Lactose Hydrolysing Enzymes in Streptococcus lactis and Streptococcus cremoris and also in some other Species of Streptococci

Two types of Streptococcus lactis could be identified: cheese starter strains, which contain β‐phosphogalactosidase and ferment lactose rapidly to lactate, and non‐dairy strains, which contain both β‐galactosidase and β‐phosphogalactosidase and ferment lactose slowly to a variety of end products. All strains had homolactic glucose fermentations and heterolactic galactose fermentations. Other species of streptococci were examined for lactose hydrolysing enzymes and found to contain β‐phosphogalactosidase, except Strep, thermophilus and Strep. faecium which had high levels of β‐galactosidase. Discrepancies were found in the lactose hydrolysing enzymes content when the cells were treated in different ways.