Micrococcus luteus

Micrococcus luteus is a bacterium found in water, soil, dairy products, humans, and animals. These bacteria are often harmless, but they can cause illness in people who have weakened immune systems. Micrococcus luteus was first identified in the 1920s. However, scientists have determined that the bacterium has existed for hundreds of thousands of years. Researchers have identified that Micrococcus luteus may be helpful as a way of eliminating oily sludge and other environmental contaminants. The bacterium may also hold the key to producing a new way for sunscreens to block ultraviolet light.

Background

The word micrococcus comes from the Greek words mikros, meaning "small," and kokkos, meaning "berry." It refers to any of a number of types of spherical bacteria that can occur singly, in pairs, or in groups or clusters. Micrococci are aerobic, meaning they survive in oxygenated environments. They are also gram-positive, which means their cell walls accept a special dye that makes them visible during laboratory testing. This testing helps scientists classify and study bacteria. Micrococci are also either saprophytic, which means they feeds on dead or decaying matter, or parasitic, meaning they live on another life form.

The word luteus is a Latin word for yellow-orange. It was added to the name of this specific form of micrococcus because of its color. Alexander Fleming, the Scottish physician and microbiologist who received the 1945 Nobel Prize for the discovery of penicillin, originally called the bacterium Micrococcus lysodeikticus. Micrococcus luteus were the bacteria on which Fleming tested a lysozyme, an enzyme he discovered in some human bodily fluids that had a negative effect on bacteria and other organisms. This 1922 experiment was one of the earliest investigations into how the human immune system works.

Bacteria are among the oldest known forms of life. They can be found in many habitats, and evidence of their presence has been found in prehistoric remains. Ancient remnants of Micrococcus luteus have been found encased in amber, a fossilized form of hardened tree sap. The amber with the bacteria was dated to about 120 million years ago.

Overview

Micrococcus luteus is found in many environments. It has been found all across Earth. In addition to living in some forms of soil, water, dust, plants, and in the air, the bacteria have been found on some forms of sea life, such as sharks, shellfish, and shrimp. The bacteria are also commonly found on mammals, including humans. In humans, they are often found on or in the skin, especially the exposed skin of the face, arms, and legs, and the mucus membranes of the nose and throat. Micrococcus luteus spreads by contact with contaminated objects, such as counters and other surfaces.

The bacteria can survive for long periods with almost no nourishment and water. They are tolerant of conditions that expose them to cold, salt, and dehydration. Micrococcus luteus can also form biofilms, a slime-like substance that encases the bacterium and protects it. These abilities allow Micrococcus luteus to survive for long periods on hard surfaces and to resist disinfection efforts. However, the bacteria do respond to heat, especially temperatures greater than 113 degrees Fahrenheit (45 degrees Celsius). Growths on surfaces can also be reduced or eliminated by application of a number of disinfectants, including 70 percent solutions of ethanol alcohol, iodine, formaldehyde, phenol disinfectants, and bleach.

While Micrococcus luteus easily spreads by contact with contaminated surfaces, the bacterium is not easily spread by person-to-person contact. Additionally, the bacterium is considered nonpathogenic because it rarely causes any significant illness. However, Micrococcus luteus can be dangerous to people who are immunocompromised, or those whose immune systems are already affected by some other illness or condition. Being immunocompromised makes people susceptible to different types of infections, including those caused by Micrococcus luteus. When infections do result, they generally respond well to a course of standard antibiotics, such as penicillin, vancomycin, clindamycin, and gentamicin.

Besides posing little risk to humans or animals, Micrococcus luteus has been shown to have some potential helpful attributes. Biotechnologists have discovered that the bacteria have potential in a field of environmental study known as bioremediation, which uses natural means of combating pollutants and contaminants in the environment. Scientists introduce bacteria and other organisms with special properties to break down various pollutants in contaminated environments. In the case of Micrococcus luteus, scientists have found that the bacterium is resistant to many of the contaminants found in toxic wastes containing oil, sludge, metals, and other pollutants. Some studies have shown that the bacterium can even break down some byproducts of nuclear waste, indicating it has the potential to help in the removal of waste products from the production of nuclear energy. Additional testing has failed to uncover any negative side effects of using Micrococcus luteus in this way.

In 2013, Norwegian scientists uncovered another potential benefit from Micrococcus luteus. While studying a strain found in Trondheim Fjord, the researchers discovered a pigment called sarcinaxanthin. This pigment absorbs the ultraviolet (UV) rays in sunlight that have a specific wavelength. Scientists have been searching for a substance that could absorb this wavelength because it penetrates deep into the skin, where most malignant melanomas, the deadliest form of skin cancer, develop. In addition to protecting against the potential cancer-causing effects of these UV rays, sarcinaxanthin can also protect against sun-induced skin damage that results in wrinkles. Researchers have synthesized a form of this substance and named it UVABlue, with a goal of creating commercial products containing the bacteria-derived substance.

Bibliography

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Greenblatt, C.L., et al. "Micrococcus Luteus—Survival in Amber." Microbial Ecology, vol. 48, no. 1,July 2004, pp. 127–27.

"Micrococcus Luteus Fleming Strain 2665." JGI Genome Portal, US Department of Energy, genome.jgi.doe.gov/miclu/miclu.home.html. Accessed 13 Nov. 2017.

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Schaefer, Pamela. "Micrococcus Luteus." Agrotekno Lab, www.agrotekno-lab.com/2014/01/micrococcus-luteus.html. Accessed 13 Nov. 2017.

"Super Sunscreen from Fjord Bacteria." Science Daily, 6 Aug. 2013, www.sciencedaily.com/releases/2013/08/130806091556.htm. Accessed 13 Nov. 2017.

Van Heerden, Esta, et al. "Bioremediation: Small Solutions to Big Problems." University of the Free State, https://www.ufs.ac.za/docs/librariesprovider22/microbial-biochemical-and-food-biotechnology-documents/exboc-documents/research-projects-documents/bioremediation-2563-eng.pdf?sfvrsn=b25af921‗0. Accessed 13 Nov. 2017.

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