sentence: Aliquots of cultures were collected during the exponential growth phase and beta-galactosidase activities were assessed to determine transcription levels.As indicated in Fig. 1 , expression levels were higher for M. smegmatis transformed with the recombinant plasmids carrying pks2 , msl3 , lipF or fadD21 gene fusions than for M. smegmatis transformed with the empty pJEM15 vector .