The optimum medium and fermentation conditions of the Xenorhabdus nematophilus from Steinernema carpocapsae BJ strain were studied. The relationship between antibiotic activity and pH, reducing sugar, total sugar, amino-nitrogen in process of fermentation was analyzed. The optimal medium contained tryptonl. 5 %, corn powderl o4, soybean flour 3 %, sucrose1 %KH2PO4 0.02 % ,MgSO4 0. 2% and activator 0. 1%, Stock cultured for 16h, inoculum size at 4%(V/V)and primary pH of medium ranged from 6.0 to 8.0, fermentation for 72h were of benefit to the yield of antibiotic. The pH, reducing sugar, total sugar and amino nitrogen in process of fermentation were related to the antibiotic activity. The yield of antibiotic increased by 56. 3 % comparison with nutrient broth.

The optimum medium and fermentation conditions of the Xenorhabdus nematophilus from Steinernema carpocapsae BJ strain were studied. The relationship between antibiotic activity and pH, reducing sugar, total sugar, amino nitrogen in process of fermentation was analyzed. The optimal medium contained trypton1.5%, corn powder1%, soybean flour 3%, sucrose1%, KH 2PO 4 0.02%,MgSO 4 0.2% and activator 0.1%, Stock cultured for 16h, inoculum size at 4%(V/V)and primary pH of medium ranged from 6.0 to 8.0, fermentation for 72h were of benefit to the yield of antibiotic. The pH, reducing sugar,total sugar and amino nitrogen in process of fermentation were related to the antibiotic activity. The yield of antibiotic increased by 56.3% comparison with nutrient broth.

The transportation of electron is inseparable from vacuum environment. The maintenance of the vacuum system of Elekta linear accelerator depends on two sputtering ionic pumps at the gun end and the target end. The traveling wave acceleration were used in Elekta linear accelerators. And the design of the electron gun filament is detachable. Because of these two reasons, the vacuum stability is relatively weak. Only two vacuum values are used to reflect the operation state of the whole vacuum system, which causes a few failures but will not trigger a the machine interlock. Considering the complexity of whole vacuum system, the problem of vacuum caused by the failure of various components in vacuum system is analyzed in this paper. It is hoped that some useful repairing experience and suggestions for the maintenance engineers of linear accelerator to solve the vacuum fault and rebuild the vacuum can be provided quickly.
Electrons ; Particle Accelerators ; Radiotherapy Dosage ; Vacuum