Glossary
Lactobacillus
A genus of bacteria that produces lactic acid, used deliberately to sour beer and regarded as a spoilage organism everywhere else.
Pronounced lak-toh-ba-SIL-us.
Also called lacto, lactic acid bacteria.
The full record
Lactobacillus has its own catalogue entry with the detail this page summarises — causes, thresholds, related styles and evidence.
Lactobacillus — Lactic acid bacteria that produce clean sourness — essential to Berliner Weisse, gose and kettle souring, and ruinous elsewhere.
Lactic acid is the clean, yoghurt-like acidity of a gose, Berliner Weisse or kettle-soured beer, as distinct from the sharper acetic acid of a Flanders red. Many strains are inhibited by hop compounds, which is why souring is usually done before hops are added.
Related
- Kettle souring — The controlled use of it.
- Pediococcus — The other main souring bacterium.
More vocabulary
Adjunct · Aroma hop · Base malt · Bittering hop · Black malt · Brettanomyces · Candi sugar · Chocolate malt · Crystal malt · Dextrin
See every term on the glossary index.
Last reviewed 2026-08-16.