Halophiles are extremophilic organisms that thrive in high salt environments and are categorized into slight, moderate, and extreme based on their halotolerance. They play significant roles in industrial applications, such as food additives and enzyme stabilization, as well as in medical and environmental processes. Taxonomically, they are diverse and found across all three domains of life: archaea, bacteria, and eukarya.

1. Asif Nawaz
M.phil 2nd
AUST

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. Saltlakebordered by Jordanto the eastandIsrael and
Palestine to the west (Cyanobacteria,Dunaliellasalina)

5. Average salt conc 13%, Halobacterium and
Halococcus (Utah united states )

6. TYPES:
 Halophiles are categorized as:
1. Slight,
2. Moderate
3. Extreme,
Due to 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

8. DIVERSTY:
• A wide variety of halophiles including heterotrophic (Chromohalobacter, Selina
vibrio)
• Chemoautotrophic (Dunaliella),
• chemolithotrophic (marinobacter sp)
• Aerobes (Halomonas halmophila) and
• Anaerobes(Halobacteroideshalobius) could be observed transforming diverse
range of substrates in hypersaline habitats.

9. 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%

10. ARCHEA:
• The domain Archaea has been further divided into two subdomains, Halobacteria
and MethanogenicArchaea.
• 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

11. APPLICATIONS OF HALOPHILES:
• INDUSTRIAL:
• 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

12. ECOTINE
 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.
 One of the most common osmotic solute in domain bacteria is ecotine.
 It was Ist discovered in Ectothiorhodspira halochloris.

13. • 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.

14. MEDICAL APPLICATIONS:
• 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.

15. ENVIROMENT:
• Several processes have been proposed for the biological
treatment of such waste waters 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
 These are added to improve degradation.

16. BIOFULES:
 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

17. OTHERS:
 Genetically engineering halophilic enzymes encoding DNA into crops to allow for
salt tolerance.
 Awellknown study has been conducted on genetic strain
holomonas sp, bacilus gabsonii EN4.
 Increasing crude oil extraction (MEOR). through microbial
enhanced oil recovery