Lactic HiVeg™ Agar

Principle And Interpretation

Lactic Agar was developed by Elliker et al (1) and recommended by APHA (2) for cultivation of lactic bacteria to promote the colony development of Lactobacilli and lactic Streptococci. Lactic HiVeg Agar is prepared by replacing animal based peptones with vegetable peptones to avoid BSE/TSE risks associated with animal peptones. Samples are analyzed by pour plate technique. Lactic acid bacteria are fastidious in nature and hence Lactic HiVeg Agar is designed to satisfy their growth requirement. Lactic acid bacteria survive at low pH, but are very sensitive to other adverse conditions.

Samples to be examined for enumeration of viable lactic acid bacteria should not be frozen prior to analysis. Many of the lactic acid bacteria are easily killed or injured by freezing. For dilution of products it is best to use sterile 0.1% Peptone HiVeg Water (MV028) as the diluent since it protects bacteria during the dilution process (3)

HiVeg hydrolysate and yeast extract provide amino acids, other nitrogenous nutrients, vitamin B complex etc. Dextrose, lactose and sucrose are the fermentable carbohydrates. Ascorbic acid provides vitamin C required for lactic acid bacteria. Sodium chloride maintains the osmotic equilibrium of the medium. Sodium acetate inhibits contaminating bacteria and restricts the swarming of lactic acid bacteria. Upon incubation, the colonies are examined for gram staining and catalase production. Gram-positive, catalase-negative cocci or rods are tentatively considered to be lactic acid bacteria (2).