Production of beta-galactosidase from Streptococcus thermophilus grown in whey

Area of Science:

• Biotechnology
• Enzymology
• Microbiology

Background:

• Beta-D-galactosidase (EC 3.2.1.23) is a key enzyme in lactose metabolism.
• Streptococcus thermophilus is a common bacterium used in dairy fermentation.
• Deproteinized cheese whey presents a potential low-cost medium for microbial cultivation.

Purpose of the Study:

• To optimize cultural conditions for beta-D-galactosidase production from Streptococcus thermophilus.
• To identify supplements that enhance enzyme yield.
• To investigate the application of the enzyme for lactose hydrolysis.

Main Methods:

• Cultivation of Streptococcus thermophilus in deproteinized cheese whey.
• Optimization of pH, temperature, and incubation time for enzyme production.
• Testing the effect of proteose peptone and corn steep liquor on enzyme yield.
• Assessing enzyme activity for lactose reduction in aqueous solutions and skim milk.

Main Results:

• Optimal production conditions identified as pH 7.0, 40°C, and 24 hours incubation.
• Proteose peptone (2.0%) and corn steep liquor (2.8%) significantly increased enzyme units (18,200 U/L and 10,000 U/L, respectively).
• Inorganic nitrogen and phosphorus sources showed insignificant impact on enzyme production.

Conclusions:

• Deproteinized cheese whey is a suitable substrate for beta-D-galactosidase production.
• Specific supplements dramatically enhance enzyme yield, offering a cost-effective strategy.
• Optimized beta-D-galactosidase has potential applications in lactose hydrolysis.