3. Results
3.1. Resistance to erythromycin
B. bifidum YIT 4007 has resistance to a wide range of erythromycin
concentration up to 5000 μg/mL while its progenitor strain YIT 4001 is
susceptible to that range of concentration. Many studies have shown
that resistance to erythromycin at a high concentration is caused by
mutations of the domain V of 23S ribosomal RNA gene in many
bacteria (Biswas et al., 2007; Ladely et al., 2009). B. bifidum YIT 4007
has three copies of 23S ribosomal RNA genes, and we amplified the