Lactic Acid Bacteria (LAB)


Lactic Acid Bacteria (LAB) are a physiologically diverse group of organisms, which can be generally described as Gram-positive, nonsporing cocci or rods with lactic acid as the major
product of carbohydrate fermentation. Traditionally, LAB consist of four genera:
1. Lactobacillus
2. Leuconostoc
3. Pediococcus
4. Streptococcus


LAB number is often used in food preparation. The LAB will have a direct impact on food because LAB will decompose sugar and an acidic solution that can reduce microbial contamination further.

LAB is degrading microbes, like many others that are able to polysaccharide product based on the type of LAB. Many species of LAB produce exopolysaccharide (EPS). EPS-producing LAB, including the genera Lactobacillus, Leuconostoc, Pediococcus and Streptococcus, produce a wide variety of structurally different polymers. Many reviews on EPS produced by LAB have been published dealing with :
– Physiology
– Fermentation
– Chemical and structural of EPS
– Biosynthesis
– Genetic and metabolic engineering
– Functional properties of LAB

Lactobacillus confusus is a heterofermentative bacterium, grampositive, coccobacilli and short rod. Lb. confusus grows at 25–42 °C. It is catalase negative and positive for esculin hydrolysis and arginine deamination. It is positive for acidification of glucose, sucrose, maltose, fructose and salicin. Lb. confusus has been found in foods as well as in humans :
– Garlic
– Banana leaves
– Sugarcane
– Carrot juice
– Raw milk
– etc.

The type Lactobacillus is heterogeneous with 33-35 mol% of G + C is a composition of the DNA. The lactobacilli are specifically fermentative and have complex nutritional requirements. They grow in and associated with many different habitats such as :
1. Human body
– oral cavity
– intestinal tract
– vagina
– etc.
2. Plants and plant materials
3. soil
4. Food fermentations
– milk
– meat
– vegetables
– etc.
5. Cereal products
6. Food spoilage
– beer
– fruit
– grain mashes
– etc.
7. Water and sewage
– etc.

Lactobacilli are used as starter cultures for several varieties of cheese, fermented plant foods, fermented meats.