Organism
Lactobacillus brevis
An obligately heterofermentative lactic acid bacterium, renamed Levilactobacillus in 2020, associated with volatile acidity, biogenic amines and mousiness rather than with clean malolactic conversion.
Also called Lactobacillus brevis.
- Kind
- Bacteria
- Binomial
- Levilactobacillus brevis
- Role
- Malolactic conversion, Spoilage
What it does
- Ferments sugar by the obligately heterofermentative phosphoketolase route, so every glucose yields acetic acid and carbon dioxide alongside lactic acid — the reason its growth in a cider with residual sugar always raises volatile acidity.
- Converts malic acid to lactic acid, and so contributes to malolactic conversion where it is part of the population, but rarely does so without other consequences.
- Decarboxylates amino acids to biogenic amines, tyramine in particular, a documented capability of this species and one reason lactic spoilage is a food-quality question as well as a flavour one.
- Produces tetrahydropyridines in some conditions, contributing to mousiness alongside Brettanomyces.
- Generates carbon dioxide in sealed containers, causing haze, gas and pressure in cider that was assumed stable.
Conditions it works in
What the organism tolerates and what suppresses it. These are the levers a maker actually has: temperature, acidity, air, alcohol and sulphite.
| Condition | What is recorded |
|---|---|
| Temperature | Grows across roughly 15 °C to 35 °C. |
| pH | Moderately acid-tolerant, generally growing down to around pH 3.5 and less reliably below it. |
| Oxygen | Facultatively anaerobic; grows in sealed packaging. |
| Alcohol tolerance | Moderate; tolerant of cider strength and known as a beer spoilage organism at lower alcohol. |
| Sulphite tolerance | Sensitive to free sulphur dioxide. |
What it produces
Compounds this organism makes. Which organism made a compound usually decides whether it reads as a feature or as a symptom.
Lactic acid
The softer acid that replaces malic when malolactic fermentation runs, halving the acid a cider carries and changing its texture as much as its sharpness.
Acetic acid
The vinegar acid, made by bacteria oxidising ethanol whenever air reaches a cider, and the one fault in cider that no later processing can undo.
Carbon dioxide
The other product of fermentation, which protects a cider from air while it is being made and, dissolved in the finished drink, changes both its texture and its perceived acidity.
Biogenic amines
Amines produced when bacteria decarboxylate amino acids, associated with long lees contact at high pH and low sulphite, and a reason bacterial activity is managed rather than simply tolerated.
Tetrahydropyridines
The compounds behind mousiness, which cannot be smelled in the glass because they are not volatile at cider pH and appear only as an aftertaste once saliva has raised the pH in the mouth.
Diacetyl
The butter compound, made mainly by lactic acid bacteria and perceptible at very low concentration, which is a defining part of some traditional ciders and an obvious fault in others.
Faults it causes
Faults this organism is implicated in. Several are faults only against a particular expectation — the same activity is a signature elsewhere.
Lactic off-flavours
Sauerkraut, sour milk, silage or cheesy notes from lactic acid bacteria working on sugars and other substrates rather than on malic acid alone.
Volatile acidity
The measurable fraction of acidity that can be steam-distilled off, dominated by acetic acid and read as vinegar sharpness in the nose and a hard, hot finish.
Mousiness
A retronasal taint of mouse cage, stale popcorn or crackers that appears only after swallowing — and that a substantial fraction of people cannot detect at all.
Unwanted refermentation
Fermentation restarting in a sealed container, generating carbon dioxide that was not planned for and pressure that a bottle may not withstand.
Microbial haze
Cloudiness caused by a growing population of spoilage organisms, and therefore a symptom of something worse rather than a clarity problem in itself.
Ropiness
Cider that pours thick and pulls into an oily thread, caused by lactic acid bacteria secreting long-chain glucan polymers into the drink.
Acrolein bitterness
An intense, lingering bitterness quite unlike tannin, produced when lactic acid bacteria convert glycerol to acrolein and the acrolein reacts with the cider’s phenolics.
Geranium taint
A sharp, unmistakable crushed-geranium-leaf smell produced when lactic acid bacteria metabolise sorbic acid added as a preservative.
Where in the process it appears
Tank maturation
Resting cider in stainless steel or a lined vessel, where the point of the container is that it contributes nothing and admits almost no oxygen.
Sulphiting
Adding sulphur dioxide to juice to suppress spoilage organisms and oxidative browning, at a level that only means anything once the juice pH is known.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
Sterile filtration
Membrane filtration at a rating that retains viable yeast and bacteria, which is what allows a sweet cider to be shelf-stable without heat or preservative — provided the filling that follows is aseptic.
Malolactic fermentation
A bacterial conversion of sharp malic acid into softer lactic acid, which lowers acidity, changes aroma, and in most traditional cider happens whether it was planned or not.
Racking
Moving cider off the sediment it has thrown, which both cleans the liquid and — by taking yeast and nitrogen away with the deposit — slows what is left of the ferment.
About Lactobacillus brevis
Levilactobacillus brevis — Lactobacillus brevis in everything written before 2020 and in most things written since — is the lactic acid bacterium a cider maker least wants. Where Oenococcus oeni can convert malic acid with comparatively little collateral chemistry, L. brevis is obligately heterofermentative, meaning it has no pathway that ferments sugar without producing acetic acid. Any growth it achieves on residual sugar shows up as volatile acidity.
It brings two further liabilities. Its amino acid decarboxylases produce biogenic amines, tyramine especially, which are a genuine compositional concern in fermented drinks independent of taste. And it is among the lactic acid bacteria implicated in mousiness: the tetrahydropyridines responsible are produced by Brettanomyces and by several lactic acid bacteria, and a cider showing mousiness may have either or both.
Mousiness is worth a note of its own because of how it presents. The compounds are not volatile at cider pH, so the fault is often undetectable on the nose and appears only retronasally, seconds after swallowing, once saliva has raised the pH in the mouth. A proportion of tasters cannot detect it at all. A cider that one taster finds unmistakably mousy and another finds clean is a well-documented phenomenon and not a disagreement about standards.
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- Can you fix a cider that has gone vinegary — Not really. Volatile acidity cannot be removed at small scale, and blending it away only dilutes it. The realistic options are to accept it, to blend a lightly affected batch into a much larger sound one, or to let it finish becoming vinegar.
- How do i sterilise cider bottles — Wash them clean first, then sanitise with a no-rinse sanitiser or a sulphite solution, and fill while still wet with it. Bottles that look clean but have dried deposits inside are the usual source of bottle spoilage.
- What is malolactic fermentation — Malolactic fermentation is a bacterial conversion of sharp malic acid into softer lactic acid, releasing carbon dioxide. It lowers total acidity and raises pH, and in cider it is often the source of a farmyard or buttery note as well.
- What is mousiness in cider — Mousiness is a fault caused by tetrahydropyridines produced by *Brettanomyces* and some lactic acid bacteria. It tastes of stale grain or a mouse cage and appears in the aftertaste rather than in the aroma.
- What is racking in cider making — Racking is siphoning cider off the sediment it has thrown into a clean vessel, leaving the lees behind. It clarifies the cider and, in traditional practice, is also used to slow a ferment by removing yeast with the lees.
- Why did my sweetened cider start fermenting again — Live yeast met the sugar that was added back. Sweetening is only stable if the yeast has been removed by sterile filtration, killed by pasteurisation, or held in check by sorbate together with sufficient sulphite.
Where to go next
- All organisms — Grouped by what each does in the ferment, and by what kind of organism it is.
- Compounds — The chemistry this microbiology produces.
- Troubleshooting — Work from the symptom in the glass back to the organism.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
Peer-reviewed literature on cider fermentation microbiology
Various journals · peer-reviewed literature · registered as competent for this subject
Covers the microbial succession of spontaneous cider fermentation, the role of non-Saccharomyces yeasts in the early stages, malolactic conversion by Oenococcus and Lactobacillus species, and the organisms behind the principal spoilage faults.
Cider and perry production technical training material
Peter Mitchell / Cider and Perry Academy · reference work · registered as competent for this subject
Searched again on 2026-08-25 and it remains the one printed source here that a bibliographic check cannot fix, because it is not a published work with an edition. It is course material issued to participants of a training programme, so there is no catalogue record to verify, no ISBN, and no lawful public copy. Its state stays `registered` for that reason rather than through inattention.
Prevalent lactic acid bacteria in cider cellars and efficiency of Oenococcus oeni strains
Sánchez, Coton, Coton, Herrero, García and Díaz, Food Microbiology 32(1):32–37 · peer-reviewed literature · retrieved 2026-08-24
Which lactic acid bacteria are actually in working Asturian cider cellars, rather than which ones the wine literature would predict. Bibliographic record verified through Crossref on 2026-08-24 and the abstract read; the full text is paywalled on ScienceDirect. Cited for the identification of the prevalent species and for the finding that strains sort by producing area, not for any figure.