ABSTRACT
The culture of Magnetospirillum magneticum WM-1 depends on several control factors that have great effect on the magnetic cells concentration. Investigation into the optimal culture conditions needs a large number of experiments. So it is desirable to minimize the number of experiments and maximize the information gained from them. The orthogonal design of experiments and mathematical statistical method are considered as effective methods to optimize the culture condition of magnetotactic bacteria WM-1 for high magnetic cells concentration. The effects of the four factors, such as pH value of medium, oxygen concentration of gas phase in the serum bottle, C:C (mtartaric acid: msuccinic acid) ratio and NaNO3 concentration, are simultaneously investigated by only sixteen experiments through the orthogonal design L16(44) method. The optimal culture condition is obtained. At the optimal culture condition (pH 7.0, a oxygen concentration 4.0%, C: C (mtartaric acid: msuccinic acid) ratio 1:2 and NaNO3 100 mg l-1), the magnetic cells concentration is promoted to 6.5×107 cells ml-1, approximately 8.3% higher than that under the initial conditions. The pH value of medium is very important factor for magnetic cells concentration. It can be proved that the orthogonal design of experiment is of 90% confidence. The results from the hysteresis of WM-1 shows that Hc = 230 Oe, Ms = 0.9 emu/g dry wt. Cells,and Mr / Ms = 0.50.
ABSTRACT
Arachidonic acid is an essential fatty acid in human nutrition and a biogenetic precursor of the biologically active prostaglandins and leukotrienes. ?~5 desaturase catalyzes the ?~5 dehydrogenation of di-homo-?-linolenic acid to form arachidonic acid in biosynthetic pathway of arachidonic acid. Using real time PCR technology,the transcriptional expression levels of gene encoding ?5 desaturase in three Mortierella alpina strains M10,M6 and M23,and in different growth phase of high arachidonic acid yielding strain M6,were determined. Results showed that there was a distinct corelationship between mRNA transcript level of ?~5 desaturase gene and biosynthesis of arachidonic acid. Results indicated that ?~5 desaturase plays an important role in arachidonic acid biosynthesis.
ABSTRACT
The culture of Magnetospirillum magneticum WM-1 depends on several control factors that have great effect on the magnetic cells concentration. Investigation into the optimal culture conditions needs a large number of experiments. So it is desirable to minimize the number of experiments and maximize the information gained from them. The orthogonal design of experiments and mathematical statistical method are considered as effective methods to optimize the culture condition of magnetotactic bacteria WM-1 for high magnetic cells concentration. The effects of the four factors, such as pH value of medium, oxygen concentration of gas phase in the serum bottle, C:C (mtartaric acid: msuccinic acid) ratio and NaNO3 concentration, are simultaneously investigated by only sixteen experiments through the orthogonal design L16(44) method. The optimal culture condition is obtained. At the optimal culture condition (pH 7.0, a oxygen concentration 4.0%, C: C (mtartaric acid: msuccinic acid) ratio 1:2 and NaNO3 100 mg l-1), the magnetic cells concentration is promoted to 6.5×107 cells ml-1, approximately 8.3% higher than that under the initial conditions. The pH value of medium is very important factor for magnetic cells concentration. It can be proved that the orthogonal design of experiment is of 90% confidence. The results from the hysteresis of WM-1 shows that Hc = 230 Oe, Ms = 0.9 emu/g dry wt. Cells,and Mr / Ms = 0.50.