Lactobacillus
The fast-souring bacteria of Berliner Weisse, gose, and modern kettle sours. Produces clean lactic tartness.
What it tastes like
Lactobacillus is the bacteria that turns sweet wort into sour wort. Different species produce different character — L. plantarum is fast and clean (24-48 hours to a 3.3 pH), L. brevis is slower with more complex character, L. delbrueckii is the traditional Berliner Weisse and lambic acidifier. Most modern American kettle sours use L. plantarum because it works fast and doesn't add weird flavors. After souring, you boil the wort (killing the Lacto), then ferment with regular ale yeast. Two-organism beer in one batch.
Best in these styles
Fermentation profile
Kettle souring procedure: mash and lauter as normal, briefly boil to kill background bugs, cool to 95-110°F, pitch Lacto (commercial pure culture OR a handful of crushed grain for the wild approach), purge with CO2 or top with plastic wrap to prevent oxidation (which produces vinegar). Hold 24-72 hours until pH hits target (3.2-3.4). Then boil to kill Lacto, add hops, ferment with regular ale yeast.
Available as
Lactobacillus is sold under multiple supplier brand names — same or near-identical strain.
| Format | Supplier | Product code | Notes |
|---|---|---|---|
| Liquid | White Labs | WLP677 L. delbrueckii | 100B cells Traditional Berliner Weisse strain |
| Liquid | Omega | OYL-605 Lacto Blend | Various Mixed Lacto strains for fast clean souring |
| Liquid | Wyeast | 5335 L. buchneri | 100B cells |
| Powder | Goodbelly probiotic shot | L. plantarum (Probiotic from grocery store) | 2.7oz bottle Cheap, accessible, works — homebrewer trick |
Comparable strains
If you can't source this strain, these alternatives bring overlapping character or fermentation behavior.
History
Lactobacillus has been souring beer for thousands of years — every wild fermentation of grain has some Lacto activity. The technique was largely abandoned in modern brewing after Pasteur's discoveries on sterile fermentation in the 1800s. Sour beer's revival in the 2000s (driven by Russian River, Cantillon, etc.) brought Lacto back. The modern 'kettle sour' technique — fast, controlled Lacto souring before primary fermentation — was popularized by US craft breweries in the early 2010s and is now standard for fruited and citrus-driven American sours.