This disclosure provides a shuttle vector for transferring genetic material between Caldicellulosiruptor spp. and an amplification cell. Generally, the shuttle vector includes an origin of replication sequence from the amplification cell, an origin of replication for Caldicellulosiruptor spp., a selectable marker for the amplification cell, and a heterologous coding sequence that complements a functional deletion in the Caldicellulosiruptor spp. genome. Also disclosed are genetically modified cells that include such a vector, and methods of making and using such shuttle vectors and genetically modified cells.
 This invention was made with government support under DE-AC05-00OR22725 awarded by the BioEnergy Science Center of the Department of Energy and 5T32GM007103-30 awarded by the National Institutes of Health. The government has certain rights in the invention.