Dynamic analysis of coliform group in the sea and estuary of Ariake-kai bay

包括大肠杆菌在内的大肠菌群细菌通常在海洋和河流等自然环境中不存在。然而，据了解，在城镇污水污染的海洋和河流中都可以检测到这种细菌。在本研究中，我们试图阐明有明开海湾海域和河口的大肠菌群动态分析。在有福凯流经熊本市的白川河，我们观察到大量的大肠菌群。而且，我们还可以在有莱凯湾的整个海域检测到细菌，尽管数量很少。通过对大肠杆菌细胞在海水中存活至少一个月的实验观察，认为有福凯海域和海岸带可能始终存在一定数量的大肠菌群，但我们发现有福凯的几个滩涂都没有检测到大肠菌群。由此可见，潮间带土壤中的某些因素(S)对大肠菌群的存活有影响。因此，我们开展了土壤中因子(S)的鉴定工作。虽然目前尚不能完全确定该因子(S)，但该因子(S)似乎是一种在60℃以上具有致死作用的微生物(S)，其细胞大小为2.0~5.0μm，滩涂因子(S)的鉴定和性质有待进一步研究。弄清潮滩对被外部细菌(如大肠杆菌)污染的自然环境的保护所起的作用应该是非常有趣的。沿着这条线的研究正在我们实验室进行。

Bacteria of coliform group concluding Escherichia coli are not usually found in natural environment such as sea and river. However, it is known that such bacteria can be detected in the sea and river polluted by sewage of towns and cities. In present study, we attempt to clarify the dynamic analysis of coliform group in the sea and estuary of Ariake-kai bay. In Shirakawa River, that flows in Ariake-kai through Kumamoto city, we observed a large amount of coliform group. And, we could detect also the bacteria in the whole sea area of Ariake-kai bay, though the amount of those was a little. From the experimental observation that cells of Escherichia coli could survive in seawater for at least one month, it is considered that a constant amount of coliform group may exist always in the sea and coastal zone of Ariake-kai.However, we found the interesting fact that coliform group could not detect in several tidelands of Ariake-kai. From these results, some factor(s) in the soil of tideland are considered to affect the survival of coliform group. Therefore, we carried out to identify the factor(s) in the soil of that. Although we could not identify perfectly the factor(s), it seems that the factor(s) are certain microorganism(s) which are lethal over the temperature of 60 ℃ and their size of cells is l.2〜5.0μm. Further study is needed on the identification and property of the factor(s) of tideland. It should be very interesting to clarify the role of tideland affecting the preservation of natural environment contaminated by external bacteria such as Escherichia coli. Studies along this line are in progress in our laboratory.