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y.-s. chen and j.l. steele. 2004.To clone and analyse seven putative promoter fragments (pepC,pepN,pepX,pepO,pepE,pepO2,hsp17) fromLactobacillus helveticusCNRZ32 for their expression inLact. helveticusCNRZ32,Lact. caseiATCC334 andLactococcus lactisMG1363.Promoter fragments were fused to the promoter-lessβ-glucuronidase (gusA) gene on pNZ272 RBS− ATG−. The resulting constructs were evaluated for their ability to drive the expression of active GusA with 0·5 mmol l−1 5-bromo-4-chloro-3-indolyl-β-d-glucuronide. All promoters exceptP pepN::gusAwere active in the examined strains. Northern hybridization was performed to examine the promoter strength. Sequence analysis of these promoters identified well conserved putative ribosomal binding and putative–10 hexamers sites.Seven promoter fragments fromLact. helveticusCNRZ32 were recognized in the lactic acid bacteria,Lact. caseiATCC334 andL. lactisMG1363, as well as inEscherichia coli.P pepN::gusAcould not be maintained in the strains examined because of toxicity associated with heterologous protein over-expression driven byP pepN.This study revealed that desirable levels of heterologous food-grade protein production in GRAS organisms can be obtained with the application of natural promoter fragments from closely related organisms. [ABSTRACT FROM AUTHOR]