🧫 Lactic acid bacteria
Also known as: LAB, lactobacilli
Bacteria that convert sugars such as lactose into lactic acid.
Lactic acid bacteria are a functional group of Gram-positive, non-spore-forming microorganisms that convert sugars into lactic acid through fermentation. The name does not denote a formal taxonomic rank. They convert lactose, the milk sugar, into lactic acid under anaerobic conditions.
In dairy products, lactose is first split by the enzyme beta-galactosidase and then converted to lactic acid, which lowers the pH. This gives fermented milks such as buttermilk their tangy flavour and thick texture. Lactobacillus delbrueckii subsp. bulgaricus is a key thermophilic starter in yogurt, usually paired with Streptococcus thermophilus; the subspecies lactis is used as a starter or adjunct in hard and semi-hard cheeses for acidification and flavour. The rapid fall in pH also improves microbial safety and shelf stability.
Many probiotics come from this group. The FAO/WHO definition describes probiotics as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. Probiotic features are attributed to specific strains rather than to a species as a whole, and most health claims need to be verified by strain-level testing, so a general promise of benefit for a whole product should be read with care.
Wine
In wine, lactic acid bacteria, primarily Oenococcus oeni, carry out malolactic fermentation: the conversion of malic acid to lactic acid, which decreases the acidity of the wine. It is a vital step for many red wines and some white wines, and matters most in cool-climate wines that are high in malic acid.
Malolactic fermentation can change the aroma. Diacetyl, which has a buttery aroma, can be objectionable above 5 mg/L but may be desirable at lower levels, depending on the style.
Most often the fermentation follows the alcoholic fermentation, which also makes it easier to keep the acidity in wines that should not undergo it. Traditionally it was carried out by indigenous lactic acid bacteria from the grapes or the winery; commercial O. oeni starter cultures now give winemakers more control over timing. Above pH 3.50, O. oeni may also metabolise sugar and raise the acetic acid, and red wines may lose some colour.
How it connects to milk
🧫 Lactic acid bacteria → kind of → 🏭 Milk processing at the dairy plant → kind of → 🥛 Milk
How it connects to Wine
🧫 Lactic acid bacteria ← related ← 🫒 Olives ← related ← 🍷 Wine
Links
- Needed for
- 🧫 Starter culture, 🫒 Spanish-style green olives, 🧀 Fontina, 🧀 Formaggella del Luinese, 🧀 Gorgonzola, 🧀 Idiazabal, 🧀 Livanjski sir, 🧀 Mont d'Or, 🧀 Montasio, 🧀 Taleggio
- Who works with it
- 🍷 Malolactic fermentation
- What they produce
- 🧪 Lactic acid
- Where it is found
- 🥣 Amasi, 🥛 Ryazhenka
- What it affects
- ❤️ Digestion, 🛡️ Immunity
- What affects it
- 🧂 Brine
- Part of
- 🏭 Milk processing at the dairy plant, 🍷 Fermentation
- Wine and milk
- 🍷 Malolactic fermentation
- In other topics
- 🫒 Olives
Frequently asked questions
What do lactic acid bacteria do?
They convert sugars, including lactose, into lactic acid. In milk this lowers the pH and gives fermented products their tangy flavour and thick texture.
Are lactic acid bacteria and probiotics the same thing?
No. Many probiotics are lactic acid bacteria, but probiotics are defined as live microorganisms that confer a health benefit in adequate amounts, and this is attributed to specific strains, not to a whole species.
Which bacteria ferment yogurt?
Lactobacillus delbrueckii subsp. bulgaricus, usually together with Streptococcus thermophilus.
Recipes
Guides
History
What to read next
- 🫒 Spanish-style green olives — Green olives treated with lye and fermented in brine by lactic acid bacteria.
- 🥣 Amasi — Thick sour milk of southern Africa: traditionally raw milk sours for 1–3 days; commercial amasi is made from pasteurised milk with a Lactococcus lactis culture.
- ❤️ Digestion — How easily milk is digested depends on fat globule size, casein type and lactose.
- 🫒 Olives — The fruit of the olive tree, pressed for oil or cured and eaten as table olives.
- 🧂 Brine — Salty water in which olives ferment and keep, with 5 to 10 % salt.
Similar
What it includes
Sources
- Lactobacillus delbrueckii: a functional powerhouse in dairy fermentation and emerging probiotic applications (review), PMC
- NCBI Bookshelf: Manipulating Host-Microbe Interactions: Probiotic Research and Regulations
- Oregon State University Extension EM 9641: Simultaneous malolactic fermentation