Lactococcus Lactis
Lactococcus Lactis - Related Videos
03:37
Assessing the Antimicrobial Activity of Nisin Variants Using an Agar Well Diffusion Assay
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2025
Source: Nickling, J. H., et.al. Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids. J. Vis. Exp. (2018)This video demonstrates an agar well diffusion assay used to evaluate the antimicrobial activity of nisin variants. It shows how Lactococcus lactis expressing the membrane-bound peptidase NisP activates nisin precursors produced in E. coli, resulting in growth inhibition halos. The size of these halos reflects the bioactivity of each nisin variant.
07:15
Invasion of Human Cells by a Bacterial Pathogen
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Cited by 44 •
2011
A general protocol for the study of invasion of host cells by a bacterial pathogen, focusing on Staphylococcus aureus and human endothelial cells.
FAQs
Lactococcus lactis channels sugars such as lactose through glycolysis, a metabolic pathway that breaks down sugar and generates lactic acid. As lactic acid accumulates, the surrounding milk becomes more acidic. This metabolic conversion links sugar utilization directly to the chemical changes that drive milk acidification during fermentation.
The lactic acid produced during sugar metabolism lowers the pH of milk. Increasing acidity inhibits competing microbes, allowing the fermentation process to proceed under conditions that favor the activity and technological effects of L. lactis. This pH shift therefore contributes both to fermentation progress and to the preservation-related properties of fermented dairy products.
Selected strains produce nisin, an antimicrobial peptide that is used in food preservation. Nisin provides a protective function distinct from acidification: lactic acid changes the environmental pH, whereas nisin contributes antimicrobial activity as a produced compound. This combination helps explain why particular strains have value beyond their role in acidifying dairy fermentations.
In dairy processing, L. lactis drives the acidification of milk that underlies production of cheese, cultured butter, and other fermented foods. Its sugar metabolism changes the milk environment and supports the desired fermentation outcome. Strain selection can also add nisin production, extending the organism's relevance to preservation-oriented food applications.
Its metabolism and genetics are well characterized, making L. lactis useful for investigating microbial physiology. Researchers can relate genetic features to metabolic behavior and fermentation relevance, while its established industrial importance keeps findings connected to practical biology. The organism therefore supports both fundamental studies and biotechnology-focused research.
Research on L. lactis supports the development of engineered production systems in addition to traditional food fermentation. Its characterized metabolism and genetics provide a foundation for studying how microbial cells can be adapted for production purposes. These applications connect dairy microbiology with broader work in biotechnology, microbial physiology, and strain engineering.