searching for a short scifi story about a castaway from a STL starship and their sentient spacesuit autodoc

Question

A passenger aboard a STL starship is thrown overboard when the ship hits an asteroid fragment at relativistic speed and explodes. He survives thanks to his spacesuit, an AI and autodoc-equipped piece of clarketech which is probably smarter than he is but his trajectory is random enough that rescue efforts fail to find him. He spends the rest of his life adrift and after he dies, the AI goes a bit crazy and starts using the autodoc's sterilization equipment to selectively breed his gut microbes with the intention of recreating something sentient, eventually successfully.

The story wasn't part of Robert Reed's Great Ship series, although Mere's life in that series was similar, nor was it Stephen Baxter's FUBAR Suit. The story was written in english and published in an anthology of short scifi stories.

Answer 1

Coffins by Robert Reed (1992) is maybe the one. Anthologized in The Best from Fantasy & Science Fiction A 45th Anniversary Anthology (1994, Ferman & Rusch, eds.), pp.153-164.

Excerpt:

The lifesuit races away from the galaxy. The darkness around it is mostly empty, save the hydrogen used for fuel. As promised, the machinery seems impervious to time and wear. Radiation begets mutations in the passengers; the computer picks and chooses. They’re wondrous creatures, these passengers. They’re tough and vigorous and almost infinitely flexible, and their best qualities can be married into an organized whole. In effect, a symbiotic mass of bacterial cultures.

One species serves as a nervous system; another is muscle; a third mimics bone; and a fourth is an efficient blood.

The culture fills the lifesuit, built along the dead man’s shape. It’s not a single organism. Not after even 10 million years is it anything more, or less, than a compilation of tightly orchestrated creatures. Yet it functions much like any multicellular creature. There are recognizable hearts and kidneys. Functional eyes appear after eons of false starts and ugly failures. Every success is nourished by the watchful computer. And when the broad work is completed, it feeds the compilation as it would any man: Rich foods are ingested by a greedy mouthlike affair, then digested, and the fragrant shit is collected from the ass and reprocessed in an endless cycle.

The lifesuit is a biosphere unto itself, enclosed and perpetual.

Ten million years of travel, then more. A busy, busy span of time, and there’s still so much work to be done.