Milestone in genomics What was the first free-living bacterial genome to be completely sequenced and made public?

Introduction / Context:The completion of the first bacterial genome marked a turning point for genomics, transforming biology with whole-genome data. Recognizing this landmark organism helps anchor timelines and contextualize later advances in sequencing technologies and assembly methods.

Given Data / Assumptions:

• We refer to free-living bacterial genomes (not organelles or viruses).
• Completion and publication in the mid-1990s via whole-genome shotgun sequencing.
• Comparing prominent model organisms of that era.

Concept / Approach:

In 1995, the genome of Haemophilus influenzae Rd (KW20) was published as the first complete genome of a free-living organism using whole-genome shotgun methods. While Mycoplasma genitalium has a smaller genome and was sequenced soon after, H. influenzae came first chronologically among free-living bacteria.

Step-by-Step Solution:

Verification / Alternative check:

Historical reviews of genomics list H. influenzae as the inaugural free-living genome; E. coli and B. subtilis followed later.

Why Other Options Are Wrong:

• E. coli and B. subtilis: Sequenced later.
• No bacterial genome sequenced: False since multiple bacterial genomes have been completed since 1995.
• Mycoplasma genitalium: Very small genome, sequenced soon after, but not the first free-living one published.

Common Pitfalls:

• Confusing “smallest genome” with “first sequenced.”

Final Answer:

Haemophilus influenzae