'Candidatus Nostocoida limicola', a filamentous bacterium from activated sludge


Blackall, L. L.; Seviour, E. M.; Bradford, D.; Rossetti, S.; Tandoi, V.; Seviour, R. J.


Five strains of 'Candidatus Nostocoida limicola' were isolated by micromanipulation from two activated sludge plants. Two (Ben17 and Ben18) were from Sunbury, Victoria, Australia, and three (Ben67, Ver1 and Ver2) were from Verona, Italy. The near complete 16S rDNA sequences were determined for five strains and the phylogenetic location of this important bulking filament in the actinomycete subphylum is reported for the first time. Phylogenetically, the Ben strains formed one group with 99.4 percent 16S rDNA similarity, and the Ver strains formed another with 99.9 percent 16S rDNA similarity. The mean similarity between the two groups was 97.4 percent. By 16S rDNA comparison, the closest relative to all strains was Terrabacter sp. strain DPO1361 (95.0-95.5 percent identical). On R2A medium, all strains generally grew as short filaments or clumps of cocci, whereas on glucose sulfide (GS) medium, all grew as irregular twisting filaments comprising Gram-positive and Gram- negative cells, which is close to their in situ morphology. Polyphosphate was stored either as granules (R2A) or throughout the trichomes (GS). None of the strains could grow without added nitrogen, reduce nitrate to nitrogen gas or grow anaerobically, whereas all could grow at 15-30 degrees Celsius, produce catalase and reduce nitrate to nitrite. All were inactive in the Hugh and Leifson test. This paper describes 'Candidatus Nostocoida limicola'.

Publication year


Publication type

Journal article


International Journal of Systematic and Evolutionary Microbiology, Vol. 50, no. 2 (Mar 2000), pp. 703-709




Society for General Microbiology


Copyright © 2000 International Union of Microbiological Societies.

Additional information

The EMBL accession numbers for the 16S rRNA sequences of Ben17, Ben18, Ben67, Ver1 and Ver2 are X85211, X85212, Y14597, Y14595 and Y14596.