Papers by Pierre Ravelonandro
European Journal of Environment and Earth Sciences
The study concerns the analysis of physic-chemical parameters in order to establish the state of ... more The study concerns the analysis of physic-chemical parameters in order to establish the state of pollution of a garbage dump site. The interpretation of the data is done by standardized principal component analysis. Thus, leachate samples were taken at 9 study stations in wet and dry periods. The results show that among the parameters studied, there is a high content of BOD5 (592,035 mg/L), EC (16,786 mS/cm) and COD (1373,684 mg/L). The concentration level of nitrates and nitrites greatly exceeds the norm; for the old landfill, the NO2- contents vary from 191,527 mg/L to 875,206 mg/L and the NO3- ranging from 384,926 mg/L to 1584,021 mg/L, we thus observe the influence of humidity on the concentrations of physic-chemical parameters. Furthermore, the chemical composition and mass concentrations of pollutants at the sites are highly dependent on the nature of the waste and the degree of pollution differs from one site to another. The considerable increase in the content of these pollu...
Deux types de ceramiques poreuses C 1 et C2 ont ete elabores a partir d'argiles kaolinitiques... more Deux types de ceramiques poreuses C 1 et C2 ont ete elabores a partir d'argiles kaolinitiques de Madagascar. Une caracterisation physico-chimique a ete realisee en vue de leur utilisation comme support de micro-organismes dans les procedes biotechnologiques. C 1 et C2 ont ete utilisees pour immobiliser des cellules de levures Saccharomyces cerevisiae type II SYGMA. Des tests d'adhesion des levures ont ete realises. C 1 et C2 apparaissent capables de fixer des levures. Les meilleurs resultats de fixation sont obtenus pendant la phase exponentielle de croissance ou a son voisinage. La fermentation alcoolique est conduite dans un bioreacteur pilote a cellules immobilisees sur des plaques en forme plate de ceramique C 1 et C2 a partir de melasse de canne a sucre de Madagascar. Le fonctionnement du systeme a ete etudie pour des taux de dilution variant de 0,096h¯¹ a 0,335h¯¹. La performance du systeme fermentation levures - support ceramique a ete evaluee sur chacune des deux cer...
Routine tests for genetically modified organisms (GMO) detection in flour samples are widely deve... more Routine tests for genetically modified organisms (GMO) detection in flour samples are widely developed, these led to the apparition of multiple methods based onto the deoxyribonucleic acid (DNA) extraction rather than the efficient techniques available. The aim of this study was to investigate flour content. Flour samples from known and unknown sources were assayed according to a modified protocol of DNA extraction. Whether the material sources were powder, the protocol we developed was based onto the adaptation of known protocol of DNA extraction from leaves to a suitable technique adapted to extract a high quality of genomic DNA from flour. The consequent accurate investiga tion previously needed a strict control of DNA that was successfully used as template. Polymerase chain reaction (PCR) analyses permitted to demonstrate the biological sources of the flour and notably the stable integration of the following foreign genes in maize. Identification of GMO through the DNA extractio...
J Chem Technol Biotechnol, 2008
BACKROUND: Spirulina platensis (Toliara, Madagascar) provides a food supplement which can fight a... more BACKROUND: Spirulina platensis (Toliara, Madagascar) provides a food supplement which can fight against malnutrition and food insufficiency in Madagascar. In this country, the current production from three open basins is not sufficient to cover needs, and presents drawbacks such as low productivity and possible contamination. Thus cultivation of S. platensis in a closed photobioreactor opens the possibility of extending this microalga production. In this study, the influence of colour and intensity of the light on S. platensis growth and protein content was investigated in a bubble column. RESULTS: Growth kinetics were obtained for four colours (green, white, red and blue) and four intensities (400, 800, 1000 and 1200 lux) of light. The influence of light colour on Spirulina growth was discussed. The highest productivity (183.6 mg L −1 d −1) and concentration (2643 mg L −1) were obtained for green light at 1200 lux. The protein content was 58%. CONCLUSION: Using green light allows improvement of S. platensis growth. Performance obtained with the closed system was higher than that reported in the literature.
This study was undertaken to evaluate the heavy metals contamination of copper, zinc, manganese, ... more This study was undertaken to evaluate the heavy metals contamination of copper, zinc, manganese, iron, chromium, nickel, lead and cadmium, to assess the environment quality of the coastal area from town activities. Nickel, lead and cadmium are used in different kind of current accumulators and they are dangerous for sea wild life and for human food resources. The five others metals are usual and at a high concentration they are able to threat environment system. Six samples had been choice at two town of Madagascar north-western coast: Nosy Be and Mahajanga, in February, 2007. These sampling points stand in front of each mean sewage mouths in each locality. and 2 give us same descriptions of each sampling points. These two sampling area are among the principal fishing area of Madagascar. Three kinds of analytical method were used for metals determination and quantification: flame spectrophotometer atomic absorption, UV spectrophotometer, and voltammeter method. The flame spectrophotometer atomic absorption gives the best result by testing with certified reference materiel. Our data suggested that Mahajanga's stations have higher values of cadmium (1 mg/kg) and lead (91 mg/kg) than the non-contaminated sediments. However, the concentrations of other metals such as copper, zinc, manganese, iron and chromium in Nosy Be sediments, were twice as higher than in those of Mahajanga. In compiling our data obtained at the same stations in the vertical water column, we would like to confirm the growing order of potential absorption between metals and sediments, nickel, copper, cadmium and lead. According to the results of determinations, we suggested that more determination should have done in open sea to assess metals in a wide scale.
Journal of Chemical Technology and Biotechnology, 2008
BACKROUND:Spirulina platensis (Toliara, Madagascar) provides a food supplement which can fight ag... more BACKROUND:Spirulina platensis (Toliara, Madagascar) provides a food supplement which can fight against malnutrition and food insufficiency in Madagascar. In this country, the current production from three open basins is not sufficient to cover needs, and presents drawbacks such as low productivity and possible contamination. Thus cultivation of S. platensis in a closed photobioreactor opens the possibility of extending this microalga production. In this study, the influence of colour and intensity of the light on S. platensis growth and protein content was investigated in a bubble column.RESULTS: Growth kinetics were obtained for four colours (green, white, red and blue) and four intensities (400, 800, 1000 and 1200 lux) of light. The influence of light colour on Spirulina growth was discussed. The highest productivity (183.6 mg L−1 d−1) and concentration (2643 mg L−1) were obtained for green light at 1200 lux. The protein content was 58%.CONCLUSION: Using green light allows improvement of S. platensis growth. Performance obtained with the closed system was higher than that reported in the literature. Copyright © 2008 Society of Chemical Industry
Food and Bioproducts Processing, 2011
Arthrospira (Spirulina) platensis Toliara isolated from alkaline and salt lakes in the south-west... more Arthrospira (Spirulina) platensis Toliara isolated from alkaline and salt lakes in the south-western area of Madagascar is a potential source of proteins that could efficiently fight against food deficiency in developing countries like Madagascar. Up to now, productivity in this country has been low, so a better understanding of the growth conditions of this species is needed to improve its production. Growth experiments were undertaken in bubble columns at laboratory scale. The influence of agitation of the culture, medium salinity (ranging from 13 to 35 g L −1 ) and CO 2 addition (ranging from 0 to 2%, v/v) on growth and protein content was examined. Because Arthrospira cells are fragile, a bubble column without additional mixing gave the best growth. Arthrospira (Spirulina) platensis showed higher specific growth rate ( max ) and protein content for lower salinity. Addition of 1% of CO 2 improved the productivity by near 60%. The feasability of semi-continuous culture was demonstrated and optimal culture conditions led to a mean productivity of 0.22 ± 0.03 g L −1 d −1 , a mean specific growth rate of 0.015 ± 0.002 h −1 and a protein content of 53 ± 2% of total dry weight.
Journal of Natural Products, 2009
Bioassay-guided fractionation of a marine extract from Trididemnum cyclops afforded the new lipop... more Bioassay-guided fractionation of a marine extract from Trididemnum cyclops afforded the new lipopeptide 39-oxobistramide K (1) and the known bistramides A (2) and D (3). Structure elucidation of 1 was carried out by analysis of one- and two-dimensional NMR spectroscopy and HRMS data. Bistramides have been reported to exhibit antiproliferative activity in the nanomolar range against a number of tumor cell lines in vitro and in vivo. The isolate 1 was tested for antiproliferative activity against the A2780 cell line and exhibited an IC(50) value of 0.34 microM.
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Papers by Pierre Ravelonandro