LB Agar (Miller) BD Difco™ 500 g. LB (Luria-Bertani) Agar, Miller is used for maintaining and propagating Escherichia coli in molecular microbiology procedures. LB Agar, Miller is based on LB Medium as described by Miller for the growth and maintenance of E. coli strains used in molecular microbiology procedures. These are nutritionally rich media designed for growth of pure cultures of recombinant strains. E. coli grows more rapidly because they provide the cells with amino acids, nucleotide precursors, vitamins and other metabolites that the microorganism would otherwise have to synthesize.