Ammonia concentrations in water can affect the severity of Flavobacterium columnare infections in fish. Two trials lasting 7 d each were conducted to determine the effect of a single immersion flush treatment of total ammonia nitrogen (TAN; 15 mg/L) on the survival of channel catfish Ictalurus punctatus infected with E columnare; the chemical was added while the water flowed continuously through the tanks. Both trials consisted of four treatments: (1) no ammonia exposure and no bacterial challenge (control), (2) ammonia exposure only, (3) bacterial challenge only, and (4) both ammonia exposure and bacterial challenge. Two hours after exposure to ammonia, the highest un-ionized ammonia level was 0.43 mg/L. The percent un-ionized ammonia is based on TAN, temperature, and pH. Caudal fins from three fish in each treatment were sampled at 24 h posttreatment to be analyzed by quantitative real-time polymerase chain reaction (qPCR). No significant difference in survival (mean +/- SE) was noted between the channel catfish in treatment 1 (95.2 +/- 1.2%) and those in treatment 2 (95.6 +/- 1.0%); however, survival in both treatments 1 and 2 differed significantly from that in treatments 3 (8.5 + 4.5%) and 4 (41.8 +/- 12.7%). Treatment 4 catfish had significantly higher survival than treatment 3 catfish. Quantitative PCR data showed that treatment 4 fish had significantly less F. columnare (7.6 x 10(5)) than did treatment 3 fish (1.2 x 10(7)), and treatment 2 fish (8.5 x 10(3)) had significantly less bacteria than did treatment 1 fish (6.9 x 10(4)), indicating that ammonia limited the F. columnare infection. The highest mean concentration of the bacteria (3.9 x 10(7)) was found on moribund fish. The ammonia concentrations tested did not negatively influence fish survival but interfered with the infection process. An in vitro assay was also conducted to evaluate the direct effects of ammonia on F columnare.

中文翻译：

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总氨浓度高对实验性感染黄杆菌的channel鱼存活的影响。

水中氨的浓度会影响鱼中黄杆菌感染的严重程度。进行了两个试验，每个试验持续7 d，以确定一次总氨氮（TAN; 15 mg / L）的浸没冲洗处理对感染E柱are鱼斑马尾Ictalurus punctatus的存活的影响。在水连续流过水箱的同时添加了化学药品。两项试验均包含四种治疗方法：（1）不暴露氨和细菌（对照），（2）仅暴露氨，（3）仅细菌，以及（4）暴露氨和细菌。暴露于氨气后两小时，未离子化氨的最高含量为0.43 mg / L。未离子化氨的百分比基于TAN，温度和pH值。在处理后24小时对每种处理的三条鱼的尾鳍进行采样，以通过定量实时聚合酶链反应（qPCR）进行分析。在处理1（95.2 +/- 1.2％）和处理2（95.6 +/- 1.0％）中，channel鱼的存活率没有显着差异（平均+/- SE）。然而，治疗1和2的存活率与治疗3（8.5 + 4.5％）和4（41.8 +/- 12.7％）的存活率显着不同。处理4 cat鱼的存活率明显高于处理3 cat鱼。定量PCR数据显示，处理4条鱼的柱状F.​​（7.6 x 10（5））明显少于处理3条鱼（1.2 x 10（7）），处理2条鱼（8.5 x 10（3））细菌比处理1条鱼少（6.9 x 10（4）），表明氨限制了F. columnare的感染。在垂死的鱼类上发现细菌的最高平均浓度（3.9 x 10（7））。所测试的氨浓度不会对鱼类的生存产生负面影响，但会影响感染过程。还进行了体外测定以评估氨对F柱面积的直接影响。