DYNAMICS OF SOME PHYSICAL AND CHEMICAL INDICATORS OF SUCEAVA RIVER WATER IN 2009

For a physical-chemical evaluation of global quality of Suceava river water, water samples were collected every two months during 2009, on the following sections (sites, locations): • Brodina at 142 km distance from mouth; • Mihoveni, 45 km distance from mouth; • Tişăuţi, 34 km distance from mouth. The values obtained from physical - chemical analyzes of water were processed and compared with the limit values of quality grades, provided by the norm on surface water quality classification, in order to determine the ecological status of water bodies according to Order nr.161/2006. Along Suceava river, the water flows increase from upstream to downstream: the maximum value 4.47 m3/s at Brodina (14.07.2009) increase at Mihoveni, the maximum value being 13.22 m3/s (14.07.2009) and at Tişăuţi, the flow recorded on 14.07.2009 is 13.7 m3/s. The annual average flows have fluctuated on very wide limits, depending on pluviometrical characteristics of rainfall on each year. Usually, the highest average flow is recorded in April, followed by June (Maxim, 2012). Higher levels of flow in these months can be explained by strong contribution of rainwater supply to which is added the water from snowmelt. The smallest amounts of water are flowing in winter and autumn. This paper systematizes the results concerning the dynamics of some experimentally determined physical and chemical indicators during 2009, on Suceava river water. (PH, OD, CBO5, CCOMn, CCOCr).In order to have an accurate picture of analyzed physico-chemical parameters, the average values of these indicators were presented for comparison. Thus, the concentration of hydrogen ions (pH) has values between 8 in the lower course and 8.3 at the upper course, at Brodina. At this value, the waters are favourable for the organisms development. The medium content of dissolved oxygen decreases from February to July and then increase until December - January, the average values ranging between 10.53 mg/l and 14.25 mg/l. Biochemical oxygen demand has an average value of 1.45 mg/l in the upper course and 6.25 mg/l at the mouth. The chemical oxygen demand falls between 2.34 mg/l at Brodina and 4.67 mg/l at mouth, on Suceava. In 2009, Suceava River in the control sections Brodina, Mihoveni and Tişăuţi was framed in quality classes I and II for all analyzed indicators

Evaluarea conţinutului de plumb în solurile Republicii Moldova

Articolul prezintă o evaluare a datelor de laborator privind conţinutul plumbului în solurile Republicii Moldova Analiza rezultatelor obţinute denotă faptul existenţei unei probleme actuale de sănătate publică, cauzată de poluarea mediului cu compuşii plumbului. Poluarea solului cu plumb prezintă o problemă stringentă de sănătate publică determinată de expunerea populaţiei la poluanţii în cauză

Influence of carbon sources on the activity of biochemical indicators of oxidative stress in saprophytic fungus Rhizopus nigricans

Reactive oxygen species are derived from molecular oxygen used in respiration and they are capable of damaging cellular components, including proteins, lipids and DNA. Oxidative stress is caused by an imbalance between production of reactive oxygen species and the ability of biological system to detoxify reactive intermediates or to repair the inflicted damages. The purpose of this paper is the determination of the antioxidant potential in saprophytic fungus Rhizopus nigricans. It was determined the influence of carbon sources, represented by grinded cereal caryopses, and their concentration from culture medium on the fungus capacity to synthesize antioxidant enzymes like catalase and peroxidase. Enzymatic assays were performed at three time intervals: 5, 10 and 15 days, using both fungus mycelium and culture liquid. After analyzing the results we can point out a correlation between the nature and concentration of carbon source, the age of fungal culture and the production of oxidoreductases. In the first time period catalase and peroxidase production is maintained at low levels, but with depletion of nutrients and accumulation of toxic metabolic byproducts a significant increase takes place in the second time period. The last time period corresponds with the entering in decline phase of culture and with drastic decrease in production of both enzymes

Researches regarding some dehydrogenases activity in fungus Rhyzopus nigricans grown on medium with different concentration of grinded wheat caryopsis

This study followed the activity of dehydrogenases in the Krebs cycle: malate dehydrogenase, isocitrate-dehydrogenase, succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, and glucose-6-phosphate dehydrogenase, an enzyme enzyme of pentose phosphate pathway in fungus Rhizopus nigricans. For conducting experiments, the fungus was cultivated on medium with different concentrations of grinded wheat caryopsis. From the composition of the liquid medium Czapeck Dox, carbon source (sucrose) was replaced with different amounts of grinded wheat caryopsis, resulting three variants: V1 = 1g/100ml, V2 = 2g/100ml, V3 = 3g / l and a control variant, in which the composition of medium remains unchanged. Experimental measurements were carried out at two intervals: 7 and 14 days, and were performed using fungus mycelium. The results showed the influence of fungus age and different concentrations of grinded wheat caryopsis from the culture medium composition, with significant differences between the two measurements and between the working version

Researches regarding catalase and peroxidase activity in fungus Rhyzopus nigricans grown on medium with different concentration of grinded wheat caryopsis

The purpose of this study was to assay catalase and peroxidase activity in the saprophytic fungus Rhizopus nigricans, grown on mediums containing grinded wheat caryopsis. For the conduct of the experiments, from the composition of culture medium Czapeck Dox, the carbon source - sucrose was replaced with different amounts of grinded wheat caryopsis, resulting three experimental variants: V1 = 10 g/l, V2 = 20 g/l, V3 = 30 g/l. The control variant composition remained unchanged. Measurements were made at two time intervals: 7 days and 14 days after inoculation, using fungus mycelium and culture liquid. Determination of catalase activity was performed using Sinha method (Artenie Vl., et al., 2008), and determination of peroxidase was carried out on the basis of ortho-dianisidine method (Cojocaru D.C., 2009). The results show that there are significant differences between the two determinations and between work options. Enzyme activity is influenced by both: the age of fungus and different concentration of grinded wheat caryopsis

Influence of some aminoacids on the activity of cellulolytic and xylanolytic enzymes in the fungus Trichoderma reesei QM-9414

Cellulases and hemicellulases are hydrolytic enzymes involved in the conversion of lignocellulose to glucose. Filamentous fungus Trichoderma reesei is one of the most known and efficient producers of cellulases and hemicellulases. These enzymes have a huge potential application in the bioconversion of agricultural wastes and production of valuable products that can be used later in different areas. Lignocellulose-degrading enzymes are induced by the presence in the cultivation medium of carbon sources such as cellulose, as well as other culture parameters such as pH, concentration of the inoculation material, nitrogen source used, etc. In this context, this study aims to investigate how different amino acids influence the activity of cellulases and hemicellulases in the fungus Trichoderma reesei. Therefore T. reesei QM-9414 was grown on medium in which the carbon source was replaced with 30 g / l wheat straw and nitrogen source with a 1 g / l various amino acids: alanine, glutamic acid, methionine, valine, asparagine, histidine and serine. Total cellulase activity, endoglucanase activity, ß-glucosidase and b-xylanase were assayed. The results demonstrate that these enzymes are stimulated by the presence in the culture medium of asparagine and glutamic acid and inhibited by the presence of methionine

Influence of ph on ß-xylanase activity in the filamentous fungi Trichoderma reesei, Trichoderma viride and Phanerochaete chrysosporium

Xylanases are industrially important enzymes. They are produced by a wide range of fungi, particularly filamentous fungi, such as Trichoderma reesei, Trichoderma viride and Phanerochaete chrysosporium. Xylanases are enzymes that catalyze the hydrolysis of 1, 4-ß-D-xylosidic bonds in xylan, resulting xylose, a primary carbon source in cellular metabolism. Cellulose and xylan are two polysaccharides that induce effectively the synthesis of xylanolytic enzymes produced by the fungi mentioned above. Xylan is found in high quantities in the cell wall of annual plants. One of the main parameters influencing the activity of xylanases is the hydrogen ion concentration, pH of these enzymes fluctuating from one species to another. To assess the impact pH has on xylanase activity, especially on ß-xylanase, filamentous fungi Trichoderma reesei, Trichoderma viride and Phanerochaete chrysosporium were grown at different levels of pH, on a modified Mandels medium, were the main carbon source consists of byproducts from local agricultural practices (wheat straws and corn stalks). A dynamic profile of the activity was mapped, during a ten day period. The results indicated that ß-xylanase activity is influenced by both the hydrogen ions concentration and the nature of the carbon source

RESEARCH ON THE INFLUENCE OF H+ IONS CONCENTRATION ON THE DYNAMICS OF THE ACTIVITIES OF CERTAIN DEHYDROGENASES OF THE KREBS CYCLE IN THE MONILINIA LAXA (ADERH. & RUHL.) HONEY FUNGUS PARASITIC ON PLUM TREES

During the process of nutrition, thus in that of their growth, microorganisms are subject to the influences of certain environmental factors that condition the microbial activity determining either the growth and reproduction, or the inhibition of activity and the inactivation of microorganisms. A well known means of expressing the H+ ions concentration in a certain environment is the pH, an important chemical factor that is closely observed when growing ascomycetes, for any alteration of its value entails conformational alterations of their enzymes, the characteristics of the substrate, such that they can no longer interact with the active site of the enzyme or be subject to catalysis. The present study comprises the results of our research on certain oxidoreductase implied in the steps of the Krebs cycle in the Monilinia laxa (Aderh.&Ruhl.) Honey, a fungus that parasites the prune. The enzymatic determinations took place at 7 and 14 days from the mycelium of the fungus cultivated in Leonian media, whose pH was adjusted to values between 2.0 and 9.0 by using NaOH 1N and HCl 0,1N solutions. We registered different values of the dehydrogenasic activity, directly correlated with the physiological condition of the fungus (given its age) and with the initial pH value of the culture’s environment