sentence: The tpbB mutant was grown in 25 mL of LB medium supplemented with carbenicillin ( 300 µ g / mL ) and gentamicin ( 15 µ g / mL ) with pMQ70 ( negative control ) and pMQ70-tpbB ( positive control ) ( A ) , pMQ70-tpbB-Y48F ( B ) , pMQ70-tpbB-Y62F ( C ) and pMQ70-tpbB-Y95F ( data not shown ) .