Lactococcus lactis

Tiny living things help make food. They are found in milk and plants.

These little things turn milk into cheese. They also make buttermilk. They can even help make bread.

They do this by using the sugar in milk. This process makes a special acid.

The acid makes the milk clump together. These clumps are used to make cheese.

Some people use them to help treat sickness. They are safe to use.

It is amazing how small things help us eat.

Lactococcus lactis is a tiny living thing. Scientists call these tiny things bacteria. These bacteria are very important for our food. They help make cheese and buttermilk. They are also used to make bread and beer.

How do they make food? It is a special way of working. These bacteria eat the sugar in milk. This sugar is called lactose. As they eat, they make a substance called lactic acid. This acid changes the milk. It makes the milk clump together into curds. These curds are then used to make many cheeses. You might eat cheeses like Cheddar or Brie.

These bacteria are also used in medicine. Scientists can change them to help people. They can carry special proteins to treat diseases. One way they help is by treating bowel sickness. They can even help fight some types of cancer cells.

Most people find these bacteria safe. They are mostly found in milk or plants. They are very useful tools for us.

Lactococcus lactis is a tiny living thing called a bacterium. It is a gram-positive bacterium, which is a way scientists group certain microbes. These bacteria are very helpful in our daily lives. They are used to make many foods like buttermilk and cheese. They even help make things like beer, wine, and pickled vegetables. This tiny microbe is a big part of the dairy industry. Scientists consider it generally recognized as safe for people to use.

How does this bacterium work to make food? It uses a way of working called fermentation. When added to milk, the bacteria use enzymes to get energy. They eat a sugar in the milk called lactose. As they eat, they create a byproduct called lactic acid. This acid makes the milk curdle, which means it clumps together. These clumps are called curds, and they are used to make cheese. This process is how we get cheeses like Brie, Cheddar, and Parmesan.

Scientists have learned a lot about where these bacteria come from. They are usually found in dairy or in plants. Some experts think they moved from plants to milk a long time ago. This happened through a process called genome erosion. In this process, the bacteria lost or turned down genes they did not need in milk. They also turned up genes that help them move nutrients. This helped them adapt to their new home in dairy products.

There are many interesting facts about this microbe. It is a coccus, which means it is shaped like a little ball. They often grow in pairs or short chains. They are usually between 0.5 and 1.5 micrometers long. In 2010, the state of Wisconsin tried to name it their official state microbe. A bill was introduced in November 2009 by several representatives. The Assembly passed the bill on May 15, 2010, but the Senate did not adopt it.

Lactococcus lactis is also very important in medicine. It was the first genetically modified organism used to treat human disease. Scientists can change its genes to carry special proteins into the body. One way is to help treat inflammatory bowel diseases. They can also use a peptide called KISS1 to help fight cancer cells. This makes the bacterium a very exciting tool for the future of science.

Lactococcus lactis is a gram-positive bacterium that plays a vital role in both the food industry and modern medicine. It is a coccus, which means it is shaped like a small sphere. These cells often group together in pairs or short chains. They are nonmotile, so they cannot move on their own, and they are nonsporulating, meaning they do not produce spores. Most L. lactis cells are between 0.5 and 1.5 micrometers in length. This microbe is essential for producing dairy items like buttermilk and many types of cheese. It is also famous for being the first genetically modified organism used alive to treat human disease.

The bacterium functions through a process called homofermentative metabolism. This means it converts sugars into lactic acid to produce energy. When L. lactis is added to milk, it uses enzymes to break down a sugar called lactose. This process creates energy molecules known as ATP. A byproduct of this energy production is lactic acid. The lactic acid causes the milk to curdle, which separates the liquid from solid clumps called curds. These curds are then used to manufacture various cheeses. This metabolic process is a cornerstone of the global dairy industry.

L. lactis is used to create many specific types of cheese. The subspecies L. lactis subsp. lactis is used in the early stages of making Brie, Camembert, and Cheddar. It is also used for Colby, Gruyère, Parmesan, and Roquefort. Beyond dairy, this bacterium is involved in the fermentation of other foods. It can be used to produce pickled vegetables, beer, wine, and certain breads. It is even used in fermented products like soymilk kefir. Because of its long history in food, it has generally recognized as safe (GRAS) status.

Scientists have studied how L. lactis evolved from living on plants to living in dairy. Most isolates come from either plant material or dairy environments. It is suggested that dairy bacteria evolved from plant isolates through genome erosion. This is a process of reductive evolution where genes that are not useful in milk are lost or downregulated. In laboratory experiments, researchers grew plant isolates in milk for long periods. This resulted in the loss of unnecessary genes and the upregulation of peptide transport. This shows how the bacteria adapted to the nutrient-rich environment of milk.

In the dairy industry, L. lactis faces challenges from bacteriophages. These are viruses that infect bacteria and can cause significant economic losses. These phages prevent the bacteria from fully metabolizing the milk substrate. The most responsible species belong to the family Siphoviridae, specifically types 936, c2, and P335. Despite these challenges, the bacterium is culturally significant. In 2010, the Wisconsin State Assembly passed a bill to name L. lactis the official state microbe. The bill was introduced in November 2009 by several representatives. However, the legislation was dropped by the Senate on April 28, 2010.

Medical research has turned L. lactis into a tool for delivering functional proteins. Because it is noninvasive and nonpathogenic, it is a promising candidate for protein delivery. One major area of study is treating inflammatory bowel diseases (IBD). Scientists have engineered L. lactis to secrete a cytokine called interleukin-10 (IL-10). This protein helps downregulate inflammatory cascades in the body. The bacteria can deliver this protein to the intestinal epithelium or through M cells into lymphoid tissue. This method may be an alternative to systemic treatments that are difficult to produce.

L. lactis is also being studied for its ability to fight cancer. Researchers created a strain, L. lactis NZ9000, that carries a plasmid with a peptide called KISS1. This peptide helps inhibit tumor metastasis, which is the spread of cancer. The secreted KISS1 protein can downregulate the expression of Matrix metalloproteinases (MMP-9). This enzyme is a key factor in how cancer cells invade and grow. By activating specific signaling pathways, the engineered bacteria can reduce cancer cell survival and induce dormancy. This makes L. lactis a potential new tool for future cancer therapies.