Effect of MTPA (A) and dimethylglycine (B) on the growth of strain PM31 on glycine betaine (15 mM). The symbols in panel A indicate the control (○) or addition at t = 0 of 5 (□), 10 (▵), 15 (▿), or 20 (◊) mM MTPA. The symbols in panel B indicate the control (○) or addition at t = 0 of 5 (□), 10 (▵), or 20 (▿) mM dimethylglycine.