Alkaline Lake: Difference between revisions

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Description of Niche

Where located?

Geological Coordinates: 1° 52′ 0″ S, 36° 16′ 0″ E

Lake Magadi is the southernmost lake in Kenya, and is located in the Rift Valley. The lake is located 2000 feet below sea level forming one of the lowest points in the valley.

Physical Conditions?

What are the conditions in your niche? Temperature, pressure, pH, moisture, etc.

Influence by Adjacent Communities (if any)

Is your niche close to another niche or influenced by another community of organisms?

Conditions under which the environment changes

Do any of the physical conditions change? Are there chemicals, other organisms, nutrients, etc. that might change the community of your niche.

Who lives there?

Which microbes are present?

a. Habmonas campisalis: obligatory alkaliphilic, nitric oxide reducing denitrifier, nitrate denitrifier

b. Amphibacillus fermentum, Amphibacillus tropicus: alkaliphilic, saccharolytic, rod-shaped gram-positive bacteria, resistant to heating and drying. Some form endospres, some don’t. All capable of both aerobic and anaerobic growth. Sodium chloride independent, sodium carbonate dependent. Metabolize glucose, mono- and disaccharides in aerobic mode, while forming formate, ethanol, and acetate when anaerobic.

c. Halonatronum saccharophilum: alkaliphilic, somewhat halophilic, chemoorganotrophic bacterium. Spore-forming, rod-shaped, gram-negative. Obligatorily carbonate- and sodium chloride dependent. Peritrichously flagellated rod. Reduces sulfate ion to hydrogen sulfide. Catabolizes glucose, fructose, sucrose, maltose, starch, glycogen, N-acetyl-D-glucosamine. Glucose fermentation yields formate, acetate, ethanol, H2, and CO2.

d. Haloakaliphilic archaea: not much known. Very distant relation to any other archaea (only 76% genetic relationship).

e. Natronoincola histidinovorans: 2 strains (1 sporogenous, 1 asporogenous); moderately haloalkaliphilic, obligatorily anaerobic, fermentative bacteria, motile, gram-positive, depends on sodium ions and bicarbonate. Only utilize two amino acids: histidine and glutamate, forming acetate and ammonium as their products

f. Tindallia magadii: alkaliphilic, obligatorily anaerobic, fermentative, asporogenous, gram-positive. Ferments the amino acids arginine and ornithine, producing acetate, propionine, and ammonia.

g. Desulfonatronovibrio hydrogenovorans: alkaliphilic, sulfate-reducing bacterium, sodium dependent.

h. Natrionella acetigena: extremely haloalkalaphilic, chemoorganotrophic, homoacetogenic bacterium. Obligate anaerobe, motile, gram-negative, spore-forming rod. Dependent on sodium carbonate, chloride ions. Ferments mainly lactate, ethanol, pyruvate, glutamate, and propanol, with acetate as the main and only product.

i. Spirochaeta alkalica, Spirochaeta Africana, Spirochaeta asiatica: mesophilic, anaerobic, saccharolytic, dissipotrophs. They differ in their final glucose metabolic products and proportions of similar products. All ferment glucose, and S. alkalica and S. Africana produce acetate, hydrogen, ethanol, and lactate, with the proportions of each differing between the two. S asiatica is strictly anaerobic, and produces acetate, ethanol, and lactate. S. Africana and alkalica are somewhat aerotolerant.

j. Natronococcus amylolyticus: haloalkalaphilic archaeon, produces alpha-amylase, appears red-orange in clusters

Non-Microbes Present

Lake Magadi is a popular destination for many animals due to the fact that it is situated between Massai Mara an Amboseli National Parks, but very few animals actually have any contact with, or live in, the lake itself. However, the lake is a popular destination for wading birds during the dry season including flamingos, heron, pelicans, and spoonbills. The birds congregate in streams of fresh water that run into the lake because this water brings in large amounts of diverse food. There is only one species of fish that can actually be found in the lake itself. Tilapia grahami, a type of small tilapia, have adapted to live in the harsh conditions of the lake, and are normally found in the lagoons on the lake’s periphery. An abundance of research has been performed on these fish, indicating that the fish have adapted to live in temperatures up to and possibly above 44◦C, a pH varying between 5-11 (though the lake naturally ranges from pH 9-11), low oxygen levels in the water (as low as 1.1 mg O2/L of water), and a salinity concentration up to 4%. These tilapia have many adaptations to survive in this lake, and due to the lakes extreme conditions, little other non-microbial life exists.

Do the microbes that are present interact with each other?

The microbes share substrates and metabolic products, but little else is known.

Do the microbes change their environment?

Do they alter pH, attach to surfaces, secrete anything, etc. etc.

Do the microbes carry out any metabolism that affects their environment?

Do they ferment sugars to produce acid, break down large molecules, fix nitrogen, etc. etc.

Current Research

A large amount of current research involving lake Magadi is to try to purify and culture novel forms of bacteria able to live in alkaline lakes. For example, in 2004 8 new strains of denitrifying bacteria were found in a lagoon with a pH of 10. Another more recent project, published in December of 2007, described experiments that isolated a new genus and species of bacteria, Methylohalomonas lacus. Two strains of these bacteria were cultured from Lake Magadi and another alkaline lake in the Kulunda Steppe in Altai, Russia, and projects are ongoing to try and find more microbial life with the adapted ability to live in the alkaline conditions of lakes such as lake Magadi.

A third research project involving lake Magadi focused on the Tilapia grahami, the small tilapia described above. There are isolated populations of these fish in lagoons around the edge of the lake, all living in differential volumes of oxygen, pH levels, temperature, and salinity. Once a year, during the flood season, there is the possibility for these isolated populations to come into contact with one another, and researchers are looking at the possible flow of genetic information between these isolated populations, and the adaptations that may have arisen from this isolation/interaction dichotomy. The research for these fish is ongoing to try and better understand how the tilapia have come to live in the areas of the lake that they do.

References

Edited by [Jonathan Kim, Eugene Vu, Trevor Parry, Daniel Zhou], students of Rachel Larsen

@@ Line 7: / Line 7: @@
 ===Where located?===
+Geological Coordinates:   1° 52′ 0″ S, 36° 16′ 0″ E
+Lake Magadi is the southernmost lake in Kenya, and is located in the Rift Valley. The lake is located 2000 feet below sea level forming one of the lowest points in the valley.
 ===Physical Conditions?===