Biochemical Test of Lactobacillus spp.


Lactobacillus spp. is a group of gram-positive, rod-shaped bacteria that belong to the lactic acid bacteria (LAB) family. They are widely distributed in nature and can be found in various habitats, such as the human and animal gastrointestinal tract, oral cavity, vagina, fermented foods, and plant materials. They are also used as probiotics, starter cultures, and bio-preservatives in the food industry.

Lactobacillus spp. have some common characteristics that distinguish them from other bacteria. Some of these are:

  • They are facultative anaerobes, meaning they can grow in the presence or absence of oxygen.
  • They produce lactic acid as the main end product of carbohydrate fermentation, which lowers the pH of their environment and inhibits the growth of pathogens and spoilage microorganisms.
  • They have a complex nutritional requirement and need various vitamins, amino acids, peptides, and minerals for growth.
  • They are catalase-negative, meaning they do not produce the enzyme catalase that breaks down hydrogen peroxide into water and oxygen.
  • They are non-spore-forming, meaning they do not form resistant structures that can survive harsh conditions.
  • They are generally non-motile, meaning they do not have flagella or other structures that enable movement.

Lactobacillus spp. can be classified into different species based on their phenotypic and genotypic characteristics. Some of the commonly used methods for the identification and differentiation of Lactobacillus spp. Are:

  • Morphological observation: The shape, size, arrangement, and staining properties of the bacterial cells can be observed under a microscope.
  • Biochemical tests: The ability of the bacteria to ferment different carbohydrates, produce gas, hydrolyze certain substrates, and utilize specific compounds can be tested using various media and reagents.
  • Molecular methods: The genetic material of the bacteria can be analyzed using techniques such as polymerase chain reaction (PCR), DNA sequencing, DNA hybridization, and ribotyping.

In this article, we will focus on some of the biochemical tests that can be used to identify and characterize Lactobacillus spp. These tests include:

  • Fermentation of L. acidophilus
  • Enzymatic reactions of Lactobacillus spp.

These tests will help us understand the metabolic capabilities and physiological functions of Lactobacillus spp., as well as their potential applications in food and health.