Expression and high-throughput screening of complex expressed DNA libraries in filamentous fungi

A circular expression vector capable of autonomous replication followed by spontaneous linearization and integration into the genome of a fungal host cell transformed with said vector, comprising in order,

• (a) a first region comprising a telomeric sequence and the selection marker pyrE;
• (b) a second region comprising a promoter operable in a fungal host cell;
• (c) a third region that promotes autonomous replication in a bacterial host cell;
• (d) a fourth region comprising the selection marker pyrG and a telomeric sequence;
• and
• (e) a fifth intervening region linking the first and fourth regions in the circular form of the expression vector which comprises one or more sites for linearization between the telomeric sequences of said first and fourth regions, but does not comprise a nucleotide sequence encoding a selectable marker operable in a bacterial host cell;
• wherein said telomeric sequences promote autonomous replication and enhance transformation in said fungal host cell;
• wherein said linearization occurs in vivo in the intervening region in the circular form of said expression vector introduced into said fungal host cell;
• wherein said second and third regions may be in any order between said first and fourth regions.