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981.
Richard?Jeannotte David?W.?Sommerville Chantal?Hamel Joann?K.?WhalenEmail author 《Biology and Fertility of Soils》2004,40(3):201-205
Quantification of phosphorus (P) concentrations in microbial biomass is required to better understand how P immobilization and turnover in soils are controlled by environmental and anthropogenic factors. Soil microbial biomass P (MBP) is generally extracted using the chloroform fumigation-direct extraction procedure and then analysed for P using the ammonium molybdate-ascorbic acid method on a flow injection analysis (FIA) system. Our objective was to determine whether a microscale malachite green method on a microplate system would provide as accurate MBP analysis as the ascorbic acid method on an FIA system. Twelve soils were collected from agricultural fields in southwestern Quebec, fumigated with chloroform and extracted with 0.5 M NaHCO3 (pH 8.5). The dissolved inorganic phosphorus (DIP) concentration in fumigated soils was not affected by the method of analysis, and results from the two systems of analysis were significantly correlated (r =0.998, P <0.05). The MBP concentrations in these agricultural soils were between 0.36 and 60.05 g P g–1, consistent with other published values. Our results indicate that MBP can be assessed equally well with the malachite green method using a microplate system as with the ascorbic acid method on an FIA system. The microplate system is rapid and requires smaller volumes of samples and reagents than the FIA system, thus reducing the quantity of waste produced. We conclude that the microscale malachite green method could be applied to measure the MBP concentration in a wide range of soils with good sensitivity, reproducibility and accuracy. 相似文献
982.
鲳鱼货架期预测模型的电子鼻评价与研究 总被引:3,自引:0,他引:3
利用电子鼻对鲳在不同贮藏温度与贮藏时间下的挥发性气味变化进行了分析,并对电子鼻测定获得的数据进行了主成分分析(PCA)与判别因子分析(DFA)。将电子鼻PCA与DFA分析获得的鲳的气味变化突变点作为气味变化的切分点与理化品质指标值(菌落总数)相结合,建立了鲳在273~283K下的Q10货架期预测模型。结果表明,电子鼻PCA与DFA分析能很好地将贮藏于273、283与293K下的鲳随着贮藏时间变化的气味进行区分。贮藏于不同温度条件下的鲳的TVBN与菌落总数值回归拟合方程均符合一级化学动力学模型(R2>0.95)。基于电子鼻PCA与DFA分析获得的283K与293K下的气味变化切分点与相同温度下理化品质指标变化具有较好的对应关系,采用Arrhenius动力学模型推导公式求得鲳在273~283K与283~293K温度段内菌落总数的Q10值,并结合283K与293K温度下电子鼻PCA与DFA分析获得的气味变化货架期切分点,从而得到鲳在273~283K与283~293K温度段内的Q10货架期预测模型为:SL(275~283K)=3×3.008 (283-T)/(10)与SL(283~293K)=1.5×3.423 (2... 相似文献
983.
984.
985.
This paper compares and discusses the accumulation of eight heavy metals (Cd, Co, Cr, Cu, Pb, Fe, Mn and Zn) and total phosphorus (TP) in surface sediments from five intensive farms of tilapia Oreochromis niloticus×Oreochromis aureu, Asian seabass Lates calcarifer and white shrimp Litopenaeus vannamei (n=75). Results indicate that the sediments were significantly contaminated by Cd, Co, Cr, Cu, Pb, Fe, Mn and Zn as well as P. The mean concentrations of Cd (0.47 mg kg?1), Co (2.25 mg kg?1), Cu (31.56 mg kg?1), Pb (23.45 mg kg?1), Fe (1.15%), Mn (145.5 mg kg?1), Zn (41.5 mg kg?1) and TP (750.69 mg kg?1) in tilapia farm surface sediments were significantly lower than the levels observed in Asian seabass and white shrimp farm surface sediments, where the concentrations were, respectively, Cd – 2.69 and 2.35 mg kg?1, Co – 17.66 and 15.22 mg kg?1, Cu – 116.84 and 110.03 mg kg?1, Pb – 38.5 and 33.26 mg kg?1, Fe – 3.4% and 3.31%, Mn – 853.61 and 728.5 mg kg?1, Zn – 105.21 and 83.92 mg kg?1 and TP – 1445.63 and 1069.8 mg kg?1. The heavy metal content of the sediments follow the order: Asian sea bass>white shrimp>tilapia. Cadmium and Cu in Asian seabass and white shrimp farm sediments would pose a major potential risk. Further, the sediment is highly enriched by Fe, P, Mn and Co. 相似文献
986.
Kwaku Amoah Xiao‐hui Dong Bei‐ping Tan Shuang Zhang Shu‐yan Chi Qi‐hui Yang Hong‐yu Liu Yuan‐zhi Yang Hai‐tao Zhang 《Aquaculture Nutrition》2020,26(5):1604-1622
This study aimed to elucidate the effects of dietary Bacillus licheniformis ATCC 11946 (BL) on the growth, immune and antioxidant activities, intestinal morphology and microbiota, and susceptibility to Vibrio parahaemolyticus (VPAHPND) in juvenile pacific white shrimp, Litopenaeus vannamei (LV). Juvenile LV (initial weight = 0.63 ± 0.001) were fed diets containing varying BL concentrations (0 (BL0), 106 (BL1), 107 (BL2) and 108 (BL3) CFU/g feed) for 8 weeks. Growth performance, immune and antioxidant enzyme activities, and intestinal morphology significantly improved in the probiotic‐treated groups than the untreated. Regardless of the treatment group, the two dominant phyla were Proteobacteria and Bacteroidetes, whereas the two dominant genera were Ruegeria and Vibrio. Increasing inclusion of probiotics in diets led to significant increase in beneficial bacterial genera (Ruegeria, and Pseudoalteromonas) and a significant decrease in some known opportunistic pathogens (Vibrio, Tenacibaculum, Photobacterium, Kangiella and Spongiimonas) with the BL3 group witnessing the best. A 7‐day challenge study with VPAHPND showed significantly high protection in the probiotic‐treated groups, with the BL3, BL2 and BL1 obtaining 51%, 34% and 22% relative percentage survival, respectively. In conclusion, BL at 108 CFU/g feed should be used to help in shrimp production since it attained the most significant improvement. 相似文献
987.
调节pH值、加钙和增氧是常用的蟹塘生态调控技术,为明确其对水质和N,P养分交换的影响,通过实验室模拟并测定了水体N,P含量及"淤泥-水界面"交换通量。结果表明:3种措施对水体N,P均有显著影响,且增氧对水体N,P的调节效应显著强于加钙和调节pH。增氧96 h后水体TN和NO_3^--N含量分别是不增氧处理的1.68和7.43倍,同时增氧削减了水体NH4+-N含量至试验结束,增氧处理NH_4^+-N含量平均降低70%~75%。"淤泥-水界面"N,P交换通量表明,增氧后TN交换通量平均提高2.47~3.74 mg·m^2/h,而对TP交换通量均无显著影响,平均仅为-0.1 mg·m^2/h。 相似文献
988.
中华绒螯蟹(Eriocheir sinensis)1龄性早熟是目前产业发展中面临的重要问题,为全面了解中华绒螯蟹 1龄性早熟性状对其子代相关性状的影响,本研究构建了 1 龄性早熟自交家系(PI)和 1 龄性早熟与 2 龄正常成熟杂交家系(PHN),综合评估其养殖性能和可食率。结果表明:(1)在扣蟹养殖阶段, PI 组 F1扣蟹平均体重始终大于 PHN 组;PI组 F1雌体的增重率(WGR)、特定生长率(SGR)和早熟率均高于 PHN组,雄体则较低,但均无显著性差异(P>0.05);PI组 F1雌体成活率显著低于 PHN 组(P<0.05),雄体略低于 PHN 组;PHN 组总产量较高,但无显著差异(P>0.05)。扣蟹终体重呈正态分布, 3.00~8.99 g 终体重扣蟹比例较高。(2)在成蟹养殖阶段,生长前期(3 5 月)PI 组平均体重低于PHN 组,生长后期(7 9 月)则以 PI 组为高;3 5 月和 7 9 月 PHN 组 F1WGR 和 SGR 均高于 PI 组,而 5 7 月则以 PI组为高;PI组 F1生殖蜕壳和性腺发育略早于 PHN组,无显著性差异(P>0.05);总体来看, PI组 F1成活率和产量均高于 PHN组,但饵料系数显著低于 PHN组(P<0.05);PHN组 F1体重<125.00 g和≥250.00 g的成蟹百分比较高,两组体重<125.00 g 的成蟹存在显著性差异(P<0.05)。(3)就总可食率(TEY)而言, PI 组 F1TEY 高于 PHN 组;就肥满度(CF)而言, PI组 F1雌体高于 PHN组,雄体则较低,但两组无显著性差异(P>0.05)。综上, 1龄早熟自交组 F1具有扣蟹平均体重大、早熟率略高,成蟹生殖蜕壳较早、成活率和产量高的特点;而 1 龄早熟与 2 龄正常成熟杂交组F1则具有扣蟹成活率和产量高,成蟹生殖蜕壳略晚、饵料系数低的特点。 相似文献
989.
The system nitrogen (N), phosphorous (P) budget, N/P utilization rate and the physiological response mechanism of the abalone Haliotis discus hannai (body weight: 12.87 ± 0.82 g) and the sea cucumber Apostichopus japonicus (body weight: 10.85 ± 1.16 g) to different co‐culture environment conditions were examined. Animals were kept in a multilayer, cubic recirculating aquaculture system at different polyculture densities (abalones at 400 ind/m2in monoculture [Group C] and abalones at 400 ind/m2with sea cucumbers at 10 ind/m2 [AS1] or 20 ind/m2 [AS2]). Each treatment was replicated four times, and the experimental cycle was 90 days. No significant difference in survival rate of abalones was detected when the stocking density of sea cucumbers increased from 10 to 20 ind/m2, but the concentrations of total ammonia nitrogen and nitrite nitrogen in the water were significantly higher in AS2 than in AS1. Survival rate, specific growth rate (SGR) of body weight of sea cucumbers and SGR of body weight of abalones were significantly lower in AS2 than in AS1. No significant difference in protease (PES), lipase, amylase and cellulase activities of abalones was identified between Group C and AS1, but the PES and amylase activities of abalones and sea cucumbers in AS1 were significantly higher than those in AS2. In AS1, the N/P output from harvesting of abalones and sea cucumbers and the N/P utilization rates were significantly higher than those in AS2. Although the N/P output from faeces was significantly lower in AS2 than in Group C and AS1, the N/P output from the water layer was significantly higher than that in AS1. The expression levels of Cu/Zn superoxide dismutase (Cu/Zn‐SOD) and heat shock protein 70 (HSP70) of both abalones and sea cucumbers in AS2 were significantly higher than those in AS1. No significant difference in expression of catalase (CAT) and HSP90of abalones was identified among these groups, but the expression levels of CAT and HSP90of sea cucumbers in AS2 were significantly higher than those in AS1. These results indicate that stocking sea cucumbers at 10 ind/m2 in the polyculture system will relieve the organic load on the system and improve the N/P utilization rate. It will also increase aquaculture production and improve the ecological and economic benefits of the system. 相似文献
990.