Horizontal gene transfer of beta-lactam biosynthesis genes from prokaryotes to eukaryotes. KückUlrich BloemendalSandra TeichertInes 2014 <p>The antibiotic biosynthesis genes are derived either from gram-positive (e.g. <i>Streptomyces</i> spp.) or gram-negative (e.g. <i>Lysobacter</i> spp.) bacteria. The first two steps of both penicillin and cephalosporin C biosynthesis are catalyzed by the gene products of <i>pcbAB</i> and <i>pcbC. P. chrysogenum</i> harbors one additional gene, <i>penDE</i> (not shown), to perform the last step of penicillin biosynthesis, whereas <i>Ac. chrysogenum</i> has obtained several additional genes for production of cephalosporin C. Genetic engineering approaches have been used to introduce these genes into <i>P. chrysogenum</i>. Chemical engineering approaches have enabled the precursors of both the <i>Ac. chrysogenum</i> and <i>P. chrysogenum</i> biosynthesis pathway to be used for the production of new cephalosporin derivatives.</p>