To investigate the influence of sodium to potassium （Na/IO ratios on the growth performance and physiological response of the Pacific white shrimp （Litopenaeus vananmei）, various concentrations of KC1 were added to...To investigate the influence of sodium to potassium （Na/IO ratios on the growth performance and physiological response of the Pacific white shrimp （Litopenaeus vananmei）, various concentrations of KC1 were added to low-salinity well water （salinity 4） in an 8-week culture trial. Six treatments with NWK ratios of 60：1, 42：1, 33：1, 23：1, 17：1, and 14：1 were replicated in triplicate. The highest weight-gain rate （3 506±48）% and survival rate （89.38±0.88）% was observed in well water with Na/K ratios of 23：1 and 42：1, respectively, while the feed conversion ratio （1.02～0.01）, oxygen consumption, and ammonia-N excretion rate was the lowest in the medium with a Na/K ratio of 23：1. Gill Na＋-K＋-ATPase activity, as an indicator of osmoregulation, peaked in the treatment where the Na/K ratio was 17：1. The total hemocyte count, respiratory burst, and immune-related enzyme activities （ALP, LSZ, PO, and SOD） ofL. vananmei were affected significantly by Na/K ratios （P〈0.05）. After challenged with Vibrio harveyi, the cumulative mortality of shrimp reared in a Na/K ratio of 23：1 （30±14.14）% was significantly lower than the control （75～7.07）%. In conclusion, the addition of K＋ to low-salinity well water in L. vannamei cultures is feasible. Na/K ratios ranging from 23：1 to 33：1 might improve survival and growth. Immunity and disease resistance are also closely related to the Na/K ratio of the low-salinity well water. The findings may contribute to the development of more efficient K^＋ remediation strategies for L. vananmei culture in low-salinity well water.展开更多
A bacterial strain, pcnb-21, capable of degrading pentaehloronitrobenzene （PCNB） under aerobic and anoxic conditions, was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identifie...A bacterial strain, pcnb-21, capable of degrading pentaehloronitrobenzene （PCNB） under aerobic and anoxic conditions, was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identified as Labrys portucalensis based upon its morphological, physiological and biochemical properties, as well as 16S rRNA gene sequence analysis. Effects of different factors, such as temperature and pH, on PCNB biodegradation were studied. Strain pcnb-21 efficiently degraded PCNB at temperatures from 20 to 30 ℃ and initial pH values from 4 to 7, which might be the first time that a Labrys strain was found capable of eflClciently degrading PC1NB. The degradation of PCNB was affected by oxygen, and the degradation decreased with increasing aeration. Exogenous electron donors such as glucose, lactic acid and succinic acid promoted the biodegradation of PCNB, while electron acceptors such as sodium nitrite, sodium sulfate, sodium nitrate and sodium sulfate inhibited PCNB biodegradation. The degradation of PCNB in sterile and non-sterile soils by a green fluorescent protein （GFP）-labeled strain, pcnb-21-gfp, was also studied. Cells of pcnb-21-gfp efficiently degraded 100 mg kg-1 PCNB in sterile and non-sterile soils and could not be detected after 42 days. Strain pcnb-21 might be useful in bioremediating PCNB-polluted soils and environment.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.30871928,31272673)the Special Fund for Agro-Scientific Research of Public Interest(No.201003020)the High Level Talent Project of Guangdong Province Universities and Colleges Pearl River Scholar(GDUPS)(No.2011)
文摘To investigate the influence of sodium to potassium （Na/IO ratios on the growth performance and physiological response of the Pacific white shrimp （Litopenaeus vananmei）, various concentrations of KC1 were added to low-salinity well water （salinity 4） in an 8-week culture trial. Six treatments with NWK ratios of 60：1, 42：1, 33：1, 23：1, 17：1, and 14：1 were replicated in triplicate. The highest weight-gain rate （3 506±48）% and survival rate （89.38±0.88）% was observed in well water with Na/K ratios of 23：1 and 42：1, respectively, while the feed conversion ratio （1.02～0.01）, oxygen consumption, and ammonia-N excretion rate was the lowest in the medium with a Na/K ratio of 23：1. Gill Na＋-K＋-ATPase activity, as an indicator of osmoregulation, peaked in the treatment where the Na/K ratio was 17：1. The total hemocyte count, respiratory burst, and immune-related enzyme activities （ALP, LSZ, PO, and SOD） ofL. vananmei were affected significantly by Na/K ratios （P〈0.05）. After challenged with Vibrio harveyi, the cumulative mortality of shrimp reared in a Na/K ratio of 23：1 （30±14.14）% was significantly lower than the control （75～7.07）%. In conclusion, the addition of K＋ to low-salinity well water in L. vannamei cultures is feasible. Na/K ratios ranging from 23：1 to 33：1 might improve survival and growth. Immunity and disease resistance are also closely related to the Na/K ratio of the low-salinity well water. The findings may contribute to the development of more efficient K^＋ remediation strategies for L. vananmei culture in low-salinity well water.
基金Supported by the National High Technology Research and Development Program of China (No. 2007AA10Z405)the National Natu-ral Science Foundation of China (No. 31070100)the Key Technology R&D Program of Jiangsu Province,China (No. BE2008669)
文摘A bacterial strain, pcnb-21, capable of degrading pentaehloronitrobenzene （PCNB） under aerobic and anoxic conditions, was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identified as Labrys portucalensis based upon its morphological, physiological and biochemical properties, as well as 16S rRNA gene sequence analysis. Effects of different factors, such as temperature and pH, on PCNB biodegradation were studied. Strain pcnb-21 efficiently degraded PCNB at temperatures from 20 to 30 ℃ and initial pH values from 4 to 7, which might be the first time that a Labrys strain was found capable of eflClciently degrading PC1NB. The degradation of PCNB was affected by oxygen, and the degradation decreased with increasing aeration. Exogenous electron donors such as glucose, lactic acid and succinic acid promoted the biodegradation of PCNB, while electron acceptors such as sodium nitrite, sodium sulfate, sodium nitrate and sodium sulfate inhibited PCNB biodegradation. The degradation of PCNB in sterile and non-sterile soils by a green fluorescent protein （GFP）-labeled strain, pcnb-21-gfp, was also studied. Cells of pcnb-21-gfp efficiently degraded 100 mg kg-1 PCNB in sterile and non-sterile soils and could not be detected after 42 days. Strain pcnb-21 might be useful in bioremediating PCNB-polluted soils and environment.
