Which genes does P. gingivalis need to grow?

A near-saturating Tn-seq screen finds ~463 (~22%) P. gingivalis genes putatively essential on blood agar.

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How many P. gingivalis genes were putatively essential in vitro?

463 genes (22.0%).

What organism was screened?

Porphyromonas gingivalis, an oral Gram-negative anaerobe.

What library design defined essentials?

A near-saturating insertion library in ATCC 33277.

What fraction of essentials match known essential homologues?

78.6% (364 genes).

Why is P. gingivalis called a keystone pathogen?

Its interactions with other bacteria and the host are critical for periodontitis.

What genetic method was used?

Tn-seq with a Mariner mini-transposon and Illumina sequencing.

What growth phenotype defined essentials?

Genes essential for growth on blood agar.

What insertion-ratio rule called essentials?

≥50-fold under-insertion vs theoretical (actual:theoretical ≤0.020).

What about essentials without DEG homologues?

~21.4% may be species- or niche-specific essentials.

Why is a quantitative mutant library useful?

It enables screens under many selective pressures for survival genes.

What advance do authors emphasize?

Availability of a P. gingivalis mutant library plus quantitative screening.