Assessment the suitability of some yeast strains for production of microbial lipids

Three yeast strains were used for production of microbial lipid globules using glucose as sole carbon source. These strains were: Candida tropicalis, C. utilis and C. Boidinii. The results showed that C. tropicalis was the most suitable organism for lipid production among the three different yeast strains under study. The efficient strain C. Tropicalis was grown on three different culture modes: Batch, twice fed batch and continuous for studying the most cultural mode for production of lipid. The lipid production rate during the second phase of twice fed batch culture was higher than that of batch culture using synthetic medium. The lipid production rate in continuous culture was higher than batch or twice fed batch, it was 2 - 3 times higher than the batch cultures. The obtained lipid was analyzed for their fatty acids composition. These compositions showed differences in their percentages of batch and continuous culture modes with C. Tropicals. Palmitic C 16: 0 and oleic C 18: 1 fatty acids were the dominant acids in both cultural modes. In batch culture C 16: 0 and C 18: 1 fatty acids were lower than those obtained from continuous culture, while unsaturated fatty acids C 18: 2 and C 18: 3 were higher

Assessment of the role of crude pectinolytic and cellulolytic enzymes on the curling of root hairs and nodulation in some legume plants

Different genera of bacteria and fungi were isolated from the rhizosphere of soybean and clover plants. They were identified and tested for their activity to produce pectinase and cellulase enzymes. The activity of these enzymes were determined by bioassay tests. The role of these crude enzymes were tested for their effect on the rhizobial invasion into root hairs of legume plants in relation to the incidence of curling root hairs and nodulation on legume roots, also were tested for their effect on the rhizobial biomass. The results revealed that the significantly highest activity of polygalacturonase and pectin-methyl estrase enzymes were produced by isolates of Erwinia sp. From bacteria, while Aspergillus sp. Isolates were the most significant active from fungi in this respect. On the other hand, the isolates of Bacillus and Rhizopus sp. Were significantly lowest in these enzymes activity. The significantly highest cellulase activity was obtained by strains of Pseudomonas and Aspergillus sp., while the isolates of Bacillus and Rhizopus sp. were the lowest in this respect. The addition of these crude enzymes, secreted by soil microflora, to the germinated legume seeds inoculated with specific rhizobia, significantly increased the number of curled root hairs and subsequently the nodule formation. Lower levels of these enzymes stimulated infection by rhizobia more than higher levels, but these crude enzymes had no effect on the rhizobial biomass

effect of organic manuring and irrigation intervals on the microbiological and enzymatic activities under wheat, in New-Valley province

Two field experiments were carried out, in two different texture locations at the Agricultural Experimental Station of El-Kharga, New Valley Governorate, during two successive seasons, to study the effect of organic manuring [Multhum] in different doses [0, 2, 4, 8 t/fed.] and two irrigation intervals [14 and 21 days] on the microbiological and enzymatic activities under wheat, and their effects on wheat yield. The results showed that the application of organic manure did not increase the biological activities under wheat after the end of the first year, while its positive effect was clarified at the end of the second year, measured by the noticeable increase in the counts of total bacteria, streptomyces and aerobic cellulose decomposers, as well as the enzymatic activity. The elongation of the irrigation interval had a negative effect on the biological activities under wheat during the course of the experiment and also significantly decreased plant height, leaf area and the yield of wheat in both types of soil under study. It seems that the irrigation interval [14 days] was the most favorite for biological activity in soil