CARLUCCI A F, SCARPINO P V, PRAMER D
Appl Microbiol. 1961 Sep;9(5):400-4. doi: 10.1128/am.9.5.400-404.1961.
The bactericidal action of sea water was measured as the difference in survival of cells of Escherichia coli in untreated and autoclaved portions of water samples. The beneficial effect of sterilization by heat on the survival of E. coli in sea water varied with season and was most marked during summer months, however, the magnitude of the effect differed greatly from sample to sample. The more obvious and commonly suggested explanations for the bactericidal action of sea water were tested experimentally. The pH and salinity of sea water were changed by autoclaving, but the direction of the former was detrimental rather than beneficial and the significance of the latter was not clarified. The survival of cells of E. coli in filtered portions of some water samples was greater than that in untreated portions and equal to that in autoclaved portions, indicating that predators and competitors removed by filtration had contributed significantly to the rapid death of the bacterium in the untreated water. However, in the majority of samples tested, survival of E. coli in autoclaved water was considerably greater than survival in filtered water. The possibility that the beneficial effect of autoclaving over and above that of filtration resulted from inactivation or destruction by heat of bacteriophages and thermolabile toxic substances such as antibiotics was considered. Moreover, the suggestion was tested that the increased survival of E. coli in autoclaved sea water was due to the ability of heat to disrupt and degrade microbial cells and thermolabile compounds and, thereby, to cause an increase in concentration of available nutrients in sea water. It was concluded that the bactericidal action of sea water is not explicable in terms of the destruction or inactivation by heat of bacteriophages or antibiotics. Although added organic matter influenced the survival of E. coli, the test organism was not an effective competitor in sea water and the nutrient levels required to offset the bactericidal action were excessive. Artificial sea water was demonstrated to exert a bactericidal action comparable to that of natural sea water. Low levels of cysteine which favor survival of E. coli in natural sea water had a similar effect in artificial sea water. Nevertheless, it is not at this time possible to conclude that the factors responsible for the bactericidal action of artificial sea water are identical with those responsible in natural sea water.
海水的杀菌作用通过测量大肠杆菌细胞在水样未处理部分和高压灭菌部分中的存活率差异来确定。加热灭菌对海水中大肠杆菌存活率的有益影响随季节变化，在夏季最为显著，然而，不同样本间这种影响的程度差异很大。针对海水杀菌作用更明显且常被提及的解释进行了实验测试。通过高压灭菌改变海水的pH值和盐度，但前者的变化方向是有害而非有益的，后者的重要性也未得到阐明。在一些水样的过滤部分，大肠杆菌细胞的存活率高于未处理部分，且与高压灭菌部分相当，这表明过滤去除的捕食者和竞争者对未处理水中细菌的快速死亡有显著贡献。然而，在大多数测试样本中，高压灭菌水中大肠杆菌的存活率远高于过滤水中的存活率。考虑了高压灭菌比过滤更有益的效果可能是由于噬菌体和抗生素等热不稳定有毒物质因加热而失活或被破坏。此外，还测试了这样一种观点，即高压灭菌海水中大肠杆菌存活率的增加是由于热能够破坏和降解微生物细胞及热不稳定化合物，从而导致海水中可利用营养物质浓度增加。得出的结论是，海水的杀菌作用无法用噬菌体或抗生素因加热而被破坏或失活来解释。虽然添加的有机物会影响大肠杆菌的存活率，但测试生物体在海水中并非有效的竞争者，抵消杀菌作用所需的营养水平过高。人工海水被证明具有与天然海水相当的杀菌作用。低水平的半胱氨酸有利于大肠杆菌在天然海水中存活，在人工海水中也有类似效果。然而，目前尚无法得出结论认为人工海水杀菌作用的影响因素与天然海水相同。
