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[Effect of KH2PO4 on Streptococcus lactis growth and nisin synthesis when the medium is kept at a constant pH]
Abstract:
When the pH of the medium was maintained at the level of 6.6--6.8 and the content of KH2PO4 in it was decreased, the biosynthetic activity of Streptococcus lactis, strain MGU, became lower. The culture assimilated low quantities of phosphorus from KH2PO4 at a high concentration of this salt in the medium; presumably, the culture required large quantities of potassium ions. If the pH of the medium is maintained at a constant value, the fermentation can be stopped 21 hr after the beginning of cultivation of Str. lactis, strain MGU.
Insights
Optimizing Streptococcus lactis fermentation requires careful control of pH and potassium phosphate levels. Lowering potassium phosphate reduces biosynthesis, suggesting a high potassium ion demand for optimal Streptococcus lactis growth.
Area of Science:
- Microbiology
- Biochemistry
- Fermentation Technology
Background:
- Streptococcus lactis is a key lactic acid bacterium used in food fermentation.
- Understanding the nutritional requirements of S. lactis is crucial for optimizing industrial processes.
- Previous studies have highlighted the importance of specific ions and pH for bacterial growth and metabolism.
Purpose of the Study:
- To investigate the impact of pH and potassium phosphate (KH2PO4) concentration on the biosynthetic activity of Streptococcus lactis, strain MGU.
- To determine the optimal conditions for S. lactis cultivation and fermentation.
- To understand the nutrient assimilation patterns of S. lactis.
Main Methods:
- Cultivation of Streptococcus lactis, strain MGU, in a controlled laboratory medium.
- Manipulation of medium pH to a range of 6.6--6.8.
- Varying the concentration of potassium phosphate (KH2PO4) in the growth medium.
- Monitoring bacterial biosynthetic activity and nutrient assimilation.
Main Results:
- A decrease in KH2PO4 content at a pH of 6.6--6.8 led to reduced biosynthetic activity in S. lactis.
- The bacterium assimilated low amounts of phosphorus from KH2PO4 when it was highly concentrated in the medium.
- High potassium ion concentration appears to be a critical factor for S. lactis metabolism.
- Fermentation by S. lactis, strain MGU, could be reliably terminated after 21 hours under constant pH conditions.
Conclusions:
- Optimal biosynthesis and fermentation by Streptococcus lactis, strain MGU, are dependent on specific pH and KH2PO4 concentrations.
- The bacterium exhibits a high requirement for potassium ions, influencing its phosphorus assimilation.
- Controlled fermentation processes for S. lactis can be achieved by maintaining stable pH and managing nutrient levels.