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The community composition,abundance and culturablity of heterotrophic bacterioplankton in the Dapeng Bay of the South China Sea were investigated by morphological method,bacterial cultivation and biochemical methods over an annual cycle.Aeromonas and Pseudomonas were the predominant genera among the Gram-negative bacteria.The bacterioplankton abundance fluctuated from 2.07×10 8 to 2.44×10 9 cells/dm 3 ,and culturable bacteria abundance ranged between 0.1×10 6 and 16.07×10 6 CFU/dm 3 .The Culturablity of heterotrophic bacteria ranged between 0.01% and 1.31%.The relationship between bacterial culturablity and the environmental factors was also studied in different sites of the Dapeng Bay.Throughout the bay,a significantly positive relationship was evidenced between bacterial culturability and temperature,meanswhile bacterial culturability was significantly inversely related with salinity.The positive relationship was shown at the central bay while a negative relationship was observed at the bay mouth and there was no significant correlation at top bay between bacterial culturablity and chlorophyll a of sea water.A positive relationship was found between culturability and DIN all the bay,but DIP showed a significantly negative relationship with bacterial culturability only at the mouth of the bay. 相似文献
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河豚毒素的微生物起源 总被引：5，自引：0，他引：5
河豚毒素（TTX）是一种毒性很强的海洋生物活性物质，为典型的神经Na^＋通道阻断剂。最初从纯科（Tetrodontidae）鱼中发现，故被Tahara命名为Tetrodotoxin（TTX）。TTX的分子结构为氨基全氢喹唑啉化合物，分子式C11H17N3O8，相对分子质量为319，该分子中含有原酸酯结构，几乎所有的碳原子均具不对称取代。它微溶于水和浓酸，极易溶于含醋酸的水溶液，不溶于有机溶剂，纯品为无嗅无色针状固体结晶，易被碱还原。TTX非常稳定，在日光下曝晒20d或在盐水中盐腌30d，其毒性仍不能被全部破坏，只有在高温加热30min以上或在碱性条件下才能被分解。其具有胍基是TTX的活性部位，通过它TTX可特异地结合于神经细胞膜钠通道上，进而抑制Na^＋内流，阻断神经兴奋的传导。 相似文献
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一种用微生物生产胶凝聚合物的工艺正在兴起,该生物聚合物在岩心驱替试验中被用于渗透率调节。将碱性卡德林生物聚合物溶液与嗜碱性产酸细菌及其培养基混合后,注入贝雷砂岩岩心。同时以岩心外的摇瓶培养作为对照。２７Ｃ培养２－５天后,摇瓶中的聚合物形成了坚硬的凝胶体。培养７天后,聚合物在岩心中开始流动时所需的压力可达２５－３５磅／英寸＾２。岩心渗透率从８５２毫达西下降到２．９９毫达西、从９０４毫达西下降到４．８ 相似文献
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目的 探索Sysmex UF-1000i尿沉渣分析仪定量检测结果中细菌和白细胞计数在诊断尿路感染中的价值,阐明标本采集送检的不同对UF-1000i诊断尿路感染的影响。方法 选取笔者医院2015年7月~2015年8月466例怀疑尿路感染的入院患者同时做细菌培养及尿常规的检验结果（A组标本）,收集2016年3月下旬~4月上旬148例尿细菌培养清洁中段尿标本,接种之后立即送检尿常规检查（B组标本）。取两组标本的细菌及白细胞计数结果,以细菌培养为金标准用SPSS 18.0统计软件分别绘制ROC曲线,求出尿沉渣细菌和白细胞计数诊断尿路感染的阈值,并计算其敏感度、特异性、阳/阴性预测值、假阳性/假阴性率和准确性,比较两组标本的各项指标。结果 尿沉渣细菌与白细胞定量检测最佳阈值,A组标本分别为101.7/μl与18.8/μl,B组标本分别为98.7/μl与11.1/μl。尿沉渣细菌与白细胞ROC曲线下面积,A组标本分别为0.604与0.661,B组标本分别为0.941与0.848。对B组标本而言,细菌与白细胞联合诊断尿路感染最佳敏感度为82.4%,特异性为92.1%,阳性预测值为77.8%,阴性预测值为93.8%,假阳性率为7.9%,假阴性率为17.6%,准确度为89.9%,并可将细菌培养降低70.9%。结论 UF-1000i尿液沉渣分析仪在诊断尿路感染中有早期筛选,辅助诊断的价值。标本达到无菌采集、中段尿并在2h内送检的要求才能使UF-1000i发挥最大价值。 相似文献
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