Low ÃŽ- Irradiation Doses on Saccharomyces Cerevisiae

Low Î’- Irradiation Doses on Saccharomyces Cerevisiae RESULTS OF LOW ÃŽ ²- IRRADIATION DOSES ON SACCHAROMYCES CEREVISIAE FERMETATION PROCESS LetiÃ…Â £ia OPREAN1, Dan CHICEA2, EnikÅ‘ GASPAR, Ecaterina LENGYEL Abstract Four different strains of Saccharomyces cerevisiae yeast samples were irradiated using a 90Sr nuclear source. The results of this ongoing study reveal that the small irradiation doses used in the work reported here produce measurable changes in the fermentation parameters and in the lipid and phospholipid levels. Key words: Saccharomyces cerevisiae, small doses, fermentation. 1. INTRODUCTION Yeasts are a growth form of eukaryotic microorganisms classified in the kingdom Fungi. Approximately 1500 species of yeasts have been described, most of which reproduce asexually by budding, although in a few cases by binary fission. Yeasts are unicellular, although some species with yeast forms may become multicellular through the formation of a string of connected budding cells known as pseudohyphae, or true hyphae as seen in most moulds. Industrial yeasts are of special interest for microbiology and biotechnology because they have a big content of lipids and phospholipids that are currently used in naturist products preparation. Nowadays, comprehensive research is being done with respect to the methods of obtaining lipids and phospholipids from lipid biocomponents, in order to identify new methods for obtaining liposomal substances, needed by the pharmaceutical, cosmetic and medical industry. At present, egg lecithin is being used instead but the use of this source has several drawbacks, such as for example the fact that it oxidizes easily. Eukaryotes (yeasts, fungi, algae) are the main microorganisms that produce lipids and phospholipids. Of great interest to microbiology and biotechnology are the researches conducted in the field of phospholipids synthesis, of obtaining phospholipids from microorganisms and of optimizing culture media for their cultivation. During the last decades, ionizing radiations have been investigated to determine their influence on living organisms. Radionuclides are released into the environment from various sources: nuclear accidents, as planned discharges from the nuclear power industry, disposal of radioactive waste, medical use, nuclear weapons development or recycling. Ionizing radiations are able to cause toxically and genetic effects on organisms, because radionuclides do accumulate in biotic and abiotic components of the environment [1]. Nuclear radiation can stimulate morphogenetic changes manifest in the early development stages [2], [3]. Nuclear radiation can directly disturb metabolic processes, such as photosynthesis, growth, plant respiration, active transport as well as ionic balance and enzyme synthesis [4]. The literature reveals that low doses of ionizing radiations can stimulate cell proliferation [5], [6]. In this study, we investigated the low doses of beta radiation influence on the four Sa ccharomyces cerevisia strings, mainly the influence on the fermentation process. The details of the samples irradiation and fermentation analysis are presented in sections 2 and 3. 2. SAMPLE IRRADIATION The samples were irradiated one at a time in an irradiation chamber that was build for this purpose. The hole in the upper part fits a glass tube than can be easily inserted and extracted. The tube is used to place the sample in the proximity of the beta irradiation source. The schematic of the irradiation chamber is presented in Fig.1. The dose debit through the glass tube, in the very location where the yest samples were placed one by one, was measured using a RFT KD27012 dosimeter with an ion chamber. Fig. 1 The beta-irradiation chamber The ÃŽ ²- source was 90Sr and decays by the scheme: (1) having Eà ¯Ã‚ Ã‚ ¢=546 keV, with a branching ratio of 100% [7]. The daughter nucleus, 90Y, is unstable as well. It decays by the scheme: (2) with the energies, branching ratios and half-lives presented in Table 1. Table 1 The ÃŽ ² energies, branching ratios and half-lives of the 90Y [7]. Eà ¯Ã‚ Ã‚ ¢ (keV) Ià ¯Ã‚ Ã‚ ¢ (%) Half-life, hours 93.83 0.0000014 64.00 519.39 0.0115 64.00 642.77 0.0018 3.19 2280.1 99.9885 64.00 Four strings of Saccharomyces cerevisiae yeast samples were used. The first string, labeled SCP, was separated from Turkish yeast having the trademark Pakmaya. The second string was labeled SCO and was separated from yeast having the trademark Dr.Oetker. The third string, labeled SCSL, was separated from French yeast having the trademark Saff Levure. The fourth string, labeled SCH, was separated from Dutch yeast having the trademark Hollandia. Two sample of each string were prepared, having a suffix 1, for the control, nonirradiated samples and 2 for the irradiated samples. The yeast sample type, irradiation time and irradiation dosis are presented in Table 2 Table 2 The sample type, irradiation time and irradiation dosis Nr. Sample Irradiation time (h) Irradiation Dosis, (Gray) 1 SCP1 0 0 2 SCP2 5 12 3 SCO1 0 0 4 SCO2 5 12 5 SCSF1 0 0 6 SCSF2 5 12 7 SCH1 0 0 8 SCH2 5 12 3. Fermentation details Both the control and the irradiated samples were cultivated in Malt Agar. Malt Agar is used for isolating and cultivating yeasts and molds from food and for cultivating yeast and mold stock cultures [8], [9]. Malt Agar contains malt extract which provides the carbon, protein and nutrient sources required for the growth of microorganisms. Agar is the solidifying agent. The acidic pH of Malt Agar allows for optimal growth of molds and yeasts while restricting bacterial growth. The eight samples described above were subject to a fermentation process conducted in identical conditions, in an ECONOMY 20 fermenter. The temperature was maintained constant at 28 °C. The acidity was maintained at pH=5.8. The maltasic activity (which is defined as catalysis of the hydrolysis of maltose by an alpha-D-glucosidase-type action) and the CO2 emission were monitored for 96 hours [10]. The results of the fermentation activity, measured as CO2 emission and the maltasic activity measured at 24 hours interval are presented in Table 3. The CO2 emission at 24 hours interval is presented in Fig. 2 and the maltasic activity in Fig. 3. Table 3 Results of the fermentation activity Nr. crt. Yeast string CO2-24h maltasic activity 24 h CO2-48h maltasic activity 48 h CO2-72h maltasic activity 72 h CO2-96h maltasic activity 96 h 1 SCP1 0.5 780 1.5 810 1.3 800 0.3 760 2 SCP2 0.8 1220 1.6 1240 1.5 1200 0.5 1200 3 SCO1 0.7 840 1.3 850 1.1 830 0.2 820 4 SCO2 0.9 1280 1.7 1290 1.5 1280 0.4 1250 5 SCSL1 0.6 760 1.4 780 1.2 750 0.3 750 6 SCSL2 0.7 1190 1.5 1210 1.3 1160 0.3 1180 7 SCH1 0.7 860 1.4 920 1.1 900 0.4 850 8 SCH2 0.8 1230 1.6 1240 1.4 1220 0.2 1220 Fig. 2 The CO2 emission for the four Saccharomyces cerevisiae yeast strings Examining Table 1, Fig. 2 and 3 we notice that the fermentation process produced by the irradiated samples (batch having the suffix 2) is more intense, which is proved by the increased CO2 emission and by the increased maltasic activity. 4. Conclusions and discussions One of the efficient procedures to select high productivity yeasts is irradiating the samples with nuclear radiation. To our knowledge, results of ÃŽ ² irradiation on yeast have not been reported yet and the literature is poor in ÃŽ ² yeast irradiation [11]. Examining the results we can conclude that for all four Saccharomyces cerevisiae yeast strings the low 12 Gray ÃŽ ² irradiation dosis had a stimulating effect in respect of the fermentation process. The SCO and SCH strings had the higher stimulation effect. Fig. 3 The maltasic activity for the four Saccharomyces cerevisiae yeast strings We believe that the differences are produced by the yeast genome changes produced by à ¯Ã‚ Ã‚ ¢ irradiation. The results of this ongoing study revealed that the small irradiation doses used in the work reported here produce measurable improvement in the fermentation parameters. Special care must be taken in evaluating the side effects of the à ¯Ã‚ Ã‚ ¢ irradiation REFERENCES V.I. Kryukov, V.I. Shishkin, S.F. Sokolenko, Radiacionnaja biologija. Radioekologija, 36, 209, (1996). I.W. Mericle, R.P. Mericle, Radiat. Botany, 7, 449, (1967). D. Chicea, M. Racuciu, Romanian Journal of Physics 52, 5-6, 589, (2007). V.A. Sidorov, Naukova dumka, Kiev, (1990). Conter, D. Dupouy, H. Planel, Int J Radiat Blot, 43, 421, (1983). F. Croute, J.P. Soleilhavoup, S. Vidal, S. Dupouy, H. Planel, Rad.Res., 92, 560, (1982). LBNL Isotopes Project Nuclear Data Dissemination Home Page. Retrieved March 11, 2002, from http://ie.lbl.gov/toi.html Ewing, Davis and Reavis, Public Health Lab. 15, 153, (1957). MacFaddin, Media for isolation-cultivation-identification-maintenance of medical bacteria, vol. 1, Williams Wilkins, Baltimore, (1985). H. Kuriyama, W. Mahakarnchanakul, S. Matsui, H. Kobayashi, Biotechnol. Lett., 15 (2), 189, (1993). J. Kiefer, M. Ebert, Biophysik., 6, 3, 271, (1970).

Heat of Formation of Magnesium Oxide

ObjetiveTo determine the heat formation of MgO (Magnesium Oxide) using Hess’s Law, which states the heat within a chemical reaction is independent of the pathway between the initial and final states.IntroductionChemical reactions require heat energy to complete, called an endothermic reaction, or produce heat energy, and thus called an exothermic reaction. The heat energy produced by such reactions can be measured using a calorimeter, a piece of equipment that can isolate the reaction in an insulated container. Using the calorimeter one can then determine the rise and fall in temperature of the reaction. When this temperature change is multiplied by the heat capacity, the amount of heat needed to raise the temperature of a body by one degree, we can measure the change in converting our initial components (reactants) to their respective products.In this experiment we will measure the amount of heat released from 3 reactions (ΔHA ΔHB ΔHC) and calculate the sum of all 3 reactions to determine ΔHT, which will give us the heat formation of MgO. If Hess’s law holds true and barring minimal experimental error, the pathway we use to determine ΔHT should have no bearing on our calculation matching the accepted calculation of MgO.MethodsAs per lab manual we used a calibrated calorimeter (using a rounded end thermometer so as to not puncture a hole in the calorimeter) to determine the heats of reaction for Magnesium (Mg) with Hydrochloric Acid (HCl) and Hydrochloric Acid with Magnesium Oxide (MgO). Then using mathematical formulas we were able to calculate the heat formation of MgO, which is measured in kJ/Mol. Since both reactions are in dilute water solutions of  HCl it was necessary to know the heat capacity of water, but because some heat would be transferred to the calorimeter whose heat capacity was unknown, we had to record a correction factor (x) based upon the specific heat of water using the equation [m(h2o)+X]Cwater+Δwate r=-1(m(ice water)CwaterΔtice water).We then recorded the mass (m) of room temperature water and ice water each in a respective cup and then poured the ice water into the room temperature water and recorded the temperature change. By knowing (x) we could then calculate the heat of reaction for Mg with HCl (ΔHA kJ/mol) and for HCl with MgO (ΔHB kJ/mol) using the equation q=m(HCl+X)C ΔT where m is the mass of the reactant used with Mg + X, C is the heat capacity of water (4.184 J/g °C), and ΔT is the total temperature change in each reaction. Using the results of these calculations and Hess’s law we can then determine the heat formation for MgO.DataAll mass readings are given in units of grams (g), and all temperature readings are given in degrees Celsius ( °C).Part AMass of the Calorimeter + RoomTemp Water (g)48.08Mass of room temp water (g)46.29Mass of Cal + room temp water + icewater (g)115.40Mass of ice water (g)67.32Temp of room temp water ( °C)42. 4Temp of the ice water ( °C)0.1Final temp. of room temp water ( °C)17.3Change in temp of ice water ( °C)17.2Change of temp of room temp water ( °C)-25.1Mass of the calorimeter (g)1.79Part 2AMass of Calorimeter (g)1.79Mass of Cal + HCl (g)103.55Mass of HCL (g)101.76Mass of Mg (g)0.5Temperature of HCl ( °C)20.3Final temperature of HCl + Mg ( °C)42.0Change in Temperature ( °C)21.7Part BMass of Calorimeter (g)1.79Mass of Cal + HCl (g)101.76Mass of HCl (g)99.88Mass of MgO (g)0.8Temperature of HCl ( °C)20.3Final temperature of HCl + MgO ( °C)25.8Change in Temperature ( °C)5.50Results and DiscussionTo calculate X using the equation [m(h2o)+X]Cwater+Δwater=-1(m(ice water)CwaterΔtice water) the variable X must be isolated and doing so we were than able to calculate the correction factor:Based on the calculations of the calorimeter correction factor, X was determined to be 0.158 g. Then using the equation q=m(HCl+X)C *ΔT, where q is equal to the amount of energ y given off, and than calculating the value in -kJ/Mol (because these are exothermic reactions) we were able to determine ΔHA and ΔHB.qA=m(HCl+X)C xΔTqA=(101.76 g + 0.158 g) x 4.184 J/g °C x 21.7 °CqA= 9250 J = 9.250 kJ 9.253602176qB= m(HCl+X)C xΔTqB=(101.76 g + 0.158 g) x 4.184 J/g °C x 5.50 °CqB=2350 J = 2.350 kJTo then calculate the heat formation of MgO ΔHT, the sum of all the reactions must be determined including ΔHC, the heat formation of water, which is already predetermined to be -285.8 kJ/mol. However to determine the proper equation for ΔHT, the stoichiometric equations must first be balanced:Therefore the heat formation of MgO was determined to be -618.35 kJ/mol. According to the textbook, the accepted value for ΔHT=-601.8 kJ/mol. To determine the accuracy of the calculation we can determine the % error:As far as accuracy goes a percent error of 2.75% is very acceptable. Because the methods of the experiment were conducted using a crude calorimeter I would have expected the percent error to be higher, assuming that because of it’s construction it would not have very high efficiency.I would expect that any error that might have occurred happened during the transference from one cup to another. Because the substances were transferred so quickly and taking into account the number of seconds that it took to replace the thermometer to begin recording data again it is possible that energy was either lost in the transfer or energy was lost before the recording was actually able to begin.ConclusionIn this lab we were able to determine the heat of formation of MgO using a simply constructed calorimeter, which was found to be -618.35 kJ/mol.

Analysis Of The Book The House On Mango Street

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The Columbine High School Shooting By Rachel Joy Scott

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