Classification/Diagnostic characteristics
Domain: Archaea
Kingdom: Monera
Phylum: Euryarchaeota
Class: Halobacteria
Order: Halobacteriales
Family: Halobacteriaceae
Genus: Archaebacteria
Species: Halophiles
The domain Archaea is split into two groups. Halophiles fall under the category Euryarchaeotes.
Halophiles are prokaryotes with the simple cellular structure and few organelles.
They contain a pink carotenoid pigment that makes them relatively easy to see in large amounts.
Halophiles are a type of extremophile, a microscopic organism that lives in very harsh conditions.
Halophiles can be a a wide variety of microbes that are able to survive in water solutions with high salt concentrations. Relationship to humans
Halophilic archaebacteria have been found in the human colon, even though it is not a salty environment. However, as multiple studies have found these organisms present, halophiles may be one of the vast species of microorganisms living in the human digestive tract. Further research into the existence of these organisms in the colon may lead to new insight into gastrointestinal health and disease. (2) Halophiles are also used in a number of industries, such as pharmaceuticals and cosmetics, for their ability to degrade the organic compound isopropyl alcohol in high saline conditions created by the industries as waste that pollutes the surrounding environment (9).
Habitat and niche
Halophiles thrive in extremely salty environments. They have been found in the Dead Sea and Great Salt Lake, Utah and in many types of brines. Extreme halophiles can live in places with a pH of 11.5, higher than any other organism.
The salt concentration in the San Francisco Bay Salt Ponds is high, and the pink color is due to the presence of halophiles
Predator avoidance
The salty, hypertonic environments that are home to halophiles are very rarely inhabited by other creatures. The location and geographic barriers of the living conditions for the halophile archaea make it extremely difficult, for any predators to survive in these conditions to even attack them. The archaea do not have any specific defense mechanisms except for their strange ability to live and survive in extreme conditions that other organisms cannot survive in, making it very difficult to prey on these halophile archaea. (10) Nutrientacquisition
In the absence of oxygen, halophiles create a light-absorbing molecule called microbial rhodopsin from a pigment called retinal and a protein. They then use the energy to make ATP. The high concentration of NaCl in the environments that halophiles inhabit limit the availability of oxygen for respiration. Halophiles are chemoheterotrophs, using light for energy and methane as a carbon source. (4) Reproductionand life cycle
Prokaryotic cells divide by a process called binary fission.
Binary fission is a process in which the DNA replicates and then the two DNA molecules head to opposite ends of the cell, called chromosome segregation. After this the cell diveds into two daughter cells during cytokinesis.
Method of reproduction for Halophile through binary fission. (8) Growth and development
Halophiles thrive in environments with incredibly high salt concentrations.
Integument
They are eukaryotes or bacteria so the integument of halophiles are cell membranes that are selectively permeable (5).
Movement
Halophiles are able to move due to their flagella, long-whiplike structures that push the organism in different directions. Clockwise rotation of flagella projects the halophile forward, while counterclockwise rotation of flagella moves the halophile backwards (1). Sensing the environment Gas exchange Waste removal
Halophiles excrete wastes through their selectively permeable cell membranes through active transport or diffusion. Archaebacteria are known to oxidize sulfur and iron autotrophically to obtain energy and excrete sulfuric acid and iron oxide respectively as waste products. (6)
Environmental physiology (temperature, water and salt regulation)
Halophiles live in extremely salty bodies of water, usually a saturated solution with at least a 2M concentration. They are able to sustain themselves in such salty environments by increasing the internal osmolarity of the cell. One way they do this is by gaining osmoprotectants, an organic compound that helps cells balance the salinity difference between it and its environment. These molecules can either be acquired through its environment or synthesized. Another way halophiles can retain water is by allowing an abundance of K+ ions into the cytoplasm to act as an osmoprotectant. This process requires the cooperation of all inter-cellular mechanisms and needs them to be adapted to function in areas of high salinity. Internal circulation
Halophiles have no need for a circulatory system, for they are unicellular. Nutrients and other chemicals that are required flow through the cytoplasm to their destinations. Chemical control (i.e. endocrine system)
Review Questions:
1. What allows halophiles to live in extremely salty conditions?
Classification/Diagnostic characteristics
Domain: Archaea
Kingdom: Monera
Phylum: Euryarchaeota
Class: Halobacteria
Order: Halobacteriales
Family: Halobacteriaceae
Genus: Archaebacteria
Species: Halophiles
The domain Archaea is split into two groups. Halophiles fall under the category Euryarchaeotes.
Halophiles are prokaryotes with the simple cellular structure and few organelles.
They contain a pink carotenoid pigment that makes them relatively easy to see in large amounts.
Halophiles are a type of extremophile, a microscopic organism that lives in very harsh conditions.
Halophiles can be a a wide variety of microbes that are able to survive in water solutions with high salt concentrations.
Relationship to humans
Halophilic archaebacteria have been found in the human colon, even though it is not a salty environment. However, as multiple studies have found these organisms present, halophiles may be one of the vast species of microorganisms living in the human digestive tract. Further research into the existence of these organisms in the colon may lead to new insight into gastrointestinal health and disease. (2) Halophiles are also used in a number of industries, such as pharmaceuticals and cosmetics, for their ability to degrade the organic compound isopropyl alcohol in high saline conditions created by the industries as waste that pollutes the surrounding environment (9).
Habitat and niche
Halophiles thrive in extremely salty environments. They have been found in the Dead Sea and Great Salt Lake, Utah and in many types of brines. Extreme halophiles can live in places with a pH of 11.5, higher than any other organism.
Predator avoidance
The salty, hypertonic environments that are home to halophiles are very rarely inhabited by other creatures.
The location and geographic barriers of the living conditions for the halophile archaea make it extremely difficult, for any predators to survive in these conditions to even attack them. The archaea do not have any specific defense mechanisms except for their strange ability to live and survive in extreme conditions that other organisms cannot survive in, making it very difficult to prey on these halophile archaea. (10)
Nutrient acquisition
In the absence of oxygen, halophiles create a light-absorbing molecule called microbial rhodopsin from a pigment called retinal and a protein. They then use the energy to make ATP. The high concentration of NaCl in the environments that halophiles inhabit limit the availability of oxygen for respiration. Halophiles are chemoheterotrophs, using light for energy and methane as a carbon source. (4)
Reproduction and life cycle
Prokaryotic cells divide by a process called binary fission.
Binary fission is a process in which the DNA replicates and then the two DNA molecules head to opposite ends of the cell, called chromosome segregation. After this the cell diveds into two daughter cells during cytokinesis.
Method of reproduction for Halophile through binary fission. (8)
Growth and development
Halophiles thrive in environments with incredibly high salt concentrations.
Integument
They are eukaryotes or bacteria so the integument of halophiles are cell membranes that are selectively permeable (5).
Movement
Halophiles are able to move due to their flagella, long-whiplike structures that push the organism in different directions. Clockwise rotation of flagella projects the halophile forward, while counterclockwise rotation of flagella moves the halophile backwards (1).
Sensing the environment
Gas exchange
Waste removal
Halophiles excrete wastes through their selectively permeable cell membranes through active transport or diffusion. Archaebacteria are known to oxidize sulfur and iron autotrophically to obtain energy and excrete sulfuric acid and iron oxide respectively as waste products. (6)
Environmental physiology (temperature, water and salt regulation)
Halophiles live in extremely salty bodies of water, usually a saturated solution with at least a 2M concentration. They are able to sustain themselves in such salty environments by increasing the internal osmolarity of the cell. One way they do this is by gaining osmoprotectants, an organic compound that helps cells balance the salinity difference between it and its environment. These molecules can either be acquired through its environment or synthesized. Another way halophiles can retain water is by allowing an abundance of K+ ions into the cytoplasm to act as an osmoprotectant. This process requires the cooperation of all inter-cellular mechanisms and needs them to be adapted to function in areas of high salinity.
Internal circulation
Halophiles have no need for a circulatory system, for they are unicellular. Nutrients and other chemicals that are required flow through the cytoplasm to their destinations.
Chemical control (i.e. endocrine system)
Review Questions:
1. What allows halophiles to live in extremely salty conditions?
References:
1. http://books.google.com/books?id=Q5icH0OdnX8C&pg=PA86&lpg=PA86&dq=halophilic+archaebacteria+movement&source=bl&ots=P0Zv_i_pPa&sig=c7gT11iJwHtouUCkye8NBo9RKDU&hl=en&sa=X&ei=neCHUt67OfPSsASKnoDYBg&ved=0CIQBEOgBMAk#v=onepage&q=halophilic%20archaebacteria%20movement&f=false
2. http://www.ncbi.nlm.nih.gov/pubmed/20438582
3. http://education-portal.com/academy/lesson/halophiles-definition-examples-classification.html#lesson
4.
https://www.boundless.com/microbiology/microbial-evolution-and-phylogeny/euryarchaeota/extremely-halophilic-archaea/
5. http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Halophile.html
6. http://onlinelibrary.wiley.com/doi/10.1016/S0168-6496%2803%2900028-X/full
7. http://science.howstuffworks.com/life/cellular-microscopic/extremophile.htm
8. http://www.uic.edu/classes/bios/bios100/lecturesf04am/binfission.jpg
9. http://www.ecomena.org/tag/halophiles/
10. http://serc.carleton.edu/microbelife/extreme/hypersaline/index.html