You could also try with DAVID Bioinformatics Resources
http://david.abcc.ncifcrf.gov/home.jsp
This tool can do GO Term enrichment analysis with different sets of GOs (GO Slim, Go Fat, etc..) and has information for E. coli. Just select "Functional Annotation" and paste your list of genes. Afterwards, under "select Identifier" pick the option "Official_gene_symbol". You can also add a background list if you want to compare the enrichment against an specific set of genes.
Number of tools are available for go enrichment analysis. But it also depend what technology you are using. For example you can not use GSEA method[which specifically design for microarray experiments] in RNASeq analysis.