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1.
Olive-mill wastewater (OMW) was investigated for its suitability to serve as a medium for lipase production by Candida cylindracea NRRL Y-17506. The OMW that best supported enzyme production was characterized by low COD and low total sugars content. In shake flask batch cultures, OMW supplementation with 2.4 g l−1 NH4Cl and 3 g l−1 olive oil led to an enzyme activity of about 10 U ml−1. The addition of glucose or malt extract and supplements containing organic N (e.g., peptone, yeast extract) either depressed or did not affect the enzyme production. Further experiments were then performed in a 3-l stirred tank reactor to assess the impact of medium pH and stirring speed on the yeast enzyme activity. The lipase activity was low (1.8 U ml−1) when the pH was held constant at 6.5, significantly increased (18.7 U ml−1) with uncontrolled pH and was maximum (20.4 U ml−1) when the pH was let free to vary below 6.5. A stirring regime, that varied depending on the dissolved oxygen concentration in the medium, both prevented the occurrence of anoxic conditions during the exponential growth phase and enabled good lipase production (i.e., 21.6 U ml−1) and mean volumetric productivity (i.e., 123.5 U l−1 h−1).  相似文献   

2.
Sulfated polysaccharides potently inhibit the infectivity of herpes simplex virus (HSV) in cultured cells. In this study, we have analyzed sulfated xylogalactofucan and alginic acid containing fractions generated from Laminaria angustata, a marine alga. The xylogalactofucan that has apparent molecular mass of 56 ± 5 kDa and unusually low sulfate content contains, inter alia, 1,3-, 1,4- and 1,2-linked fucopyranosyl residues. The algin (molecular mass: 32 ± 5 kDa) contains gulo- (55.5%) and mannuronic (44.5%) acid residues. Introduction of sulfate groups enhanced the macromolecules capability to inhibit the infection of cells by HSV-1. The 50% inhibitory concentration (IC50) values of these macromolecules against HSV-1 were in the range of 0.2-25 μg ml−1 and they lacked cytotoxicity at concentrations up to 1000 μg ml−1. The sulfate content appeared to be an important hallmark of anti-HSV-1 activity. Our results suggest the feasibility of inhibiting HSV attachment to cells by direct interaction of polysaccharides with viral particles.  相似文献   

3.
Lim YR  Yeom SJ  Kim YS  Oh DK 《Bioresource technology》2011,102(5):4277-4280
The optimum conditions for the production of l-arabinose from debranched arabinan were determined to be pH 6.5, 75 °C, 20 g l−1 debranched arabinan, 42 U ml−1 endo-1,5-α-l-arabinanase, and 14 U ml−1 α-l-arabinofuranosidase from Caldicellulosiruptor saccharolyticus and the conditions for sugar beet arabinan were pH 6.0, 75 °C, 20 g l−1 sugar beet arabinan, 3 U ml−1 endo-1,5-α-l-arabinanase, and 24 U ml−1 α-l-arabinofuranosidase. Under the optimum conditions, 16 g l−1l-arabinose was obtained from 20 g l−1 debranched arabinan or sugar beet arabinan after 120 min, with a hydrolysis yield of 80% and a productivity of 8 g l−1 h−1. This is the first reported trial for the production of l-arabinose from the hemicellulose arabinan by the combined use of endo- and exo-arabinanases.  相似文献   

4.
In this study, interactions between Cry1Ac, a toxic crystal protein produced by Bacillus thuringiensis (Berliner), and Beauveria bassiana on the mortality and survival of Ostrinia furnacalis was evaluated in the laboratory. The results showed that Cry1Ac is toxic to O. furnacalis. Not only were larval growth and development delayed, but pupation, pupal weight and adult emergency also decreased when larvae were fed on artificial diet containing purified Cry1Ac toxin. When third instars O. furnacalis were exposed to combination of B. bassiana (1.8 × 105, 1.8 × 106 or 1.8 × 107 conidia ml−1) and Cry1Ac, (0.2 or 0.8 μg g−1), the effect on mortality was additive, however, the combinations of sublethal concentrations showed antagonism between Cry1Ac (3.2 or 13 μg g−1) and B. bassiana (1.8 × 105 or 1.8 × 106 conidia ml−1). When neonates were reared on sublethal concentrations of Cry1AC until the third instar, and survivors exposed B. bassiana conidial suspension, such treatments showed additive effect on mortality of O. furnacalis except for the combination of Cry1Ac (0.2 μg g−1) and B. bassiana (1.8 × 106 conidia ml−1) that showed antagonism.  相似文献   

5.
Calcification and primary production responses to irradiance in the temperate coralline alga Lithothamnion corallioides were measured in summer 2004 and winter 2005 in the Bay of Brest. Coralline algae were incubated in dark and clear bottles exposed to different irradiances. Net primary production reached 1.5 μmol C g−1 dry wt h−1 in August and was twice as high as in January–February. Dark respiration showed significant seasonal variations, being three-fold higher in summer. Maximum calcification varied from 0.6 μmol g−1 dry wt h−1 in summer 2004 to 0.4 μmol g−1 dry wt h−1 in winter 2005. According to PE curves and the daily course of irradiance, estimated daily net production and calcification reached 131 μg C g−1 dry wt and 970 μg CaCO3 g−1 dry wt in summer 2004, and 36 μg C g−1 dry wt and 336 μg CaCO3 g−1 dry wt in winter 2005. The net primary production of natural L. corallioides populations in shallow waters was estimated at 10–600 g C m−2 y−1, depending on depth and algal biomass. The mean annual calcification of L. corallioides populations varied from 300 to 3000 g CaCO3 m−2. These results are similar to those reported for tropical coralline algae in terms of carbon and carbonate productivity. Therefore, L. corallioides can be considered as a key element of carbon and carbonate cycles in the shallow coastal waters where they live.  相似文献   

6.
The microalgae, Chlorella sp., were cultivated in various culture modes to assess biomass and lipid productivity in this study. In the batch mode, the biomass concentrations and lipid content of Chlorella sp. cultivated in a medium containing 0.025–0.200 g L−1 urea were 0.464–2.027 g L−1 and 0.661–0.326 g g−1, respectively. The maximum lipid productivity of 0.124 g d−1 L−1 occurred in a medium containing 0.100 g L−1 urea. In the fed-batch cultivation, the highest lipid content was obtained by feeding 0.025 g L−1 of urea during the stationary phase, but the lipid productivity was not significantly increased. However, a semi-continuous process was carried out by harvesting the culture and renewing urea at 0.025 g L−1 each time when the cultivation achieved the early stationary phase. The maximum lipid productivity of 0.139 g d−1 L−1 in the semi-continuous culture was highest in comparison with those in the batch and fed-batch cultivations.  相似文献   

7.
We evaluated the kinetic culture characteristics of the microalgae Cyanobium sp. grown in vertical tubular photobioreactor in semicontinuous mode. Cultivation was carried out in vertical tubular photobioreactor for 2 L, in 57 d, at 30 °C, 3200 Lux, and 12 h light/dark photoperiod. The maximum specific growth rate was found as 0.127 d−1, when the culture had blend concentration of 1.0 g L−1, renewal rate of 50%, and sodium bicarbonate concentration of 1.0 g L−1. The maximum values of productivity (0.071 g L−1 d−1) and number of cycles (10) were observed in blend concentration of 1.0 g L−1, renewal rate of 30%, and bicarbonate concentration of 1.0 g L−1. The results showed the potential of semicontinuous cultivation of Cyanobium sp. in closed tubular bioreactor, combining factors such as blend concentration, renewal rate, and sodium bicarbonate concentration.  相似文献   

8.
In this study, interactions on the mortality and debilitating effects between Cry1Ac, a toxic protein produced by Bacillus thuringiensis (Berliner) and HaCPV (Chinese strain) on first and third instars larvae of Helicoverpa armigera were evaluated in laboratory. When first instar was exposed to combination of Bt cotton leaf discs containing HaCPV (6 × 106, 1 × 107, and 3 × 107 PIB ml−1) the effect on mortality was additive, when such instar larvae exposed to combination of Cry1Ac (0.9, 2.7, or 8.1 μg g−1) and the same concentrations of HaCPV the effect on mortality was additive except for the combination of Cry1Ac (0.3 μg g−1) and HaCPV concentrations that showed synergism. When third instars of H. armigera were infected using a suspension containing both HaCPV and Cry1Ac, most combinations of them showed additive effect except for the combination of Cry1Ac (0.3 μg g−1) and HaCPV (3 × 107 PIB ml−1) that showed synergism. However, when they exposed to Bt cotton leaf discs and HaCPV the effect on mortality was synergism except combination of Bt cotton leaf discs and HaCPV (6 × 106 PIB ml−1) that showed additive. Most of the combinations are showed additive effect in the toxicity and in combinations of Cry1Ac at lowest and HaCPV at highest concentrations synergism is observed. Not only were larval growth and development delayed, but pupation and pupal weight also decreased when larvae were fed on artificial diet containing Cry1Ac and HaCPV or transgenic Bt cotton leaf discs specially in first instar.  相似文献   

9.
Optimization of media components for the growth and biomass production of Halobacterium salinarum VKMM 013 was carried out using response surface methodology. A second order quadratic model was estimated and media components were determined based on quadratic regression equation generated by model. These were 6.35 g L−1 of KCl, 9.70 g L−1 of MgSO4, 13.38 g L−1 of gelatin and 12.00 g L−1 of soluble starch in nutrient broth supplemented with artificial seawater with 20% (w/v) of NaCl. In these optimal conditions, the obtained cell concentration of 0.746 g L−1 dry weight was in agreement with the predicted cell concentration. The optimized media significantly shortened the time required for cell culture to reach the stationary phase while providing a nearly 2.4-fold increase in biomass production. Furthermore, in cell cultures of three other halophilic archaea the use of optimized media enhanced growth rate and provided high-cell density.  相似文献   

10.
Fly-ash-tolerant Rhizobium strains were isolated from plants grown in fly-ash-contaminated soil, axenically under laboratory conditions. Saplings of both plants were raised in N2-free Jenson medium and inoculated with 2.6 × 108 cell ml−1 and 5.2 × 108 cell ml−1 of culture after 10 d of growth. Plants were transferred into 100% fly-ash under natural condition. Rhizobium-inoculated plants grown on 100% fly-ash showed marked increase in relation to root-shoot length, biomass yield, photosynthetic pigment, protein content and nodulation frequency compared to uninoculated plant grown in control (100% fly-ash). Inoculation of fly-ash-tolerant Rhizobium increased the accumulation of Fe, Zn, Cu Cd and Cr in different tissues vis-à-vis enhanced translocation of metals to the aboveground part of plant. Although inoculation of fly-ash-tolerant Rhizobium strains (VR-1 and VA-1) enhanced the translocation of more Fe to shoot parts, nevertheless, the amount of Rhizobium inoculants supplied to the plant was found to be very important since it has a positive role in increasing plant growth through increased N2 supply via nitrogenase activity. Results suggest that an integrated approach employing biotechnological means and inoculation of plants with host-specific fly-ash-tolerant Rhizobium strain may prove a stimulus to a fly-ash management programme.  相似文献   

11.
Acarbose, a potent α-glucosidase inhibitor, is as an oral anti-diabetic drug for treatment of the type two, noninsulin-dependent diabetes. Actinoplanes utahensis ZJB-08196, an osmosis-resistant actinomycete, had a broad osmolality optimum between 309 mOsm kg−1 and 719 mOsm kg−1. Utilizing this unique feature, an fed-batch culture process under preferential osmolality was constructed through intermittently feeding broths with feed medium consisting of 14.0 g l−1 maltose, 6.0 g l−1 glucose and 9.0 g l−1 soybean meal, at 48 h, 72 h, 96 h and 120 h. This intermittent fed-batch culture produced a peak acarbose titer of 4878 mg l−1, increased by 15.9% over the batch culture.  相似文献   

12.
The BGL1 gene, encoding β-glucosidase in Saccharomycopsis fibuligera, was intracellular, secreted or cell-wall associated expressed in an industrial strain of Saccharomyces cerevisiae. The obtained recombinant strains were studied under aerobic and anaerobic conditions. The results indicated that both the wild type and recombinant strain expressing intracellular β-glucosidase cannot grow in medium using cellobiose as sole carbon source. As for the recombinant EB1 expressing secreted enzyme and WB1 expressing cell-wall associated enzyme, the maximum specific growth rates (μmax) could reach 0.03 and 0.05 h−1 under anaerobic conditions, respectively. Meanwhile, the surface-engineered S. cerevisiae utilized 5.2 g cellobiose L−1 and produced 2.3 g ethanol L−1 in 48 h, while S. cerevisiae secreting β-glucosidase into culture broth used 3.6 g cellobiose L−1 and produced 1.5 g ethanol L−1 over the same period, but no-full depletion of cellobiose were observed for both the used recombinant strains. The results suggest that S. cerevisiae used in industrial ethanol production is deficient in cellobiose transporter. However, when β-glucoside permease and β-glucosidase were co-expressed in this strain, it could uptake cellobiose and showed higher growth rate (0.11 h−1) on cellobiose.  相似文献   

13.
Three Algerian populations of female Pistacia atlantica shrubs were investigated in order to check whether their terpenoid contents and morpho-anatomical parameters may characterize the infraspecific variability. The populations were sampled along a gradient of increasing aridity from the Atlas mountains into the northwestern Central Sahara.As evidenced by Scanning Electron Microscopy, tufted hairs could be found only on seedling leaves from the low aridity site as a population-specific trait preserved also in culture. Under common garden cultivation seedlings of the high aridity site showed a three times higher density of glandular trichomes compared to the low aridity site. Increased aridity resulted also in reduction of leaf sizes while their thickness increased. Palisade parenchyma thickness also increases with aridity, being the best variable that discriminates the three populations of P. atlantica.Analysis of terpenoids from the leaves carried out by GC-MS reveals the presence of 65 compounds. The major compounds identified were spathulenol (23 μg g−1 dw), α-pinene (10 μg g−1 dw), verbenone (7 μg g−1 dw) and β-pinene (6 μg g−1 dw) in leaves from the low aridity site; spathulenol (73 μg g−1 dw), α-pinene (25 μg g−1 dw), β-pinene (18 μg g−1 dw) and γ-amorphene (16 μg g−1 dw) in those from medium aridity and spathulenol (114 μg g−1 dw), α-pinene (49 μg g−1 dw), germacrene D (29 μg g−1 dw) and camphene (23 μg g−1 dw) in leaves from the high aridity site. Terpene concentrations increased with the degree of aridity: the highest mean concentration of monoterpenes (136 μg g−1 dw), sesquiterpenes (290 μg g−1 dw) and total terpenes (427 μg g−1 dw) were observed in the highest arid site and are, respectively, 3-, 5- and 4-fold higher compared to the lower arid site. Spathulenol and α-pinene can be taken as chemical markers of aridity. Drought discriminating compounds in low, but detectable concentrations are δ-cadinene and β-copaene. The functional roles of the terpenoids found in P. atlantica leaves and principles of their biosynthesis are discussed with emphasis on the mechanisms of plant resistance to drought conditions.  相似文献   

14.
The isolation of lectins from Myracrodruon urundeuva bark (MuBL) and heartwood (MuHL) as well as the termiticidal activity of MuHL against Nasutitermes corniger has already been described. This work reports on the purification of a leaf lectin (MuLL) and the characterization of MuBL, MuHL, and MuLL; also described are the resistance of hemagglutinating activity of the three lectins to trypsin activity from N. corniger gut and the termiticidal activity on N. corniger of MuBL (LC50 of 0.974 mg ml−1 on workers and 0.787 mg ml−1 on soldiers) and MuLL (LC50 of 0.374 mg ml−1 on workers and 0.432 mg ml−1 on soldiers). The antibacterial effect of MuBL, MuHL, and MuLL on bacteria from gut of N. corniger was also investigated and lectins showed similar bacteriostatic activity (MIC of 62.5 ??g ml−1 for workers and 125 ??g ml−1 for soldiers). MuBL and MuHL were more efficient bactericidal agents on bacteria in the workers’ gut (MBC of 125 ??g ml−1) than MuLL (MBC of 250 ??g ml−1) and similar bactericidal activity was detected on bacteria in the gut of soldiers (MBC of 250 ??g ml−1). The termiticidal activity of M. urundeuva lectins can be explained by the chitin-binding property, resistance to termite digestive enzyme, and the antibacterial effect on symbiotic bacteria of N. corniger gut.  相似文献   

15.
The feasibility of replacing yeast extract (YE) by corn steep liquor (CSL), a low cost nutrient source, for syngas fermentation to produce ethanol using Clostridium strain P11 was investigated. About 32% more ethanol (1.7 g L−1) was produced with 20 g L−1 CSL media in 250-mL bottle fermentations compared to media with 1 g L−1 YE after 360 h. Maximum ethanol concentrations after 360 h of fermentation in a 7.5-L fermentor with 10 and 20 g L−1 CSL media were 8.6 and 9.6 g L−1, respectively, which represent 57% and 60% of the theoretical ethanol yields from CO. Only about 6.1 g L−1 of ethanol was obtained in the medium with 1 g L−1 YE after 360 h, which represents 53% of the theoretical ethanol yield from CO. The use of CSL also enhanced butanol production by sevenfold compared to YE in bottle fermentations. These results demonstrate that CSL can replace YE as the primary medium component and significantly enhance ethanol production by Clostridium strain P11.  相似文献   

16.
Cryopreservation of sperm is common procedures in aquaculture, particularly used for routine in artificial insemination. However, these application cause damages and adversely affected sperm motility, viability and consequently lower hatching rates. The objective of this study is to determine whether propolis has an effect on cryopreservation and fertilization ability and to investigate the potential protective effect of propolis on spermatozoa of Cyprinus carpio. Many studies have been done in cryopreservation offish spermatozoa, but none of them contain propolis in extender composition. The extenders were prepared by using modified Kurokura Solution to which 10% Me2SO added with different levels of propolis (0.2, 0.4, 0.6, 0.8 and 1 mg ml−1) and 10% egg yolk (as a control without propolis). The pooled semen samples diluted at the ratio of 1:9 by the extenders were subjected to cryopreservation. The percentage and duration of motility and fertilization tests of cryopreserved sperm samples have been done immediately after thawing and compared with control and fresh semen. The extenders containing propolis exhibited higher percentage motility and motility duration than control group (P < 0.05). Especially the group IV (0.8 mg ml−1 propolis) and the group V (1 mg ml−1 propolis) showed significant positive effects on both post thaw motility and hatching ability. The propolis maintained the integrity of the spermatozoa during the cryopreservation process. Evaluating with its contents, it has been shown that propolis is an appropriate cryoprotective agent in fish semen.  相似文献   

17.
Electroreduction and adsorption of cefixime was studied in phosphate buffer by cyclic voltammetry (CV), differential pulse cathodic adsorptive stripping voltammetry (DPCAdSV), and square-wave cathodic adsorptive stripping voltammetry (SWCAdSV) at hanging mercury drop electrode (HMDE). These fully validated sensitive and reproducible cathodic adsorptive stripping voltammetric procedures were applied for the trace determination of the bulk drug in pharmaceutical formulations and in human urine. The optimal experimental parameters were as follows: accumulation potential = −0.1 V (vs. Ag/AgCl, 3 M KCl), accumulation time = 50 s, frequency = 140 Hz, pulse amplitude = 0.07 V, and scan increment = 10 mV in phosphate buffer (pH 2.6). The first peak current showed a linear dependence with the drug concentration over the range of 50 ng ml−1 to 25.6 μg ml−1. The achieved limit of detection and limit of quantitation were 3.99 and 13.3 ng ml−1 by SWCAdSV and 7.98 and 26.6 ng ml−1 by DPCAdSV, respectively. The procedure was applied to assay the drug in tablets. Applicability was also tested in urine samples. Peak current was linear with the drug concentration in the range of 1 to 60 μg ml−1 of the urine, and minimum detectability was found to be 12.6 ng ml−1 by SWCAdSV and 58.4 ng ml−1 by DPCAdSV.  相似文献   

18.
Leaves and flowers of Artemisia gorgonum (Asteraceae) collected in Fogo, Cape Verde islands, were phytochemically investigated and resulted in isolation and characterization of three guaianolides 1, 2, 5, and a secoguainolide 4, in addition to eight known guaianolides 6-11 and two known germacranolides 12, 13. Structures were elucidated by 1D and 2D NMR experiments. Careful examination of the 13C NMR spectrum led to revision of the structure of a previously described guaianolide from 2 to 3. Most compounds exhibited mild antiplasmodial activities, ridentin (13) being the most interesting with an IC50 of 3.8 ± 0.7 μg ml−1 against Plasmodium falciparum FcB1 and weak cytotoxicity in a vero cell line (IC50 71.0 ± 3.9 μg ml−1).  相似文献   

19.
Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3 h−1) and maximal specific non-growth PHB production rate (0.16 g g−1 h−1) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016 g L−1), glycerol (0.05 g L−1), non-growth related PHB synthesis (0.011 g L−1) and nitrogen/PHB related inhibition constant (0.405 g L−1), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23 h) and better PHB yield (0.347 g g−1). Initial concentration of biomass 16.8 g L−1 and glycerol concentration in broth between 3 and 5 g L−1 were decisive factors for increasing of productivity.  相似文献   

20.
A hydrolytic enzyme designated as a 1,3-β-d-glucanase having an antifungal activity was purified and characterized from Streptomyces torulosus PCPOK-0324. Fungal growth inhibitors in the culture filtrates from an antagonistic S. torulosus PCPOK-0324 exhibited higher antifungal activity against the hyphal growth of Phytophthora capsici and Rhizoctonia solani. The 1,3-β-d-glucanase was purified by four chromatographic steps from culture supernatant. The molecular weight of the purified enzyme was estimated to be 31.5 kDa. The optimal pH and temperature were 7.5 and 50 °C. Both the purified enzyme and the antibiotic extract inhibited R. solani and P. capsici with minimal inhibitory concentration values of 12.50 and 6.25 mU ml−1 and 3.95 and 1.94 μg ml−1, respectively. Our findings collectively show that the 1,3-β-d-glucanase in combination with the antibiotic extract have strong synergistic antifungal activity against the hyphal growth of both fungi causing root rot disease in pepper plants.  相似文献   

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