For all other acb genes, fold changes between 4.9 and 9.7 were found on transcript level. These acb genes code for the proteins of acarbose biosynthesis, an exporter and the extracellular alpha-amylase (acbZ). The fold change of acbZ was determined as 8.0 comparing the growth and the stationary phase. However, it was grouped in cluster 32 together with acbB, acbA, acbE and acbD.