Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor...Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification efficiency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization （FISH）, Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.展开更多
[ Objective] This study aimed to develop tissue culture and rapid propagation methods for pedicels of HemerocaUis hybrida. [ Method] Tender pedicels of dwarf H. hybrida were used as experimental materials to sdect cal...[ Objective] This study aimed to develop tissue culture and rapid propagation methods for pedicels of HemerocaUis hybrida. [ Method] Tender pedicels of dwarf H. hybrida were used as experimental materials to sdect callus induction, subculture and rooting media for rapid propagation of H. hybrida.[ Result ] MS ＋ 2.0 - 3.0 mg/L 6-BA ＋ 0.2 - 0.3 mg/L NAA, MS ＋ 1.0 - 2.0 mg/L 6-BA ＋ 0.1 - 0.2 mg/L NAA, MS and 1/2MS ＋ 0.2 mg/L NAA were the appropriate me- dium for callus induction, subculture and rooting, respectively. [ Conclusion] The in vitro culture and clustered seedling rooting technology used in this study are effective methods for rapid propagation of H. hybrida, which provide technieal reference for industrialized production of H. hybrida.展开更多
基金supported by the National Science Council of China (No.50578023)
文摘Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification efficiency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization （FISH）, Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.
基金Supported by China Agricultural University (Yantai) Project(yt2007.14)
文摘[ Objective] This study aimed to develop tissue culture and rapid propagation methods for pedicels of HemerocaUis hybrida. [ Method] Tender pedicels of dwarf H. hybrida were used as experimental materials to sdect callus induction, subculture and rooting media for rapid propagation of H. hybrida.[ Result ] MS ＋ 2.0 - 3.0 mg/L 6-BA ＋ 0.2 - 0.3 mg/L NAA, MS ＋ 1.0 - 2.0 mg/L 6-BA ＋ 0.1 - 0.2 mg/L NAA, MS and 1/2MS ＋ 0.2 mg/L NAA were the appropriate me- dium for callus induction, subculture and rooting, respectively. [ Conclusion] The in vitro culture and clustered seedling rooting technology used in this study are effective methods for rapid propagation of H. hybrida, which provide technieal reference for industrialized production of H. hybrida.
