Organism
Bacillus species
Aerobic spore-forming bacteria from soil and plant surfaces, relevant to juice handling and heat processing rather than to the ferment itself.
- Kind
- Bacteria
- Binomial
- Bacillus spp.
- Role
- Spoilage, Present throughout
What it does
- Forms heat-resistant endospores that survive juice pasteurisation, which is why heat treatment of juice is designed around acid-tolerant spore-formers rather than around vegetative organisms.
- Grows in juice only where acidity is low, since most species need a higher pH than apple juice provides; acid-tolerant relatives such as Alicyclobacillus are the recognised concern in fruit juice processing.
- Produces a range of extracellular enzymes including pectinases and amylases, which can degrade juice constituents where growth does occur.
- Arrives with soil on fruit, so its presence tracks fruit handling and washing rather than cellar practice.
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 | Species range widely, from roughly 10 °C to above 50 °C for thermophilic members. |
| pH | Most species require above about pH 4.5; apple juice and cider are below that. |
| Oxygen | Aerobic to facultatively anaerobic depending on species. |
| Alcohol tolerance | Low; not a cider organism once fermentation has produced ethanol. |
| Sulphite tolerance | Not the operative control; acidity and ethanol exclude the group from cider. |
What it produces
Compounds this organism makes. Which organism made a compound usually decides whether it reads as a feature or as a symptom.
Pectin lyase
The chain-cutting activity in a commercial pectinase preparation, which raises press yield and clears a juice by destroying the colloid pectin creates — and destroys the possibility of keeving in the same stroke.
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.
Faults it causes
Faults this organism is implicated in. Several are faults only against a particular expectation — the same activity is a signature elsewhere.
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.
Mould taint
Musty, earthy, cellar-damp or rotten-fruit character carried in from mouldy fruit or from mouldy equipment, and a marker that the patulin question needs asking.
Where in the process it appears
Fruit washing
Removing soil, grass, stones and surface contamination from gathered fruit, usually in a water flume, before it reaches the mill.
Fruit sorting
Taking rotten, mouldy and damaged fruit and foreign material out of the crop before it reaches the mill, which is the primary control on patulin in cider.
Juice pasteurisation
Heat treatment of juice before fermentation, which inactivates enzymes and microorganisms, and in doing so removes the wild flora that would otherwise ferment it.
Juice storage
Holding unfermented juice sound between pressing and fermentation, by chilling, sulphiting, gas blanketing, freezing or aseptic filling.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
About Bacillus species
Bacillus has almost no role in fermented cider and a real one in the juice trade, which is why it appears on the canonical list at all. The genus is aerobic and mostly requires a pH well above what apple juice offers, so vegetative growth in juice is unusual and growth in cider is not a practical concern. What survives is the spore.
Spore survival is what makes the group a processing question. A pasteurisation calculated to destroy yeasts and vegetative bacteria will not destroy bacterial endospores, and juice processors design thermal regimes accordingly. In fruit juice specifically, the recognised spore-forming spoilage organism is Alicyclobacillus acidoterrestris, a relative separated out of Bacillus, which is unusual in tolerating both acid and heat and which produces guaiacol taint in juice. That is a juice-industry problem rather than a cider-cellar problem, and CiderHQ notes it here rather than overstating what Bacillus itself does.
For a cidery the practical content is short. Wash and sort the fruit, keep soil out of the mill, and the group is not something the ferment has to deal with.
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.
- 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.
- Where does the fizz in cider come from — Either from fermentation trapped in a sealed container, or from carbon dioxide dissolved into the cider under pressure before filling. The French cider appellations permit only the first, and require at least 1.0 to 1.5 bar at 20 °C depending on the name.
- How long can apple juice sit before i ferment it — Only hours at room temperature before wild fermentation begins. Chilled and sulphited it can be held for a day or two; beyond that it needs freezing, pasteurising or fermenting.
- Will pasteurised apple juice ferment — Not on its own — pasteurisation kills the wild yeast — but it ferments readily once a cultured yeast is pitched.
- Are apples washed before making cider
- Do you need to sort apples before pressing
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.
Hochschule Geisenheim University — beverage technology
Hochschule Geisenheim · university · retrieved 2026-08-24
German beverage-technology research covering apple wine and fruit juice processing, including the enzymology of clarification.