Table 1. HRP labelled oligonucleotide probes used in this study.

Probea	Target group	Probe sequence (5′-3′)	Reference
EUB338I	Most but not all Bacteria	GCTGCCTCCCGTAGGAGT	[16]
EUB338II	Planctomycetes	GCAGCCACCCGTAGGTGT	[17]
EUB338III	Verrucomicrobiales	GCTGCCACCCGTAGGTGT	[17]
ALF968	Alphaproteobacteria	GGTAAGGTTCTGCGCGTT	[18]
BET42a	Betaproteobacteria	GCCTTCCCACTTCGTTT	[19]
GAM42a	Gammaproteobacteria	GCCTTCCCACATCGTTT	[19]
DELTA495a	Most Deltaproteobacteria	AGTTAGCCGGTGCTTCCT	[20]
DELTA495b	Deltaproteobacteria	AGTTAGCCGGCGCTTCCT	[20]
DELTA495c	Deltaproteobacteria	AATTAGCCGGTGCTTCCT	[20]
EPSY914	Epsilonproteobacteria	GGTCCCCGTCTATTCCTT	[21]
CF319a	Bacteroidetes	TGGTCCGTGTCTCAGTAC	[22]
HGC69a	Actinobacteria (high G+C content−Gram+bacteria)	TATAGTTTACCACCGCCGT	[23]
LGC354a	Firmicutes (low G+C content−Gram+bacteria)	TGGAAGATTCCCTACTGC	[24]
LGC354b	Firmicutes (low G+C content−Gram+bacteria)	CGGAAGATTCCCTACTGC	[24]
LGC354c	Firmicutes (low G+C content−Gram+bacteria)	CCGAAGATTCCCTACTGC	[24]
CYA664	Most Cyanobacteria	GGAATTCCCTCTGCCCC	[25]
CYA762	Most Cyanobacteria	CGCTCCCCTAGCTTTCGTC	[25]
ARCH915	Archaea	GTGCTCCCCCGCCAATTCCT	[26]
NON338	Negative control probe	ACTCCTACGGGAGGCAGC	[27]

^aProbes EUB338I, EUB338II and EUB338III were equimolarly mixed together to obtain the EUB-mix; the probes LGC354a, LGC354b and LGC354c were equimolarly mixed together to obtain the LGC-mix; Probes DELTA495a, DELTA495b and DELTA495c were equimolarly mixed together to obtain the DELTA-mix; Probes CYA664 and CYA762 were equimolarly mixed together to obtain the CYA-mix.