Microbiotica raises £36M Series C for precision microbiome medicines

Microbiotica has closed the first £36M ($48M) of a Series C led by British Business Bank to take MB310, its oral microbiome medicine for ulcerative colitis, into Phase 2 – the Cambridge company announced the round on 16 October.

Microbiome medicine is the corner of biotech that promised the most and, for a decade, delivered the least. And yet here is a state-owned bank leading a Series C for gut bacteria in a capsule. Below, I lay out the round, the science behind it and why the name on the lead cheque matters more than the amount.

A £36M first close with the state out front

Microbiotica, based at Chesterford Research Park near Cambridge, has raised £36M ($48M) as the first close of its Series C, announced on 16 October. British Business Bank, the UK government’s economic development bank, led the round. Tencent, IP Group, Cambridge Innovation Capital, Flerie Invest and Seventure Partners joined, and the company says every one of its Series B investors returned.

The money has one job: moving MB310, a once-daily oral capsule for ulcerative colitis, into a randomised, double-blind, placebo-controlled Phase 2 trial. “We believe Microbiotica is emerging as a world leader in the development of microbiome therapeutics,” said Carmine Circelli, senior investment director for life sciences at British Business Bank, in the announcement.

The round follows a £50M ($67M) Series B announced in March 2022, co-led by Flerie Invest and Tencent – the same names still at the table four years later. That continuity is its own data point in a field where investors have had plenty of exit ramps.

Eight gut strains in a once-daily capsule

Microbiotica spun out of the Wellcome Sanger Institute in 2016 with a straightforward thesis: if you can read the microbiome precisely enough, you can prescribe it. The company pairs one of the largest cultured collections of gut bacteria with a proprietary reference genome database, bioinformatics and machine learning, and uses clinical trial samples to identify the exact strains present in patients who respond to treatment.

MB310, the lead programme, packs eight live gut commensal bacterial strains into that one daily capsule. In the Phase 1b COMPOSER-1 study, the company reports the drug met its primary and secondary endpoints, with statistically significant clinical remission versus placebo in ulcerative colitis patients. A second programme, MB097, is in a Phase 1b study in advanced melanoma in combination with MSD’s KEYTRUDA, and the company lists Cancer Research UK, Genentech and Cambridge University Hospitals among its partners.

The $4.6bn case for bugs as drugs

The market Microbiotica sells into is small and steep. Roots Analysis (updated September 2026) puts global microbiome therapeutics at roughly $0.5bn in 2025, heading for $4.6bn by 2035 – a 25.4% CAGR over 2026-2035. The base is tiny because the category is young: US regulators approved the first faecal-microbiota products only in 2022 and 2023, and the field has spent the years since rebuilding credibility trial by trial. The disease itself is no niche – the company cites up to 5 million people living with ulcerative colitis globally.

For scale against our own records: Undecimal Bio’s $18M seed for RNA medicines, logged days earlier, is the more typical size for European clinical-stage bets this month – while the largest cheque in our October data, CMR Surgical’s $400M strategic round, landed in the same city. Cambridge is quietly having a very good quarter.

Patient capital, patient biology

So why does the lead matter more than the amount? Because of who it is not. Generalist growth investors have largely stayed away from European clinical-stage biotech since the 2022 correction, and the gap is being filled by capital that does not mark to market every quarter: state-backed banks, strategics, specialist life-science funds. In the US, crossover funds do this job. In Europe, increasingly, it is the state – and a Treasury-owned bank writing the lead cheque for gut bacteria is a sentence nobody would have written in 2016.

The good news is that this kind of money fits the biology. Live biotherapeutics need a decade, not a fund cycle, and a first close structure tells us the syndicate is still open – what to watch next is the second close, and above all the Phase 2 readout that this £36M is built to buy. If MB310 repeats its Phase 1b remission data at scale, Europe will have a world-leading asset in a category it already dominates scientifically.

Europe has never lacked gut science; it lacked backers willing to fund the decade it takes. One bank just signed up for it – keep your eyes on that second close, and on the readout behind it. The full picture of who is funding European biotech this quarter is in our fundraising data.