Nitrogen fixation by some locally isolated bacteria

Several bacterial isolates were tested for their potentiality to fix atmospheric nitrogen. Azomonas macrocytogenes was selected as the experimental organism because of the paucity of knowledge on the N[2] fixation by this organism. Total N[2]fixed was obtained with the modified Winogradsky N[2]free medium. Glucose was superior among the different carbon sources tested, supporting the highest value of total N[2]fixed. The essential amino [except cystine] were detected both within the cells as well as in the culture broth. Low levels of ammonia were found in the cell exudates, whereas relatively higher yields were detected intracellularly

Physiological profile of nitrogen-fixation by Azomones macrocytogenes

The N[2]fixing efficiency of Azomonas macrocytogenes is markedly affected by the volume of the culture medium as well as by the rate of shaking. The organism exhibits its highest N[2]fixing potentiality when grown in 250 ml Erlenmeyer flask containing 150 ml medium and shaked at 100 rpm. The optimal pH value for N[2]fixation is achieved with the medium adjusted to pH 5.8 using phosphate buffer. Maximal total N[2]fixed as well as the efficiency of N[2]fixation are achieved after 8 days of incubation. A low glucose level [5g/1] permits high values of total N[2]fixed and efficiency of N[2]fixation. The addition of sodium succinate [2g/1] supports better total N[2]fixed as well as higher N[2]fixing efficiency

Riboflavin formation by some mold fungi cultivated on hydrocarbon containing media

The potentiality of some mold fungi isolated from petroleum sludge-to produce riboflavin when grown on hydrocarbon-containing media was tested. Aspergillus terreus was found to be distinguished by its capacity to produce riboflavin when cultivated on the different culture media tested. It was able to grow more luxuriantly and produce good riboflavin output on solar containing medium. Solar concentration of 5% v/v favoured high riboflavin productivity. However, maximal B[2]yields were achieved after 20 days incubation at 30?C. Initial pH value of 5.5-6.0 was found to be optimum for growth of A. terreus and its riboflavin production