Life science tools · DNA synthesis

Ansa Biotechnologies

An enzymatic DNA synthesis company in Emeryville that sells the genes other vendors decline. It shipped its first product in 2024, reached 50 kilobases in 2025, and now has a peer reviewed paper and a Danaher distributor behind the claim.

The sequences nobody else would make

In the spring of 2025 a batch of complex, repetitive DNA arrived for synthesis in Emeryville, California. Several other vendors had already turned the job down. The longest piece ran to about 41,000 bases.

The customer was George Church, the Harvard Medical School and MIT geneticist whose lab has spent three decades pressing on the limits of what can be written. “The company successfully delivered a set of complex, repetitive sequences up to 41 kb that several other companies had declined to synthesize, all in about half the time of current industry standards,” he said in an Ansa press release that May.

A testimonial inside a company release is the weakest evidence there is. What makes this one worth a second look is that the harder record behind it has begun to fill in.

Why long DNA is hard

Almost all synthetic DNA is still made the way it was made in the late 1980s. The nucleoside phosphoramidite method extends a strand one base at a time using acid and organic solvents. The founders’ own 2018 abstract stated the constraint: direct synthesis tops out near 200 bases, and the process produces hazardous waste.

Anything longer gets stitched together from short pieces, usually in the customer’s own laboratory, and the stitching fails most reliably on the features that make a construct interesting: repeats, strong secondary structure, extreme GC content. A researcher can wait weeks to learn the gene cannot be built at all.

Two graduate students and a tethered enzyme

Daniel Lin-Arlow came to biology from computing and joined Jay Keasling’s laboratory at UC Berkeley to learn to engineer cells. He spent much of his time waiting on DNA. “I decided I was going to step back from engineering cells and instead work on tools for DNA synthesis, because I knew that for this revolution to happen, we really needed to tighten up the feedback loop,” he told Forbes in 2023.

Sebastian Palluk was working on enzymatic synthesis in the same orbit, at Lawrence Berkeley National Laboratory and the Joint BioEnergy Institute. Their idea was to stop treating the nucleotide and the enzyme as separate reagents. They tethered one deoxyribonucleoside triphosphate to one molecule of terminal deoxynucleotidyl transferase, the template independent polymerase vertebrates use to diversify antibody genes. Each conjugate adds its single base, then stays bound to the growing end, physically blocking any other conjugate from adding a second. Cleave the linker and the strand is ready again. No harsh chemistry ever touches the molecule. Nature Biotechnology published the method on June 18, 2018. The demonstration was ten bases long.

A third co-founder, Jared Ellefson, worked on directed evolution of polymerases. By the company’s account he had a method running within five months that could test millions of TdT variants in an afternoon. Fifty Years led a pre-seed round in December 2018.

From ten bases to fifty thousand

Horizons Ventures led a $7.9 million seed in 2020. Northpond Ventures led a $68 million Series A announced in April 2022. In March 2023 the company reported synthesizing a 1,005 base oligonucleotide in a single run, encoding part of an AAV vector, and called it the longest ever reported. The figure underneath that headline matters more: about 28 percent of the molecules were sequence perfect, which is what a stepwise yield near 99.9 percent looks like compounded a thousand times.

Then the company changed shape. In February 2024 Jason T. Gammack, formerly chief commercial officer at Inscripta and co-founder and CEO of Resolve Biosciences, became chief executive. Lin-Arlow moved to chief scientific officer, Palluk to chief technology officer. First shipments were 600 base pairs. Clonal DNA reached 5 kilobases, then 7.5, then early access at 50 kb in May 2025 and a global launch that October.

50 kb is not written end to end, and the company does not say it is. Ansa synthesizes strands of roughly 750 to 1,000 bases, then joins more than 20 of them in one reaction by a method Gammack has described as similar to Golden Gate assembly. “If you want to build big Lego castles, you should start with big Lego pieces,” he told GenomeWeb in December 2025. The claim is not that assembly has been abolished. It is that bigger, cleaner pieces make the assembly work.

The screening question

Every seller of synthetic DNA sits on a control point. Rebuilding a virus from ordered fragments has been a documented possibility for more than twenty years, and the industry answer since 2009 has been the International Gene Synthesis Consortium and its voluntary Harmonized Screening Protocol. Ansa says it joined before it sold anything. Its screening vendor, Aclid, reports tens of thousands of Ansa constructs screened at an average of 2.49 seconds each, and says federal framework compliance is what let Ansa serve federally funded laboratories. All of that is self reported or vendor reported. No independent audit is public.

What is proven, and what is still claimed

Read plainly: the chemistry is real, it has now been used outside the company in a peer reviewed paper, and the product has been picked up by a Danaher business with every reason to build its own. The length record and the yield figures remain company reported. Revenue, volume and margin have never been disclosed, and the most testable commercial promise, an on-time guarantee that refunds the whole order, carries no published failure rate.

What to watch

• Whether the 50 kb product holds its turnaround under distributor volume. IDT began listing it in January 2026.
• The 1 kb error corrected fragment product the CEO said would launch in early 2026.
• Any published on-time performance figure. The guarantee is the central marketing claim and is unaudited.
• The competitive answer. Twist says chemical synthesis still wins on speed and cost, and enzymatic rival Molecular Assemblies shut down in 2024.
• Whether order screening becomes a legal requirement rather than a voluntary protocol.

In their words

Ansa Biotechnologies funding profile on HVCFHealthcare Venture Capital Fund

Related companies

• Kern Systems: Also in Industrial Bio. A Boston company spun out of George Church’s Harvard lab to write digital data into DNA with enzymes instead of chemistry
• 20n: Also in Industrial Bio. A Y Combinator biotech whose software invented a fermentation route to the active ingredient in Tylenol, then published its whole stack as open source in March 2017 and
• Culture Biosciences: Also in Industrial Bio. A cloud lab that ran other companies’ fermentation for them, now selling the bioreactor itself through Cytiva
• Synvivia: Also in Industrial Bio. A UC Berkeley spinout that built molecular on and off switches so engineered microbes die unless they are fed a specific chemical

Sources

1. Public recordDe novo DNA synthesis using polymerase-nucleotide conjugatesNature Biotechnology · Jun 18, 2018
2. Public recordGenome synthesis, assembly, and rebooting of high G+C% mycobacteriophagesPNAS · Nov 10, 2025
3. Public recordNSF SBIR awards 1914354 and 2036532NSF · 2019 to 2023
4. Public recordForm D filings, CIK 0001816722SEC EDGAR · 2020 to 2025
5. IndependentThis Company Is Using Enzymatic DNA Synthesis To Usher In The Next GenerationForbes, John Cumbers · May 12, 2023
6. IndependentAnsa Targets Nucleic Acid Synthesis Market With Ultra-Long Clonal DNA ServiceGenomeWeb, Huanjia Zhang · Dec 17, 2025
7. IndependentAnsa Biotechnologies ties up $68M for DNA synthesis platformFierce Biotech · Apr 11, 2022
8. IndependentAnsa snares $54.4M in series B financingFierce Pharma · Oct 2, 2025
9. CompanySuccessful de novo Synthesis of World’s Longest Oligonucleotide at 1005 BasesBusiness Wire · Mar 9, 2023
10. CompanyAnsa Breaks Traditional Synthetic DNA Length BarriersBusiness Wire · May 7, 2025
11. CompanyAnsa Redefines DNA Synthesis with 50 kb Sequence-Perfect Clonal ProductBusiness Wire · Oct 22, 2025
12. PartnerIDT Expands Synthetic Biology Portfolio with Ansa Clonal DNAIDT · Jan 14, 2026
13. VendorPioneering synthetic DNA with speed and precision, Ansa case studyAclid · 2026