Etude des dégâts qualitatifs et quantitatifs dus aux Bruches sur les légumineuses au Maroc

Les pertes qualitatives et quantitatives des légumineuses en post-récoltes demeurent un important souci des agriculteurs au Maroc. Les ravageurs de stockage sont l’un des facteurs les plus destructifs des stocks de légumineuses. Pour ce fait, le présent travail porte sur l’identification des différentes espèces d’insectes attaquant les légumineuses stockées au Maroc, et l’évaluation de leurs effets nuisibles sur les pertes en qualité, quantité et faculté germinative des grains. Les résultats mettent en évidence la dominance des coléoptères de la famille Bruchidae, qui attaquent plus de la moitié des quantités stockées surtout pour les cultures de fève et féverole. Les pertes pondérales et le pouvoir germinatif ont aussi été  étudiés. Les résultats ont montré une perte en poids des grains bruchés pouvant aller jusqu’à 34%. Le pouvoir germinatif a été négativement affecté; il a oscillé entre 75 et 85% selon le nombre d’opercule par grain.    

Microbial Desulfurization of Diesel Oils by Selected Bacterial Strains

Because of increasingly stringent regulations concerning the sulfur content of motor fuels, sulfur removal by biocatalytic means is often considered as a potential alternative to conventional deep hydrodesulfurization processes used in the refinery industry. The first microbial strain able to selectively oxidize sulfur of molecules such as dibenzothiophene (DBT) without altering its carbon content, Rhodococcus erythropolis IGTS8, was isolated more than ten years ago. The metabolic pathway (4S pathway) was elucidated and the genes involved characterized and sequenced. The present study aimed at exploiting microbial diversity to select new strains potentially interesting for ultradeep desulfurization of diesel oils, taking into account industrially important criteria. In a first step, 15 pure strains able to use DBT as a sole sulfur source and to convert it to 2-hydroxybiphenyl (HBP) were obtained from different soils. In a second step, 5 isolates belonging to the Rhodococcus/Gordonia cluster and exhibiting good growth characteristics and high biodesulfurization activities in both aqueous and organic media were selected. The action of resting cells from these strains towards different types of diesel oils was also determined in order to better assess the potentiality of biodesulfurization, especially as a finishing step complementary to deep hydrodesulfurization (HDS). Actually, in spite of their taxonomic similarity, the 5 strains displayed different activities towards the diesels oil tested. Biodesulfurization yield was also dependent upon the diesel oil used, especially its sulfur content. Some HDS-recalcitrant compounds such as 4,6-dimethyl dibenzothiophene, could be completely removed, but highly-alkylated dibenzothiophenes were resistant to the action of the biocatalysts

Properties of Allyl Alcohol-Resistant Mutants of Clostridium butyricum Grown on Glycerol

Mutants of Clostridium butyricum E5 exhibiting resistance to allyl alcohol which produced the same quantities of 1,3-propanediol as the wild-type strain but more acetate than butyrate were isolated. The acetate-butyrate formation plays a major function in the regulation of the internal redox balance. Allyl alcohol resistance can be attributed not to the loss of 1,3-propanediol dehydrogenase but to a shift in the reductive properties of the enzyme. The data support the view that cellular regulation is modified to avoid intracellular accumulation of 3-hydroxypropionaldehyde

Les nématodes des légumineuses alimentaires à grosses graines dans le bassin méditerranéen

National audienc