Biochemical and ultrastructural studies of Penicillium chrysogenum, Talaromyces leycettanus and T. thermophilus.

A comparative study of the lipids, proteins, amino acids and of the ultrastructure of lipid bodies of Penicillium chrysogenum (mesophilic), Talaromyces leycettanus (thermotolerant) and T. thermophilus (thermophilic) was done. The highest lipid content was found in T. thermophilus and highest protein content in P. chrysogenum whilst a total of 17 amino acids were found in P. chrysogenum and T. thermophilus and only sixteen were detected in T. leycettanus. Ultrastructural features of lipid bodies are reported and compared.

Fungi Associated with Dates in Saudi Arabia.

The fungal counts per gram of air-dried dates, of eight local date-palm varieties, varied markedly on different synthetic media. Seri and Shakra varieties had highest fungal counts whereas Medina had the lowest. Aspergilus flavus , A. niger , Penicillium rubrum , P. oxalicum , Rhizopus stolonifer , Stemphylium verruculosum and Fusarium sp. were generally associated with various date varieties. Apparent colonization of the fungi was obtained by increasing the relative humidity to 90% at 30 and 40°C. Best growth of the isolated fungi in artificial media was obtained at 60% glucose concentration.

Bacillus stearothermophilus from Saudi Arabian Soils.

Ten thermophilic Gram-positive bacteria were isolated from various soils of Saudi Arabia. The strains are spore-forming rods belonging to the species Bacillus stearothermophilus. The cells are motile, strictly aerobic, catalase and oxidase positive. The sporangia appear to be swollen and their position varies from terminal in some to sub-terminal in others. The thermal stability of some enzymes of these bacteria was investigated; extracellular alpha-amylase appears to be very sensitive to pH and temperature. The ultrastructure of these bacteria shows specific changes in the cell wall when grown at the maximum, minimum and optimum growth temperatures, respectively.