LACTIC BACTERIA DIFFERENTIAL AGAR

Lactic Bacteria Differential Agar is formulated as per McDonald et al for differentiation of homofermentative lactobacilli and heterofermentative streptococci. Lactobacilli and Streptococci are used as starter cultures in food and dairy industry. Streptococci grow first and produce metabolites, lowering the redox potential which enables Lactobacilli to grow. Lactobacilli synthesize products, which stimulate growth of Streptococci.
Heterofermentative lactic acid bacteria produce CO2, lactic acid, acetic acid, ethanol and mannitol. Homofermentative lactic acid bacteria produce only lactic acid. Homofermentative lactic acid bacteria produce lactic acid from fructose and is indicated by yellow colour formation. Heterofermentative lactic acid bacteria induce lesser acidification and thus vary in the colour formation by the indicator in the medium. Homofermentative bacteria cultivated on this medium form bluishgreen colony on agar while heterofermentative bacteria do not form much-coloured colony on agar surface.

for di?erentiation of homo-fermentative and hetero-fermentative lactic acid bacteria