Table 1.

Different methods for predicting operons are shown. The first column provides a citation for the method. The second column indicates the year of publication. The third column indicates the number of genomes for which operon predictions were made. The fourth column indicates if a webserver interface is provided for accessing the predictions. The final seven columns indicate features used for predictions: intergenic distance between genes in an operon, conservation of genes as determined through comparative genomics, functional annotation of genes, transcription signals in the form of promoter regions or terminators, codon usage of genes, microarray gene expression data, and RNA-Seq data.

Reference	Year	# of Genomes	Web-server	IG	Conservation	Function/Annotation	Promoter and/or Terminator	Codon Usage	Micro-array	RNA-Seq
[19]	2002	1		♦					♦
[20]	2002	1		♦					♦
[4]	2005	2		♦	♦	♦
[11]	2005	124		♦	♦	♦		♦
[15]	2009	>500	♦	♦	♦
[13]	2010	2		♦	♦	♦
[23]	2010	1					♦			♦
[8]	2011	3		♦	♦		♦
[17]	2012	>1200	♦	♦	♦	♦
[16]	2014	2072	♦	♦	♦	♦
[12]	2014	4		♦			♦			♦
[26]	2014	1					♦			♦
[24]	2016	1								♦
[7]	2018	8	♦	♦	♦	♦
[25]	2018	1					♦			♦