Which bacterium became the first organism to have its complete genome sequence published in 1995?

Haemophilus influenzae became the first organism to have its complete genome sequence published in 1995.

The strain sequenced was H. influenzae Rd, a laboratory strain. Researchers at The Institute for Genomic Research used whole-genome shotgun sequencing, in which the genome is broken into many fragments, sequenced, and computationally assembled by matching overlaps. The result contained about 1.83 million base pairs and roughly 1,740 protein-coding genes.

The publication was a landmark for genomics because it showed that an entire bacterial genome could be sequenced and assembled efficiently rather than mapped base by base using only traditional methods. The work helped establish whole-genome shotgun sequencing as a practical strategy.

Haemophilus influenzae is a bacterium associated with human respiratory disease, although the sequenced Rd strain is a laboratory strain. It should not be confused with influenza virus: the bacterium was named because it was once mistakenly thought to cause influenza.