Studies on the pollution by coliform bacteria in the river

In order to investigate the pollution by coliform bacteria in the river, the distribution of bavteria was surveyed with regard to the Tabuse River of relatively good water quality, the Yanai River polluted by domestic draunage, the Nakura River polluted by drainage from corral and the Drainages flowing into these rivers from paddy field, sewerage system, corral, etc. The bacterial species in the strains isolated from coliform bacteria in each river were classified by the biochemical test and the relationship with the pollution by the coliform bacteria was studied. 1) The numbers of coliform bacteria measured by the BGLB medium-MPN method were distributed in the order of 10^3-10^4 in the Tabuse River, 10^4-10^5 in the Yanai River and also 10^4-10^5 in the Nakura River. 2) The numbers of Escherichia coli measured by the EC medium-MPN method, were 7-11% of those of coliform bacteria in the Tabuse River, 0-23% in the Yanai River and 8-27% in the Nalura river. 3) Comparing the strains isolated from coliform bacteria, the percentage of genus Klebsiella was the highest and that of genus Enterobacter was secondly high in the Tabuse River and the upper part pf the Yanai River. On the other hand, in the middle and the lower parts of the Yanai River, it was confirmed that those of ganus Klebsiella decreased and genus Enterobacter increased. The percentage of E. coli was 8-16% of the strains isolated from coliform bacteria and 8-44% in the Yanai River. 4) In the strains of coliform bacteria isolated from drainage from paddy field, genus Klebsoella was the highest percentage, genus Enterobacter and genus Citrobacter were the next. As for treatment water from sewerage system before the sterilization, the percentages of E.coli was 52-72%, the highest, and genus Citrobacter and the genus Enterobacter came next. 5) In the Nakura River, the pollutiono by coliform bacteria was recoginized and it was considered to be caused by drainage from corral. In this river, the percentage of E.coli was 16-56% of coliform bacteria. High percentage of genus Citrobacter and genus Enterobacter, and low percentage of genus Klebsiella were found. 6) In the strains of coliform bacteria isolated from drainage from corral there were E.coli of 40%, genus Citrobacter of 20%, genus Enterobacter of 20% and genus Klebsiella of 8%. As for drainage from ranch, there were E.coli of 28%, genus Serratia of 20%, genus Enterobacter of 16%, genus Citrobacter of 8% and genus Klebsiella of 8%. In the feces of pigs and cows the percentage of E.coli were 80% and 84% in each. 7) It was found that the number of coliform bacteria by the BGLB-MPN did not always show the pollution by E.coli. The pollution by E.coli in the river was supporsed to be caused by domestic drainage. On the other hand, the pollution of the river where corral were located was found to be caused by drainages from corral and ranch.