Increasing the Production of Carotenoids in Chlorella sorokiniana IG-W-96 by Changing the Concentration of Nutrients and Phytohormones

Introduction  Carotenoids have many effects on human health. These compounds are produced by plants and microalgae. The extraction of carotenoids from microalgae such as Chlorella has received much attention, since microalgae grow all year round (regardless of the season) and at a much faster rate than plants in non-arable lands. The aim of this research was to optimize the concentrations of nutrients (nitrogen and phosphorous) in the growth medium of microalgae with the objective of maximizing carotenoids content. At the optimized nutrient conditions, the effect of phytohormones on production of carotenoids using Chlorella sorokiniana IG-W-96 was investigated.   Materials and Methods Chlorella sorokiniana IG-W-96 was cultivated in BG11 growth medium with light intensity of 25000 lux and light: dark cycle of 16: 8 supplied with compressed air flow of 0.5 vvm containing 6% vol carbon dioxide. Under three concentrations of nitrate (0.04, 0.25, 1.5 ) and three concentrations of phophate (0.01, 0.04, 0.16 ) and carotenoid concentration was measured. Full factorial experimnetal design was performed and the resuts of the experiments were analyzed using Minitab (ver. 21.01.1). Finally, the best concentrations of nitrate and phosphate were chosen for pigments production, and at that concentration, naphthalene acetic acid (0, 2.5, 5, 7.5, 10 and 12 ppm) was added to the culture medium to check its effect on pigments production. By measuring the dry weight of C. sorokiniana, its growth rate was determined. After extracting the pigments with solvent, the concentration of the pigments was determined by measuring the amount of light absorption.   Results and Discussion Dry weight The results showed that the highest amount of dry weight was related to the treatment with nitrate amount of 0.25 , and nitrate more and less than this amount caused a decrease in growth. This result was not dependent on the amount of phosphate and was true for all phosphate concentrations. Nitrate reduction from 1.5 to 0.25 increased the growth of microalgae up to 81.8%, so that the dry weight of 0.88  reached 1.6 . However,  reduction of nitrate from 0.25 to 0.04  decreased the dry weight by 65.6%. In order to reach the maximum growth rate, it is necessary to determine the appropriate concentration of each nutrient.   Carotenoids Unlike the dry weight, not only the pigment production did not decrease with the excessive of nitrate concentration, but also the maximum amount of pigment production was related to the treatment with the maximum amount of nitrate concentration. Based on the results obtained, the concentration of carotenoids was higher in the concentration of 1.5  of nitrate and 0.04  of phosphate (6.7 ). When the nitrate concentration was very low (0.04 ), changing the phosphate concentration had no significant effect on the production rate of any of the pigments. Only when the nitrate concentration was high (1.5 ), change in phosphate concentration caused a change in pigments concentration. The increase of phosphate concentration from 0.01 to 0.04 increased the carotenoids concentration to 1.65-fold. Of course, increasing phosphate concentration to 0.16 did not affect the pigments concentration.  Based on the statistical analysis, the P-value<0.05 indicated that the effect of the factors and the model was significant. In this situation, in order to increase the production of carotenoids, naphthalene acetic acid was added to the phytohormone culture medium. At the optimal concentration of 2.5 ppm of naphthalene acetic acid, the concentration of carotenoids increased by 26.71% and reached 8.49 . However, phytohormone had no significant effect on dry weight.   Conclusion Carotenoid production using microalgae could be maximized through optimization of nutrients concentrations (nitrate and phosphate) in the growth medium. Phytohormones could further increase the prodcution of carotenoids at optimum concnetrations

Modulation of crude glycerol fermentation byClostridium pasteurianum DSM 525 towards theproduction of butanol

High production yields and productivities are requisites for the development of an industrial butanol production process based on biodiesel-derived crude glycerol. However, impurities present in this substrate and/or the concentration of glycerol itself can affect the microbial metabolism. In this work, the effect of crude glycerol concentration on the production of butanol and 1,3-propanediol (1,3-PDO) by Clostridium pasteurianum DSM 525 is studied. Also, the effect of acetate and butyrate supplementation to the culture medium and the culture medium composition are evaluated. The results showed a marked effect of crude glycerol concentration on the product yield. The competitive nature of butanol and 1,3-PDO pathways has been evident, and a shift to the butanol pathway once using higher substrate concentrations (up to 35 g l 1) was clearly observed. Butyrate supplementation to the culture medium resulted in a 45% higher butanol titre, a lower production of 1,3-PDO and it decreased the fermentation time. Acetate supplementation also increased the butanol titre but the fermentation was longer. Even though glycerol consumption could not be increased over 32 g l 1, when the concentrations of NH4Cl and FeCl2 were simultaneously increased, the results obtained were similar to those observed when butyrate was supplemented to the culture medium; a 35% higher butanol yield at the expense of 1,3-PDO and a shorter fermentation. The results herein gathered suggest that there are other factors besides butanol inhibition and nutrient limitation that affect the glycerol consumption.The authors acknowledge the financial support from the Strategic Project PEst-OE/EQB/LA0023/2013; the project ref. RECI/BBB-EBI/0179/2012 (project number FCOMP-01-0124-FEDER-027462); and the PhD grant given to R. Gallardo (ref SFRH/BD/42900/2008) funded by Fundacao para a Ciencia e a Tecnologia. The authors thank the MIT-Portugal Program for the support given to R. Gallardo

Optimization for the Production of Surfactin with a New Synergistic Antifungal Activity

-surfactin and the optimization of its production by the response surface method.O. A production of 134.2 mg/L, which were in agreement with the prediction, was observed in a verification experiment. In comparison to the production of original level (88.6 mg/L), a 1.52-fold increase had been obtained.-surfactin

Mathematical modelling of clostridial acetone-butanol-ethanol fermentation

Clostridial acetone-butanol-ethanol (ABE) fermentation features a remarkable shift in the cellular metabolic activity from acid formation, acidogenesis, to the production of industrial-relevant solvents, solventogensis. In recent decades, mathematical models have been employed to elucidate the complex interlinked regulation and conditions that determine these two distinct metabolic states and govern the transition between them. In this review, we discuss these models with a focus on the mechanisms controlling intra- and extracellular changes between acidogenesis and solventogenesis. In particular, we critically evaluate underlying model assumptions and predictions in the light of current experimental knowledge. Towards this end, we briefly introduce key ideas and assumptions applied in the discussed modelling approaches, but waive a comprehensive mathematical presentation. We distinguish between structural and dynamical models, which will be discussed in their chronological order to illustrate how new biological information facilitates the ‘evolution’ of mathematical models. Mathematical models and their analysis have significantly contributed to our knowledge of ABE fermentation and the underlying regulatory network which spans all levels of biological organization. However, the ties between the different levels of cellular regulation are not well understood. Furthermore, contradictory experimental and theoretical results challenge our current notion of ABE metabolic network structure. Thus, clostridial ABE fermentation still poses theoretical as well as experimental challenges which are best approached in close collaboration between modellers and experimentalists

On the sample complexity of reinforcement learning with a generative mode

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The Effect of Nitrate Levels and Harvest Times on Fe, Zn, Cu, and K, Concentrations and Nitrate Reductase Activity in Lettuce and Spinach

Leafy vegetables are considered as the main sources of nitrate in the human diet. In order to investigate the effect of nitrate levels and harvest times on nitrate accumulation, nitrate reductase activity, concentrations of Fe, Zn, Cu and K in Lettuce and Spinach and their relation to nitrate accumulation in these leafy vegetables, two harvest times (29 and 46 days after transplanting), two vegetable species of lettuce and spinach and two concentrations of nitrate (10 and 20 mM) were used in a hydroponics greenhouse experiment with a completely randomized design and 3 replications. Modified Hoagland and Arnon nutrient solutions were used for the experiment. The results indicated that by increasing nitrate concentration of solution, nitrate accumulation in roots and shoots of lettuce and spinach increased significantly (P ≤ 0.05), and the same trend was observed for the nitrate reductase activity in the shoots of the two species. Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species, where as it increased the K and Zn concentrations in the shoots of the two species in each both harvest times, the nitrate accumulation increased, but the nitrate reductase activity decreased in the shoots of the two species over the course of the growth. The Concentration of Fe, Cu and K decreased in the shoots of lettuce and the spinach with the time, despite the increase in Zn concentration in the shoots. The results also indicated that increasing nitrate concentrations of solution to the levels greater than the plant capacity for reduction and net uptake of nitrate, leads to the nitrate accumulation in the plants. Nitrate accumulation in plant tissue led to decreases in fresh shoot yield and Fe and Cu concentrations and nitrate reductase activities in both lettuce and spinach