An Overview of Saltpan Halophilic Bacterium

Hypersaline environments provide an excellent medium for natural microbial communities which serve as a potential source of pharmaceutical substances. Salt is widely present in the earth. Almost 73% of earth was covered with marine water which contains 2.5% of common salt. Protease enzyme activity widespread in microorganisms, plant and animals. Proteolytic enzymes used in the industrial application and bioremediation process. In recent years’ new mutant’s microbe resistant to commonly used antibiotics. Protease inhibitors used as potential antibiotics for controlling microbial infections. A Hypersaline environment such as salt pans and salt lakes has high salt concentration and pH. The saltpan provides a diversity of different environmental conditions of alkalinity, salinity, temperature, pH and nutrition. Halophilic organisms growing between 0.5 and 3.0 M salt concentration. Extreme environments are the best source of bioactive compound producing halophiles microbes.


Introduction
Extreme halophiles are a group of microorganisms. They can able to grow in at various areas of high salt concentration. In the hypersaline environment, the salt concentration of the ocean is 3-5% and the Dead Sea is 31.5%. Halophiles were found in each domain of life primarily consist of archaea [1]. Extreme environments were characterized by extreme physicochemical conditions which make inhabitable for higher life forms [2]. Halophilic microorganisms used for enzyme production of valuable enzymes and bioactive compounds. Halophilic bacteria also produce secondary metabolites of extracellular polysaccharides such as proteins, enzymes, amylase, cellulases and amino acids etc [3,4]. Saltpans are large ponds filled with saltwater from the marine or another source. The salinity of the water gradually increases as water evaporates until it reaches saturation (26% at 20°C). The salt then precipitates out and it's harvested. These hypersaline environments are commonly used in salt industries. These environments are favorable for halophiles which occurrence becomes visible due to the pigment production. Salt pan soil is characterized by saline soil, contains the high amount of soluble salts Ca 2+ , Mg 2+ , K + , and Na + . The dead sea contains many salts with different concentration [5,6].

Halophilic Bacteria
Halophilic microorganisms are salt loving bacteria that inhabit in the hypersaline environments. These group is mainly prokaryotic and eukaryotic microorganisms. Normally halophiles living in the salt-rich environments that loss of water and die as a result of osmosis [7]. The halophilic and halotolerant bacterial media contain more than 5% salinity, some microorganisms are adapted different extreme environmental conditions of temperature like pH, salinity, radiation and pressure [8,9]. The marine bacteria Bacillus pumilus and Halobacterium salinarum isolated from the soil sediment sample [10,11]. The new halophilic genera, Halothermothrix, Halanaerobacter, Halocella, Acetohalobium and Orenia [12]. Solar saltpans are located originate all around the world and deliver ideal settings for halophilic and halotolerant bacteria [13]. Halophilic microbial yields are in tall demand in the pharmaceutical industry anywhere they have used an antidote to a variability of the plant, animal and human pathogens as well as the spare of some biochemical pesticides. The development of new molecular methods similar next generation sequencing has revolutionized our understanding of microbial ecology and detection of novel genes [14].
However, the intensive research focused the biotechnological applications of halophiles. Saline environments still offer a massive diversity of microbes with the potential to produce an array of natural products which can only be unlocked by concerted research efforts. Combination of culture and molecular approaches is employed to characterize halophilic bacteria from saltpan water samples and profile their potential biotechnological applications [15].

Enzyme Production
Halophilic bacteria produce various industrially important enzymes such as amylase and protease. These commercially important enzymes involved in the vital role of biotechnology [16]. Amylase enzyme is used in the pharmaceutical and treatment of digestive disorders [17]. This also used for various textile, detergent, food, paper and chemical industries. Protease enzyme used in medical, detergent and food processing industries. Amylases and proteases are also discovered from some microorganisms like bacteria, fungi and actinomyces but the genus Bacillus harvest has largest amylase activity. Isolation, identification and maintenance of these halophilic microbes are difficult; very few studies have been reported the applications [18]. However, only a minor fraction of the existing halophile diversity has been discovered, largely for enzyme production and other applications like the production of bioactive compounds and compatible solutes that are useful as stabilizers for bimolecular or stress protective agents [19]. The secondary metabolites of halophilic microbes contain a variety of bioactive compounds like lipopeptides, polypeptides, polyketides, isocoumarins and macrolactins [20,21]. The significance of halophilic bacteria used in the salt making progression. This process accepted in the 1970s when it was realized that microorganisms play a role in responsible the quality and quantity of the salt harvested. The development of biological management performs for the operation of solar salterns [22]. Anaerobic microorganisms are interested in the extreme level environments because environmental parameters such as temperature and salinity regulate the rates of organic matter remineralization [23].
Extremozymes since halophilic archaea are not only extremely high salt tolerant nevertheless also thermal tolerant because the specific environment in which they living. They look to be the very good aspirant for industrial application, besides existence salt-loving, they may consume excellent activity, at high temperature, low water activity and high pH. Present day, only a few reports have occurred on the characterization of halophilic archaea isolated from Algerian saline ecosystem that studies absorbed mainly on saline lakes [24][25][26][27].

Biosurfactants
Biosurfactants as a green over synthetic surfactant due to them lower toxicity to higher biodegradability and prodigious stability at altered physiochemical conditions [28]. The biosurfactants to reduce surface tension and form stable emulsions are a virtue for countless applications [29]. Besides, biosurfactants are to inhibit some pathogenic organisms. Numerous studies have optional, some powerful biosurfactants with broad spectrum activity contrary to anthropoid, plant and nourishment pathogens [30][31][32].
Halophiles may deliver organic compounds such as antimicrobials, enzymes, pigments, compatible solutes and lipids that are highly stable and active under extreme conditions and which strength have a biotechnological possible pharmaceutical, biosurfactants Laundry industry, food coloring [33,34].

Enzymes
The Cellulases enzymes that hydrolyze the cellulose molecule on the β-1,4 glycosidic bonds. Cellulases take an important share in the worldwide enzyme market owed to their various uses including cotton processing, paper recycling, detergent formulation, juice extraction, and animal feed additives for uses in agricultural biotechnology and production of transportation fuel (bioenergy) besides bio based products [35][36][37]. Amongst thermophilic bacteria, Bacillus species producing some extracellular polysaccharide-hydrolyzing enzymes, which consist of cellulose. Halophilic enzymes have salt enriched solvation ammos [38,39]. Proteomic analysis exposed that outer membrane proteins and periplasmic proteins of N. pentaromativorans are the major protein components of OMVNovo originated from the membrane-associated protein fraction. To the best of our knowledge, to first describe the OMV purified from halophilic marine bacteria [40].

Bioremediation
Bioremediation of voguish salty environment inexorably requires the application of halotolerant and halophilic microorganisms, which are able to grow under such harsh conditions. Externally added bacteria may contain some deleterious effects on the ecosystem, applying or activating the indigenous microflora is preferred if possible [56]. Halotolerant and halophilic bacteria are generally tolerating conspicuous amounts of toxic metals in their environment. Therefore, they were utilized in bioremediation of oil [17,57] Microbial degradation of azo dyes under anaerobic cultures often follows via an enzymatic reaction. This is outstanding to the strong electron withdrawing propensity of the azo groups associated with oxygen commencing the reduced electron carrier [58][59][60][61]. Many microorganisms are capable of decolorizing the azo dyes, including Gram-positive, Gram-negative bacteria [62][63][64] and some fungi [65,66]. This review highlights the various strategies adopted by the halophiles to compensate for their saline surroundings and includes descriptions of recent studies used these kind microorganisms for bioremediation of petroleum hydrocarbon polluted environments [67].

Pharmaceutical Uses
Consumption of Sea bio metabolites gained incredible importance in past few years because due to their potential values. Through the accumulative problem of drug resistance, there is a dire need to separate, identify and utilize newer molecules of biomedical prominence. Saltpans are stayed an extreme environment, which resides organisms that survive in high salinities, high temperatures withstand severe solar radiation. In future, these organisms could give an excellent support to sources of novel secondary metabolites. Several halophilic and halotolerant microbes inhabiting in the saltpans are yet to be fully explored as potential producers of pharmaceutically important molecules. Scarce reports are accessible on their antimicrobial potential in India [68][69][70][71]. They revised some of the topical new bioactive compounds from marine bacteria and fungi. Bacteria from Weihai solar saltern, China have been screened, applied usage of antimicrobial and cytotoxic activity of halophiles [72]. Extreme environments containing alkalophilic, oligotrophic, piezophilic, xerophilic and halophilic have willpower be the greatest source for bioactive compound producing microbes. The halophiles can be lightly classified as faintly, moderately or extremely halophilic be contingent on their necessity for NaCl [73].
membranes and entire cells. The industrial important applications of these compounds in enzyme technology are most encouraged. The other compatible solutes such as trehalose, glycerol, proline, ectoines, sugars, and hydroxyectoine. The halophilic bacteria have the highest efficiency of protection of lactate dehydrogenase against freeze-thaw treatment and heat stress. Moreover, halophilic bacteria produce a number of extra and intracellular enzymes and antimicrobial compounds that are commercial interest on the proteolytic enzyme from a reasonable halophile, Bacillus [75]. Halolamina salifodinae and Halolamina salina were isolated from a salt mine [76].
The role of halophilic bacteria in environmental biotechnology is promising for (1) recovery of saline soil (2), alkaline industrial wastewater (3) and degradation of toxic compounds. Halophilic microbes serve as a biotechnological potential source of compatible solutes, enzymes and additional compounds of industrial interest.
Halophilic microorganism produces a large variety of stable and exclusive biopolymers which have differentiated biological activities and hence are emerging with better and novel industrial and therapeutic applications. Their novel characteristics and capacity for largescale culturing make halophiles are potentially valuable for biotechnology important [77]. Halophiles are widely used in numerous common fermentation processes [78].

Conclusion
This review was clearly focused on Halophilic microorganisms consume initiate relatively few commercially feasible applications. Halophiles are produced a large variability of stable and unique biopolymers which have varied biological activities and hence are developing with greater novel industrial, therapeutic applications, treatment of saline or hypersaline wastewaters, the production of exopolysaccharides, bioplastics, biodegradation and biofuels. Biopolymers are got from halophiles. These are gaining tremendous importance because of their high stability in extreme salt conditions, with wide industrial and pharmacological applications.