FLAVOBACTERIUM YA1 AS A POLLUTION INDEX BACTERIUM OF DOMESTIC WASTE IN STREAM WATER

About 400 aerobic heterotrophic bacteria, including three pollution an d one unpollution index bacterial types, isolated from a total of 22 s tream waters were examined to determine their utilization of low molec ular weight organic compounds and their hydrolysis of high molecular w eight organic compounds. The results showed that the ability to utiliz e low molecular weight organic compounds of two yellow pigmented bacte rial types of the pollution index bacteria was much lower than that of other bacterial types. Those two bacteria which could not completely utilize the low molecular weight organic compounds, Flavobacterium YA1 and Flavobacterium YI, were then investigated. The quality of stream water was found to be reflected only by these two types, because the r atio of these isolates positively correlated significantly with many w ater quality variables. In investigating the validity of these bacteri a as pollution indicators, the bacterial number of Flavobacterium YA1 in polluted water with domestic waste was much higher than that in cle an water such as tap water, whereas Flavobacterium YI was detected onl y in clean water. These results suggest that Flavobacterium YA1 may be a good candidate as a pollution indicator of domestic waste in stream water.