抄録
The bacterial community in a full-scale activated sludge plant for the food industry was investigated for about a year using terminal-restriction fragment length polymorphism (T-RFLP) analysis. The microscopic observation and 16S rDNA-based analysis indicated that the filamentous bacteria that were most frequently observed in this plant were Caldilinea-like bacteria, and that the actynomycetes bacteria that were dominant in the scum were Dermatophilus-like bacteria. The Tetrasphaera sp. of actynomycetes was also detected in the airation tank. According to the T-RFLP analysis, Caldilinea-like bacteria tended to appear frequently when diluted sludge volume index (DSVI) deteriorated unstably and easily. This suggests that these filamentous bacteria had a negative influence on sludge settleability, however, no correlation between the intensity of the T-RF and DSVI was observed. The influence of actinomycetes, on the other hand, was not clear, because these bacteria were detected even when DSVI was low and stable, although they increased when DSVI increased. Therefore, other factors also would have influences on sludge settleability in this plant. We also applied multidimensional scaling analysis on the bases of T-RFs to evaluate the whole bacterial community. The plots obtained were roughly divided into two groups, showing that the community structure changed depending on the sludge settling character.
