Table 1.

Fluorescently labelled oligonucleotide probes applied in this study

Probe sequence (5′–3′)	Probe name	Target group	Fluorophore	Reference
GCTGCCTCCCGTAGGAGT	EUB338 (I)a	Most bacteria	Cy5-Cy5c	[63]
GCAGCCACCCGTAGGTGT	EUB338 (II)a	Planctomycetales	Cy5-Cy5c	[64]
GCTGCCACCCGTAGGTGT	EUB338 (III)a	Verrucomicrobiales	Cy5-Cy5c	[64]
AGTTAGCCGGTGCTTCCT	Delta495ab	Most Deltaproteobacteria and most Gemmatimonadetes	6-Fam-6-Famc	[65]
AGTTAGCCGGCGCTTCCT	Delta495bb	Deltaproteobacteria	6-Fam-6-Famc	[65]
AATTAGCCGGTGCTTCCT	Delta495cb	Deltaproteobacteria	6-Fam-6-Famc	[65]
ACCGGTATTCCTCCCGAT	DSB706	Desulfobulbaceae (cable bacteria) and Thermodesulforhabdus	Atto 565	[66]
ACTCCTACGGGAGGCAGC	NONEUB	None (negative control probe)	Cy5-Cy5c, 6-Fam-6-Famc, Atto 565	[67]

With exception of the probe with the fluorescent tag Atto 565, all probes were doubly labelled at the 5′ and 3′ end

^aProbes applied as an equimolar mix (EUB mix)

^bProbes applied as an equimolar mix (Delta mix) with a competitor probe mix (Delta comp. mix)

^cDoubly labelled at both 5′ and 3′ end