Garbisu position of those strains. The DNA G+C
Garbisu et al (2003) investigated Basic concepts on heavy metal soil bioremediation. Bioremediation by using organisms is a rapidly changing and growing area of environmental biotechnology which is used for relatively more effective and cheap method than traditional physicochemical methods. So far enough experience and expertise are required for a successful bioremediation process because technically it is not so complex. Successful bioremediation process involves and depends upon many disciplines like microbiology, engineering, ecology, geology and chemistry. It is impossible to produce the same result of remediation in laboratory as in the field as situation and conditions are not the same, this is reason behind ending of many remediation companies. Many conventional methods do not give acceptable solutions for detoxification of metals from soils. Those microorganism which use metals as terminal electron acceptors are used for detoxification of metals from contaminated sites. Metal polluted soils can be sometimes clean up by phytoextraction which is a cost effective method. Margesin et al (2001) investigated Potential of halotolerant and halophilic microorganisms for biotechnology. Halotolerant microorganisms can be used in various fields of biotechnology. In the field of biotechnology bacteriorhodopsin incorporates in holography, spatial light modulators, optical computing, and optical memories. Reconcilable solutes are helpful as stabilizers of biomolecules and whole cells, salt antagonists, and stress-protective agents. Biopolymers and enzymes are active and stable at elevated salt concentrations and used for microbial enhanced oil recovery. Halotolerant microorganisms are extremely important in food biotechnology as well as in degradation of organic pollutants and production of alternative energy. García et al (2004) had worked on Halomonas organivorans sp. nov., a moderate halophile able to degrade aromatic compounds. In southern Spain a group of halotolerant bacteria was isolated and characterized, it can degrade aromatic organic compounds containing hypersaline habitats. Phenotypic, phylogenetic and genotypic methods were used to determine taxonomic position of those strains. The DNA G+C content ranged from 61.0-62.9 mol%. They have 90-100% DNA-DNA hybridization values known by DNA-DNA hybridization studies. By the complete analysis of 16S rRNA gene sequence it was suggested that they have gene similarity with strains Halomonas salina and Halomonas halophila of genus Halomonas, but there were phenotypic dissimilarities so they were placed as novel species in genus Halomonas and named as Halomonas organivorans sp. nov. with strain G-16.1T (=CECT 5995T=CCM 7142T) as the type strain. This novel species can use a lot of organic compounds and is helpful for decontamination of polluted saline habitats. Zhang et al (2008) worked on Halomonas korlensis sp. nov., a moderately halophilic, denitrifying bacterium isolated from saline and alkaline soil. In korla north-western China five Gram negative, rod shaped, halotolerant and denitrifying strains labelled KX1T, XK2, XK3, XK4, AND XK5 were isolated from saline and alkaline soil. They could grow anaerobically using nitrate or nitrite as terminal electron acceptors and vigorously produced gas from nitrate. Phylogenetic analysis of 16S rRNA revealed these strains have gene similarities with Halomonas ventosae Al12T (95.6 %), Halomonas alimentaria YKJ-16T (95.5 %) and Halomonas shengliensis SL014B-85T (95.2 %) of genus Halomonas within the family Halomonadaceae. Sequence similarities below 97% represent a new species. All the five strains represent same species by BOX-PCR fingerprinting and DNA-DNA hybridization, their major fatty acid were C18:1?t, C16:0 and C18:1?7t and G+C content of DNA was 65.3 mol%. The final result of all the phenotypic and genotypic analysis was that these strains are novel species within genus Halomonas, their name proposed as Halomonas korlensis sp. nov. and type strain is XKIT (5CGMCC 1.6981T5DSM 19633T). Le Borgne et al (2008) studied Biodegradation of organic pollutants by halophilic bacteria and archaea. Hyperslaine environments are significant for surface expansion as well as for ecological importance. It is determined that 5% of industrial discharges are saline or hypersaline. As halophilic microbes adapted to that environment so they could be considered as better candidates for degradation of such saline effluents as compared to conventional non-extremophiles. As halotolerant and halophiles have more capacity to degrade a variety of saline contaminating compounds. But there is still need to explore more about potential of these halotolerant microorganisms to bioremediate such environments. There is also need to know about overall degradation mechanism, enzymes involved in the process and metabolism regulation.