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1.
Transgenic Brassica compestris L.spp.chinensis plants expressing a choline oxidase(codA) gene from Arthrobacter globiformis were obtained through Agrobacterium tumefaciens-mediated transformation.In the transgenic plants,codA gene expression and its product transportation to chloroplasts were detected by the enzyme-linked immunosorbent assay(ELISA) examination,immunogold localization,and 1 H-nuclear magnetic resonance( 1 H-NMR) . Stress tolerance was evaluated in the T3 plants under extreme temperature and salinity conditions.The plants of transgenic line 1(L1) showed significantly higher net photosynthetic rate(Pn) and Pn recovery rate under high(45°C,4 h) and low temperature(1°C,48 h) treatments,and higher photosynthetic rate under high salinity conditions(100,200,and 300 mmol/L NaCl,respectively) than the wild-type plants.The enhanced tolerance to high temperature and high salinity stresses in transgenic plants is associated with the accumulation of betaine,which is not found in the wild-type plants.Our results indicate that the introduction of codA gene from Arthrobacter globiformis into Brassica compestris L.spp.chinensis could be a potential strategy for improving the plant tolerance to multiple stresses.  相似文献   

2.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 °C to 28 °C, were evaluated in shake flask. The result indicated that 37 °C was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 °C. This result was verified by batch fermentation in 5-L bioreactor under 37 °C and 30 °C temperature, respectively. The specific cell growth rate at 37 °C was higher than that at 30 °C during earlier stage of cultivation. The maximum value [5.5 U/(h·g DCW)] of elastase formation rate occurred at 24 h at 30 °C compared to 4.6 U/(h·g DCW) at 30 h at 37 °C. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 °C or 30 °C, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 °C, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 °C in batch process. It was concluded that cultivation at constant temperature of 30 °C was appropriate for elastase production by Bacillus sp. EL31410. Project (No. 20276064) supported by the National Natural Science Foundation of China  相似文献   

3.
Surface display is effectively utilized to construct a whole-cell biocatalyst. Codon optimization has been proven to be effective in maximizing production of heterologous proteins in yeast. Here, the cDNA sequence of Rhizopus oryzae lipase (ROL) was optimized and synthesized according to the codon bias of Saccharomyces cerevisiae, and based on the Saccharomyces cerevisiae cell surface display system with α-agglutinin as an anchor, recombinant yeast displaying fully codon-optimized ROL with high activity was successfully constructed. Compared with the wild-type ROL-displaying yeast, the activity of the codon-optimized ROL yeast whole-cell biocatalyst (25 U/g dried cells) was 12.8-fold higher in a hydrolysis reaction using p-nitrophenyl palmitate (pNPP) as the substrate. To our knowledge, this was the first attempt to combine the techniques of yeast surface display and codon optimization for whole-cell biocatalyst construction. Consequently, the yeast whole-cell ROL biocatalyst was constructed with high activity. The optimum pH and temperature for the yeast whole-cell ROL biocatalyst were pH 7.0 and 40 °C. Furthermore, this whole-cell biocatalyst was applied to the hydrolysis of tributyrin and the resulted conversion of butyric acid reached 96.91% after 144 h.  相似文献   

4.
Utilization of a two-line breeding system via photoperiod-thermo sensitive male sterility has a great potential for hybrid production in wheat (Triticum aestivum L.). 337S is a novel wheat male sterile line sensitive to both short daylength/low temperature and long daylength/high temperature. Five F2 populations derived from the crosses between 337S and five common wheat varieties were developed for genetic analysis. All F1’s were highly fertile while segregation occurred in the F2 populations with a ratio of 3 fertile:1 sterile under short daylength/low temperature. It is shown that male sterility in 337S was controlled by a single recessive gene, temporarily designated as wptms3. Bulked segregant analysis (BSA) coupled with simple sequence repeat (SSR) markers was applied to map the sterile gene using one mapping population. The wptms3 gene was mapped to chromosome arm 1BS and flanked by Xgwm413 and Xgwm182 at a genetic distance of 3.2 and 23.5 cM, respectively. The accuracy and efficiency of marker-assisted selection were evaluated and proved essential for identifying homozygous recessive male sterile genotypes of the wptms3 gene in F2 generation.  相似文献   

5.
This study was conducted to investigate the combined effects of elevated CO2 levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam. and Lolium perenne L. exposed to two CO2 levels (360 and 1 000 μl/L) and three Cd levels (0, 4, and 16 mg/L) under hydroponic conditions. The results show that elevated levels of CO2 increased shoot biomass more, compared to root biomass, but decreased Cd concentrations in all plant tissues. Cd exposure caused toxicity to both Lolium species, as shown by the restrictions of the root morphological parameters including root length, surface area, volume, and tip numbers. These parameters were significantly higher under elevated levels of CO2 than under ambient CO2, especially for the number of fine roots. The increases in magnitudes of those parameters triggered by elevated levels of CO2 under Cd stress were more than those under non-Cd stress, suggesting an ameliorated Cd stress under elevated levels of CO2. The total Cd uptake per pot, calculated on the basis of biomass, was significantly greater under elevated levels of CO2 than under ambient CO2. Ameliorated Cd toxicity, decreased Cd concentration, and altered root morphological traits in both Lolium species under elevated levels of CO2 may have implications in food safety and phytoremediation.  相似文献   

6.
The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coli Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) were studied. Compared with ALASs encoded by hemA genes from Agrobacterium radiobacter (AR-ALAS) and Rhodobacter sphaeroides (RS-ALAS), the specific activity of RC-ALAS reached 198.2 U/mg, which was about 31.2% and 69.5% higher than those of AR-ALAS (151.1 U/mg) and RS-ALAS (116.9 U/mg), respectively. The optimum pH values and temperatures of the three above mentioned enzymes were all pH 7.5 and 37 °C, respectively. Moreover, RC-ALAS was more sensitive to pH, while the other two were sensitive to temperature. The effects of metals, ethylene diamine tetraacetic acid (EDTA), and sodium dodecyl sulfate (SDS) on the three ALASs were also investigated. The results indicate that they had the same effects on the activities of the three ALASs. SDS and metal ions such as Co2+, Zn2+, and Cu2+ strongly inhibited the activities of the ALASs, while Mn2+ exerted slight inhibition, and K+, Ca2+, Ba2+, Mg2+, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [(k cat/K m)S-CoA] of RC-ALAS was 1.4989, which was higher than those of AR-ALAS (0.7456) and RS-ALAS (1.1699), showing its high catalytic efficiency. The fed-batch fermentation was conducted using the recombinant strain containing the R. capsulatus hemA gene, and the yield of 5-aminolevulinic acid (ALA) achieved was 8.8 g/L (67 mmol/L) under the appropriate conditions.  相似文献   

7.
Biotransformation of phytosterol(PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this paper.The parameters of the biotransformation process were optimized using fractional factorial design and response surface methodology.Androstenedione was the sole product in the fermentation broth catalyzed by the mutant M.neoaurum ZJUVN-08 strain.Results showed that molar ratio of hydroxypropyl-β-cyclodextrin(HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione production.By analyzing the statistical model of three-dimensional surface plot,the optimal process conditions were observed at 0.1 g/L inducer,pH 7.0,molar ratio of HP-β-CD to PS 1.92:1,8.98 g/L PS,and at 120 h of incubation time.Under these conditions,the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized(5.99 g/L),while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized(84.03%).The predicted optimum conditions from the mathematical model were in agreement with the verification experimental results.It is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.  相似文献   

8.
Lovastatin production by Aspergillus terreus ATCC 20542 in solid-state fermentation (SSF) was studied. Various substrates were used to evaluate the ability of A. terreus to produce lovastatin. The results showed that either rice or wheat bran was suitable substrate for lovastatin production in SSF. The maximum yield of lovastatin (2.9 mg/g dry substrate) using rice as substrate was achieved after incubating for 11 d at the following optimized process parameters: 50%～60% initial moisture content,pH 5.5,incubation temperature 28 °C.  相似文献   

9.
Naturally fermented pickles harbour many lactic acid bacteria (LAB). Forty-three LAB strains with conjugated linoleic acid (CLA)-producing ability were isolated from three naturally fermented pickle brines. Of these isolates, lp15 identified as Lactobacillus plantarum by API 50 CHL system and full-length 16S rDNA sequence analysis exhibited the highest CLA-producing ability (26.1% conversion) at 48 h in de Man Rogosa Sharpe (MRS) broth in the presence of 100 μg/ml of linoleic acid (LA). Compared to other strains, L. plantarum strain lp15 showed the highest tolerance upon increased levels of LA in the medium, i.e., up to 600 μg/ml. This strain converted about 25% of LA into CLA isomers [predominantly cis-9, trans-11 CLA (9-CLA) and trans-10, cis-12 CLA (10-CLA)], of which 75% was 9-CLA. Interestingly, though the conversion rate of LA into CLA by lp15 remained stable between 100 to 600 μg/ml LA levels in the medium, it dropped sharply at 1000 μg/ml. Taken together, the lp15 strain displayed relatively high LA tolerance with higher conversion rate, which implies that this strain is a valuable candidate for enhancing the CLA content in food-sources like pickles.  相似文献   

10.
实验研究石斑木果皮红色素的理化性质和光、温度、金属离子、食品添加剂等对色素稳定性的影响．结果表明：该色素在80℃以下较稳定;日光照射,金属离子K^＋、Na^＋、Mg^2＋、Ca^2＋、Cu^2＋、Mn^2＋、Fd^3＋等对色素液的吸光度有明显的不良影响;高浓度VitC和柠檬酸对色素降色明显;蔗糖和苯甲酸钠对色素无较大影响．  相似文献   

11.
Background and objective:Hepatic sinusoidal obstruction syndrome(HSOS) is characterized by painful hepatomegaly,ascites,increased body weight,and jaundice.Gynura segetum(Compositae),a plant widely used in Chinese traditional medicine,often leads to the development of HSOS.However,the mechanism is unclear.The aim was to study the role of matrix metalloproteinase-9(MMP-9) in the onset of HSOS induced by Gynura segetum.Methods:Twenty-five male Sprague-Dawley rats were randomly divided into two groups.Twenty were exposed to 600 mg/kg daily Gynura segetum extract solution for three weeks;five control rats were exposed to tap water alone.Liver sections were evaluated by light microscopy with a modified scoring system.Routine transmission electron microscopy(TEM) methods were used to evaluate the ultrastructual features of fixed liver tissue,and blood samples were collected to determine liver enzyme concentrations.MMP-9 expression was assessed by both immunohistochemical staining and enzyme-linked immunosorbent assay(ELISA) methods.Results:A stable and reproducible rat model of HSOS was achieved by long-term exposure to Gynura segetum extract.The treated rats presented clinical symptoms and the histopathological manifestation of HSOS,including abnormal liver enzyme concentrations(alanine aminotransferase(ALT):(84.8±13.62) vs.(167.0±72.63) U/L,P<0.05;aspartate aminotransferase(AST):(27.6±6.31) vs.(232.8±108.58) U/L,P<0.05).Hematoxylin and eosin(H&E) staining and TEM together revealed deposition of red blood cells,the damage and destruction of hepatic sinusoidal endothelial cells,collapse of hepatic sinusoids,hemorrhage of subendothelial cells,atrophy and destruction of hepatocytes,etc.Compared with controls,the expression of MMP-9 in the blood sample,the lung and liver tissues of HSOS rats was increased.Conclusions:MMP-9 may have an important role in early pathological changes of HSOS,and thus the onset of the disease.  相似文献   

12.
Hydantoinase and N-carbamoylase play important roles in the production of optically pure amino acids from racemic 5-monosubstituted hydantoins. In this report, hydantoinase and the N-carbamoylase from Burkholderia cepecia, njut01 were purified to homogeneity by chromatography (Pharmacia Explorer 100 system). The substrate specificity, enantioselectivity, pH dependence of activity and temperature stability of the activity were characterized. The results show that the hydantoinase and N-carbamoylase induced from Burkholderia cepecia, njut01 are both strict D-stereo selective enzymes. They both hydrolyze substrates with side chains containing aliphatic and aromatic residues with higher activity and affinity toward aromatic than aliphatic substituted substrates. The hydantoinase is a homotetramer with subtmit molecular weight near 52,000 and is active between pH 6.5 and 10 with an optimum near pH 9.0. The enzyme is active at temperatures up to 60~C, however, it appears instable at higher temperatures. The subunit molecular weight of N-carbamoylase is about 35KD. The N-carbamoylase is active in the pH range from 6.0 to 9.5. The optira-pH is 7.2 and the optinfizing bioconversion temperature of the N-carbamyolase is 52℃.  相似文献   

13.
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14.
The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain ,Aspergillusfoetidus ZU-GI in solid-state fermentation （SSF）. Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 ℃ incubation temperature, 18^h cultivation period of seed, 10% inoculum volume, 5.0-6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2037.51 U/g dry matter near the 144th hour of fermentation.  相似文献   

15.
In this paper, crude monkshood polysaccharide was isolated from Radix Aconiti Lateralis Preparata. The effects of crude monkshood polysaccharide on Escherichia coli and Staphylococcus aureus were investigated by microcalorimetry. The power-time curves of the bacterial growth at various concentrations (c) of crude monkshood polysaccharide were plotted with a TAM air isothermal microcalorimeter at 37 °C. The growth rate constant (μ), inhibitory ratio (I), peak-height (P m), and peak-time (t m) were calculated. From the data, the relationship between μ and c also was established. The growth rate constant μ decreased with the increasing concentrations of crude monkshood polysaccharide. Moreover, P m reduced and t m increased with increasing concentrations. The experimental results revealed that crude monkshood polysaccharide had inhibitory activity towards S. aureus and E. coli. Results obtained from our study strongly suggest that microcalorimetry is a fast, simple, and more sensitive technology that can be easily performed to study the effect of drugs on bacteria.  相似文献   

16.
茄子皮天然红色素的提取及稳定性的研究   总被引：4，自引：0，他引：4  
以茄子皮为原料,用酸性无水乙醇溶液浸泡提取天然红色素,并通过实验对色素溶液在不同pH值下在温度,光照,氧化还原剂,金属离子的稳定性进行了研究.实验证明:茄子皮天然红色素可以适用大多数食品,是一种值得开发的天然食用色素资源.  相似文献   

17.
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18.
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19.
This report describes in vitro micropropagation of Boscia senegalensis, so-called famine foods, that helped the people in Darfur and Kordofan, Sudan survive during the 1984–1985 famine. Four types of explants prepared from green mature zygotic embryos were cultured on Murashige and Skoog (MS) medium augmented with 1–5 mg/L 6-benzyladenine (BA). The highest number of shoots per explant (14.3±0.9) was achieved on MS medium supplemented with 3 mg/L BA, while the highest shoot length [(3.5±0.4) cm] was obtained with 1 mg/L BA. The shoot cluster, when subcultured to its same medium, significantly increased the rate of shoot multiplication by the end of the third subculture. The maximum mean number of shoots per explant (86.5±3.6) was produced after three multiplication cycles on 3 mg/L BA-supplemented medium. In vitro induced shoots were excised and rooted on half strength MS medium fortified with 0.25 mg/L indole-3-butyric acid (IBA) to obtain complete plantlets. B. senegalensis-regenerated plantlets obtained in vitro for the first time, were hardened and 95% survived under greenhouse conditions.  相似文献   

20.
Succinic acid is considered as an important platform chemical. Succinic acid fermentation with Actinobacillus succinogenes strain BE-1 was optimized by central composite design (CCD) using a response surface methodology (RSM). The optimized production of succinic acid was predicted and the interactive effects between glucose, yeast extract, and magnesium carbonate were investigated. As a result, a model for predicting the concentration of succinic acid production was developed. The accuracy of the model was confirmed by the analysis of variance (ANOVA), and the validity was further proved by verification experiments showing that percentage errors between actual and predicted values varied from 3.02% to 6.38%. In addition, it was observed that the interactive effect between yeast extract and magnesium carbonate was statistically significant. In conclusion, RSM is an effective and useful method for optimizing the medium components and investigating the interactive effects, and can provide valuable information for succinic acid scale-up fermentation using A. succinogenes strain BE-1.  相似文献   

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