Freeze drying and frozen preservation way was used to preserve a moderately thermophilic culture for bioleaching of chalcopyrite concentrate.After preservation of 15 months,the cell viability rate decreases to 22% wit...Freeze drying and frozen preservation way was used to preserve a moderately thermophilic culture for bioleaching of chalcopyrite concentrate.After preservation of 15 months,the cell viability rate decreases to 22% with a cell density of 7×107 mL-1.When the growth time was extended from 8 days to 14 days,cell density would increase in a large scale to about 3×108 mL-1.In the bioleaching experiments,unpreserved and preserved cultures were compared for dissolving chalcopyrite concentrate.Before 44 days,the unpreserved culture can reach a high copper extraction of about 17.4 g/L.While the preserved culture shows a rather low copper extraction,which is only 9.7 g/L.When the bioleaching time was extended to 80 days,copper extraction by preserved culture increases remarkably,and the concentration of copper finally achieves up to 18.3 g/L.On the other hand,copper extraction by the unpreserved culture does not show remarkable increase from 44th to the 80th day,and finally the total copper extraction is 19.8 g/L.As a result,total copper extraction in 80 days by preserved culture approaches that by unpreserved culture and freeze drying and frozen preservation even after 15 months does not bring much decrease of bioleaching ability.展开更多
In the work reported here, the potential of different methods （cold and hot water, and ethanolic） of extraction of Indian almond （Terminalia catappa L.）, fresh and fallen leaves as an anti-bacterial agent was inve...In the work reported here, the potential of different methods （cold and hot water, and ethanolic） of extraction of Indian almond （Terminalia catappa L.）, fresh and fallen leaves as an anti-bacterial agent was investigated. The hot water extract did not show any spectrum of activity against the selected bacteria while the cold water extract showed slight antibacterial activity suggesting that the effective components are heat labile. The ethanolic extracts of the leaves have higher antibiotic spectrum of activity than the cold water extract showing ethanol to be a better solvent in extracting the effective component. The fallen leaves seem to have a higher concentration of the effective component against the bacteria while ethanolic extract of the fresh leaves have similar spectrum of activity to Ciprofloxacin and Nitrofuratoin. These suggest that some effective components are lost when leaves fall off while some seem to increase in concentration. Fresh and fallen leaves contain tannin and flavonoids. In addition, the fallen leaves contain flavones. This might be responsible for the higher activity of fallen leaves extract observed against Pseudomonas and Staphylococcus spp. in our study. Combined use of extracts from fresh and fallen leaves broadened the spectrum of activity.展开更多
基金Project(2004CB619201) supported by the National Basic Research Program of ChinaProjects(50321402,30428014) supported by the National Natural Science Foundation of ChinaProject(NCET-06-0691) supported by the Program for New Century Excellent Talents in Chinese Universities
文摘Freeze drying and frozen preservation way was used to preserve a moderately thermophilic culture for bioleaching of chalcopyrite concentrate.After preservation of 15 months,the cell viability rate decreases to 22% with a cell density of 7×107 mL-1.When the growth time was extended from 8 days to 14 days,cell density would increase in a large scale to about 3×108 mL-1.In the bioleaching experiments,unpreserved and preserved cultures were compared for dissolving chalcopyrite concentrate.Before 44 days,the unpreserved culture can reach a high copper extraction of about 17.4 g/L.While the preserved culture shows a rather low copper extraction,which is only 9.7 g/L.When the bioleaching time was extended to 80 days,copper extraction by preserved culture increases remarkably,and the concentration of copper finally achieves up to 18.3 g/L.On the other hand,copper extraction by the unpreserved culture does not show remarkable increase from 44th to the 80th day,and finally the total copper extraction is 19.8 g/L.As a result,total copper extraction in 80 days by preserved culture approaches that by unpreserved culture and freeze drying and frozen preservation even after 15 months does not bring much decrease of bioleaching ability.
文摘In the work reported here, the potential of different methods （cold and hot water, and ethanolic） of extraction of Indian almond （Terminalia catappa L.）, fresh and fallen leaves as an anti-bacterial agent was investigated. The hot water extract did not show any spectrum of activity against the selected bacteria while the cold water extract showed slight antibacterial activity suggesting that the effective components are heat labile. The ethanolic extracts of the leaves have higher antibiotic spectrum of activity than the cold water extract showing ethanol to be a better solvent in extracting the effective component. The fallen leaves seem to have a higher concentration of the effective component against the bacteria while ethanolic extract of the fresh leaves have similar spectrum of activity to Ciprofloxacin and Nitrofuratoin. These suggest that some effective components are lost when leaves fall off while some seem to increase in concentration. Fresh and fallen leaves contain tannin and flavonoids. In addition, the fallen leaves contain flavones. This might be responsible for the higher activity of fallen leaves extract observed against Pseudomonas and Staphylococcus spp. in our study. Combined use of extracts from fresh and fallen leaves broadened the spectrum of activity.
