The Corynebacterium glutamicum insertion sequence IS31831 was used to construct two artificial transposons: Tn31831 and miniTn31831. The transposition vectors were based on a gram-negative replication origin and do not replicate in coryneform bacteria. Strain Brevibacterium flavum MJ233C was mutagenized by miniTn31831 at an efficiency of 4.3 x 10(4) mutants per microgram DNA. Transposon insertions occurred at different locations on the chromosome and produced a variety of mutants. Auxotrophs could be recovered at a frequency of approximately 0.2%. Transposition of IS31831 derivatives led not only to simple insertion, but also to cointegrate formation (5%). No multiple insertions were observed. Chromosomal loci of B. flavum corresponding to auxotrophic and pigmentation mutants could be rescued in Escherichia coli, demonstrating that these transposable elements are useful genetic tools for studying the biology of coryneform bacteria.