Removal of toxic Co-EDTA complex by a halophilic solar-salt-pan isolate Pseudomonas aeruginosa SPB-1

Biofilm formation on MgFe-LDH@quartz sand as novel wetland substrate under varied C/N ratios for BDE-47 removal

Layered double hydroxide (LDH)-coated substrates could enhance the removal of various wastewater-born pollutants. However, research on biofilms attached to LDH-coatings and their synergistic purification effects on strongly hydrophobic persistent organic pollutants (POPs) remains limited. This study aims to investigate biofilm formation on MgFe-LDH@quartz sand and its effectiveness in removing tetrabromodiphenyl ether (BDE-47), an emerging halogenated POP in municipal wastewater. Under different C/N ratios (3, 5, and 10), BDE-47 removal rates ranged from 28.0% to 41.6% after 72 h. The optimal performance was achieved with LDH coating at C/N = 5, when substrate biofilm reached its highest extracelluar polymer substances (EPS) content, dehydrogenase activity and relative hydrophobicity. Moreover, distinct distribution patterns of EPS components' fluorescence peaks were observed in the LDH-coating treatment using three dimensional excitation-emission matrix (3D-EEM). While substrate adsorption was the primary mechanism for BDE-47 removal, accounting for 59.6%-83.4% of the total, biofilm adsorption and degradation contributed a relatively lower amount, ranging from 11.5% to 21.4%, and were more dependent on the C/N ratio. Notably, the maximum carrying capacity of protein predicted by the logistic growth model exhibited a strong positive correlation with the total BDE-47 removal rate (R2 = 0.82, p < 0.05), highlighting the importance of biofilm extracelluar proteins.

Microbial biofilms: Recent advances and progress in environmental bioremediation

Microbial biofilms are formed by adherence of the bacteria through their secreted polymer matrices. The major constituents of the polymer matrices are extracellular DNAs, proteins, polysaccharides. Biofilms have exhibited a promising role in the area of bioremediation. These activities can be further improved by tuning the parameters like quorum sensing, characteristics of the adhesion surface, and other environmental factors. Organic pollutants have created a global concern because of their long-term toxicity on human, marine, and animal life. These contaminants are not easily degradable and continue to prevail in the environment for an extended period. Biofilms are being used for the remediation of different pollutants, among which organic pollutants have been of significance. The bioremediation of organic contaminants using biofilms is an eco-friendly, cheap, and green process. However, the development of this technology demands knowledge on the mechanism of action of the microbes to form the biofilm, types of specific bacteria or fungi responsible for the degradation of a particular organic compound, and the mechanistic role of the biofilm in the degradation of the pollutants. This review puts forth a comprehensive summary of the role of microbial biofilms in the bioremediation of different environment-threatening organic pollutants.

Kinetic modelling of the uranium biosorption by Deinococcus radiodurans biofilm

Increasing number of reports on uranium contamination in groundwater bodies is a growing concern. Deinococcus radiodurans biofilm-based U(VI) bioremediation has great potential to provide solution. This study focuses on the kinetic modelling of uranium biosorption by D. radiodurans biofilm biomass and identification of the functional groups involved in the sequestration process. The effect of temperature, pH and amount of biofilm dry mass were studied using two uranyl ion concentrations (100 and 1000 mg/L). D. radiodurans dry biomass showed good affinity for uranyl ion adsorption. The kinetic experiments revealed that the biosorption process was spontaneous and exothermic in nature. The modelling of kinetic adsorption data revealed that U(VI) sorption by D. radiodurans biofilm biomass follows a pseudo-second-order reaction. Mechanism of U(VI) sorption was suggested to follow an intra-particle diffusion model, which includes covalent bonding between U(VI) and functional groups present on the surface of biofilm biomass, and diffusional barrier acts as a rate limiting step. External mass transfer was the rate-limiting step as evident from Boyd and Elovich plot. Chemical modifications in surface functional groups of biofilm biomass, confirmed the involvement of carboxyl, phosphate, and hydroxyl groups in uranium binding as a significant loss in U(VI) sorption capacity was recorded in these chemically modified biomasses. XRD data indicated the formation of metal deposits, predominantly as uranyl phosphates.

Recent Advances in Biosorption of Copper and Cobalt by Filamentous Fungi

Copper (Cu) and Cobalt (Co) are among the most toxic heavy metals from mining and other industrial activities. Both are known to pose serious environmental concerns, particularly to water resources, if not properly treated. In recent years several filamentous fungal strains have been isolated, identified and assessed for their heavy metal biosorption capacity for potential application in bioremediation of Cu and Co wastes. Despite the growing interest in heavy metal removal by filamentous fungi, their exploitation faces numerous challenges such as finding suitable candidates for biosorption. Based on current findings, various strains of filamentous fungi have high metal uptake capacity, particularly for Cu and Co. Several works indicate that Trichoderma, Penicillium, and Aspergillus species have higher Cu and Co biosorption capacity compared to other fungal species such as Geotrichum, Monilia, and Fusarium. It is believed that far more fungal species with even higher biosorption capability are yet to be isolated. Furthermore, the application of filamentous fungi for bioremediation is considered environmentally friendly, highly effective, reliable, and affordable, due to their low technology pre-requisites. In this review, we highlight the capacity of various identified filamentous fungal isolates for biosorption of copper and cobalt from various environments, as well as their future prospects.

Bioremoval of Cobalt(II) from Aqueous Solution by Three Different and Resistant Fungal Biomasses

The biosorption of Co(II) on three fungal biomasses: Paecilomyces sp., Penicillium sp., and Aspergillus niger, was studied in this work. The fungal biomass of Paecilomyces sp. showed the best results, since it removes 93% at 24 h of incubation, while the biomasses of Penicillium sp. and Aspergillus niger are less efficient, since they remove the metal 77.5% and 70%, respectively, in the same time of incubation, with an optimum pH of removal for the three analyzed biomasses of 5.0 ± 0.2 at 28°C. Regarding the temperature of incubation, the most efficient biomass was that of Paecilomyces sp., since it removes 100%, at 50°C, while the biomasses of Penicillium sp. and Aspergillus niger remove 97.1% and 94.1%, at the same temperature, in 24 hours of incubation. On the contrary, if the concentration of the metal is increased, the removal capacity for the three analyzed biomasses decreases; if the concentration of the bioadsorbent is increased, the removal of the metal also increases. It was observed that, after 4 and 7 days of incubation, 100%, 100%, and 96.4% of Co(II) present in naturally contaminated water were removed, respectively.

A review of the applications of ion floatation: wastewater treatment, mineral beneficiation and hydrometallurgy

The applications, progress and outlook of ion flotation are discussed.

Draft Genome Sequence of a Pseudomonas aeruginosa Strain Able To Decompose N , N -Dimethyl Formamide

Pseudomonas aeruginosa is a Gram-negative bacterium, which uses a variety of organic chemicals as carbon sources. Here, we report the genome sequence of the Cu1510 isolate from wastewater containing a high concentration of N,N-dimethyl formamide.

Effect of biofilm parameters and extracellular polymeric substance composition on polycyclic aromatic hydrocarbon degradation

This study with ten marine isolates demonstrates that the attached phenotypes of the marine bacteria showed significant variation in biofilm architecture and, in turn, biodegradation of PAHs.

Reduction of [Co(iii)–EDTA]−complex by a novel process using phototrophic granules: a step towards sustainable bioremediation

This study shows that phototrophic granules are more efficient as compared to microbial granules or monoculture bacterial culture and are a self-sustainable system to be used in bioremediation process of environmental contaminants.

Microbial reduction of [Co(III)-EDTA]⁻ by Bacillus licheniformis SPB-2 strain isolated from a solar salt pan

Naturally stressed habitats are known to be repositories for novel microorganisms with potential bioremediation applications. In this study, we isolated a [Co(III)-EDTA](-) reducing bacterium Bacillus licheniformis SPB-2 from a solar salt pan that is exposed to constant cycles of hydration and desiccation in nature. [Co(III)-EDTA](-) generated during nuclear waste management process is difficult to remove from the waste due to its high stability and solubility. It is reduced form i.e. [Co(II)-EDTA](2-) is less stable though it is toxic. This study showed that B. licheniformis SPB-2 reduced 1mM [Co(III)-EDTA](-) in 14 days when grown in a batch mode. However, subsequent cycles showed an increase in the reduction activity, which was observed up to four cycles. Interestingly, the present study also showed that [Co(III)-EDTA](-) acted as an inducer for B. licheniformis SPB-2 spore germination. Vegetative cells germinated from the spores were found to be involved in [Co(III)-EDTA](-) reduction. More detailed investigations showed that after [Co(III)-EDTA](-) reduction, i.e. [Co(II)-EDTA](2-) complex was removed by B. licheniformis SPB-2 from the bulk liquid by adsorption phenomenon. The bacterium showed a D10 value (radiation dose required to kill 90% cells) of ∼250 Gray (Gy), which signifies the potential use of B. licheniformis SPB-2 for bioremediation of moderately active nuclear waste.

Characterization of Stenotrophomonas acidaminiphila NCW-702 biofilm for implication in the degradation of polycyclic aromatic hydrocarbons

AIMS

Biofilm formation and polycyclic aromatic hydrocarbons (PAHs) degradation by a marine bacterium Stenotrophomonas acidaminihila NCW-702 was investigated.

METHODS AND RESULTS

The biofilm structure was studied by confocal laser scanning microscopy (CLSM). Both planktonic and biofilm cultures were used for PAHs (phenanthrene and pyrene) degradation. In 7 days, Sten. acidaminiphila biofilm culture efficiently degraded 71·1 ± 3·1% and 40·2 ± 2·4% of phenanthrene and pyrene, respectively, whereas 38·7 ± 2·5% of phenanthrene and 29·7 ± 1% of pyrene degradation was observed in planktonic culture. The presence of phenolic intermediates in the culture supernatant during degradation process was evaluated by Folin-Ciocalteu reagent. The average thickness and diffusion distance of Sten. acidaminiphila NCW-702 biofilm was found to be 23·94 ± 2·62 μm and 2·68 ± 0·7 μm, respectively. Bacterial biofilms have numerous metabolic features that aid in the degradation of hydrophobic organic pollutants.

CONCLUSIONS

Biofilm of Sten. acidaminiphila NCW-702 was able to degrade PAHs more efficiently as compared to planktonic cells. The findings support the efficacy of biofilms over planktonic culture in bioremediation applications.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study provides a constructive application of bacterial biofilms for the bioremediation of hydrophobic organic contaminants. The biofilm mode remediation process has the advantage of reusability of bacterial biomass and is also a low cost process as compared to cell immobilization techniques.