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Soybean cultivation in tropical regions relies on symbioses with nitrogen-fixing Bradyrhizobium and plant growth-promoting bacteria (PGPBs), reducing environmental impacts of N fertilizers and pesticides. We evaluate the effects of soybean inoculation with different bacterial consortia combined with PGPBs or microbial secondary metabolites (MSMs) on rhizosoil chemistry, plant physiology, plant nutrition, grain yield, and rhizosphere microbial functions under field conditions over three growing seasons with four treatments: standard inoculation of Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens consortium (SI); SI plus foliar spraying with Bacillus subtilis (SI + Bs); SI plus foliar spraying with Azospirillum brasilense (SI + Az); and SI plus seed application of MSMs enriched in lipo-chitooligosaccharides extracted from B. diazoefficiens and Rhizobium tropici (SI + MSM). Rhizosphere microbial composition, diversity, and function was assessed by metagenomics. The relationships between rhizosoil chemistry, plant nutrition, grain yield, and the abundance of microbial taxa and functions were determined by generalized joint attribute modeling. The bacterial consortia had the most significant impact on rhizosphere soil fertility, which in turn affected the bacterial community, plant physiology, nutrient availability, and production. Cluster analysis identified microbial groups and functions correlated with shifts in rhizosoil chemistry and plant nutrition. Bacterial consortia positively modulated specific genera and functional pathways involved in biosynthesis of plant secondary metabolites, amino acids, lipopolysaccharides, photosynthesis, bacterial secretion systems, and sulfur metabolism. The effects of the bacterial consortia on the soybean holobiont, particularly the rhizomicrobiome and rhizosoil fertility, highlight the importance of selecting appropriate consortia for desired outcomes. These findings have implications for microbial-based agricultural practices that enhance crop productivity, quality, and sustainability.

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Asphaltenes are the most polar and heavy fraction of petroleum, and their complex structure and toxicity make them resistant to biodegradation. The ability to tolerate high asphaltene concentrations is crucial to reducing the toxicity-related inhibition of microbial growth and improving their capacity for adaptation, survival, and biodegradation in soils highly contaminated with asphaltenes. This study developed a highly tolerant consortium for efficient asphaltene biodegradation in soils from 22 bacterial isolates obtained from heavy-crude oil-contaminated soils. Isolates corresponded to the Rhodococcus, Bacillus, Stutzerimonas, Cellulosimicrobium, Pseudomonas, and Paenibacillus genera, among others, and used pure asphaltenes and heavy crude oil as the only carbon sources. Surface plate assays were used to evaluate the tolerance of individual isolates to asphaltenes, and the results showed variations in the extension and inhibition rates with maximum tolerance levels at 60,000 mg asphaltenes l-1. Inhibition assays were used to select non-antagonistic bacterial isolates among those showing the highest tolerance levels to asphaltenes. A consortium made up of the five most tolerant and non-antagonistic bacterial isolates was able to degrade up to 83 wt.% out of 10,000 mg asphaltenes kg-1 in the soil after 52 days. Due to its biological compatibility, high asphaltene tolerance, and ability to utilise it as a source of energy, the degrading consortium developed in this work has shown a high potential for soil bioremediation and is a promising candidate for the treatment of aged soil areas contaminated with heavy and extra-heavy crude oil. This would be the first research to assess and consider extreme bacterial tolerance and microbial antagonism between individual degrading microbes, leading to the development of an improved consortium capable of efficiently degrading high amounts of asphaltenes in soil.

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Microbial degradation of aromatic hydrocarbons is an emerging technology, and it is well recognized for its economic methods, efficiency, and safety; however, its exploration is still scarce and greater emphasis on cyanobacteria-bacterial mutualistic interactions is needed. We evaluated and characterized the phenanthrene biodegradation capacity of consortium dominated by Fischerella sp. under holoxenic conditions with aerobic heterotrophic bacteria and their molecular identification through 16S rRNA Illumina sequencing. Results indicated that our microbial consortium can degrade up to 92% of phenanthrene in five days. Bioinformatic analyses revealed that consortium was dominated by Fischerella sp., however different members of Nostocaceae and Weeksellaceae, as well as several other bacteria, such as Chryseobacterium, and Porphyrobacter, were found to be putatively involved in the biological degradation of phenanthrene. This work contributes to a better understanding of biodegradation of phenanthrene by cyanobacteria and identify the microbial diversity related.

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This work provides the basis for implementing a continuous treatment system using a bacterial consortium for wastewater containing a pesticide mixture of iprodione (IPR) and chlorpyrifos (CHL). Two bacterial strains (Achromobacter spanius C1 and Pseudomonas rhodesiae C4) isolated from the biomixture of a biopurification system were able to efficiently remove pesticides IPR and CHL at different concentrations (10 to 100 mg L-1) from the liquid medium as individual strains and free consortium. The half-life time (T1/2) for IPR and CHL was determined for individual strains and a free bacterial consortium. However, when the free bacterial consortium was used, a lower T1/2 was obtained, especially for CHL. Based on these results, an immobilized bacterial consortium was formulated with each bacterial strain encapsulated individually in alginate beads. Then, different inoculum concentrations (5, 10, and 15% w/v) of the immobilized consortium were evaluated in batch experiments for IPR and CHL removal. The inoculum concentration of 15% w/v demonstrated the highest pesticide removal. Using this inoculum concentration, the packed-bed bioreactor with an immobilized bacterial consortium was operated in continuous mode at different flow rates (30, 60, and 90 mL h-1) at a pesticide concentration of 50 mg L-1 each. The performance in the bioreactor demonstrated that it is possible to efficiently remove a pesticide mixture of IPR and CHL in a continuous system. The metabolites 3,5-dichloroaniline (3,5-DCA) and 3,5,6-trichloro-2-pyridinol (TCP) were produced, and a slight accumulation of TCP was observed. The bioreactor was influenced by TCP accumulation but was able to recover performance quickly. Finally, after 60 days of operation, the removal efficiency was 96% for IPR and 82% for CHL. The findings of this study demonstrate that it is possible to remove IPR and CHL from pesticide-containing wastewater in a continuous system.

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Polycyclic Aromatic Hydrocarbons (PAHs) impose adverse effects on the environment and human life. The use of synthetic microbial consortia is promising in bioremediation of contaminated sites with these pollutants. However, the design of consortia taking advantage of natural interactions has been poorly explored. In this study, a dual synthetic bacterial consortium (DSC_AB) was constructed with two key members (Sphingobium sp. AM and Burkholderia sp. Bk), of a natural PAH degrading consortium. DSC_AB showed significantly enhanced degradation of PAHs and toxic intermediary metabolites relative to the axenic cultures, indicating the existence of synergistic relationships. Metaproteomic and gene-expression analyses were applied to obtain a view of bacterial performance during phenanthrene removal. Overexpression of the Bk genes, naph, biph, tol and sal and the AM gene, ahdB, in DSC_AB relative to axenic cultures, demonstrated that both strains are actively participating in degradation, which gave evidence of cross-feeding. Several proteins related to stress response were under-expressed in DSC_AB relative to axenic cultures, indicating that the division of labour reduces cellular stress, increasing the efficiency of degradation. This is the one of the first works revealing bacterial relationships during PAH removal in a synthetic consortium applying an omics approach. Our findings could be used to develop criteria for evaluating the potential effectiveness of synthetic bacterial consortia in bioremediation.

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Background: The gastrointestinal (GI) bacterial communities of sea lions described to date have occasionally revealed large intraspecific variability, which may originate from several factors including different methodological approaches. Indeed, GI bacterial community surveys commonly rely on the use of a single hypervariable region (HR) of 16S rRNA, which may result in misleading structural interpretations and limit comparisons among studies. Here, we considered a multi-locus analysis by targeting six HRs of 16S rRNA with the aims of (i) comprehensively assessing the GI bacterial consortium in rectal samples from Zalophus californianus pups and (ii) elucidating structural variations among the tested HRs. In addition, we evaluated which HRs may be most suitable for identifying intrinsic, structurally related microbiome characteristics, such as geographic variations or functional capabilities. Methods: We employed a Short MUltiple Regions Framework (SMURF) approach using the Ion 16S™ Metagenomic Kit. This kit provides different proprietary primers designed to target six HRs of the 16S rRNA gene. To date, the only analytical pipeline available for this kit is the Ion Reporter™ Software of Thermo Fisher Scientific. Therefore, we propose an in-house pipeline to use with open-access tools, such as QIIME2 and PICRUSt 2, in downstream bioinformatic analyses. Results: As hypothesized, distinctive bacterial community profiles were observed for each analyzed HR. A higher number of bacterial taxa were detected with the V3 and V6-V7 regions. Conversely, the V8 and V9 regions were less informative, as we detected a lower number of taxa. The synergistic information of these HRs suggests that the GI microbiota of Zalophus californianus pups is predominated by five bacterial phyla: Proteobacteria (~50%), Bacteroidetes (~20%), Firmicutes (~18%), Fusobacteria (~7%), and Epsilonbacteraeota (~4%). Notably, our results differ at times from previously reported abundance profiles, which may promote re-evaluations of the GI bacterial compositions in sea lions and other pinniped species that have been reported to date. Moreover, consistent geographic differences were observed only with the V3, V4, and V6-V7 regions. In addition, these HRs also presented higher numbers of predicted molecular pathways, although no significant functional changes were apparent. Together, our results suggests that multi-locus analysis should be encouraged in GI microbial surveys, as single-locus approaches may result in misleading structural results that hamper the identification of structurally related microbiome features.

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In this study, bioleaching was carried out for the recovery of metals (copper, zinc, tin, lead, gold and silver) from printed circuit boards residues (PCBs), one of the most important wastes from electrical and electronic equipment, using an acidophilic iron-oxidizing bacterial consortium enriched with minerals from a gold mine in the Arequipa region, Peru. High-throughput sequencing and analysis of the 16S rRNA biomarker revealed that this consortium was predominantly composed of Tissierella, Acidiphilium and Leptospirillum bacteria, from which the latter is known to grow by chemolithotrophy through iron oxidation. After the enrichment process, the acidophilic iron-oxidizing consortium was first tested for its tolerance to different PCBs concentrations, showing best growth up to 10 g/L of PCBs and a tolerance index of 0.383. Based on these results, the bioleaching efficiency of the consortium was investigated for 10 g/L of PCBs in stirred tank reactors coupled to an aeration system, for 18 days. High bioleaching efficiencies were achieved for copper and zinc (69% and 91%, respectively), indicating that these two metals can be easily extracted in this leaching system. Lower extraction efficiencies were achieved for tin (16%) and gold (28%), while for lead and silver only a residual recovery (<0.25%) was detected. These results indicate that the enriched bacterial consortium originating from the Arequipa region, Peru, has a high capacity to recover different metals of economic importance.

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In this research, a combined photocatalytic and biological treatment is proposed for the elimination of pollutants present in textile wastewater using a natural erionite zeolite (PE) and aluminum oxide (PA) synthesized by the sol-gel method as photocatalysts, and solar radiation. Both catalysts were characterized by XRD, SEM, and EDS. For biological treatment two bacterial consortium were used: BC1 (Escherichia coli N16, Serratia k120, Pseudomonas putida B03 and Enterobacter hormaechei), and consortium BC2 (Escherichia coli N16, Serratia Mc107, Enterobacter N9, Enterobacter hormaechei Mc9). The photocatalytic and microbiological treatments were carried out initially separately and subsequently in a sequential manner, first the photocatalytic followed by the microbiological to determine if a synergistic effect was achieved. Comparing the photocatalytic performance, erionite showed higher performance of dyes degradation (54.75%) than alumina (28.62%). While in the biological process, BC1 decreased the dye concentration to 56.93% and BC2 to 53.56%. Finally, the best combined process was PA+BC1 reaching pollutants degradation 64.62%, showing that the application of both processes promotes a decolorization in textile wastewater. The water resulting from the combined photocatalysis-microbiological degradation processes was tested for toxicity using Daphnia magna, obtaining that none of the effluents shows toxicity.

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Liquid waste from biological stains is considered non-domestic wastewater difficult to treat, generating high environmental impact. Therefore, the objective of this work was to carry out secondary and tertiary treatment of these effluents at a pilot scale, using a fungal/bacterial consortium followed by Chorella sp., for 15 days. In addition, to obtain an adsorbent material for Malachite Green dye removal, sludge generated in the plant and pine bark co-pyrolysis was performed. For microalgae isolation and selection of the Chlorophyceae class, Chlorococcales order, and Chorella sp. genus Winogradsky columns were employed. After 15 days of pilot plant treatment, removal percentages of 91 ± 2%, 90 ± 4% and 17 ± 2% were obtained for Colour Units, Chemical Oxygen Demand and Nitrates, respectively. Two types of class II biochar (BC500 and BC700) and one of class III (BC300) were produced. The highest value for Fixed carbon (FC) was obtained at 300 °C (27.3 ± 3%), decreasing as the temperature increased by 25.9 ± 5% and 24.8 ± 2%, for BC500 and BC700, respectively. Biochar yield was 62.1 ± 3%, 46.3 ± 4% and 31.6 ± 3% for BC300, BC500 and BC700, respectively. Finally, BC500 and BC700 biochar efficiently adsorbed Malachite Green obtaining qe values of 0.290 ± 0.032, 0.281 ± 0.015, 0.186 ± 0.009 and 0.191 ± 0.012 mg g-1 at pH values of 4.0 and 8.0 ± 0.2, respectively. Pseudo-second order model demonstrated a chemical adsorption took place, which was influenced by pH. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02780-1.

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Cold stress decreases the growth and productivity of agricultural crops. Psychrotolerant plant growth-promoting bacteria (PGPB) may protect and promote plant growth at low temperatures. The aims of this study were to isolate and characterize psychrotolerant PGPB from wild flora of Andes Mountains and Patagonia of Chile and to formulate PGPB consortia. Psychrotolerant strains were isolated from 11 wild plants (rhizosphere and phyllosphere) during winter of 2015. For the first time, bacteria associated with Calycera, Orites, and Chusquea plant genera were reported. More than 50% of the 130 isolates showed ≥33% bacterial cell survival at temperatures below zero. Seventy strains of Pseudomonas, Curtobacterium, Janthinobacterium, Stenotrophomonas, Serratia, Brevundimonas, Xanthomonas, Frondihabitans, Arthrobacter, Pseudarthrobacter, Paenarthrobacter, Brachybacterium, Clavibacter, Sporosarcina, Bacillus, Solibacillus, Flavobacterium, and Pedobacter genera were identified by 16S rRNA gene sequence analyses. Ten strains were selected based on psychrotolerance, auxin production, phosphate solubilization, presence of nifH (nitrogenase reductase) and acdS (1-aminocyclopropane-1-carboxylate (ACC) deaminase) genes, and anti-phytopathogenic activities. Two of the three bacterial consortia formulated promoted tomato plant growth under normal and cold stress conditions. The bacterial consortium composed of Pseudomonas sp. TmR5a & Curtobacterium sp. BmP22c that possesses ACC deaminase and ice recrystallization inhibition activities is a promising candidate for future cold stress studies.

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Diclofenac (DCF) belongs to the class of nonsteroidal anti-inflammatory drugs, which is one of the most consumed by population and detected in raw sewage. Several studies have reported variable removal rates by biodegradation of diclofenac in wastewater treatment plants (WWTPs). This study deals with the evaluation of the biodegradation of DCF by a bacterial consortium (obtained from pure cultures of Enterobacter hormaechei D15 and Enterobacter cloacea D16), which were isolated from household compost and Algerian WWTP, respectively, as sole carbon source and by co-metabolism, using glucose as carbon source. A 98% removal rate of DCF was observed when it is used as the sole carbon source, whilst only 44% of DCF was removed in co-metabolic conditions. Two metabolites were identified using ultra-high-performance liquid chromatography coupled to electrospray injection tandem mass spectrometry analysis (UHPLC-ESI-MS/MS); one of them was identified as 4'-hydroxy-DCF, and the second metabolite was suspected to be a nitro derivative of DCF, according to comparison with the literature. Biodegradation of DCF by this bacterial consortium generates relatively safe final by-products.

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17α-ethinylestradiol (EE2) is a synthetic estrogen that can cause harmful effects on animals, such as male feminization and infertility. However, the impact of the EE2 contamination on microbial communities and the potential role of bacterial strains as bioremediation agents are underexplored. The aim of this work was to evaluate the impact of EE2 on the microbial community dynamics of aerated submerged fixed-film reactors (ASFFR) simulating a polishing step downstream of a secondary sewage treatment. For this purpose, the reactors were fed with a synthetic medium with low COD content (around 50 mg l-1), supplemented (reactor H) or not (reactor C) with 1 µg l-1 of EE2. Sludge samples were periodically collected during the bioreactors operation to assess the bacterial profile over time by 16S rRNA gene amplicon sequencing or by bacterial isolation using culture-dependent approach. The results revealed that the most abundant phyla in both reactors were Proteobacteria and Bacteroidetes. At genus level, Chitinophagaceae, Nitrosomonas and Bdellovibrio predominated. Significant effects caused by EE2 treatment and bioreactors operating time were observed by non-metric multidimensional scaling. Therefore, even at low concentrations as 1 µg l-1, EE2 is capable of influencing the bioreactor microbiome. Culture-dependent methods showed that six bacterial isolates, closely related to Pseudomonas and Acinetobacter genera, could grow on EE2 as the sole carbon source under aerobic conditions. These organisms may potentially be used for the assembly of an EE2-degrading bacterial consortium and further exploited for bioremediation applications, including tertiary sewage treatment to remove hormone-related compounds not metabolized in secondary depuration stages.

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RESUMEN Los residuos líquidos producidos al elaborar tinciones biológicas contienen mezclas de compuestos químicos y microorganismos, que generan un elevado impacto ambiental si no son tratados adecuadamente. Por esta razón, en el presente trabajo se evaluaron a Pleurotus ostreatus, Trametes versicolor, Enterobacter xianfangensis, Pseudomonas azotoformans, Pseudomonas sp., Bacillus subtilis y Pseudomonas fluorescens, para el tratamiento de un residuo líquido que contenía colorantes trifenilmetánicos y azóicos, a escala de laboratorio. Inicialmente, se seleccionaron las cepas con menor efecto antagónico y se determinó su potencial para producir las enzimas Lacasa, Manganeso Peroxidasa y Lignino Peroxidasa, al emplear sustratos inductores y mezclas de colorantes. Para el consorcio fúngico/bacteriano la disminución de las unidades de color y demanda química de oxígeno fueron del 99 % y 70 % a las 96 h. La remoción de estos parámetros se relacionó con la interacción positiva e incremento de las poblaciones de hongos, bacterias y la producción de enzimas ligninolíticas, obteniendo valores a las 96 h de 7.0 y 14.0 unidades logarítmicas para hongos y bacterias, con unas actividades enzimáticas de 75 U/L, 205 U/L y 0.63 U/L para Lacasa, MnP y LiP, respectivamente. Con el presente trabajo se demostró que con el uso consorcios fúngicos/bacterianos se incrementa la remoción de colorantes y se disminuye el tiempo de proceso. Sugiriendo que estos microorganismos podrían ser evaluados en plantas de tratamiento que integren diferentes unidades de tratamiento para optimizar la remoción de contaminantes con baja biodegradabilidad.

ABSTRACT The liquid wastes generated when biological stains are prepared, contain a mixture of chemical compounds and microorganisms, with high environmental impact. For this reason, Pleurotus ostreatus, Trametes versicolor, Enterobacter xianfangensis, Pseudomonas azotoformans, Pseudomonas sp., Bacillus subtilis and Pseudomonas fluorescens, were used to evaluate the treatment of a liquid waste containing triphenylmethane and azo dyes, on a laboratory scale. Initially, the strains with less antagonistic effect among them were selected for their potential to produce enzymes as Laccase, Manganese Peroxidase and Lignin Peroxidase. The enzymatic activity was determined by using inducing substrates and dye mixtures. For fungal/bacterial consortium, the decrease in color, Chemical Oxygen Demand and in Biochemical Oxygen demand was of 99 %, 70 % and 65 % at 96 h, respectively. The removal of these parameters was related to the positive interaction between the populations of fungi, bacteria and the production of ligninolytic enzymes, obtaining values of 7.0 and 14.0 logarithmic units for fungi and total bacteria at 96 h with enzymatic activities of 75 U/ L, 205 U/L and 0.63 U/L for Laccase, MnP and LiP. The present work demonstrates that using of fungal/bacterial consortia, the removal of dyes is increased, and the process time is decreased. Suggesting that these microorganisms could be evaluated in treatment plants that integrate different treatment units to optimize the removal of contaminants with low biodegradability.

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The presence of polycyclic aromatic hydrocarbons (PAHs) in marine environments as a result of contamination is an environmental concern, especially in regions where oil spills such as the Deepwater Horizon have occurred. While numerous PAHs have been studied for their effects on microbes, the family of dibenzopyrenes has yet to be investigated. In this preliminary study, the impacts of these molecules on the community structure of a bacterial consortium isolated from oil-impacted Gulf of Mexico sediment were examined using high-throughput sequencing, demonstrating intriguing negative impacts on species diversity and abundance. While no measurable degradation of the dibenzopyrenes was observed after 28-day incubation, the abundance of known oil-degrading bacteria from orders such as Oceanospirillales, Caulobacterales, Sphingomonadales, and Nitrosococcales were shown to be enhanced. Of the five isomers of dibenzopyrene studied, dibenzo[a,h]pyrene supported the fewer number of microbial species suggesting the isomer was more toxic compared to the other isomers.

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Microalgal-bacterial processes have emerged as environmental friendly systems for the cost-effective treatment of anaerobic effluents such as biogas and nutrients-laden digestates. Environmental parameters such as temperature, irradiation, nutrient concentration and pH effect the performance of the systems. In this paper, the potential of a microalgal-bacterial photobioreactor operated under high pH (≈9.5) and high alkalinity to convert biogas into biomethane was evaluated. The influence of the illumination regime (continuous light supply vs 12h/12h light/dark cycles) on the synthetic biogas upgrading efficiency, biomass productivity and nutrient removal efficiency was assessed in a High-Rate Algal Pond interconnected to a biogas absorption bubble column. No significant differences in the removal efficiency of CO2 and H2S (91.5±2% and 99.5%±0.5, respectively) were recorded regardless of the illumination regime. The high fluctuations of the dissolved oxygen concentration during operation under light/dark cycles allowed to evaluate the specific growth rate and the specific partial degradation rate of the microalgae biomass by photosynthesis and respiration, respectively. The respiration reduced the net microalgae biomass productivity under light/dark cycles compared with process operation under the continuous light supply.

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Background: Methyl tert-butyl ether (MTBE) is a pollutant that causes deleterious effects on human and environmental health. Certain microbial cultures have shown the ability to degrade MTBE, suggesting that a novel bacterial species capable of degrading MTBE could be recovered. The goal of this study was to isolate, identify and characterize the members of a bacterial consortium capable of degrading MTBE. Results: The IPN-120526 bacterial consortium was obtained through batch enrichment using MTBE as the sole carbon and energy source. The cultivable fraction of the consortium was identified; of the isolates, only Stenotrophomonas maltophilia IPN-TD and Sphingopyxis sp. IPN-TE were capable of degrading MTBE. To the best of our knowledge, this report is the first demonstrating that S. maltophilia and Sphingopyxis sp. are capable of degrading MTBE. The degradation kinetics of MTBE demonstrated that S. maltophilia IPN-TD had a significantly higher overall MTBE degradation efficiency and rate (48.39 ± 3.18% and 1.56 ± 0.12 mg L-1 h-1, respectively) than the IPN-120526 consortium (38.59 ± 2.17% and 1.25 ± 0.087 mg L-1 respectively). The kinetics of MTBE removal by both cultures fit first-order and pseudo-first-order reaction models. Conclusions: These findings suggest that S. maltophilia IPN-TD in axenic culture has considerable potential for the detoxification of MTBE-contaminated water.

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Abstract Removal of synthetic dyes is one of the main challenges before releasing the wastes discharged by textile industries. Biodegradation of azo dyes by alkaliphilic bacterial consortium is one of the environmental-friendly methods used for the removal of dyes from textile effluents. Hence, this study presents isolation of a bacterial consortium from soil samples of saline environment and its use for the decolorization of azo dyes, Direct Blue 151 (DB 151) and Direct Red 31 (DR 31). The decolorization of azo dyes was studied at various concentrations (100–300 mg/L). The bacterial consortium, when subjected to an application of 200 mg/L of the dyes, decolorized DB 151 and DR 31 by 97.57% and 95.25% respectively, within 5 days. The growth of the bacterial consortium was optimized with pH, temperature, and carbon and nitrogen sources; and decolorization of azo dyes was analyzed. In this study, the decolorization efficiency of mixed dyes was improved with yeast extract and sucrose, which were used as nitrogen and carbon sources, respectively. Such an alkaliphilic bacterial consortium can be used in the removal of azo dyes from contaminated saline environment.

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Removal of synthetic dyes is one of the main challenges before releasing the wastes discharged by textile industries. Biodegradation of azo dyes by alkaliphilic bacterial consortium is one of the environmental-friendly methods used for the removal of dyes from textile effluents. Hence, this study presents isolation of a bacterial consortium from soil samples of saline environment and its use for the decolorization of azo dyes, Direct Blue 151 (DB 151) and Direct Red 31 (DR 31). The decolorization of azo dyes was studied at various concentrations (100-300mg/L). The bacterial consortium, when subjected to an application of 200mg/L of the dyes, decolorized DB 151 and DR 31 by 97.57% and 95.25% respectively, within 5 days. The growth of the bacterial consortium was optimized with pH, temperature, and carbon and nitrogen sources; and decolorization of azo dyes was analyzed. In this study, the decolorization efficiency of mixed dyes was improved with yeast extract and sucrose, which were used as nitrogen and carbon sources, respectively. Such an alkaliphilic bacterial consortium can be used in the removal of azo dyes from contaminated saline environment.

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Removal of synthetic dyes is one of the main challenges before releasing the wastes discharged by textile industries. Biodegradation of azo dyes by alkaliphilic bacterial consortium is one of the environmental-friendly methods used for the removal of dyes from textile effluents. Hence, this study presents isolation of a bacterial consortium from soil samples of saline environment and its use for the decolorization of azo dyes, Direct Blue 151 (DB 151) and Direct Red 31 (DR 31). The decolorization of azo dyes was studied at various concentrations (100300 mg/L). The bacterial consortium, when subjected to an application of 200 mg/L of the dyes, decolorized DB 151 and DR 31 by 97.57% and 95.25% respectively, within 5 days. The growth of the bacterial consortium was optimized with pH, temperature, and carbon and nitrogen sources; and decolorization of azo dyes was analyzed. In this study, the decolorization efficiency of mixed dyes was improved with yeast extract and sucrose, which were used as nitrogen and carbon sources, respectively. Such an alkaliphilic bacterial consortium can be used in the removal of azo dyes from contaminated saline environment. (AU)

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AIMS: This study was designed to isolate, identify and characterize micro-organisms or mixed cultures capable of simultaneously removing Cr (VI) and phenol in the surrounding area of a tannery localized in Elena, Córdoba, Argentina. In addition, nutritional and physical factors were optimized in order to improve the removal efficiency in a real effluent. METHODS AND RESULTS: The consortium SFC 500-1, composed of two bacterial strains belonging to Acinetobacter and Bacillus genus, was isolated from the heavily polluted wastewater discharge channel of a local tannery. SFC 500-1 was able to remove phenol at environmentally relevant concentrations (1000 mg l(-1) ) and reduce Cr (VI) to Cr (III), which was immobilized in the bacterial biomass. The consortium simultaneously removed these contaminants under a wide range of physicochemical conditions and different growth media, even in a tannery effluent. CONCLUSION: The ability of SFC 500-1 to simultaneously reduce Cr (VI) and degrade phenol in different synthetic growth media and even in the effluent from which it was isolated with high efficiency makes this consortium a potential candidate for the biotreatment of effluents. SIGNIFICANCE AND IMPACT OF THE STUDY: This finding is important, taking into account that industrial effluents present complex mixtures of toxic substances as well as native flora which often affect the bioremediation process. Considering the ecological advantages of using native bacteria for bioremediation, as well as the high efficiency of the consortium SFC 500-1 to simultaneously remove Cr (VI) and phenol, this could be a suitable biological system to improve the biotreatment of polluted effluents through a bioaugmentation strategy.

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