RESUMO
BACKGROUND: Spinosad (a mixture of spinosyns A and D) is a unique natural pesticide produced by Saccharopolyspora spinosa. With regard to attempts to improve S. spinosa by classical mutagenesis, we propose that the bottleneck of screening out high-spinosad-production strains is probably caused by the fermentation media. OBJECTIVES: The current study aimed to identify a new medium to extensively investigate the potential of S. spinosa strains to produce spinosad. MATERIALS AND METHODS: Statistical and regressive modeling methods were used to investigate the effects of the carbon source and to optimize the production media. RESULTS: The spinosad production of S. spinosa Co121 increased 77.13%, from 310.44 ± 21.84 µg/mL in the initial fermentation medium (with glucose as the main carbon source) to 549.89 ± 38.59 µg/mL in a new optimized fermentation medium (98.0 g of mannitol, 43.0 g of cottonseed flour, 12.9 g of corn steep liquor, 0.5 g of KH2PO4, and 3.0 g of CaCO3 in 1 L of H2O; pH was adjusted to 7.0 before autoclaving). After screening 4,000 strains, an overall 3.33-fold increase was observed in spinosad titers, starting from the parental strain Co121 in the original fermentation medium and ending with the mutant strain J78 (1035 ± 34 µg/mL) in the optimized medium. CONCLUSIONS: The optimized fermentation medium developed in this study can probably be used to improve spinosad production in screening industrial strains of S. spinosa.
RESUMO
In order to observe the effects of different culture media and temperature on protoscoleces of Echinococcus multi‐locularis ,they were randomly divided into RPMI‐1640 group ,D‐MEM group and M199 group ,and cultured in three degrees of temperature (4 ,25 and 37 ℃) with 10% fetal calf serum (FCS) .Protoscoleces were counted by light microscope with 0 .1%eosin staining ,and calculated survival rate (per 100 protoscoleces) everyday until all the parasites died .At the same time ,the average number of the preservation days was observed .The experiment results showed that the survival rate of protoscoleces in RPMI‐1640 and D‐MEM groups were higher than that in M199 group (P0 .05) .The survival rate of protoscoleces in RPMI‐1640 group at 4 ℃ and 37 ℃and D‐MEM group at 25 ℃ were higher ,but there was no significant effect of 4 ,25 and 37 ℃ on the survival rate of proto‐scoleces (P>0 .05) .Significant difference were found in the survival rate of protoscoleces on the 3rd day and the 9th day in these three groups (P<0 .05) .The average number of the preservation days were 34 days in RPMI‐1640 group at 4 ℃ ,36 days in D‐MEM group at 25 ℃ and 23 days in M199 group at 4 ℃ .It was concluded that the effects of different culture media and tem‐perature on protoscoleces are different ,and the RPMI‐1640 at 4 ℃ and D‐MEM at 25 ℃ are more suitable for culturing proto‐scoleces in v itro .
RESUMO
Age impact in mouse model of secondary hepatic alveolar echinococcus was investigated in this research . Twenty-nine 8-week-old ,twenty-five 18-week-old and twenty-five 28-week-old female mice were anesthetized with 20% ure-thane by intraperitoneal injection and then transhepatically injected by Echinococcus multilocularis (E .m) tissue suspension through skin incision and abdominal muscle to liver in all three groups to establish mouse model of secondary hepatic alveolar e-chinococcus .Results showed that the survival rates for the three groups of mice were 62 .1% ,84% and 68% ,respectively (P>0 .05) .The E .m infection rates in liver were 72 .2% ,71 .4% and 76 .5% ,respectively (P>0 .05) .The diameter of E .m cysts in liver were 0 .915 ± 0 .103 cm ,1 .247 ± 0 .112 cm and 1 .215 ± 0 .197 cm ,respectively (P>0 .05) .The mass of E .m cysts in liver were 0 .332 ± 0 .035 g ,0 .532 ± 0 .155 g and 0 .382 ± 0 .085 g ,respectively (P> 0 .05) .HE stain showed no difference in pathology .Results indicated that the establishment of secondary hepatic alveolar echinococcus model by using transhepatic injection through skin incision and abdominal muscle of 18-week-old mice was capable of simplifying operation and improving the survival rate of the mice .
