I feel that Iron-reducing bacteria alone would not be the answer to this... A lot of the treatment has to do with the source of the waste where maximum segregation and treatment is possible before it enters a common pool (both in terms of solid waste and liquid effluent)... Tackling this issue is a more serious one and a more urgent one at present...

Thank you. we must characterise the industrial waste and the treatment may be applied as per the requirement. Different unit operations are to be incorporated in the process to achieve our goal. Iron reducing bacteria(IRB) are of great interest because of their novel electron transfer capabilities and impact in natural environment. Various studies have shown that microbial Ferric reduction plays an important role in decomposition of both natural and anthropogenic organic C in several diverse environment .

Dear Sir,

Characterization of industrial waste is a simple process if we know the raw materials being used in the particular industry and the outcome of the industrial process (keeping in mind that we hold good the confidentiality of the information obtained which is purely for the purpose of finding a solution to a prevalent problem).

This way both the environment and the industry are happy with the outcome... The impact of Iron reducing bacteria seems promising in regions where domestic effluent is a problem, and if tests are to be conducted, I feel these are the regions that need to be targeted... You could try working with an enclosed water body to begin with like a small pond or a lake or even an aquaculture farm that needs recycling... Once promising results are obtained, you could then look into trials in open systems.

Best regards,

Dominique.

Microorganisms have the ability to change the oxidation state of metals. Microbialprocesses have opened up new opportunities for us to explore novel applications. Effect of anaerobic dissimilatory iron (III) reducing bacterial consortium on different phases of iron present in lateritic nickel ore is of important significance. Such conversion in lateritic nickel ore are helpful in better recovery of sorbed metal values like Ni and Co by subsequent bioleaching or acid leaching. Understanding of this important area of research will help in exploiting in bioremediation and other area of biotechnology research. All this require multidisciplinary approach & interaction with scientific community. This technology can be applied to copper, uranium and gold

Chromate is a priority pollutant all over the world, the hazard of which can be mitigated by reduction to the trivalent form of chromium.. Thus, dissimilatory iron reduction may provide a primary pathway for the sequestration and detoxification of chromate in anaerobic soils and water

Dear Dominique,Your suggestion regarding 'in situ' bioremdiation of industrial effluents is interesting. With respect to the constituents of the waste, using appropriate microbial consortia of fermentors, iron-reducing bacteria etc, a recycling process can be made practical.

Several studies have highlighted the capability of Shewanella decolorationis to neutralise the toxic dyes of dye industry effluent. Several other species of Shewanella, a facultative iron reducing bacteria, are being used in bioremediation of heavy metals like Hg, V, Tc and also radionuclides like U (IV).

Hence, IRB can be used in bioremediation of both solid and liquid industrial waste exploiting its capacity to reduce the oxidised metals as also mentioned by Sukla sir..

Yeah the discussion regarding Iron reducing bacteria is interesting. A lot of work is presently being carried out with this microbial approach to provide an alternative to the conventional physico-chemical methods adopted for mineral processing. They have also found thier use in bioremediation which is very attractive.

Yes i feel the discussion is interesting. Solid, liquid wastes can be treated through this microbial remediation approach. Also much can be done regaring the genomic and proteomic approaches using these microorganisms.

I am not an expert on this field. However, it seems to me that for the bulk of organic materials aerobic treatment is considerably faster. Therefore use of iron reducing capabilities can be especially useful for several aerobically hard to biodegrade contaminants. Combination of anaerobic/aerobic treatment should be beneficial.

Thank you Titus for the valuable suggestion. We can possibly treat the organic materials in aerobic condition followed by anerobic degradation using iron reducing bacteria wherein, a complete biomediation of the waste can be achieved.

. Geobacter sulfurreducens is a dissimilatory metal-reducing bacterium that can reduce soluble U(VI) to insoluble U(IV). Such microbial reduction shows significant promise for in situ bioremediation of subsurface environments contaminated with U, Tc, and other toxic metals such as chromium.Exploiting microbial function for purposes of bioremediation, energy production, carbon sequestration and other missions requires an in-depth and systems level understanding of the molecular components of the cell that confer its function. Inherent to developing this systems-level understanding is the ability to acquire global quantitative measurements of the proteome (i.e., the proteins expressed in the cell) These types of measurements in a high throughput manner for the metal reducing bacteria Shewanella oneidensis and Geobacter sulfurreducens by applying the art proteomics technologies based on high-resolution separations combined with Fourier transform ion cyclotron resonance mass spectrometry.

Bioremediation is an option that offers the possibility to destroy or render harmless various contaminants using natural biologically activity. Bioremediation has been used at a number of sites worldwide with varying degree of success. The control and optimisation of bioremediation processes is a complex system of many factors. The existence of microbial population capable of degrading the pollutants, the availability of contaminants to the microbial population and the environment factors(Type of soil, temperature, pH, the presence of oxygen or other electron acceptors, and nutrients).

This is a very important area of reserch. A lot of metals along with other chemicals are being discharged to the waste stream of different industries. It can be recovered by using microbial processes.I think iron reducing bacteria can play a major role in recovering metals from industrial waste.This process can be scaled up with minimum cost.

The area of application of IRB towards bioremediation is very interesting. Since I am working in the area of biosurfactants, I think any IRB producing biosurfactants can be employed towards bioremediation like removal of heavy metal from contaminated soil and water etc.

DIRB are now coming to be known as potential actors in bioremedication programme. I think revealing much of the genomic and proteomic aspects of such microorganisms will provide better insights into the capablities of thier action as well as contribute towards their efficiency. Following this their application in a large scale can be tried which will open up many doors for commercial remediation programme. I suggest more discussion on the genomic and proteomic aspects of these microorganisms.

Oil spills and petroleum impacted wetlands have detrimental effects on the natural habitats. These contaminants require quick detoxification which can be achieved by Intrinsic bioremediation. Alteromonas putrefaciens, first of a kind of Shewanella was isolated from oil fields for its efficiency in iron reduction coupled to the oxidation of hydrocarbons. Hence, iron reducing bacteria with capability to utilise hydrocarbons can be enriched for bioremediation.

In addition to this, Mangrove regions hold a key to understanding the soil conditions in which they grow... The aerial roots produced by the Avicennia sp. increase in number when the aeration in the soil in low. This low soil aeration also leads to problems faced by benthic dwellers... Being a mineral rich as well as organic rich river deposit on the banks of the estuary, is there any possibility that IRB in combination with other bioremediation microorganisms can be used to flux the nutrients in these soils and improve their aeration?

Nanotechnology has also emerged as an efficient tool towards bioremediation. Zero valent iron designed in form of permeable reactive barriers, were found to be effective towards treatment of hazardous waste water. Even nanoscale iron particles and their derivatives have proved to be versatile remediation tools for various chlorinated compounds as DDT, Carbon tetrachloride, hexachlorobenzene, lindane etc. Thus by utilizing the capability of IRB to synthesize iron nanoparticles we can bring about an important green revolution towards bioremediation using nanobiotechnology.

I thank Dominique for your interesting query and Eepsita for your interesting contribution. It will be good if we can have an idea of the existing IRB and other micro-organisms thriving in those conditions. Thereafter, we can analyse the potential effect on utilisation of nutrients and on mineral dissolution. Also, studying the microbial interaction among those consortia can further help us understand the existing situation.

However, IRB do not hold a direct effect on soil aeration. Probably, the use of chemicals or mechanical methods may improve their aeration.

Presently IRB is gaining interest among researchers for application in remediation of metal pollution. Many of researchers reported IRB as a consortium of related microbes, hence it need to identification of potential microbes involve in the process. I would like to add another point like, the metabolic role of metals in microbial metabolic system need to establish. So the designated microbes can be further apply in remediation of metal remediation.

Iron reducing bacterias are usually known to act much better in a consortium, involving chain of electron transfer reactions. This suggests that there are groups of enzymes that act in the process.Molecular tool such as PCR-DGGE,PCR-TGGE,ARDRA,etc needs to be studied To gain deeper insight of Microbial communities present in isolated Iron Reducing Bacteria.

This is a significant area of reserch. Metals and other toxic chemicals discharged to the waste stream from different industries can be recovered by applying microbial processes like iron reducing bacteria can play a major role in recovering metals from industrial waste.This process can be further improved through the use of biosurfactants produced through certain types of bacteria for better isolation. In this aspects, bioserfactant coated nanoparticles may play a role in further improvement.

The quick detoxification and removal of minerals from steel and petrochemical industries can be achieved through metal reducing bacteria. The bacteria which reduces iron with simultaneous oxidation of hydrocarbon are very much effective for both the industry. After that their isolation can be improved through the use of biosurfactant producing bacteria. Nanoparticle coated with biosurfactant and nanofibrous membrane coated with biosurfactant are helpful in this regard.

Successful bioremediation technology is dependent on an interdisciplinary approach involving microbiology, ecology, geology and chemistry. Bioremediation technology does not result in the production of high value added products.Thus venture capital has been slow to invest in technology. As a result commercial activity in R & D has lagged far behind other industrial sector.The trend is slowly changing and the regulatory hurdles are decreasing. The site specific bioavailability influence on bioremediation are being considered.

The application of molecular microbiology techniques in studying microbial populations in populated sites with out the need for culturing has led to the discovery of novel and unrecognized microorganisms. Such complex microbial diversity and dynamics in contaminated soil offer a resounding opportunity for bioremediation strategy.

IRB and SRB have a remarkable role in CT dechlorination. A distinguised feature of IRB and SRB compared with other anaerobes is the reactivity of their metabolic products, namely sulphide and ferrous iron, towards CT. These compounds can reduce CT rapidly and completely under suitable conditions, whereas the products of methanogenesis, fermentation and nitrate reduction are inert. In the presence of SRB and/or IRB, CT can be reduced not only via cometabolic processes described previously, but also through direct abiotic interaction with sulphide and ferrous iron.

As mentioned by Sandeep, integrative approaches exploiting the dynamic interactions of IRB and SRB can produce enhanced effect on bioremediation. But, the study of interaction mechanism and their synergy during this process is in its infancy and requires intensive investiagtions.

I appreciate the novel approach for the bioremediation of industrial waste by IRB using the concept of " Nanoparticle coated with biosurfactant and nanofibrous membrane coated with biosurfactant " said by Sukla Sir. Because biosurfactant can chelate heavy metals like lead, Hg,Cd etc from industrial waste.

I have attached a file related to this matter (bioremediation by biosurfactants).

So I can say one thing.....Any biosurfactant producing IRB can be used for the bioremediation of industrial waste or contaminated soil or contaminated water or phytoremediation.

Depends upon the kind of wastes or effluents you are dealing with. First I would characterize the effluent and thereafter select particular bacteria candidates for bioremediation,

I have an idea to reduce Iron from Fe-contaminated waste by using ferric iron reductases enzyme.

As reported by Schröder I et al. "Assimilatory ferric reductases are essential components of the iron assimilatory pathway that generate the more soluble ferrous iron, which is then incorporated into cellular proteins. Dissimilatory ferric reductases are essential terminal reductases of the iron respiratory pathway in iron-reducing bacteria. While our understanding of dissimilatory ferric reductases is still limited, it is clear that these enzymes are distinct from the assimilatory-type ferric reductases."

http://www.ncbi.nlm.nih.gov/pubmed/12829278

The information on assimilatory ferric reductase enzyme is interesting. Though the understanding of this enzyme is limited, its role in iron assimilation pathways is clear. I think more studies on the electron transfer pathways of IRB should bring in more insights into its application.

I agree with Sukla sir. Though the information on ferric reductase enzyme is limited and much more scope to reveal the understanding in electron transfer pathways, it still plays a crucial role. Yes, the dissimilatory ferric reducatses are essential terminal reductases in iron respiratory chain. Revealing information through scientific modules can help predict certain strains with better iron reducing capabilities. Then only, these microorganisms can be applied to relevant areas of application. Its good to see that Arun has provided an information and the approach suggested by Luis Rafel is to this context.

I am happy to learn many things suggested by all the contributers to this question and also would like to pour in my ideas and experience with there discussions.

IRB are known to exist abundantly in sedimentary soils and can prove to be a natural clean-up tool for bioremediation of heavy metal contaminated soils. Stimulation of IRB can can provide in situ immobilization and detoxification of metals Tec (VII), Cr(IV), V , etc and many radionuclides.

IRBs are beautiful examples in sedimentary environment remediation. Bioremediation is an interdisciplinary approach and involves biotechnology, soil chemistry, pollutant bioavailability and biological mechanisms. However, a large gap still persists to understand such remedial processes. Lack of updated knowledge, scarcity of successful cases and commercialization of these processes are few factors that contribute to the paucity in implementation of such technologies.

It is urgent need to construct the data base to collect the results of molecular ecological assessments of contaminated and bioremediation sites as naturally occurring microbial consortia have been utilised in a variety of bioremediation process.

Geobacter uraniireducens has been reported to have capability towards Uranium bioremediation. Geobacter species are Gram -ve bacteria of the family

Geobacteraceae within the class Delta-proteobacteria. Geobacter strains are often considered as the dominant members of subsurface sediments under metal-reducing condition. A detailed isolation and characteristics of this organisms can be found at the following address:

http://www.geobacter.org/publication-files/18450691.pdf

Reduction of Fe(III) and formation of dissolved Fe(II) in anaerobic digester of activated sludge prevents sulphate reduction and the formation of sulphide, and enhances the accumulation of phosphate in sludge. Ini­tiation of iron-reducing microbial activity in anaerobic digesters can improve the quality of sewage sludge as a raw material for production of organic fertilizer.(Journal of Residuals Science & Technology, Vol. 1, No. 3—July 2004 )

Petroleum hydrocarbons are widespread in our environment as fuel and chemical compounds. The uncontrolled release of petroleum hydrocarbons negatively impacts many of the soil and water resources. have been show to be feasible. In situ biological treatment involves the stimulation of native microbial community to levels that effectively degrade contaminanis. Treatment using in situ biological methods can prove to be efficient and cost effective for the cleanup of contaminated soils and groundwater.

Shewanella bacteria has the ability to reduce insoluble minerals and perform external redox chemistry. The biochemical pathways of Shewanella bacteria useful for both recycling and power production. When used in the anode chamber of a fuel cell, mimics of the mechanisms used by these metal reducing bacteria could create a usable electric current. The reaction could even be fueled by sewage and other waste materials. The cell membranes of Shewanella bacteria living in oxygen-free environments allow minerals to do the electro-chemical work of oxygen via a series of membrane-bound iron-reducing proteins.Someday, sewage treatment facilities may double as power plants that use these redox active bacteria. Artificial derivative processes could someday make bioremediation and energy production more environmentally friendly.

The microbial catalysis of uranium(VI) reduction has shown promising strategy for the potential remediation of uranium-contaminated groundwaters. Dissimilatory Fe(III)-reducing bacteria and sulfate-reducing bacteria are the two major groups of microorganisms capable of U(VI) reduction. Bacterial U(VI) reduction may be catalyzed by both direct (enzymatic) and indirect (chemical) mechanisms. Both Fe(III)-reducing bacteria and sulfate-reducing bacteria utilize U(VI) as an electron acceptor, and a subset of these groups have been shown to conserve energy for growth via U(VI) reduction. The products of microbial Fe(III) and sulfate reduction, Fe(II) and hydrogen sulfide, can also react abiotically to reduce U(VI). In the terrestrial subsurface, Fe(III)-reducing bacteria are likely to outcompete sulfate-reducing bacteria because Fe(III) is usually a much more abundant electron acceptor than sulfate in subsurface sediments. Thus, Fe(III)-reducing bacteria are thought to have a high bioremediation potential in uranium-contaminated subsurface sediments.

Understanding specific genes and their protein products is essential to understand the pathways involved in the bioremediation of radionuclides. Combining ‘-omics’-based approaches may assist in the identification of specific microbes effective for in situ bioremediation of radionuclides. Study of the molecular mechanisms behind the microbial transformation of radionuclides using ‘-omics’-based approaches and exploiting them in applications such as bioremediation would assist in tracking the responsible microbial metabolic products towards cell-free bioremediation and further assist in efficient removal of radionuclides from the environment.

I agree with sukla sir. An omic based apporach for identification of specific microbes will definitely be helpful for in-situ bioremediation of radionuclides.

Proteomics experts and resources at EMSL contributed to a study published in Science centered on the discovery of new bacteria and the metabolic roles, such as carbon cycling, of bacteria in the environment. The bacteria studied were part of microbial communities collected directly from an acetate-amended subsurface aquifer as part of the U.S. Department of Energy’s Integrated Field Research Challenge (IFRC).

http://ow.ly/fzQsj

I saw this interesting news. Congratulations to the team whoese groundbreaking results could lead to improved methods to stimulate bacteria to uptake atmospheric carbon, thereby reducing greenhouse gases, and to better apply microbes to remediate toxic metal-contaminated environments.

Also thanks are extended to Sukla sir for such a lovely infromation.

Magnetic susceptibility (MS) variations in hydrocarbon contaminated sediments are being investigated. MS can serve as a proxy for intrinsic bioremediation due to the activity of iron-reducing bacteria and for the application of geophysics to iron cycling studies.(Geophysical Research Letters Volume 38, Issue 21, November 2011)

Phylogenetic analysis of microbes thriving in the acidic contaminated sites of U (VI) as studied by Petrie et al., 2003 were found to be predominated by new Fe (III) reducing organisms like Anaeromyxobacter sp., Paenibacillus, Brevibacillus spp., etc. where as Geobacteraceae sequences were found abundant in the pristine sediments. Hence, the isolation, characterization and enhancement of the adapted cultures from these contaminated sites can be a better strategy as compared to the use of regular model metal-reducing organisms like Shewanellae and Geobacteraceae.

Waste water containing large amounts of heavy metals especially iron should be treated before being discharged into environment.The World Health Organization (WHO) declares a maximum admissible concentration of iron of 0.3 mg/L in drinking water . Iron can also create undesirable problems in ecosystems or industrial processes in its high concentrations .High removal efficiency (92.9%) and metal uptake capacity (28.7 mg/g or 0.514 mmol/g) in batch system demonstrated that chitosan can be used as an effective adsorbent for removal of Fe(II).(Adsorption of Fe(II) from Aqueous Phase by Chitosan: Application of Physical Models and Artificial Neural Network for Prediction of Breakthrough,IJE TRANSACTIONS B: Application Vol. 26, No. 8, (August 2013) 845-8580

. Computer technology approaches used to predict nutrient use and contaminant removal by Geobacter over time matched well with actual physical measurements made on site for pollution clean-up of groundwater. It turns out that we can now use advanced computer technology to predict the real-life functions of bacteria. With this tool we can improve bacteria-mediated pollutant removal, wastewater treatment, and novel bio-energy solutions.(www.scilogs.com/from_the_lab.../computers-and-electrifying-bacteria)

http://www.scilogs.com/from_the_lab.../computers-and-electrifying-bacteria

The conductive pili, or nanowires, of the bacterium Geobacter sulfurreducens

carry a catalytically active uranium reductase that converts soluble

uranium (IV), which is toxic, into a mineral form that is insoluble and thus

no longer toxic, according to Gemma Reguera and her colleagues at Michigan

State University in East Lansing. These bacteria may prove useful for

treating sites contaminated with this toxic metal. Details appear in the September 6, 2011, Proceedings of the National Academy of Sciences (doi:10.1073/pnas.1108616108).

http://10.1073/pnas.1108616108