Comparison of electrochemical dissolution of chalcopyrite and bornite in acid culture medium

The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.

Effects of Genotypes and Basic Medium on Culture of Maize Mature Embryos

[Objective]This study was to screen out suitable genotypes and basic medium for the culture of maize mature embryos.[Method]Using mature embryos of nine maize genotypes as explants,the effects of genotypes and basic medium on callus induction and subculture were investigated.[Result]The genotypes performed better in callus induction and subculture were found in turn 853-35,853-209,Dan 34 and 81162.MS medium is better than N6 medium in the callus induction from maize embryos,while N6 medium is more suitable for callus subculture.[Conclusion]Our study further improved the tissue culture system in maize with mature embryos as explants.

Propagation of Abies beshanzuensis by Water Cultured Medium

[Objective] The experiment aimed to explore the influences of phytohormones (ABT and IAA) and nutrient solution on rooting of Abies beshanzuensis M.H.Wu by water cultured medium. [Method] The Abies beshanzuensis M.H.Wu were treated by water (CK), 10 mg/L ABT+ water, 10 mg/L IAA+ water, 10 mg/L ABT+ hoagland solution, 10 mg/L IAA+ hoagland solution, then the rooting process was observed and the formation rate of callus, rooting rate, number of rooting, and root length were investigated and analyzed. [Result] ABT and IAA had obvious influences on callus induction, rooting rate and the number of root of Abies beshanzuensis M.H.Wu by water culture, so they were suitable to be used in water propagation of Abies beshanzuensis M.H.Wu. The treatments of phytohormones had no regular influences on the longest root length and average root length. The nutrient solutions would not generate obvious influence on propagation of Abies beshanzuensis M.H.Wu at firstly stage, but they generated influence on root growth after rooting. [Conclusion] The research provided new ideas for propagation of Abies beshanzuensis M.H.Wu, which could make it out of endangerment situation quickly.

Screening and Characterization of Nitrite-Degrading Bacterial Isolates Using a Novel Culture Medium

In this study,a novel culture medium that simulates shrimp pond conditions was established to screen nitrite-degrading isolates.The medium was supplemented with nitrite as a nitrogen source and shrimp feed as the major carbon source,to achieve the high nitrogen and low carbon nutritional status found in shrimp farming ponds.Screening using this medium identified potent denitrifying Bacillus isolates,among which Bacillus subtilis M7-1 was considered best.M7-1 was able to completely degrade nitrite-N in 24 h without much consumption of dissolved oxygen.Efficient denitrification activity took place in liquid cultures within a set of non-stringent ranges of pH(5.0–9.0),salinity(0–30)and temperature(25–35℃).The denitrifying enzyme gene was amplified,sequenced and further identified as nirS type.In biosecurity assessments,M7-1 had no negative effects on shrimps at a dose of 106 cfu mL−1.M7-1 could therefore be used in aquaculture to reduce and control the nitrogen concentration,and to promote the development of sustainable and healthy culture systems.

Optimization of Culture Conditions and Medium Composition for the Marine Algicidal Bacterium Alteromonas sp. DH46 by Uniform Design

Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.

Study on Microwave Sterilization of Solid Culture Medium

In this paper,microwave sterilization craft of solid culture medium in fungus growth is studied.The results show that microwave not only can be used to sterilize the micro-organisms which is useless for fungus growth in the solid culture medium,but also has positive effect on fungus growth;and the sterilization process is featured with shorter time and higher efficiency compared with the traditional method.

Improved elastase production by Bacillus sp. EL31410—further optimization and kinetics studies of culture medium for batch fermentation

An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface method-ology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K2HPO4, MgSO47H2O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM, showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K2HPO4 0.206 g/100 ml and MgSO47H2O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth.

Evaluation of Endotoxin in Culture Medium for Human in vitro Fertilization

To determine whether the presence of bacterial endotoxin in the commercial culture media utilized for human in vitro fertilization （IVF）, and evaluate the difference in detecting endotoxin in culture medium between the human sperm motility assay and the 2-cell mouse embryo assay. Methods Thirty-six batches of culture media commonly used in IVF laboratories from 3 manufacturers were determined for thepresence ofendotoxin before using the medium for the assisted reproductive programs （group A）. After being used, 25 specimens among above media were also tested （group B）. The chromogenic limulus amoebocyte lysate （LAL） test was used for quantification the content of endotoxin. In addition, the human sperm motility assay was compared with the 2-cell mouse embryo assay to evaluate the difference in detecting endotoxin in culture medium. Results Endotoxin was not detected in group A. However, 2 samples were positive in group B, Sperm did not show significant change in motility in group A during 24 h of incubation when compared with the control （P〉0. 05）. However, in group A the 2-cell embryo development to blastocyst was suppressed in 3 batches of media. Conclusions Regular screening of each batch of culture medium should be performed if possible although there was no evidence of endotoxin contamination in commercially prepared pre-tested media. Culture environment should be stringently controlled in case the medium is polluted. The sensitivity of the sperm motility assay was lower than that of the mouse embryo assay for detecting low levels of endotoxin or toxic compounds in the medium.

Investigation of Oxidation-Reduction Properties of Growing Mediums for Cell Culture of Mammals under the Effect of Cosmo-Geophysical Factors

In model experiments were studied the effect of cosmo-geophysical factors of environment (hypomagnetic conditions during 2 days ≈ 1 mkT;electromagnetic irradiation (10 min - 2 MHz with amplitude 5 V/m and power 30 mkVt, background 2 - 4 mkVt), γ-quantum (10 min—from the source 137Cs) and its combined effect on the physic-chemical properties (ORP and pH) of growing medium for cell culture of mammals as nutrition medium 199 (PanEco, Russia). It was used a clear solution of medium (solution 1) and with the adding of 10% embryo bull serum—model of bio-medium (solution 2). Hypomagnetic conditions evoked the decreasing of ORP and pH value in both solutions, electromagnetic irradiation in the solution 1 which evoked the decreasing of ORP and the increasing of pH value, and in the solution 2, on the contrary, the increasing of ORP with the unchanging pH value. γ-radiation sharply decreased ORP value and didn’t change pH in solution 1, i.e. the reduction properties increased. There is insignificant increasing of ORP value and the decreasing of pH is noted in the solution 2, that it is characterized with the increasing of oxidative properties of solution. Under the combined effect of hypomagnetic conditions and electromagnetic irradiation, the values of investigating parameters in the solution 1 decreased and in the solution 2 increased. It was observed acute decreasing of ORP value in both solutions under the combined effect of hypomagnetic conditions and γ-radiation, i.e. the reductive properties of the solutions increased sharply. In this the concentration H+ significantly decreased, (p γ-radiation led to the decreasing of ORP and pH values in both solutions. Thus, the studying factors significantly change the oxidation-reduction properties of growing mediums. The investigation of the processes in biological mediums plays the important role in the assessment of environment effect during the flight in inter-planet space.

Statistical optimization of medium composition and culture condition for the production of recombinant anti-lipopolysaccharide factor of Eriocheir sinensis in Escherichia coli

Anti-lipopolysaccharide factors （ALFs） are important antimicrobial peptides that are isolated from some aquatic species. In a previous study, we isolated ALF genes from Chinese mitten crab, Eriocheir sinensis. In this study, we optimized the production of a recombinant ALF by expressing E. sinensis ALF genes in Eseherichia coli maintained in shake-flasks. In particular, we focused on optimization of both the medium composition and the culture condition. Various medium components were analyzed by the Plackett-Burman design, and two significant screened factors, （NH4）2SO4 and KH2PO4, were further optimized via the central composite design （CCD）. Based on the CCD analysis, we investigated the induction start-up time, the isopropylthio-D-galactoside （IPTG） concentration, the post-induction time, and the temperature by response surface methodology. We found that the highest level of ALF fusion protein was achieved in the medium containing 1.89 g/L （NH4）2SO4 and 3.18 g/L KH2PO4, with a cell optical density of 0.8 at 600 nm before induction, an IPTG concentration of 0.5 mmol/L, a post-induction temperature of 32.7~C, and a post-induction time of 4 h. Applying the whole optimization strategy using all optimal factors improved the target protein content from 6.1% （without optimization） to 13.2%. We further applied the optimized medium and conditions in high cell density cultivation, and determined that the soluble target protein constituted 105% of the total protein. Our identification of the economic medium composition, optimal culture conditions, and details of the fermentation process should facilitate the potential application of ALF for further research.

Response of Two Sweet Potato （Ipomoea batatas L. Lam） Varieties Regenerated on Low Cost Tissue Culture Medium

Plant tissue culture continues to be of great interest within the realms of molecular biology, plant breeding and plant health However, different plant cultivars have different culture efficiencies to tissue culture. In this research, the response of two Kenyan sweet potato varieties, KEMB 36 and Tainurey, cultured on a low cost tissue culture medium was evaluated. The low cost medium contained plant nutrients that were obtained from locally available fertilizers. Each conventional Murashige and Skoog （MS） macronutrient was individually substituted with a locally available fertilizer. The conventional source of micronutrients was substituted with Stanes~ Iodized Microfood while sucrose was obtained from table sugar. Performance of the two cultivars was monitored over a period of six weeks. KEMB 36 had a better performance than Tainurey with an average of eight nodes, seven leaves, three roots and height of four centimeters per plantlet indicating genotype-dependent response.

The Skin Whitening Effect of Co-Cultured Conditioned Medium: Involvement of Synergy between Stem Cells and Immune Cells

Many researchers have described that mesenchymal stem cells conditioned medium and immune cells conditioned medium have a clear whitening effect when they are used as cosmetic ingredients. In this study, we confirmed the whitening efficacy of various concentrations of immune cells and stem cell conditioned media. The author tried to study a conditioned medium that has a strong whitening effect even with a composition of less than 20% (the most used concentration in cosmetics). Because of the fact that the conditioned medium contains various cytokines and growth factors secreted by stem cells or immune cells, it is known to have effects such as wound healing, antioxidant, and whitening effect. Recently, stem cells have been used not only in the development of cosmetic raw materials but also in skincare procedures, and there are reports being released of cosmetics using immune cells conditioned medium. The concentration-dependent whitening effect equivalently increased as the concentration of the mono-cultured conditioned medium was obtained through the stem cells or immune cells culture. In the case of co-culture, whitening results are like the effect of positive control such as arbutin in the medium carrying only 10% of the co-cultured conditioned medium. It is possible that enhanced whitening efficiency in co-cultured conditioned medium leads to a major innovation in the global cosmetic market.

Shoot tissue culture of Robinia pseudoacacia f. decaisneana

Robinia pseudoacacia f. decaisneana is a transfiguration of Robinia pseudoacacia. For enhancing propagation coefficient of the species, the experiment of shoot tissue culture of Robinia pseudoacacia f. decaisneana was conducted in Forestry College of Shenyang Agricultural University from July 1999 to July 2001. The experiment included medium selection of explant induction survival, initial culture, subculture as well as rooting culture, and forming seedling with callus. The results showed that shoot segment in vitro survive rate is larger in spring than in autumn, and green dense callus could form plantlet. The best medium for initial culture was SH+0.5mg/L BA+0.05 mg/L NAA, with a propagation coefficient of 4.1 (per micro-cutting in a month), and for subculture it was B5+0.5 mg/L BA+0.05 mg/L NAA+ 10 mg/L Glu., with a propagation coefficient of 4.7. The best rooting medium was 1/2MS+0.5 mg/L NAA+10 mg/L Glu., with a rooting rate of 84.4%. These results provide reference data for reproduction of superior individuals of Robinia pseudoacacia f. decaisneana.

Effects of Four Culture Media on Callus Induction Rate of Wheat Anther

Effects of four culture media including MS, N6, C17 and K on wheat anther callus induction in vitro culture were studied. The results showed that the callus in- duction rate of four kinds of culture medium was in the order of K〉C17〉N6〉MS.

Tissue Culture of Toona ciliata

In this study, a screening experiment was carried out among MS, WPM, DCR, MT, B5 and N6. The results showed that for proliferation culture of Toona ciliate, the optimum basic medium was WPM, and the optimum medium was WPM ＋ 6-BA 0.5 mg/L ＋ IBA 0.05 mg/L. The proliferation coefficient reached 4.29. The optimum rooting culture medium was 1/2 MS ＋ IBA 0.5 mg/L ＋ NAA 0.5 mg/L with rooting rate of 100%. In the optimum rooting ＇culture medium, the roots of T. ciliate developed neatly, and the seedlings grew well.

Screening of High-quality Substrate for Soilless Culture of Begonia cucullata Willd.

In order to investigate a better soilless culture medium and the possibility of grass clippings as alternative substrate for peat moss to grow Begonia cucullata Willd. in pots, the seedlings of widely cultivated B. cucullata were grown in pots with eight types of soilless substrates： T1（peat： perlite=1：1）, T2（peat： perlite： pine bark=1：1：1）, T3（corn stover： perlite： pine bark=1：1：1）, T4（corn stover： perlite： pine bark=2：1：1）, T5（grass clipping： perlite： pine bark=1：1：1）, T6（grass clipping： perlite：pine bark=2：1：1）, T7（vermiculite： perlite： pine bark=1：1：1） and T8（vermiculite： perlite： pine bark=2：1：1）, respectively, in a shade house of Shanghai Chenshan Botanical Garden to evaluate plant growth performance. The results showed that the stem diameter of B. cucullata increased significantly from day 30 to day 60 after potting,and the plant height, leaf number and leaf area increased largest from day 60 to day 90 after potting in all treatments. The growth of plants performed best in T6,with the highest branch number, leaf thickness, flower number, aboveground fresh and dry weights and relative chlorophyll content. Therefore, the substrate with grass clipping： perlite： pine bark=2：1：1 was the best culture medium for growing B. cucullata in this study, and the grass clippings could replace peat moss as alternative substrate for growing B. cucullata in containers.

Establishment of a Highly Efficient Regeneration System for the Mature Embryo Culture of Wheat

Establishment of a highly efficient regeneration system for the mature embryo of wheat will provide a convenient tool for wheat tissue culture and transformation, thereby facilitating the transformation of foreign genes into wheat. By using the mature embryos derived from 20 different wheat lines including Shi 4185, Yumai 66, Lunxuan 987, CB037, Yangmai 6, Xinchun 9, Bobwhite, Han 6172, Zheng 9023, Jimai 20, Ningchun 4, and Jing 411, the effects of some factors including inoculation methods, initiating culture media, organic additives, antioxidants, and auxins on the regeneration from the explants were evaluated. The results indicated that the scraping embryo culture was better than the whole embryo culture, the Aa medium was better than the SD2 medium and dicamba was better than 2,4-D in increasing the regeneration frequency. An Adi medium was established in this study by adding silver nitrate, cysteine, ascorbic acid, dicamba, glutamine into the Aa medium at the concentration of 4,40, 100, 2, and 5 mg L^-1, respectively. By using the Adi medium and the scraping technique, the regeneration frequencies of the mature embryos of CB037, Lunxuan 987, Hart 6172, Yangmai 6, Bobwhite, Zheng 9023, Shi 4 185, and Jimai 20 became 85.6, 60,1, 46.0, 42.1,42.0, 34.0, 33.0, and 32.0%, respectively, which were about 5-8 times higher than that obtained from the conventional culture mediums and techniques. This novel regeneration system could be helpful in wheat transformation.

COMPARISON OF POLYSACCHARIDES ISOLATED FROM THE MYCELIA OF A CULTIVATED STRAIN OF PORIA COCOS GROWN IN DIFFERENT LIQUID CULTURE MEDIA

Mycelium of a cultivated strain of Poria cocos was grown by submerged fermentation in a liquid mediumcontaining corn steep liquor with orbital shaking. Six polysaccharides coded as ac-PCM1, ac-PCM2, ac-PCM3-Ⅰ andⅡ, ac-PCM4-Ⅰand Ⅱ were isolated from the myelium by extracting with 0.9% NaCl aqueous solution, hot water, 0.5 mol/L NaOHaqueous solution and 88% formic acid. Exo-polysaccharide was obtained from the culture medium and coded as ac-PCM0.The monosaccharide composition and molecular weights of these polysaccharides were characterized by using infraredspectroscopy, gas chromaography, elemental analysis, ^(13)C-NMR, viscometry and light scattering. The results indicated thatac-PCM0, ac-PCM1 and ac-PCM2 are heteropolysaccharides containing glucose, galactose, mannose and fucose, and ac-PCM3-Ⅰ and ac-PCM3-Ⅱ mainly consist of D-glucose. The content of the glucose in the polysaccharides increased with theisolation progress. Remarkably, α-glucan and β-glucan coexisted in the extract by NaOH aqueous solution (ac-PCM3), andcould be separated by chemical methods. The protein in the ac-PCM polysaccharides cultured from the medium containingcorn steep liquor was higher than that in the ab-PCM from the medium with bran extract. Therefore, the polysaccharidesfrom Poria cocos mycelia cultured in different media have different chemical composition, molecular weights and conformations.

Relationship Between Differential Expression of Bax and Bcl-2 Genes and Developmental Differences of Porcine Parthenotes Cultured in PZM-3 and NCSU-23

The developmental competence of porcine parthenotes cultured in porcine zygote medium-3 （PZM-3） and North Carolina State University-23 （NCSU-23） media was investigated. After in vitro maturation oocytes were electro-activated, and the subsequent developmental competence, rates of apoptotic, fragmented and arrested embryos from the two media were evaluated. Also, the ratio of mRNA expression of Bcl-2 and Bax gene was determined. Results demonstrated that cleavage, blastocyst, hatched blastocyst rates, and blastocyst cell numbers were significantly higher in PZM-3 than in NCSU-23. The rate of fragmented embryos in PZM-3 was lower than in NCSU-23 on d 1 and 3 （P〈0.05） while the percentage of arrested embryo was lower in PZM-3 than in NCSU-23 on d 4 and 5 （P〈0.05）. TUNEL positive signals were higher in NCSU-23 than in PZM-3 from d 3 to 7 （P〈0.05）. The ratios of Bcl-2 and Bax mRNA expression in embryos were higher on d 5 than on d 3 and 1 in PZM-3 （P〈0.05）. In contrast, the ratios of Bcl-2 and Bax mRNA expression in embryos on d 1 were higher than on d 3 and 5 in NCSU-23 （P〈0.05）. Additionally, the ratios of Bcl-2 and Bax mRNA expression in embryos in PZM-3 were higher than in NCSU-23 on d 3 and 5 （P〈0.05）. In conclusion, lower apoptotic embryo rates and down-regulating Bax together with up-regulating expression of Bcl-2 transcripts may be responsible for the better developmental competence of porcine parthenotes in PZM-3.

Effects of different culture media on the growth of Indian sandalwood(Santalum album L.) seedlings in Zhanjiang,Guangdong,southern China

We studied the effects of different culture media on the growth of India sandalwood （Santalum album L.） seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subsoil, burnt soil, agricultural soil, peaty soil and coconut dust, were used as the basic culture materials and seven different treatments of composition were used as potting media. Kuhnia rosmarinifolia Vent. was used as a primary host plant for all treatments. Statistically significant differences were found between treatments in respects of survival rate （p 〈 0.001）, height （p 〈 0.001）, ground diameter （p 〈 0.001） and biomass （p = 0.002）, as well as for quality index （p 〈 0.001） of S. album seedlings after 6-month growth in containers with different culture media. Among all treatments, the treatment combining burnt soil, peat and coconut dust in a weight ratio of 1：1：1 plus 2% calcium super-phosphate as basal manure achieved the best performance for most of the seedling growth parameters, including survival rate （98%）, height （35.81 cm）, ground diameter （0.56 cm）, biomass （4.46 g） and quality index （0.65）, followed by the treatment using only burnt soil plus 2% calcium super-phosphate as the culture medium （survival rate 86%, height 29.23 cm, ground diameter 0.48 cm, biomass 3.36 g and quality index 0.52）, while the treatment using only lateritic subsoil plus the basal manure as the medium obtained the poorest results in survival rate （38%）, height （12.04 cm）, ground diameter （0.19 cm）, biomass （0.26 g） and quality index （0.043）. Increasing the proportion of lateritic subsoil in the medium when mixed with peat and coconut dust did not show statistically significant differences in survival, height, ground diameter, biomass nor in quality index. In consideration of cost, using burnt soil plus 2% calcium super-phosphate as basal manure may be the optimum culture medium for large-scale production of Indian sandal- wood seedlings in Guangdong, southern China.