Re-appraisal of the Phylogeny and Fluorescence in Situ Hybridization (FISH) Probes for Identifying the Eikelboom Morphotype ‘Haliscomenobacter Hydrossis’ in Japanese Municipal Wastewater Treatment Plants

抄録

The Eikelboom filamentous bacterial morphotype ‘Haliscomenobacter hydrossis’ is ubiquitous in Japanese and other wastewater treatment plants (WWTPs). However, it is still largely ‘identified’ microscopically on its distinctive morphology, and only one species Haliscomenobacter hydrossis is recognized currently. Thus, little is known about the true level of phylogenetic diversity among members of this morphotype. Here, using 16S rRNA gene amplicon data we reveal that populations of this morphotype belong to several clades. Fluorescence in situ hybridization (FISH) probes were designed against members of each of these morphotypes, together with a new probe more specific than those currently available to target members of the genus Haliscomenobacter. Japanese municipal WWTPs were surveyed to evaluate the abundances of ‘H. hydrossis’ morphotype using FISH analysis with the existing and newly designed FISH probes. Data showed that some ‘H. hydrossis’ morphotypes appeared to show suppressed growth in biological nitrogen removal processes, although process configuration seemed not to be a critical factor in determining their abundances. Their excessive growth appears to cause activated bulking incidents in WWTPs. These data may assist in extending our currently poor understanding of ‘H. hydrossis’ phylogeny and systematics and provide tools to study its global distribution.