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Widespread occurrence of acid soils across the globe is a serious issue in agriculture that has been generally managed with intensive use of chemical amendments. Although green microalgae are the primary colonizers of soils even under extreme acid conditions, only a few investigations focused on their role in health improvement of such soils. In this study we tested the hypothesis: that acid‐tolerant microalgae have the potential for ameliorating soil acidity and enhancing soil health through enrichment of carbon content, exopolysaccharides, indole acetic acid besides stimulating dehydrogenase activity in acid soils. Inoculation of two acid soils collected from Australian fields with acid‐tolerant microalgae, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, alone or in combination, resulted initially in the development of a soil algal crust as evidenced by significant increase in chlorophyll a in both the soils. Also, there was a significant increase (>200%) in the release of exopolysaccharides that facilitated soil aggregate stability. The increase in soil pH was about one unit (from 4.8 to 5.6 in soil A or 4.3–5.3 in soil B) under the influence of individual or co‐cultures of the microalgal strains after 90 days. Algalized acid soils exhibited a significant increase in carbon content (29–57%), dehydrogenase activity (>500%) and production of indole acetic acid (200–500%). Thus, the present study reports for the first time on the great potential of green microalgae in amelioration of acid soils besides improving soil health and fertility. [ABSTRACT FROM AUTHOR]

Phenotypic plasticity or genetic adaptation in an organism provides phenotypic changes when exposed to the extreme environmental conditions. The resultant physiological and metabolic changes greatly enhance the organism's potential for its survival in such harsh environments. In the present novel approach, we tested the hypothesis whether acid-adapted microalgae, initially isolated from non-acidophilic environments, can survive and grow in acid-mine-drainage (AMD) samples. Two acid-adapted microalgal strains, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, were tested individually or in combination (co-culture) for phenotypic changes during their growth in samples collected from AMD. The acid-adapted microalgae in AMD exhibited a two-fold increase in growth when compared with those grown at pH 3.5 in BBM up to 48 h and then declined. Furthermore, oxidative stress triggered several alterations such as increased cell size, granularity, and enhanced lipid accumulation in AMD-grown microalgae. Especially, the apparent limitation of phosphate in AMD inhibited the uptake of copper and iron in the cultures. Interestingly, growth of the acid-adapted microalgae in AMD downregulated amino acid metabolic pathways as a survival mechanism. This study demonstrates for the first time that acid-adapted microalgae can survive under extreme environmental conditions as exist in AMD by effecting significant phenotypic changes. [ABSTRACT FROM AUTHOR]

Phytoremediation uses plants and associated microbes to remove pollutants from the environment and is considered a promising bioremediation method. Compared with well-described single contaminant treatments, the number of studies reporting phytoremediation of soil mixed pollutants has increased recently. Endophytes, including bacteria and fungi, exhibit beneficial traits for the promotion of plant growth, stress alleviation, and biodegradation. Moreover, endophytes either directly or indirectly assist host plants to survive high concentrations of organic and inorganic pollutants in the soil. Endophytic microorganisms can also regulate the plant metabolism in different ways, exhibiting a variety of physiological characteristics. This review summarizes the taxa and physiological properties of endophytic microorganisms that may participate in the detoxification of contaminant mixtures. Furthermore, potential biomolecules that may enhance endophyte mediated phytoremediation are discussed. The practical applications of pollutant-degrading endophytes and current strategies for applying this valuable bio-resource to soil phytoremediation are summarized. [ABSTRACT FROM AUTHOR]

The soil microbiota plays a major role in maintaining the nutrient balance, carbon sink, and soil health. Numerous studies reported on the function of microbiota such as plant growth-promoting bacteria and fungi in soil. Although microalgae and cyanobacteria are ubiquitous in soil, very less attention has been paid on the potential of these microorganisms. The indiscriminate use of various chemicals to enhance agricultural productivity led to serious consequences like structure instability, accumulation of toxic contaminants, etc., leading to an ecological imbalance between soil, plant, and microbiota. However, the significant role of microalgae and cyanobacteria in crop productivity and other potential options has been so far undermined. The intent of the present critical review is to highlight the significance of this unique group of microorganisms in terms of maintaining soil fertility and soil health. Beneficial soil ecological applications of these two groups in enhancing plant growth, establishing interrelationships among other microbes, and detoxifying chemical agents such as insecticides, herbicides, etc. through mutualistic cooperation by synthesizing enzymes and phytohormones are presented. Since recombinant technology involving genomic integration favors the development of useful traits in microalgae and cyanobacteria for their potential application in improvement of soil fertility and health, the merits and demerits of various such advanced methodologies associated in harnessing the biotechnological potential of these photosynthetic microorganisms for sustainable agriculture were also discussed. [ABSTRACT FROM AUTHOR]

The excessive generation and discharge of wastewaters have been serious concerns worldwide in the recent past. From an environmental friendly perspective, bacteria, cyanobacteria and microalgae, and the consortia have been largely considered for biological treatment of wastewaters. For efficient use of bacteria‒cyanobacteria/microalgae consortia in wastewater treatment, detailed knowledge on their structure, behavior and interaction is essential. In this direction, specific analytical tools and techniques play a significant role in studying these consortia. This review presents a critical perspective on physical, biochemical and molecular techniques such as microscopy, flow cytometry with cell sorting, nanoSIMS and omics approaches used for systematic investigations of the structure and function, particularly nutrient removal potential of bacteria‒cyanobacteria/microalgae consortia. In particular, the use of specific molecular techniques of genomics, transcriptomics, proteomics metabolomics and genetic engineering to develop more stable consortia of bacteria and cyanobacteria/microalgae with their improved biotechnological capabilities in wastewater treatment has been highlighted. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Acid-tolerant microalgae withstand higher levels of cadmium (Cd) at pH 3.5. • Desmodesmus sp. MAS1 exhibited better tolerance than Heterochlorella sp. MAS3. • Both the microalgal strains removed >58% of 2 mg L−1 Cd at pH 3.5. • Lipid accumulation increased with higher concentrations of Cd at pH 3.5. • Cd stress induced biodiesel production rich in long chain hydrocarbons. Abstract Two acid-tolerant microalgae, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, originally isolated from non-acidophilic environment, were tested for their ability to withstand higher concentrations of an invasive heavy metal, cadmium (Cd), at an acidic pH of 3.5 and produce biomass rich in biodiesel. The growth analysis, in terms of chlorophyll, revealed that strain MAS1 was tolerant even to 20 mg L−1 of Cd while strain MAS3 could withstand only up to 5 mg L−1. When grown in the presence of 2 mg L−1, a concentration which is 400-fold higher than that usually occurs in the environment, the microalgal strains accumulated >58% of Cd from culture medium at pH 3.5. FTIR analysis of Cd-laden biomass indicated production of significant amounts of biodiesel rich in fatty acid esters. This is the first study that demonstrates the capability of acid-tolerant microalgae to grow well and remove Cd at acidic pH. [ABSTRACT FROM AUTHOR]

Abstract Remediation of soil contaminated with pollutants using biological agents is more a sustainable and greener approach as compared to physico-chemical technologies. We recently confirmed that a microalga, Chlorella sp. MM3, and a bacterium, Rhodococcus wratislaviensis strain 9, can degrade high-molecular weight PAHs. In this study, an algal–bacterial system of these two strains was developed by long-term growth on a mixture of phenanthrene, pyrene, and benzo[ a ]pyrene (BaP). In a soil spiked with 50 mg L−1 phenanthrene, 10 mg L−1 of pyrene and 10 mg L−1 of BaP, the algal–bacterial system degraded these PAHs almost completely in slurry phase within 30 days. Also, the algal–bacterial system was able to successfully remediate these three PAHs in a soil long-term contaminated with 245.1 mg kg−1 of 16 PAHs and several heavy metals under slurry phase in 21 days. Use of such appropriate assays as chlorophyll estimation for the microalga and semi-quantitative PCR for the bacterium confirmed survival of both the strains during soil bioremediation. Moreover, the residual toxicity test involving Escherichia coli DH5α that expresses green fluorescent protein indicated the successful bioremediation of PAHs-contaminated soil in slurry phase. For the first time, here we demonstrate the great potential of an algal–bacterial synergy in bioremediation of soil long-term contaminated with PAHs even in the presence of toxic heavy metals. Graphical abstract Unlabelled Image Highlights • A novel algal–bacterial system was developed for PAHs bioremediation. • This system degraded phenanthrene, pyrene and BaP spiked in soil slurry. • Bioremediation of soil long-term contaminated with several PAHs was successful. • The algal–bacterial system survived in soil slurry during bioremediation of PAHs. • Residual toxicity testing confirmed the successful bioremediation of PAHs in slurry. [ABSTRACT FROM AUTHOR]

Abstract A Gram-positive bacterium, Rhodococcus wratislaviensis strain 9, completely degraded 280 μM of phenanthrene, 40% of 50 μM pyrene or 28% of 40 μM benzo[ a ]pyrene (BaP), each supplemented in M9 medium, within 7 days. PCR screening with gene-specific primers indicated that the strain 9 harbors genes which code for 2,3-dihydroxybiphenyl 1,2-dioxygenase (bphC), 4-nitrophenol 2-monooxygenase component B (npcB) as well as oxygenase component (nphA1), 4-hydroxybenzoate 3-monooxygenase (phbH), extradiol dioxygenase (edo), and naphthalene dioxygenase (ndo), all of which are largely implicated in biodegradation of several aromatic hydrocarbons. An orthogonal design experiment revealed that BaP biodegradation was greatly enhanced by surfactants such as Tween 80, Triton X-100 and linoleic acid, suggesting that bioavailability is the major limiting factor in bacterial metabolism of BaP. Both pyrene and BaP induced the overexpression of amidohydrolase, a metallo-dependent hydrolase, possibly involved in their biodegradation by strain 9. The up-regulation of amidohydrolase gene induced by BaP, in particular, was also confirmed by semi-quantitative RT-PCR. Catechol 2,3-dioxygenase and the large subunit of ndo, but not amidohydrolase, accumulated when the strain 9 was grown on phenanthrene. To our knowledge, this is the first report on overexpression of amidohydrolase and its possible implication in bacterial degradation of high-molecular weight PAHs. Graphical abstract Unlabelled Image Highlights • Rhodococcus wratislaviensis strain 9 degrades phenanthrene, pyrene and BaP. • Strain 9 harbors several major genes implicated in hydrocarbon biodegradation. • Bioavailability is the major limiting factor in bacterial degradation of BaP. • Phenanthrene induces catechol 2,3-dioxygenase and the large subunit of ndo. • Pyrene and BaP induce the overexpression of metallo-dependent amidohydrolase. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Two strains of non-acidophilic microalgae (NAM) were acclimated to pH 3.0. • Flow cytometry analysis indicated their ability to withstand acidic pH. • Both the acclimated strains yielded good amounts of biomass and neutral lipids. • FTIR analysis confirmed accumulation of more triacylglycerols in NAM strains. • First report on biodiesel production in good amounts by NAM strains at pH 3.0. Abstract The overwhelming response towards algal biodiesel production has been well-recognized recently as a sustainable alternative to conventional fuels. Most microalgae cannot grow well at acidic pH. The present study, therefore, investigated whether non-acidophilic microalgae Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 can be acclimated to extreme-acidic pH for sustainable production of biomass and biodiesel. Growth analysis indicated that both the microalgal strains possessed a passive uptake of CO 2 at pH 3.0 with biomass production of 0.25 g dry wt. L−1 in Desmodemus sp. and 0.45 g dry wt. L−1 in Heterochlorella sp.. Flow-cytometry analysis for reactive oxygen species, membrane permeability and neutral-lipids revealed the capabilities of both strains to adapt to the stress imposed by acidic pH. Lipid production was doubled in both the strains when grown at pH 3.0. In-situ transesterification of biomass resulted in 13–15% FAME yield in the selected microalgae, indicating their great potential in biofuel production. [ABSTRACT FROM AUTHOR]

Owing to certain drawbacks, such as energy-intensive operations in conventional modes of wastewater treatment (WWT), there has been an extensive search for alternative strategies in treatment technology. Biological modes for treating wastewaters are one of the finest technologies in terms of economy and efficiency. An integrated biological approach with chemical flocculation is being conventionally practiced in several-sewage and effluent treatment plants around the world. Overwhelming responsiveness to treat wastewaters especially by using microalgae is due to their simplest photosynthetic mechanism and ease of acclimation to various habitats. Microalgal technology, also known as phycoremediation, has been in use for WWT since 1950s. Various strategies for the cultivation of microalgae in WWT systems are evolving faster. However, the availability of innovative approaches for maximizing the treatment efficiency, coupled with biomass productivity, remains the major bottleneck for commercialization of microalgal technology. Investment costs and invasive parameters also delimit the use of microalgae in WWT. This review critically discusses the merits and demerits of microalgal cultivation strategies recently developed for maximum pollutant removal as well as biomass productivity. Also, the potential of algal biofilm technology in pollutant removal, and harvesting the microalgal biomass using different techniques have been highlighted. Finally, an economic assessment of the currently available methods has been made to validate microalgal cultivation in wastewater at the commercial level. [ABSTRACT FROM AUTHOR]

Desert ecosystem is generally considered as a lifeless habitat with extreme environmental conditions although it is colonized by extremophilic microorganisms. Cyanobacteria, microalgae, and bacteria in these habitats could tolerate harsh and rapidly fluctuating environmental conditions, intense ultraviolet radiation, and lack of water, leading to cell desiccation. They possess valuable metabolites withstanding extreme environmental conditions and make them good candidates for industrial applications. Moreover, most natural microorganisms in these extreme habitats exist as consortia that provide robustness and extensive metabolic capabilities enabling them to establish important relationships in desert environments. Engineering of such consortia of cyanobacteria, microalgae, and bacteria would be functional in the sustainable development of deserts through improving soil fertility, water preservation, primary production, pollutant removal, and maintaining soil stability. Modern tools and techniques would help in constructing highly functional cyanobacterial/microalgal-bacterial consortia that are greatly useful in the establishment of vegetation in deserts as well as in biotechnological applications. [ABSTRACT FROM AUTHOR]

A Gram-positive bacterium, Rhodococcus wratislaviensis strain 9, was isolated from groundwater contaminated with nitrophenolics and trichloroethene following enrichment culture technique. The cells of strain 9 grown on LB broth (uninduced) degraded 720 μM p -nitrophenol (PNP) within 12 h, and utilized as a source of carbon and energy. Orthogonal experimental design analysis to determine optimal conditions for biodegradation of PNP showed that pH had a significant positive effect ( P  ≤ .05) on bacterial degradation of PNP, while glucose, di- and tri-nitrophenols exhibited significant negative effect. Cell-free extracts obtained from PNP-grown culture that contained 20 μg mL −1 protein degraded 90% of 720 μM PNP within 5 h of incubation. Two-dimensional protein analysis revealed differential expression of the oxygenase component of PNP monooxygenase and an elongation factor Tu in PNP-grown cells, but not in those grown on glucose. The strain 9 remediated laboratory wastewater containing 900 μM PNP efficiently within 14 h, indicating its great potential in bioremediation of PNP-contaminated waters. [ABSTRACT FROM AUTHOR]

Microalgae and bacteria offer a huge potential in delving interest to study and explore various mechanisms under extreme environments. Acid mine drainage (AMD) is one such environment which is extremely acidic containing copious amounts of heavy metals and poses a major threat to the ecosystem. Despite its extreme conditions, AMD is the habitat for several microbes and their activities. The use of various chemicals in prevention of AMD formation and conventional treatment in a larger scale is not feasible under different geological conditions. It implies that microbe-mediated approach is a viable and sustainable alternative technology for AMD remediation. Microalgae in biofilms play a pivotal role in such bioremediation as they maintain mutualism with heterotrophic bacteria. Synergistic approach of using microalgae -bacteria biofilms provides supportive metabolites from algal biomass for growth of bacteria and mediates remediation of AMD. However, by virtue of their physiology and capabilities of metal removal, non-acidophilic microalgae can be acclimated for use in AMD remediation. A combination of selective acidophilic and non-acidophilic microalgae together with bacteria, all in the form of biofilms, may be very effective for bioremediation of metal-contaminated waters. The present review critically examines the nature of mutualistic interactions established between microalgae and bacteria in biofilms and their role in removal of metals from AMDs, and consequent biomass production for the yield of biofuel. Integration of microalgal-bacterial consortia in fuel cells would be an attractive emerging approach of microbial biotechnology for AMD remediation. [ABSTRACT FROM AUTHOR]

Derelict mines pose potential risks to environmental health. Several factors such as soil structure, organic matter, and nutrient content are the greatly affected qualities in mined soils. Soil microbial communities are an important element for successful reclamation because of their major role in nutrient cycling, plant establishment, geochemical transformations, and soil formation. Yet, microorganisms generally remain an undervalued asset in mined sites. The microbial diversity in derelict mine sites consists of diverse species belonging to four key phyla: Proteobacteria, Acidobacteria, Firmicutes, and Bacteroidetes. The activity of plant symbiotic microorganisms including root-colonizing rhizobacteria and ectomycorrhizal fungi of existing vegetation in the mined sites is very high since most of these microbes are extremophiles. This review outlines the importance of microorganisms to soil health and the rehabilitation of derelict mines and how microbial activity and diversity can be exploited to better plan the soil rehabilitation. Besides highlighting the major breakthroughs in the application of microorganisms for mined site reclamation, we provide a critical view on plant−microbiome interactions to improve revegetation at the mined sites. Also, the need has been emphasized for deciphering the molecular mechanisms of adaptation and resistance of rhizosphere and non-rhizosphere microbes in abandoned mine sites, understanding their role in remediation, and subsequent harnessing of their potential to pave the way in future rehabilitation strategies for mined sites. [ABSTRACT FROM AUTHOR]

Microalgae inhabiting the real contaminated sites are capable of degrading organic pollutants. In the present study, the potential of a microalga, Chlorella ssp. MM3, a soil isolate from a former cattle dip site, was assessed in degrading pyrene both in aqueous medium and soil slurry. Strain MM3 can grow on pyrene in culture medium at concentrations as high as 250 μM. When grown in presence of 50 μM pyrene, the cell density increased from 1.1 × 10 5 cells mL − 1 to 16.45 × 10 5 cells mL − 1 within 7 days. With an initial cell density of 3 × 10 7 cells mL − 1 , nearly 70% of 50 μM pyrene was degraded after 7 days of incubation. When compared with Triton X-100, Tween 80 was a better non-ionic surfactant for pyrene biodegradation. Nearly 20% increase in degradation of pyrene was observed with the use of 0.005% Tween 80. Differential protein expression in pyrene-grown cells of the microalga resulted in distinct accumulation of dihydrolipoamide acetyltransferase (or dihydrolipoyl transacetylase), one of the three components of pyruvate dehydrogenase complex, indicating a possible role of this enzyme in microalgal degradation of pyrene. The microalgal cells immobilized in calcium alginate completely degraded 50 μM of pyrene within 10 days in nonsterile soil slurry treated with 0.005% Tween 80. Our results clearly indicate that the strain MM3 has a great potential for its use in remediating soils contaminated with pyrene. [ABSTRACT FROM AUTHOR]

Mixture toxicity studies are very complex due to the complexity exhibited by the chemicals involved, and the net interaction effects are highly dependent on mixture combinations, exposure dose and the test organism. For assessing the toxicity of mixtures, factorial analysis has been widely used, while the usage of models developed by artificial neural network (ANN) analysis and genetic algorithm (GA) is very limited. We combined for the first time the factorial design experiment with ANN and GA to develop a model for predicting the interactive toxicological effects using a soil microalga, Chlorella sp. MM3. The chemicals included in the mixtures were two polyaromatic hydrocarbons (PAHs), phenanthrene and benzo[ a ]pyrene, and two heavy metals (HMs), cadmium and lead. Three biochemicals implicated in oxidative stress, viz., malondialdehyde (a measure for lipid peroxidation, LPO), catalase activity and proline accumulation were used as the toxicity criteria. Validation of the predicted results related to the biochemicals with the experimental data clearly indicated that the model developed with the combination of ANN and GA is greatly effective in predicting the toxicity of PAHs and HMs mixtures toward microalga with < 10% relative error. Both catalase and LPO were found to be the promising biomarkers for predicting microalgal toxicity of PAHs and HMs mixtures. In addition, a significant positive correlation was evident between the removal of PAHs/uptake of HMs and LPO. [ABSTRACT FROM AUTHOR]

Abstract: Millions of natural and synthetic organic chemical substances are present in both soil and aquatic environments. Toxicity and/or persistence determine the polluting principle of these substances. The biological responses to these pollutants include accumulation and degradation. The responses of environments with organic pollutants are perceptible from the dwindling degradative abilities of microorganisms. Among different biological members, cyanobacteria and microalgae are highly adaptive through many eons, and can grow autotrophically, heterotrophically or mixotrophically. Mixotrophy in cyanobacteria and microalgae can provide many competitive advantages over bacteria and fungi in degrading organic pollutants. Laboratory culturing of strict phototrophic algae has limited the realization of their potential as bioremediation agents. In the natural assemblages, mixotrophic algae can contribute to sequestration of carbon, which is otherwise emitted as carbon dioxide to the atmosphere under heterotrophic conditions by other organisms. Molecular methods and metabolic and genomic information will help not only in identification and selection of mixotrophic species of cyanobacteria and microalgae with capabilities to degrade organic pollutants but also in monitoring the efficiency of remediation efforts under the field conditions. These organisms are relatively easier for genetic engineering with desirable traits. This review presents a new premise from the literature that mixotrophic algae and cyanobacteria are distinctive bioremediation agents with capabilities to sequester carbon in the environment. [Copyright &y& Elsevier]

We isolated strain CERAR5, a Stenotrophomonas sp., from an aquifer contaminated with chlorinated hydrocarbons that utilizes up to 1.0 mM PNP within 62 h in M9 medium as a source of carbon and nitrogen. To assess the potential of this strain for use in bioremediation, we investigated the influence of external sources of carbon and nitrogen on bacterial degradation of PNP following a full factorial design analysis. Glucose, sodium acetate, phenol, sodium nitrate and ammonium chloride were the factors chosen, while per cent removal of PNP, growth of the bacterial strain, and change in pH of the medium were the responses measured. Glucose and acetate had significant positive influence on the removal PNP. In particular, acetate exhibited a significant positive effect on all the three responses measured, clearly suggesting that the addition of acetate greatly contributes to an efficient bioremediation of habitats contaminated with PNP by Stenotrophomonas sp. CERAR5. [ABSTRACT FROM AUTHOR]

The nontarget effects, in terms of biochemical changes induced by p-nitrophenol (PNP) in three soil microalgae, Chlorella sp., Chlorococcum sp., and Heterochlamydomonas sp., and the PNP removal efficiency of these isolates, were determined. On exposure to 20 mg L−1 PNP, Chlorella sp. showed greater activity of peroxidase, superoxide dismutase, and glutathione reductase as well as high contents of proline and carotenoids. While Heterochlamydomonas sp. exhibited higher levels of catalase and protein, Chlorococcum sp. produced greater amounts of malondialdehyde, a measure of lipid peroxidation, in the presence of PNP. Chlorella sp. tolerated PNP by producing large quantities of antioxidants coupled with less lipid peroxidation, while Chlorococcum sp. was susceptible, as evidenced by low antioxidant production and high lipid peroxidation. During 7-d exposure, Chlorella sp., Heterochlamydomonas sp., and Chlorococcum sp. were able to remove 39, 18, and 4% of 20 mg L−1 PNP, respectively. The present results indicate that proline, carotenoids and malondialdehyde are the potential biomarkers for assessing PNP toxicity toward microalgae, and their response could be considered for differentiating tolerant and susceptible strains. Moreover, there is a clear correlation between PNP removal and antioxidant synthesis in microalgae on exposure to the pollutant. Environ. Toxicol. Chem. 2012; 31: 1980-1988. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Microbial metabolites are of huge biotechnological potential and their production can be coupled with detoxification of environmental pollutants and wastewater treatment mediated by the versatile microorganisms. The consortia of cyanobacteria/microalgae and bacteria can be efficient in detoxification of organic and inorganic pollutants, and removal of nutrients from wastewaters, compared to the individual microorganisms. Cyanobacterial/algal photosynthesis provides oxygen, a key electron acceptor to the pollutant-degrading heterotrophic bacteria. In turn, bacteria support photoautotrophic growth of the partners by providing carbon dioxide and other stimulatory means. Competition for resources and cooperation for pollutant abatement between these two guilds of microorganisms will determine the success of consortium engineering while harnessing the biotechnological potential of the partners. Relative to the introduction of gene(s) in a single organism wherein the genes depend on the regulatory- and metabolic network for proper expression, microbial consortium engineering is easier and achievable. The currently available biotechnological tools such as metabolic profiling and functional genomics can aid in the consortium engineering. The present review examines the current status of research on the consortia, and emphasizes the construction of consortia with desired partners to serve a dual mission of pollutant removal and commercial production of microbial metabolites. [Copyright &y& Elsevier]

The widespread presence of the versatile solvent, N , N ′-dimethylformamide (DMF), in industrial wastewaters, and the growing concern over its ecotoxicity necessitate the implementation of an effective remediation technology. Mesorhizobium tamadayense MM3441, isolated from a soil contaminated with polycyclic aromatic hydrocarbons, utilized higher concentrations of DMF as sole carbon and nitrogen source. To our knowledge, the strain MM3441 is the only member of the genus, Mesorhizobium , capable of degrading DMF. This strain, with methylotrophic mode of nutrition, also exhibited resistance to several organic solvents. Optimal growth of the strain was observed at pH 7.0 in the presence of 5000 mg L−1 DMF. The strain removed 95% of 5000 mg L−1 DMF within nine days of incubation. DMF utilization was accompanied by the accumulation of dimethylamine (DMA) and ammonia in the culture medium. Both the resting cell and dimethylformamidase (DMFase) assays provided the circumstantial evidence that DMF degradation by the strain MM3441 proceeds via the typical pathway yielding DMA. However, DMFase expression is not inducible with DMF, suggesting that the enzyme is constitutively expressed. Based on the DMF degradation ability and metabolic flexibility of the strain MM3441, the present study advocates its potential use in bioremediation of the environments contaminated with DMF. Image 1 • Mesorhizobium tamadayense MM3441 has a great potential in degrading DMF. • This N 2 -fixing methylotroph removed 95% of 5000 mg L−1 DMF in nine days. • DMF degradation by MM3441 followed a typical DMA-forming pathway. • The enzyme DMFase is constitutively expressed in the strain MM3441. • Strain MM3441 is the first known DMF degrader of the genus Mesorhizobium. [ABSTRACT FROM AUTHOR]