Actinobacillus succinogenes is a ruminal microorganism of biotechnological importance due to its capacity to produce succinic acid at high yields. Despite the scientific interest in this organism, molecular vehicles for the transfer and expression of genetic material are limited compared to the existing demand. To facilitate gene cloning and expression in A. succinogenes, we report the generation and characterization of two novel shuttle expression vectors containing the chloramphenicol acetyltransferase gene (catA) as a selection marker and replication origins from A. succinogenes, other members of the Pasteurellaceae family, and Escherichia coli. Vector pAVP