Improved Medium for Lactic Streptococci and Their Bacteriophages

摘要: Incorporation of 1.9% beta-disodium glycerophosphate (GP) into a complex medium resulted in improved growth by lactic streptococci at 30 C. The medium, called M17, contained: Phytone peptone, 5.0 g; polypeptone, yeast extract, 2.5 beef lactose, ascorbic acid, 0.5 GP, 19.0 1.0 M MgSO(4).7H(2)O, ml; and glass-distilled water, 1,000 ml. Based on absorbance readings total counts, all strains Streptococcus cremoris, S. diacetilactis, lactis grew better M17 than similar lacking GP or broth. Enhanced was probably due to the increased buffering capacity since pH values below 5.70 were not reached after 24 h C cremoris strains. also proved useful for isolation bacterial mutants ability ferment lactose; such formed minute colonies agar plates, whereas wild-type cells 3 4 mm diameter. sterile skim milk final concentration enhanced acid-producing activity when inoculated from containing GP. superior other media demonstrating distinguishing between streptococcal bacteriophages. Plaques larger 6 diameter developed with some phage-host combinations, turbid plaques, indicative lysogeny, easily demonstrated systems.