Introduction Halophiles are organisms that thrive in high salt concentrations. They are a type of extremophile organisms. The name comes from the Greek word for "salt-loving". While most halophiles are classified into the Archaea domain, there are also bacterial halophiles and some eukaryota, such as the alga Dunaliella salina or fungus Wallemia ichthyophaga

1. Halophiles
By;
SanaUllah
Jamil Ahmad
SaeedUllah
(M.phil II)

2. Introduction
• Halophiles are organisms that thrive in high salt concentrations.
• They are a type of extremophile organisms. The name comes from the
Greek word for "salt-loving".
• While most halophiles are classified into the Archaea domain, there
are also bacterial halophiles and some eukaryota, such as
the alga Dunaliella salina or fungus Wallemia ichthyophaga

3. Habitat
• Habitats like soda lakes,
• Thalassohaline,
• Athalassohaline,
• Dead Sea,
• Carbonate springs,
• Salt lakes,
• Alkaline soils and many others favors the existence of halophiles.

4. Salt lake bordered by Jordan to the east and Israel and Palestine to the west
(Cyanobacteria, Dunaliella salina)

5. Utah, United States great salt lake.
Average salt conc 13%, Halobacterium and Halococcus.

6. An aerial view shows the pink water
of Great Salt Lake brushing up
against the Eco-sculpture "Spiral
Jetty" on a salt-crust shore. Image
credit: Bonnie Baxter.
Salt flats at Lake Magadi,
Kenya. The flats are red
due to the proliferation of
halobacteria.
Owens Lake. The pink coloration
is caused by halobacteria living in
a thin layer of brine on the surface
of the lake bed.

7. Taxonomy
Methods of chemotaxonomy,multilocus sequence analysis,numerical
taxonomy,comparative genomics and proteomics have allowed
taxonomists to classify halophiles.
These versatile microorganisms occupy all three major domains of life
i.e.,
• Archaea 21.9%
• Bacteria 50.1%
• Eukarya. 27.9%

8. Archaea
• The domain Archaea has been further divided into two subdomains,
Halobacteria and Methanogenic Archaea.
• Halobacteria is represented by one of the largest halophile
family,Halobacteriaceae with 36 genera and 129 species requiring high
NaCl concentrations which discriminate them from other halophiles

9. Diversity
• A wide variety of halophiles including heterotrophic (Chromohalobacter,
Selina vibrio)
• Chemoautotrophic (Dunaliella),
• chemolithotrophic (marinobacter sp)
• Aerobes (Halomonas halmophila) and
• anaerobes (Halobacteroides halobius) could be observed transforming
diverse range of substrates in hypersaline habitats.

10. Types
Halophiles are categorized as slight, moderate, or extreme, by the extent of
their halotolerance.
 Slight halophiles prefer 0.3 to 0.8 M (1.7 to 4.8% — seawater is 0.6 M or 3.5%),
e.g, Erythrobacter flavus
moderate halophiles 0.8 to 3.4 M (4.7 to 20%), e.g, Desulfohalobium
and extreme halophiles 3.4 to 5.1 M (20 to 30%) salt content. E.g, Salinibacter
ruber

12. What happens at high salinity to most organisms?
• The greater the difference in salt concentration between in and outside the cell - the
greater the osmotic pressure (hydrostatic pressure produced by a solution in a space
divided by a semipermeable membrane due to a differential in the concentrations of
solute).
• If we drink salty water we desiccate the cells -enzymes and DNA denature or break!
Plants: trigger ionic imbalances -damage to sensitive organelles such as chloroplast.
Animals: a high salt concentration within the cells -water loss from cells -brain cells
shrinkage -altered mental status, seizures, coma, death.
(Natural salts were used to remove moisture from the body during mummification).

13. Adaptations of Halophiles
to their environment

14. Adaptations of halophiles to hyper saline
environment
• (a) The integrity of non-halophile macromolecules is
compromised, and the flow of water out of the cell produces a
Turgor effect.
• (b) Moderate halophiles maintain their structures via the synthesis
of compatible organic solutes.
• (c) Extreme halophiles maintain their structures via equilibration
of cellular and environmental salt concentrations.

15. Cellular adaptation
• To avoid excessive water loss under such conditions, halophiles have evolved two
distinct strategies:
 High salt-in strategy
 Low-salt, organic salute-in strategy

16. High salt-in strategy
• Accumulation of inorganic ions intracellularly to balance the salt concentration in
their environment.
• This process involves the Cl- pumps that are found only in halophiles that
transport Cl- from the environment into the cytoplasm.
• Extreme halophiles of the archaeal Halobacteriaceae family and the bacterial
Halanaerbiales family maintain their osmotic balance by concentrating K+ inside
cells.
• This is achieved by the concerted action of the membrane-bound proton-pump
bacteriorhodopsin.

17. Mechanism of bacteriorohodopsin

18. Low-salt, organic solute-in strategy
• This strategy is adapted by moderate halophiles.
• Highly saline environment is incompatible for the survival of moderate halophiles.
• Thrive in habitats of fluctuating salinity, i.e., salt concentrations can reach molar
levels and then fall to near-freshwater concentrations after a rainfall.
• The required adaptations involve evolution of compatible organic solutes
(osmolytes) in the halophiles.

19. • Glycine betaine in Halorhodospria halochloris was the first reported bacterial
osmolyte.
• These substances within the cells of microorganisms are regulated according to the
salt concentration outside the cell.

20. Protein adaptations
• A high-salt environment substantially impacts protein solubility and stability and
consequently function by dehydration.
• A noticeable difference between proteins from halophiles and nonhalophiles is that
those of halophiles have a larger proportion of glutamate and aspartate on their
surfaces.
• Also they have less hydrophobic amino acids.
• The acidic residues on halophilic proteins bind hydrated cations which would
maintain a shell of hydration around the protein

22. Cell membrane adaptation
• The membranes of extremely halophilic Archaea are characterized by the
abundance of a phosphatidyl glycerol methyl phosphate (PGP-Me).
• These membranes are stable in concentrated 3-5 m NaCl solutions.
• Whereas membranes of non-halophilic Archaea, which do not contain PGP-Me,
are unstable and leaky under such conditions.
• Halobacterium halobium
• Halobacterium salinarum
• Archaeal lipids are characterized by ether linkages and isoprenoid chains, mainly
phytanyl in contrast to the ester linkages and straight fatty acyl chains of non-
Archaea.

24. Applications of Halophiles

25. Applications of halophiles
Industrial application:
• carotene from carotene rich halobacteria and halophilic algae can be
used as food additives or as food-coloring agents it may also improve
dough quality of backing breed.
• Halophilic organisms used in the fermentation of soy sauce and Thai
fish sauce.
• Halobacterium salinarum
• Halobacterium sp. SP1

26. Ectoine
 Ectoine is commercially produced by extracting the compound from
halophilic bacteria.
 Industrial process for mass production of ectoine and hydroxyectoine were
developed by using Halomonas elongata and Marinococcus M52,
respectively.
 This procedured is based on bacterial milking.

27. • One of the most common osmotic solutes in the domain Bacteria is
ectoine (1,4,5,6-tetrahydro-2- methyl-4-pyrimidine carboxylic acid).
• It was Ist discovered in Ectothiorhodspira halochloris.

28. • Ectoine can protect
• unstable enzymes
• nucleic acid against high salinity
• thermal denaturation
• desiccation and freezing.
• Therefore increased the shelf life of enzymes.
• Stabilizes the activity of trypsin and chymotrypsin.
• It can also reduced the sun burn cell when exposed to U.V light.
• Ectoine also inhibits aggregation and neurotoxicity of Alzheimer’s β-
amyloid.

29. Poly-β-hydroxyalkanoate production by halophilic bacteria
• Poly-β-hydroxyalkanoate (PHA), a polymer containing β-hydroxybutyrate
and β-hydroxyvalerate units, is accumulated by many prokaryotes, Bacteria
as well as Archaea, as a storage polymer.
• It is used for the production of biodegradable plastics with properties
resembling that of polypropylene Halomonas boliviensis , H. mediterranei

30. Medical application
• Haloarchaea were the first members of archaea found to produce
bacteriocins, named halocins.
• They are peptide or protein antibiotics secreted into the environment to
kill or inhibit the sensitive haloarchaeal strains that occupy the same
niche.

31. Environmental
• Several processes have been proposed for the biological treatment of
such wastewaters to remove organic carbon and toxic compounds.
• Several dunaliella growth facilitates the waste water treatment in
oxidation ponds .
• Optimization study has been proved through Halobacterium salinarum
was added to improve degradation.

32. Biofuel production
• The halophilic alga Dunaliella salina commercial source of β-carotene
and as a potential source of glycerol production, may also be
considered as the raw material for biofuel production.

33. Enzymes from halophile microorganisms

34. Other applications
 Increasing crude oil extraction through microbial enhanced oil recovery
(MEOR).
 Genetically engineering halophilic enzymes encoding DNA into crops to allow
for salt tolerance.
 A well known study has been conducted on genetic strain holomonas sp,
bacilus gabsonii EN4.

35. References
• Gupta, R.S.; Naushad, S.; Baker, S. Phylogenomic analyses and molecular signatures for the class
Halobacteria and its two major clades: A proposal for division of the class Halobacteria into an
emended order Halobacteriales and two new orders, Haloferacales ord nov and Natrialbales ord. nov.,
containing the novel families Haloferacaceae fam. nov. and Natrialbaceae fam. nov. Int. J. Syst.
Evol. Microbiol. 2015, 65, 1050–1069.
• Temperton B, Giovannoni SJ (2012) Metagenomics Microbial diversity through a scratched lens. Curr Opin Microbiol 15: 605-
612.
• Moreno ML, Perez D, García MT, Mellado E (2013) Halophilic bacteria as a source of novel hydrolytic enzymes. Life 3: 38-
51.
• Waditee-Sirisattha R, Kageyama H, Takabe T (2016) Halophilic microorganism resources and their applications in industrial
and environmental biotechnology. AIMS Microbiol 2: 42-54
• Bose U, Hewavitharana AK, Ng YK, Shaw PN, Fuerst JA, et al. (2015) LC-MS-Based metabolomics study of marine bacterial
secondary metabolite and antibiotic production in salinisporaarenicola. Mar Drugs 13: 249-266.
• Litchfield CD (2011) Potential for industrial products from the halophilicArchaea. IndMicrobiolBiotechnol 38: 1635-1647
• Bose A, Chawdhary V, Keharia H, Subramanian RB (2014) Production and characterization of a solvent tolerant protease from
a novel marine isolate Bacillus tequilensis P15. Ann Microbiol 64: 343-354.