Quantification of Gordona amarae Strains in Foaming Activated Sludge and Anaerobic Digester Systems with Oligonucleotide Hybridization Probes

Abstract

Previous studies have shown the predominance of mycolic acid-containing filamentous actinomycetes (mycolata) in foam layers in activated sludge systems. Gordona (formerlyNocardia) amarae often is considered the major representative of this group in activated sludge foam. In this study, small-subunit rRNA genes of four G. amarae strains were sequenced, and the resulting sequences were compared to the sequence ofG. amarae type strain SE-6. Comparative sequence analysis showed that the five strains used represent two lines of evolutionary descent; group 1 consists of strains NM23 and ASAC1, and group 2 contains strains SE-6, SE-102, and ASF3. The following three oligonucleotide probes were designed: a species-specific probe forG. amarae, a probe specific for group 1, and a probe targeting group 2. The probes were characterized by dissociation temperature and specificity studies, and the species-specific probe was evaluated for use in fluorescent in situ hybridizations. By using the group-specific probes, it was possible to place additional G. amarae isolates in their respective groups. The probes were used along with previously designed probes in membrane hybridizations to determine the abundance of G. amarae, group 1, group 2, bacterial, mycolata, and Gordona rRNAs in samples obtained from foaming activated sludge systems in California, Illinois, and Wisconsin. The target groups were present in significantly greater concentrations in activated sludge foam than in mixed liquor and persisted in anaerobic digesters. Hybridization results indicated that the presence of certain G. amarae strains may be regional or treatment plant specific and that previously uncharacterizedG. amarae strains may be present in some systems.

Populations related to Alkanindiges, a novel genus containing obligate alkane degraders, are implicated in biological foaming in activated sludge systems

“… d. References: 1, Zheng and colleagues (1996); 2, Manz and colleagues (1992); 3, de los Reyes and colleagues (1997); 4, de los Reyes and colleagues (1998). …”

Identifying the abundant and active microorganisms common to full-scale anaerobic digesters

“…Methane gas production from organics is mediated by the tightly coupled synergistic activities of complex microbial communities and is essentially covered by four sequential stages: hydrolysis, fermentation, acetogenesis and methanogenesis. The anaerobic digestion process is generally robust, but occasionally reactors experience operational problems such as foaming events and periods of low efficiency or failure [2][3][4] . A better understanding of the underlying microbiology will facilitate optimisation of the biological processes, and consequently the microbiology has been widely studied using various approaches with both lab and full-scale systems [5][6][7] .…”

Characterization of Nocardia farcinica, a Filamentous Bacterium Isolated from Foaming Activated Sludge Samples

“…The identification of the isolate via conventional techniques could not be regarded as conclusive because several filamentous bacteria exhibit similar morphologies and staining characteristics. Additionally, actinomycetes undergo morphological transitions depending on their growth stages, for example, from coccal to hyphael stage and vice versa (de los Reyes et al, 1998). To overcome this limitation, the isolate was subjected to FISH to verify the conventional identification results and to confirm the identity of the isolate.…”