Evaluating acetaldehyde synthesis from L-/sup 14/C(U)) threonine by Streptococcus thermophilus and Lactobacillus bulgaricus

Journal Article · Thu May 01 00:00:00 EDT 1986 · J. Dairy Sci.; (United States)

DOI:https://doi.org/10.3168/jds.S0022-0302(86)80526-4· OSTI ID:5618116

Wilkins, D W; Schmidt, R H; Shireman, R B; Smith, K L; Jezeski, J J

To evaluate the synthesis of acetaldehyde from threonine during growth of yogurt cultures, Streptococcus thermophilus MS1 and Lactobacillus bulgaricus MR1 were grown in defined medium in which 10% of the total threonine was composed of L-(carbon-14(U))threonine. Acetaldehyde production was monitored by formation of 2,4-dinitrophenylhydrazone followed by separation and analysis using high performance liquid chromatography. After growth for 8 h at 42/sup 0/C, approximately 2.0% of the total acetaldehyde (780.4 nmol) produced was from L-(carbon-14)threonine. Threonine aldolase activity was determined in cell-free extracts from S. thermophilus and L. bulgaricus grown in Elliker broth. Increasing incubation temperature from 30 to 42/sup 0/C decreased threonine aldolase activity in cells of the streptococcus harvested after 8 h of incubation. Effect of incubation temperature was more dramatic in cells harvested after 18 h where the activity of cells grown at 48/sup 0/C was 89% lower than that of cells grown at 30/sup 0/C. Cell extracts from S. thermophilus MS1 possessed higher threonine aldolase activity than did those from L. bulgaricus MR1. Increased assay temperature from 30 to 42/sup 0/C increased threonine aldolase activity in S. thermophilus MS1.

• Research Organization: Univ. of Florida, Gainesville, FL (United States)
• OSTI ID: 5618116
• Journal Information: J. Dairy Sci.; (United States), Vol. 69:5
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
MILK PRODUCTS
FOOD PROCESSING
ACETALDEHYDE
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CHROMATOGRAPHY
ENZYME ACTIVITY
GROWTH
LACTOBACILLUS
STREPTOCOCCUS
TEMPERATURE DEPENDENCE
THREONINE
TRACER TECHNIQUES
ALDEHYDES
AMINO ACIDS
BACTERIA
CARBOXYLIC ACIDS
FOOD
HYDROXY ACIDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROCESSING
SEPARATION PROCESSES
SYNTHESIS
553001* - Agriculture & Food Technology- Tracer Techniques- (-1987)