The synthetic gene tbage (for sequence see additional file 1) is based on the protein sequence of Anabaena sp. CH1 GlcNAc-2-epimerase (GenBank: ABG57042) and was reverse translated into a nucleotide sequence using the GeneOptimizer ® software (Geneart, Regensburg, Germany). The codon usage was optimized for H. jecorina (http://www.kazusa.or.jp/codon). The synthetic gene tneub (for sequence see additional file 1) was similarly obtained based on the protein sequence from Campylobacter jejuni NCTC11168 NeuNAc synthase (http://old.genedb.org/ genedb/cjejuni/index.jsp, Cj1141).