Membranes Distinguish Sweet From Sour

Biological Strategy

Bacteria

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Sense Chemicals (Odor, Taste, etc.) From the Environment

Chemicals are important for signaling and communication among living systems, either intentionally (such as when two living systems try to find one another) or unintentionally (such as when a plant emits a chemical signal that an herbivore can use to find a tasty bite). They are also important for other uses, such as navigating or finding sources for minerals. But chemical signals are often relatively weak and disperse when moving through water or gases. Therefore, detecting them requires specialized abilities, including a way to determine where they are coming from. A well known example of sensing chemicals can be seen in ants following a pheromone trail laid down by others in their colony to locate a quality and abundant food source.

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Bacteria

Domain Bacteria (“small staff”): L. acidophilus, Staphylococcus

From inside of our own bodies to the deepest parts of the ocean, bacteria have adapted to almost every possible environment. All bacteria are unicellular, microscopic, and lack a membrane-bound nucleus and organelles, and come in three basic shapes: spherical (cocci), rod (bacilli), and spiral (spirilla). Some strains can be deadly, like Staphylococcus aureus (MRSA) while others, like Lactobacillus acidophilus, found in our intestinal microbiome, keep us healthy. Cyanobacteria, also known as blue green algae, caused the Great Oxidation Event 2.4 billion years ago, producing Earth’s first oxygenated atmosphere.

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The membrane of colon bacilli cells find sweet-tasting chemicals and avoid bitter or sour ones via sensory proteins.

“Chemoreception occurs even in unicellular organisms…Protozoa such as amoebae and microbes such as colon bacilli show chemotaxis; they gather and escape from some chemical substances. The former is called positive chemotaxis and the latter negative chemotaxis. Colon bacilli show positive chemotaxis for amino acids tasting sweet and negative chemotaxis for chemical substances tasting strongly bitter or sour. This behavior is quite reasonable because substances tasting sweet become energy sources for living organisms whereas substances tasting strongly bitter or sour are often harmful.” (Toko 2000:26)

Last Updated August 18, 2016

References

Book

Biomimetic Sensor Technology

22/08/2005 | Kiyoshi Toko

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