that suggested E n was highest during the night under high temperatures and low humidity along with high soil water availability, typically for the riparian forest in the extreme arid region of China. This study used the heat ratio method to measure sap velocity (V s) for mature and saplings Populus euphratica Oliv., and then E n was conservatively calculated as total nocturnal sap flow (F s, the product of V s and sapwood area A s) between 01:00 to 06:00. A gas exchange system was used to measure the leaf transpiration rate (T r) and stomatal conductance (g s) of saplings. For mature trees, nighttime V s was extensive and logarithmic correlated to VPD (similar to daytime). For saplings, g s and T r was extensive in different months, and also a strong logarithmic relationship was found between V s and VPD for both daytime and nighttime periods. Both of stem sap flow and leaf gas exchange suggusted the occurrence of E n, whether mature or sapling trees. E n contribution to daily transpiration (E d) was high just as expected for P. euphratica, which was confirmed by proportional E n to E d (E n/E d) means taken in 2012 (24.99%) and 2013 (34.08%). Compared to mature trees, E n/E d of saplings in 2013 was lower with means of 12.06%, that supported further by the shorter duration times and less T r,n (16.64%) and g s,n (26.45%) of leaf, suggesting that E n magnitude is associated to individual the tree size, that effect to stored water of individual trees, although this hypothesis requires further research. 相似文献
2.
Kim A. Falinski Michael B. Timmons Chatham Callan Charles Laidley 《Journal of applied phycology》2018,30(4):2203-2214
The effects of superficial gas velocity (Ugr), gas entrance velocity (ν), and bubble size on the growth of Tisochrysis lutea was investigated in 600-mL photobioreactors operated with airlift pumps. Superficial gas velocities, calculated from measured air flow rates, ranging from 7 to 93 mm s?1 were created using a 1.6-mm diameter syringe. We tested the effects of sparger velocity over a range of 2.48 to 73.4 m s?1 and the effects of bubble size by using two styles of air stones and an open glass pipette, which created a bubble sizes in the range of 0.5 to 5 mm. We calculated oxygen mass transfer coefficient, kLa, values for all experimental conditions. Cell growth increased linearly with increased superficial gas velocity and decreased with increased sparger velocity. Results indicated that smaller bubble size leads to some initial cell damage, but after time, the increased gas transfer as reflected by the kLa value produced higher growth than larger bubbles. Two mechanisms were observed to correlate with cell damage in T. lutea: increasing velocity at the sparger tip and bubble bursting at the surface. These results demonstrate a method to test sensitivity of T. lutea to aeration, which is important for the design of airlift systems. 相似文献
3.
Rajesh Kondamudi K. N. Swamy Y. Venkateswara Rao T. Vishnu Kiran K. Suman D. Sanjeeva Rao P. Raghuveer Rao D. Subrahmanyam N. Sarla B. Ramana Kumari S. R. Voleti 《Acta Physiologiae Plantarum》2016,38(6):160
Carbon balancing within the plant species is an important feature for climatic adaptability. Photosynthesis and respiration traits are directly linked with carbon balance. These features were studied in 20 wild rice accessions Oryza spp., and cultivars. Wide variation was observed within the wild rice accessions for photosynthetic oxygen evolution or photosynthetic rate (A), dark (R d), and light induced respiration (LIR) rates, as well as stomatal density and number. The mean rate of A varied from 10.49 μmol O2 m?2 s?1 in cultivated species and 13.09 μmol O2 m?2 s?1 in wild spp., The mean R d is 2.09 μmol O2 m?2 s?1 and 2.31 μmol O2 m?2 s?1 in cultivated and wild spp., respectively. Light induced Respiration (LIR) was found to be almost twice in wild rice spp., (16.75 μmol O2 m?2 s?1) compared to cultivated Oryza spp., Among the various parameters, this study reveals LIR and A as the key factors for positive carbon balance. Stomatal contribution towards carbon balance appears to be more dependent on abaxial surface where several number of stomata are situated. Correlation analysis indicates that R d and LIR increase with the increase in A. In this study, O. nivara (CR 100100, CR 100097), O. rufipogon (IR 103404) and O. glumaepatula (IR104387) were identified as potential donors which could be used in rice breeding program. Co-ordination between gas exchange and patchiness in stomatal behaviour appears to be important for carbon balance and environmental adaptation of wild rice accessions, therefore, survival under harsh environment. 相似文献
4.
Shu Zhang Jian Huang Rong Hu Guo Guo Xiaoli Shang Jianwei Wu 《Biotechnology letters》2017,39(8):1219-1227
Objective
To engineer Pichia pastoris for heterologous production of cellulase from Musca domestica and explore its potential for industrial applications.Results
A new beta-glucosidase gene (bg), encoding 562 amino acids, was cloned from M. domestica by using rapid amplification of cDNA ends. The gene bg was linked to pPICZαA and expressed in P. pastoris with a yield of 500 mg l?1. The enzyme has the maximum activity with 27.6 U mg?1 towards cellulose. The beta-glucosidase has stable activity from 20 to 70 °C and can tolerate one-mole glucose. It has the maximum activities for salicin (25.9 ± 1.8 U mg?1), cellobiose (40.1 ± 2.3 U mg?1) and cellulose (27.6 ± 3.5 U mg?1). The wide-range substrate activities of the beta-glucosidase were further verified by matrix-assisted laser desorption/ionization mass spectra. Structural analysis shows that the beta-glucosidase belongs to glycoside hydrolase family Ι and possesses O-glycosylation sites.Conclusions
Thus, a multifunctional beta-glucosidase was expressed from M. domestica and provides a potential tool for industrial application of cellulose.5.
We investigated the effect of riboflavin on the biocontrol activity of Bacillus subtilis Tpb55 against Phytophthora nicotianae (Pn), which causes tobacco black shank. Riboflavin (0.2 mg ml?1) significantly improved the biocontrol activity of Tpb55 (2.0 × 108 cfu ml?1). Riboflavin (0.02–0.5 mg ml?1) alone could not significantly inhibit Pn growth. However, it enhanced the B. subtilis population, both in vitro and in tobacco roots and significantly increased the activity of defense enzymes, peroxidase, catalase, superoxide dismutase, and β-1,3-glucanase, in the roots of B. subtilis-treated tobacco seedlings. Our results indicate that riboflavin can stimulate the growth of B. subtilis Tpb55 and induce resistance to Pn in tobacco plants. These findings should boost the prospects for practical application of B. subtilis Tpb55 as a biocontrol agent against black shank of tobacco. 相似文献
6.
Changling Zhang Haifeng Pan Lingli Yao Wenna Bao Jinxin Wang Zhipeng Xie Jianguo Zhang 《Biotechnology letters》2016,38(8):1301-1306
Objectives
To enhance activity of cis-epoxysuccinate hydrolase from Klebsiella sp. BK-58 for converting cis-epoxysuccinate to tartrate.Results
By semi-saturation mutagenesis, all the mutants of the six important conserved residues almost completely lost activity. Then random mutation by error-prone PCR and high throughput screening were further performed to screen higher activity enzyme. We obtained a positive mutant F10D after screening 6000 mutations. Saturation mutagenesis on residues Phe10 showed that most of mutants exhibited higher activity than the wild-type, and the highest mutant was F10Q with activity of 812 U mg?1 (k cat /K m , 9.8 ± 0.1 mM?1 s?1), which was 230 % higher than that of wild-type enzyme 355 U mg?1 (k cat /K m , 5.3 ± 0.1 mM?1 s?1). However, the thermostability of the mutant F10Q slightly decreased.Conclusions
The catalytic activity of a cis-epoxysuccinate hydrolase was efficient improved by a single mutation F10Q and Phe10 might play an important role in the catalysis.7.
Ravi Padma-Malini Chinniah Rathika Sivanadham Ramgopal Vijayan Murali Pannerselvam Dharmarajan Subramanian Pushkala Karuppiah Balakrishnan 《Biochemical genetics》2018,56(5):489-505
The aim of present study was to elucidate the association of CTLA4 +49 A/G and HLA-DRB1*/DQB1* gene polymorphism in south Indian T1DM patients. The patients and controls (n?=?196 each) were enrolled for CTLA4 and HLA-DRB1*/DQB1* genotyping by RFLP/PCR-SSP methods. The increased frequencies of CTLA4 ‘AG’ (OR?=?1.99; p?=?0.001), ‘GG’ (OR?=?3.94; p?=?0.001) genotypes, and ‘G’ allele (OR?=?2.42; p?=?9.26?×?10?8) were observed in patients. Reduced frequencies of ‘AA’ (OR?=?0.35; p?=?7.19?×?10?7) and ‘A’ (OR?=?0.41; p?=?9.26?×?10?8) in patients revealed protective association. Among HLA-DRB1*/DQB1* alleles, DRB1*04 (OR?=?3.29; p?=?1.0?×?10?5), DRB1*03 (OR?=?2.81; p?=?1.9?×?10?6), DQB1*02:01 (OR?=?2.93; p?=?1.65?×?10?5), DQB1*02:02 (OR?=?3.38; p?=?0.0003), and DQB1*03:02 (OR?=?7.72; p?=?0.0003) were in susceptible association. Decreased frequencies of alleles, DRB1*15 (OR?=?0.32; p?=?2.55?×?10?7), DRB1*10 (OR?=?0.45; p?=?0.002), DQB1*06:01 (OR?=?0.43; p?=?0.0001), and DQB1*05:02 (OR?=?0.28; p?=?2.1?×?10?4) in patients were suggested protective association. The combination of DRB1*03+AG (OR?=?5.21; p?=?1.4?×?10?6), DRB1*04+AG (OR?=?2.14; p?=?0.053), DRB1*04+GG (OR?=?5.21; p?=?0.036), DQB1*02:01+AG (OR?=?4.44; p?=?3.6?×?10?5), DQB1*02:02+AG (OR?=?20.9; p?=?9.5?×?10?4), and DQB1*02:02+GG (OR?=?4.06; p?=?0.036) revealed susceptible association. However, the combination of DRB1*10+AA (OR?=?0.35; p?=?0.003), DRB1*15+AA (OR?=?0.22; p?=?5.3?×?10?7), DQB1*05:01+AA (OR?=?0.45; p?=?0.007), DQB1*05:02+AA (OR?=?0.17; p?=?1.7?×?10?4), DQB1*06:01+AA (OR?=?0.40; p?=?0.002), and DQB1*06:02+AG (OR?=?0.34; p?=?0.001) showed decreased frequency in patients, suggesting protective association. In conclusion, CTLA4/HLA-DR/DQ genotypic combinations revealed strong susceptible/protective association toward T1DM in south India. A female preponderance in disease associations was also documented. 相似文献
8.
Bianca Kreuzinger-Janik Sonja Kruscha Nabil Majdi Walter Traunspurger 《Hydrobiologia》2018,805(1):231-243
To identify the mechanisms whereby substrate embeddedness and water velocity influence Nooksack dace (Rhinichthys cataractae subsp. cataractae) prey capture efficiency, we stocked dace in foraging arenas with varying substrate types over a range of velocities (0, 25, 35 cm s?1) and measured their efficiency of prey capture. We stocked a known number of mayfly (Ephemeroptera), black fly (Simuliidae), and chironomid (Chironomidae) larvae in each foraging arena and measured the number of invertebrates remaining after 12 h. Foraging efficiency for mayflies was significantly reduced over unembedded substrate, and capture efficiency for all taxa decreased at higher velocities in all substrate treatments. Decreased foraging efficiency indicates that higher velocities may degrade the accuracy of prey strikes, that dace may alter their foraging behavior to reduce energy expenditures at higher velocities, that there is less available foraging habitat within their velocity tolerances, or that invertebrates become more interstitial at higher velocities. Although it is difficult to unambiguously discriminate among these mechanisms with our experimental design, our results suggest that dace are adapted to foraging in low-velocity micro-habitats within the boundary layer, and that their foraging efficiency may be sensitive to both the refuging ability of their prey and velocity and turbulence at their focal point. 相似文献
9.
Abelmoschus manihot, an ornamental plant, was examined for phytoremediation purposes in accordance with the ability to accumulate cadmium and physiological mechanisms of cadmium tolerance. A net photosynthetic rate (A N) glasshouse experiment for 60 days was conducted to investigate the influence of different cadmium amounts (0–100 mg kg?1) on the growth, biomass, photosynthetic performance, reactive oxygen species (ROS) production, antioxidative enzyme activities, Cd uptake and accumulation of A. manihot. Exposure to cadmium enhanced plant growth even at 100 mg kg?1, without showing symptoms of visible damage. The cadmium concentration of shoots (stems or leaves) and roots was more than the critical value of 100 mg kg?1 and reached 126.17, 185.26 and 210.24 mg kg?1, respectively. BCF values of A. manihot plants exceeded the reference value 1.0 for all the Cd treatments, and TF values were greater than 1 at 15–60 mg kg?1 Cd treatment. The results also showed that cadmium concentrations of 60 mg kg?1 or less induced a significant enhancement in plant net photosynthetic rate (A N), stomatal conductance (G s), transpiration rate (T r), photosynthetic pigments and F v/F m. These parameters were slightly decreased at the higher concentration (100 mg kg?1). The ROS production (O2 ?, H2O2) and antioxidative response including SOD, CAT and POD were significantly enhanced by increasing cadmium. These results suggest that A. manihot can be considered as a Cd-hyperaccumulator and the hormetic effects may be taken into consideration in remediation of Cd contamination soil. 相似文献
10.
Ya-Jun Wang Bin-Bin Ying Min Chen Wei Shen Zhi-Qiang Liu Yu-Guo Zheng 《World journal of microbiology & biotechnology》2017,33(7):144
A new anti-Prelog short-chain dehydrogenase/reductase (SDR) encoding gene lcsdr was cloned from Lactobacillus composti DSM 18527, and heterologously expressed in Escherichia coli. LcSDR is nicotinamide adenine dinucleotide phosphate (NADPH)-dependent and has a molecular weight of approximately 30 kDa. The optimal pH and temperature were 6.5 and 30?°C, respectively. The maximal reaction rate Vmax was 133.9 U mg?1; the Michaelis–Menten constant K m of LcSDR were 0.345 mM for acetophenone (1a), and 0.085 mM for NADPH. Through introducing an EsGDH-catalyzed NADPH regeneration system, a biocatalytic process for (R)-1-phenylethanol ((R)-1b) was developed with outstanding time–space yield. Under the optimized conditions, 50 g l?1 1a was converted to (R)-1b in 2 h with a yield of 93.8%, enantiomeric excess of product (e.e.p) above 99% and space–time yield of 562.8 g l?1 d?1. 相似文献
11.
The effect of supplementation of reduced glutathione (GSH) to cryoprotectant solution on the generation of reactive oxygen species (ROS) (e.g., H2O2, OH·, and O 2 ·? ) and antioxidants (e.g., SOD, POD, CAT, AsA, and GSH), as well as membrane lipid peroxidation (i.e., MDA content) mitigation in cryopreserving of embryogenic calli (EC) of Agapanthus praecox subsp. orientalis was investigated. The vitrification-based cryopreservation method was used in this study. The addition of GSH at a final concentration of 0.08 mM to the cryoprotectant solution has significantly improved cryotolerance of A. praecox EC. The EC post-thaw survival rate increased by 68.34 % using the cryoprotectant solution containing 0.08 mM GSH as compared to the control (GSH-free). EC treated with GSH displayed the reduction in OH· generation activity and the contents of H2O2 and MDA, as well as enhancement in the inhibition of O 2 ·? generation and the antioxidant activity. Treatment with exogenous GSH also increased endogenous AsA and GSH contents after dehydration step. Expression of stress-responsive genes, e.g., peroxidase (POD), peroxiredoxin, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and glutathione peroxidase (GPX), was also increased during cryopreservation processes. The expression of DAD1 (Defender against apoptotic cell death) was elevated, while cell death-related protease SBT was suppressed. These results demonstrated that the addition of GSH to cryoprotectant solution affects the ROS level and could effectively improve survival of A. praecox EC through enhancing antioxidant enzyme activities and decreasing cell death. 相似文献
12.
Anisa Mitra Pratap Kumar Mukhopadhyay Sumit Homechaudhuri 《Proceedings of the Zoological Society》2018,71(4):403-414
Five isocaloric (430 kcal 100 g?1), isonitrogenous (40% CP) experimental diets were formulated with different concentrations of Bacillus licheniformis fb11 probionts (isolated from the gut of Chitala chitala) viz. Control (without probionts), 5 × 104 CFU g?1 (D1), 5 × 105 CFU g?1 (D2), 5 × 106 CFU g?1 (D3), 5 × 107 CFU g?1 (D4), 5 × 108 CFU g?1 (D5) to evaluate its efficiency in C. chitala juvenile. The best growth performance, feed utilisation, specific α-amylase, total protease and lipase activity were observed with the diet D3 (P < 0.05). The lowest Presumptive Pseudomonas Count, Motile Aeromonad Count, Total Coliform Count was observed for D3 (P < 0.05) on 90th day of trial. Two uppermost values were achieved in case of crude protein for D3 and D2 (P > 0.05). The highest lipid content (12.12 ± 0.4 g 100 g?1) was found for D5 (P < 0.05). The highest gross energy (18.75 ± 0.21 MJ 100 g?1) of carcass was recorded for D3. Thus B. licheniformis fb11 at the concentration 5 × 106 CFU g?1 as probiotic supplement promoted growth, digestion in C. chitala juvenile significantly by modulating intestinal microflora. 相似文献
13.
Takavar Mohammadian Mojtaba Alishahi Mohammad Reza Tabandeh Masoud Ghorbanpoor Dariush Gharibi 《Probiotics and antimicrobial proteins》2018,10(4):616-628
In this study, the effects of orally administrated two native probiotics (Lactobacillus plantarum and Lactobacillus delbrueckii ssp. bulguricus), isolated from the intestine of Shabot fish, Tor grypus, on some immune response parameters and immune-related genes expression against Aeromonas hydrophila in T. grypus were evaluated. Four hundred and eighty juveniles weighing 45?±?10 g were randomly divided into four groups (with three replications) and fed with the experimental diet containing 5?×?107 cfu g?1 of L. plantarum (G1), Lactobacillus bulgaricus (G2), Lactobacillus casei (G3), and a control diet (without probiotics) for 60 continuous days. At the end of the dietary treatments, fish were challenged with a lethal concentration of A. hydrophila (5?×?108 CFU ml?1) via intra peritoneal (i.p) injection. Blood and head kidney samples were taken from six fish in each treatment before challenging and 6, 12, 24, and 48 h and also 7 days after injection. The results showed that lysozyme, complement, bactericidal, and NBT activity of probiotic-treated groups were significantly elevated (P?<?0.05). The IL-8, IL-1β, and TNF-α gene expressions were significantly higher in all probiotic-treated groups (P?<?0.05). Meanwhile, a high direct correlation was observed between serum immune parameters and expression of immune-related genes (P?<?0.0001); furthermore, the highest correlation (R 2?=?0.634, P?<?0.0001) was recorded between IL-1β expression and NBT activity. It can be concluded that not only two native probiotics strains stimulate serum immune responses parameters and immune-related gene expression in T. grypus, but also a high correlation was seen among these indices. The study suggests that gastrointestinal colonization is preferred for host specificity as the strain previously derived from shabot fish displayed better colonization than the non-indigenous bacteria strain such as L. casei. Therefore, these native probiotics bacteria can be accounted as suitable candidates to immune stimulation in fish. 相似文献
14.
Cate Macinnis-Ng Sarah Wyse Andrew Veale Luitgard Schwendenmann Mike Clearwater 《Trees - Structure and Function》2016,30(1):19-33
Key message
Analysis of sap flux density during drought suggests that the large sapwood and rooting volumes of larger trees provide a buffer against drying soil.Abstract
The southern conifer Agathis australis is amongst the largest and longest-lived trees in the world. We measured sap flux densities (F d) in kauri trees with a DBH range of 20–176 cm to explore differences in responses of trees of different sizes to seasonal conditions and summer drought. F d was consistently higher in larger trees than smaller trees. Peak F d was 20 and 8 g m?2 s?1 for trees of diameters of 176 and 20 cm, respectively, during the wet summer. Multiple regression analysis revealed photosynthetically active radiation (PAR) and vapour pressure deficit (D) were the main drivers of F d. During drought, larger trees were more responsive to D whilst smaller trees were more responsive to soil drying. Our largest tree had a sapwood area of 3,600 cm2. Preliminary analysis suggests stem water storage provides a buffer against drying soil in larger trees. Furthermore, F d of smaller trees had higher R 2 values for soil moisture at 30 and 60 cm depth than soil moisture at 10 cm depth (R 2 = 0.68–0.97 and 0.55–0.67, respectively) suggesting that deeper soil moisture is more important for these trees. Larger trees did not show a relationship between F d and soil moisture, suggesting they were accessing soil water deeper than 60 cm. These results suggest that larger trees may be better prepared for increasing frequency and intensity of summer droughts due to deeper roots and/or larger stem water storage capacity.15.
Lixia Yang Liangzhen Jiang Wei Li Yun Yang Guolin Zhang Yinggang Luo 《Journal of industrial microbiology & biotechnology》2017,44(10):1431-1441
Geranyl diphosphate (GPP), the unique precursor for all monoterpenoids, is biosynthesized from isopentenyl diphosphate and dimethylallyl diphosphate via the head-to-tail condensation reaction catalyzed by GPP synthase (GPPS). Herein a homomeric GPPS from Camptotheca acuminata, a camptothecin-producing plant, was obtained from 5′- and 3′-rapid amplification of cDNA ends and subsequent overlap extension and convenient PCR amplifications. The truncate CaGPPS was introduced to replace ispA of pBbA5c-MevT(CO)-MBIS(CO, ispA), a de novo biosynthetic construct for farnesyl diphosphate generation, and overexpressed in Escherichia coli, together with the truncate geraniol synthase-encoding gene from C. acuminata (tCaGES), to confirm CaGPPS-catalyzed reaction in vivo. A 24.0 ± 1.3 mg L?1 of geraniol was produced in the recombinant E. coli. The production of GPP was also validated by the direct UPLC-HRMSE analyses. The tCaGPPS and tCaGES genes with different copy numbers were introduced into E. coli to balance their catalytic potential for high-yield geraniol production. A 1.6-fold increase of geraniol production was obtained when four copies of tCaGPPS and one copy of tCaGES were introduced into E. coli. The following fermentation conditions optimization, including removal of organic layers and addition of new n-decane, led to a 74.6 ± 6.5 mg L?1 of geraniol production. The present study suggested that the gene copy number optimization, i.e., the ratio of tCaGPPS and tCaGES, plays an important role in geraniol production in the recombinant E. coli. The removal and addition of organic solvent are very useful for sustainable high-yield production of geraniol in the recombinant E. coli in view of that the solubility of geraniol is limited in the fermentation broth and/or n-decane. 相似文献
16.
Claudio M. P. Pereira Camila F. P. Nunes Leonardo Zambotti-Villela Nivia M. Streit Daiane Dias Ernani Pinto Carolina B. Gomes Pio Colepicolo 《Journal of applied phycology》2017,29(2):751-757
This study reports for the first time the extraction and quantification of sterols in six species of brown macroalgae from Antarctica: Adenocystis utricularis, Ascoseira mirabilis, Cystosphaera jacquinotii, Desmarestia anceps, Desmarestia antarctica, and Himantothallus grandifolius. Ultrasound irradiation was used as a promotor to extract sterols from algal biomass. The extracts were analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for sterol quantization (ergosterol, brassicasterol, fucosterol, β-sitosterol, campesterol, cholesterol, and stigmasterol). In general, fucosterol was the most abundant (6.60 to 48.13 mg kg?1), followed by β-sitosterol (5.29 to 16.49 mg kg?1), stigmasterol (2.69 to 14.84 mg kg?1) in five of the six examined algae. The sterol campesterol was found in lower concentrations (0.07 to 0.15 mg kg?1) in all studied samples. 相似文献
17.
Single cells of five different Microcystis species (M. ichthyoblabe, M. viridis, M. flos-aquae, M. wesenbergii, and M. aeruginosa) were batch-cultured at different temperatures and light intensities: (a) 25 °C and 50 μmol photons m?2 s?1 (control culture); (b) 25 °C and 10 μmol photons m?2 s?1; and (c) 15 °C and 50 μmol photons m?2 s?1. The extracellular polysaccharide content was significantly higher in treatments b and c than in the control treatment. All Microcystis species existed as single cells under the control treatment but formed colonies in treatments b and c. All of the colonies were irregular with indistinct margins. M. ichthyoblabe, M. viridis, M. flos-aquae, and M. wesenbergii formed colonies with similar morphologies and their cells were loosely aggregated. In contrast, M. aeruginosa formed denser colonies with no distinct holes. The colony morphologies differed from the classic morphology of M. ichthyoblabe field-grown colonies but resembled that of small colonies found in Lake Taihu (Yangtze Delta Plain, China) during early spring. This indicates that field- and laboratory-grown colonies are governed by similar formation processes. We suggest that in laboratory and field environments, M. ichthyoblabe (or M. flos-aquae) colonies are representative of small colonies formed from single Microcystis cells, whereas the morphology of older colonies evolves to resemble M. wesenbergii and M. aeruginosa colonies. 相似文献
18.
Paolo Ascenzi Diego Sbardella Federica Sinibaldi Roberto Santucci Massimo Coletta 《Journal of biological inorganic chemistry》2016,21(3):421-432
Horse heart carboxymethylated cytc (CM-cytc) displays myoglobin-like properties. Here, the effect of cardiolipin (CL) liposomes on the nitrite reductase activity of ferrous CM-cytc [CM-cytc-Fe(II)], in the presence of sodium dithionite, is reported between pH 5.5 and 7.6, at 20.0 °C. Cytc-Fe(II) displays a very low value of the apparent second-order rate constant for the NO2 ?-mediated conversion of cytc-Fe(II) to cytc-Fe(II)-NO [k on = (7.3 ± 0.7) × 10?2 M?1 s?1; at pH 7.4], whereas the value of k on for NO2 ? reduction by CM-cytc-Fe(II) is 1.1 ± 0.2 M?1 s?1 (at pH 7.4). CL facilitates the NO2 ?-mediated nitrosylation of CM-cytc-Fe(II) in a dose-dependent manner, the value of k on for the NO2 ?-mediated conversion of CL–CM-cytc-Fe(II) to CL–CM-cytc-Fe(II)-NO (5.6 ± 0.6 M?1 s?1; at pH 7.4) being slightly higher than that for the NO2 ?-mediated conversion of CL–cytc-Fe(II) to CL–cytc-Fe(II)-NO (2.6 ± 0.3 M?1 s?1; at pH 7.4). The apparent affinity of CL for CM-cytc-Fe(II) is essentially pH independent, the average value of B being (1.3 ± 0.3) × 10?6 M. In the absence and presence of CL liposomes, the nitrite reductase activity of CM-cytc-Fe(II) increases linearly on lowering pH and the values of the slope of the linear fittings of Log k on versus pH are ?1.05 ± 0.07 and ?1.03 ± 0.03, respectively, reflecting the involvement of one proton for the formation of the transient ferric form, NO, and OH?. These results indicate that Met80 carboxymethylation and CL binding cooperate in the stabilization of the highly reactive heme-Fe atom of CL–CM-cytc. 相似文献
19.
Ho-Sang Lee Z-Hun Kim Hanwool Park Choul-Gyun Lee 《Bioprocess and biosystems engineering》2016,39(5):815-823
Lumostatic operation was applied for efficient astaxanthin production in autotrophic Haematococcus lacustris cultures using 0.4-L bubble column photobioreactors. The lumostatic operation in this study was performed with three different specific light uptake rates (q e) based on cell concentration, cell projection area, and fresh weight as one-, two- and three-dimensional characteristics values, respectively. The q e value from the cell concentration (q e1D) obtained was 13.5 × 10?8 μE cell?1 s?1, and the maximum astaxanthin concentration was increased to 150 % compared to that of a control with constant light intensity. The other optimum q e values by cell projection area (q e2D) and fresh weight (q e3D) were determined to be 195 μE m?2 s?1 and 10.5 μE g?1 s?1 for astaxanthin production, respectively. The maximum astaxanthin production from the lumostatic cultures using the parameters controlled by cell projection area (2D) and fresh weight (3D) also increased by 36 and 22 % over that of the controls, respectively. When comparing the optimal q e values among the three different types, the lumostatic cultures using q e based on fresh weight showed the highest astaxanthin productivity (22.8 mg L?1 day?1), which was a higher level than previously reported. The lumostatic operations reported here demonstrated that more efficient and effective astaxanthin production was obtained by H. lacustris than providing a constant light intensity, regardless of which parameter is used to calculate the specific light uptake rate. 相似文献
20.
Seung-Hye Hong Ho-Phuong-Thuy Ngo Lin-Woo Kang Deok-Kun Oh 《Biotechnology letters》2015,37(4):849-856
A recombinant alcohol dehydrogenase (ADH) from Kangiella koreensis was purified as a 40 kDa dimer with a specific activity of 21.3 nmol min?1 mg?1, a K m of 1.8 μM, and a k cat of 1.7 min?1 for all-trans-retinal using NADH as cofactor. The enzyme showed activity for all-trans-retinol using NAD + as a cofactor. The reaction conditions for all-trans-retinol production were optimal at pH 6.5 and 60 °C, 2 g enzyme l?1, and 2,200 mg all-trans-retinal l?1 in the presence of 5 % (v/v) methanol, 1 % (w/v) hydroquinone, and 10 mM NADH. Under optimized conditions, the ADH produced 600 mg all-trans-retinol l?1 after 3 h, with a conversion yield of 27.3 % (w/w) and a productivity of 200 mg l?1 h?1. This is the first report of the characterization of a bacterial ADH for all-trans-retinal and the biotechnological production of all-trans-retinol using ADH. 相似文献