Genus/species: Lactobacillus delbrueckii subspecies delbrueckii, lactis or bulgaricus
Gram Stain: Positive
Cell: rods that may appear long and filamentous
Colony: yellow/ off-white, raised, large, spherical
Liquid Growth: dispersed
Produces lactic acid as the sole end product. Their growth substrates can be amygdalin, lactose, maltose, D-Mannose, salicin, sucrose, or trehalose. They can live with or without oxygen. Nutrients requirements include: pyridoxamine phosphate, thymidine acid, casein, and histidine and seride peptides are stimulatory to their growth. Lactobacillus bulgaricus requires pantothenic acid and niacin.
They occur in nutrient rich and acidic habitats. They can be found in milk, cheese, yeast, grain mash, human intestine, grapes, and grape must/wine.
They are non-motile, do not produce spores, and their optimum growth temperature is 37-42 degrees Celcius.
Role in wine:
They can be found on grapes and in musts/wines. They are malolactic bacteria that break down malic acid in wine and produce lactic acid. This reaction decreases the acidity of wine, and can be useful if a pH is too low. They also produce acetoin and diacetyl which can greatly contribute to the wine aroma profile.
- SO2: > 50mg/L
- Sorbate: YES
- DMDC: NO
- ph: <3.2 li="">
- Acids: fumaric
- Ethanol: >14.0%
- Anaerobiosis: NO
- Heat: Pasteurization, YES