Lactobacillus delbrueckii

Genus/species: Lactobacillus delbrueckii subspecies delbrueckii, lactis or bulgaricus

Gram Stain: Positive

Morphology:

Cell: rods that may appear long and filamentous
Colony: yellow/ off-white, raised, large, spherical
Liquid Growth: dispersed

Physiological Traits: 
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.

Ecological Traits: 
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.

Distinguishing Features: 

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.

Sensitivities:

  • SO2: > 50mg/L
  • Sorbate: YES
  • DMDC: NO 
  • ph: <3.2 li="">
  • Acids: fumaric
  • Ethanol: >14.0%
  • Anaerobiosis: NO
  • Heat: Pasteurization, YES