Bioremediation Of Metals Research Articles

Health Effects of Heavy Metal Contamination in Drinking Water

Water is essential for life, be it the life of animals, plants or human beings. It’s our prime duty to protect, manage and preserve the quality of water. Uncontrolled anthropogenic activities have resulted in contamination of fresh water resources thereby affecting the health of living beings. Rampant industrialization is a major environmental problem on the global scale for the pollution of fresh water with toxic effluents containing heavy metals. Contamination of surface water by heavy metals is the greatest quality issues because of their toxic nature, increased release and negative impact on the health of human beings. Water-borne diseases remain one of the major health concerns in the world. Heavy metals are individual metals and metal compounds that can impact human health. Exposure of humans to metals such as antimony, arsenic, barium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, tin, zinc, etc results in chronic and acute toxicities. The toxicity of heavy metals depends on their concentration, period of exposure and route of exposure. Humans are exposed to heavy metals either by inhalation from the atmosphere, intake through drinking water, or by ingestion through the skin by dermal contact. The present review describes the analysis of ‘heavy metal contamination in drinking water’ with reference to definition, sources, health effects on humans and preventive measures. This study suggests that, the best way to get rid of heavy metal contamination in drinking water is to remove toxic heavy metals by using the best water purification system. Also, the ground water resources must be monitored for quality assessment, source identification and bioremediation of heavy metals.

Insights into the differential proteome landscape of a newly isolated Paramecium multimicronucleatum in response to cadmium stress

Employing microbial systems for the bioremediation of contaminated waters represent a potential option, however, limited understanding of the underlying mechanisms hampers the implication of microbial-mediated bioremediation. The omics tools offer a promising approach to explore the molecular basis of the bioremediation process. Here, a mass spectrometry-based quantitative proteome profiling approach was conducted to explore the differential protein levels in cadmium-treated Paramecium multimicronucleatum. The Proteome Discoverer software was used to identify and quantify differentially abundant proteins. The proteome profiling generated 7,416 peptide spectral matches, yielding 2824 total peptides, corresponding to 989 proteins. The analysis revealed that 29 proteins exhibited significant (p ≤ 0.05) differential levels, including a higher abundance of 6 proteins and reduced levels of 23 proteins in Cd2+ treated samples. These differentially abundant proteins were associated with stress response, energy metabolism, protein degradation, cell growth, and hormone processing. Briefly, a comprehensive proteome profile in response to cadmium stress of a newly isolated Paramecium has been established that will be useful in future studies identifying critical proteins involved in the bioremediation of metals in ciliates. SignificanceCiliates are considered a good biological indicator of chemical pollution and relatively sensitive to heavy metal contamination. A prominent ciliate, Paramecium is a promising candidate for the bioremediation of polluted water. The proteins related to metal resistance in Paramecium species are still largely unknown and need further exploration. In order to identify and reveal the proteins related to metal resistance in Paramecia, we have reported differential protein abundance in Paramecium multimicronucleatum in response to cadmium stress. The proteins found in our study play essential roles during stress response, hormone processing, protein degradation, energy metabolism, and cell growth. It seems likely that Paramecia are not a simple sponge for metals but they could also transform them into less toxic derivatives or by detoxification by protein binding. This data will be helpful in future studies to identify critical proteins along with their detailed mechanisms involved in the bioremediation and detoxification of metal ions in Paramecium species.

Health effects of heavy metal contaminants Vis-à-Vis microbial response in their bioremediation

Toxic heavy metals are currently significant environmental pollutants as their growing ecotoxicity becomes a serious public health concern. Their multiple application in several fields such as the mining industry, agriculture, medicine, technology and many others, leads to a widespread distribution into the environmental systems. Since toxic metals are not biodegradable, their accumulation in soil, water and air contaminates the food chain, which poses a danger to human health. Because of extensive damage caused by metal intoxication on various organs of the human body, the search for therapeutic methods is very important. Removal of heavy metals from the body is usually carried out by the most common and conventional chelation therapy methods. However, for removal from environment the use of chemical methods is often expensive and can lead to the production of secondary pollutants. There is a remarkable attentiveness with respect to recent progress in heavy metals remediation over the past few decades with special emphasis on bioremediation utilized in various environmental areas. The present review is focused to throw light on the possible sources and related intake routes of the harmful metals, the symptoms of poisoning, their impact on the environment and health and the molecular mechanisms, which threaten human health effects. It also aims to provide an overview of the available studies on microbial bioremediation of heavy metals from the environment, including the mechanisms involved in metal removal and some future directions in microbial biodegradation technology.

OPTIMISATION OF TECHNOLOGY AND SELECTION OF BIOSORBENTS BASED ON HAWTHORN, MOUNTAIN ASH AND MOTHERWORT TO IMPROVE THE QUALITY OF FERMENTED MILK PRODUCT

The accelerated development of urbanisation brings with it environmental problems and adverse effects on human health. Air pollution, water pollution and limited access to natural resources are becoming serious challenges. However, innovative products incorporating enterosorption technologies present a potential solution to improve public health. These products contribute to the effective removal of toxic substances from the body, mitigating the negative health effects of urbanisation.In the context of yoghurt with LABR, it has been found to be more stable to whey separation and moisture retention. Prebiotics have a positive effect on water retention, although this effect may diminish over time. The optimal concentration of LABR bacteria also emphasises the importance of a precise balance, after which additional increases do not bring significant improvements. These results can be used to optimise the production of yoghurt, taking into account its structure and properties over its shelf life.Considering the study data, it can be concluded that an optimal combination of L. acidophilus bacterial concentration and metal concentration, reached on the fourth day after the addition of prebiotics, is necessary to maximise the efficiency of heavy metal bioremediation. These results have practical implications for heavy metal removal processes in aqueous media, providing a basis for optimising bioremediation conditions in industrial and environmental applications.

Inhibitory effects of Pseudomonas sp. W112 on cadmium accumulation in wheat grains: Reduced the bioavailability in soil and enhanced the interception by plant organs

Microorganisms play an important role in heavy metal bioremediation and soil fertility. The effects of soil inoculation with Pseudomonas sp. W112 on Cd accumulation in wheat were investigated by analyzing the transport, subcellular distribution and speciation of Cd in the soil and plants. Pseudomonas sp. W112 application significantly decreased Cd content in the roots, internode and grains by 10.2%, 29.5% and 33.0%, respectively, and decreased Cd transfer from the basal nodes to internodes by 63.5%. Treatment with strain W112 decreased the inorganic and water-soluble Cd content in the roots and increased the proportion of residual Cd in both the roots and basal nodes. At the subcellular level, the Cd content in the root cell wall and basal node cytosol increased by 19.6% and 61.8%, respectively, indicating that strain W112 improved the ability of the root cell wall and basal node cytosol to fix Cd. In the rhizosphere soil, strain W112 effectively colonized and significantly decreased the exchangeable Cd, carbonate-bound Cd and iron-manganese oxide-bound Cd content by 43.5%, 27.3% and 17.6%, respectively, while it increased the proportion of residual Cd by up to 65.2%. Moreover, a 3.1% and 23.5% increase in the pH and inorganic nitrogen content in the rhizosphere soil, respectively, was recorded. Similarly, soil bacterial community sequencing revealed that inoculating with strain W112 increased the abundance of Pseudomonas, Thauera and Azoarcus, which are associated with inorganic nitrogen metabolism, and decreased that of Acidobacteria, which is indicative of soil alkalinization. Hence, root application of Pseudomonas sp. W112 improved soil nitrogen availability and inhibited Cd accumulation in the wheat grains in a two-stage process: by reducing the Cd availability in the rhizosphere soil and by improving Cd interception and fixation in the wheat roots and basal nodes. Pseudomonas sp. W112 may be a suitable bioremediation agent for restoring Cd-contaminated wheat fields.

Bioindicator responses to extreme conditions: Insights into pH and bioavailable metals under acidic metal environments

Acid mine drainage (AMD) caused environmental risks from heavy metal pollution, requiring treatment methods such as chemical precipitation and biological treatment. Monitoring and adapting treatment processes was crucial for success, but cost-effective pollution monitoring methods were lacking. Using bioindicators measured through 16S rRNA was a promising method to assess environmental pollution. This study evaluated the effects of AMD on ecological health using the ecological risk index (RI) and the Risk Assessment Code (RAC) indices. Additionally, we also examined how acidic metal stress affected the diversity of bacteria and fungi, as well as their networks. Bioindicators were identified using linear discriminant analysis effect size (LEfSe), Partial least squares regression (PLS-R), and Spearman analyses. The study found that Cd, Cu, Pb, and As pose potential ecological risks in that order. Fungal diversity decreased by 44.88% in AMD-affected areas, more than the 33.61% decrease in bacterial diversity. Microbial diversity was positively correlated with pH (r = 0.88, p = 0.04) and negatively correlated with bioavailable metal concentrations (r = −0.59, p = 0.05). Similarly, microbial diversity was negatively correlated with bioavailable metal concentrations (bio_Cu, bio_Pb, bio_Cd) (r = 0.79, p = 0.03). Acidiferrobacter and Thermoplasmataceae were prevalent in acidic metal environments, while Puia and Chitinophagaceae were identified as biomarker species in the control area (LDA>4). Acidiferrobacter and Thermoplasmataceae were found to be pH-tolerant bioindicators with high reliability (r = 1, P < 0.05, BW > 0.1) through PLS-R and Spearman analysis. Conversely, Puia and Chitinophagaceae were pH-sensitive bioindicators, while Teratosphaeriaceae was a potential bioindicator for Cu–Zn–Cd metal pollution. This study identified bioindicator species for acid and metal pollution in AMD habitats. This study outlined the focus of biological monitoring in AMD acidic stress environments, including extreme pH, heavy metal pollutants, and indicator species. It also provided essential information for heavy metal bioremediation, such as the role of omics and the effects of organic matter on metal bioavailability.

Bioremediation of toxic metals and Limnocharis flava (L.) Buchenau growth in acidic contaminated soil supported by microbial inoculants

An in situ pot experiment was carried out in a net house to study the combined effect of a mixture of microbial inoculants at different levels of 0, 1, 1.5, 2, 2.5, and 3 g/kg in dry soil with Limnocharis flava (L.) Buchenau plants grown on agricultural land contaminated with lead (Pb) and cadmium (Cd). The results showed that plant growth, fresh inflorescence yields and accumulation of Pb and Cd in L. flava plant parts gradually increased with increasing levels of the applied microbial inoculants in the contaminated soil. The highest total content of Pb and Cd was determined in roots (6.63–32.46 and 0.12–0.72 mg/kg dw), followed by stems and leaves (1.20–3.08 and 0.04–0.09 mg/kg dw) and inflorescence parts (0.012–0.120 and 0.011–0.065 mg/kg fw). The application of microbial inoculants in the range of 2–2.5 g/kg dry soil stimulated the growth and fresh inflorescence yields of L. flava, increased the accumulation of Pb and Cd in inedible parts, ensuring safety for edible parts of L. flava plants in accordance with QCVN8-2:2011/BYT and FAO/WHO regulations. The results of the present work indicate that the flexibility of Pb and Cd can be increased when soil is mixed with microbial inoculants. Long term ex situ experiments are needed to investigate the impact of microbial inoculants mixed with biochar, minerals and nanomaterial for phytomanagement of soil contaminated with multiple metals.

Biomineralization of heavy metals based on urea transport and hydrolysis within a new bacterial isolate, B. intermedia TSBOI

A newly isolated ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced calcite precipitation (MICP) which is a promising technique for the remediation of heavy metals in polluted environments. Brucella intermedia TSBOI achieved 90–100% removal of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. A distinctive feature lies in B. intermedia TSBOI’s capacity for the transport and hydrolysis of urea, considered to be critical for its strong urease activity. This study explored the mechanisms of this capacity at the genetic, molecular and protein levels through complete genome sequencing, molecular docking and enzymatic reaction kinetics. The results revealed that, for urea hydrolysis, B. intermedia TSBOI exhibited a comprehensive urease gene cluster, with the key gene ureC demonstrating an absolute expression level approximating to 4 × 104 copies/RNA ng under optimal conditions. Results also confirmed the strong spontaneous, energy-independent binding ability of it’s urease to urea, with the lowest Gibbs free energy binding site linking to the three amino acids, alanine, asparagine and serine. The urea transport gene yut presented and expressed, with the absolute expression enhanced in response to increasing urea concentrations. The significant positive correlation between ureC/yut expression levels and urease activity provided a theoretical basis for B. intermedia TSBOI's heavy metal bioremediation potential. Environmental ImplicationHeavy metals (Cu, Pb and Zn) were studied in this study. Heavy metals are hazardous due to their toxicity, persistence, and ability to bioaccumulate in living organisms. They can cause severe health issues, harm ecosystems, and contaminate air, water, and soil. A novel ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced carbonate precipitation capability was isolated which removed 90–100% of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. Its advantages in urea hydrolysis and transport facilitate the remediation of actual heavy metal contaminated environments.

A Case Study of Fungal Geoactivities as Sustainable Approach for the Bioremediation of Synthetic Dyes and Metals from Wastewater

A Case Study of Fungal Geoactivities as Sustainable Approach for the Bioremediation of Synthetic Dyes and Metals from Wastewater

The cadmium tolerance and bioaccumulation mechanism of Tetratostichococcus sp. P1: insight from transcriptomics analysis

ABSTRACT Cadmium (Cd) has become a severe issue in relatively low concentration and attracts expert attention due to its toxicity, accumulation, and biomagnification in living organisms. Cd does not have a biological role and causes serious health issues. Therefore, Cd pollutants should be reduced and removed from the environment. Microalgae have great potential for Cd absorption for waste treatment since they are more environmentally friendly than existing treatment methods and have strong metal sorption selectivity. This study evaluated the tolerance and ability of the microalga Tetratostichococcus sp. P1 to remove Cd ions under acidic conditions and reveal mechanisms based on transcriptomics analysis. The results showed that Tetratostichococcus sp. P1 had a high Cd tolerance that survived under the presence of Cd up to 100 µM, and IC50, the half-maximal inhibitory concentration value, was 57.0 μM, calculated from the change in growth rate based on the chlorophyll content. Long-term Cd exposure affected the algal morphology and photosynthetic pigments of the alga. Tetratostichococcus sp. P1 removed Cd with a maximum uptake of 1.55 mg g−1 dry weight. Transcriptomic analysis revealed the upregulation of the expression of genes related to metal binding, such as metallothionein. Group A, Group B transporters and glutathione, were also found upregulated. While the downregulation of the genes were related to photosynthesis, mitochondria electron transport, ABC-2 transporter, polysaccharide metabolic process, and cell division. This research is the first study on heavy metal bioremediation using Tetratostichococcus sp. P1 and provides a new potential microalga strain for heavy metal removal in wastewater. Abbreviations:BP: Biological process; bZIP: Basic Leucine Zipper; CC: Cellular component; ccc1: Ca (II)-sensitive cross complementary 1; Cd: Cadmium; CDF: Cation diffusion facilitator; Chl: Chlorophyll; CTR: Cu TRansporter families; DAGs: Directed acyclic graphs; DEGs: Differentially expressed genes; DVR: Divinyl chlorophyllide, an 8-vinyl-reductase; FPN: FerroportinN; FTIR: Fourier transform infrared; FTR: Fe TRansporter; GO: Gene Ontology; IC50: Growth half maximal inhibitory concentration; ICP: Inductively coupled plasma; MF: molecular function; NRAMPs: Natural resistance-associated aacrophage proteins; OD: Optical density; RPKM: Reads Per Kilobase of Exon Per Million Reads Mapped; VIT1: Vacuolar iron transporter 1 families; ZIPs: Zrt-, Irt-like proteins.

Enhanced bioremediation of acid mine-influenced groundwater with micro-sized emulsified corn oil droplets (MOD) and sulfate-reducing bacteria (Desulfovibrio vulgaris) in a microcosm assay

High concentrations of metals and sulfates in acid mine drainage (AMD) are the cause of the severe environmental hazard that mining operations pose to the surrounding ecosystem. Little study has been conducted on the cost-effective biological process for treating high AMD. The current research investigated the potential of the proposed carbon source and sulfate reduction bacteria (SRB) culture in achieving the bioremediation of sulfate and heavy metals. This work uses individual and combinatorial bioaugmentation and bio-stimulation methods to bioremediate acid-mine-influenced groundwater in batch microcosm experiments. Bioaugmentation and bio-stimulation methods included pure culture SRB (Desulfovibrio vulgaris) and microsized oil droplet (MOD) by emulsifying corn oil. The research tested natural attenuation (T 1), bioaugmentation (T2), biostimulation (T3), and bioaugmentation plus biostimulation (T4) for AM-contaminated groundwater remediation. Bioaugmentation and bio-stimulation showed the greatest sulfate reduction (75.3%) and metal removal (95–99%). Due to carbon supply scarcity, T1 and T2 demonstrated 15.7% and 27.8% sulfate reduction activities. Acetate concentrations in T3 and T4 increased bacterial activity by providing carbon sources. Metal bio-precipitation was substantially linked with sulfate reduction and cell growth. SEM-EDS study of precipitates in T3 and T4 microcosm spectra indicated peaks for S, Cd, Mn, Cu, Zn, and Fe, indicating metal-sulfide association for metal removal precipitates. The MOD provided a constant carbon source for indigenous bacteria, while Desulfovibrio vulgaris increased biogenic sulfide synthesis for heavy metal removal.

Isolation and Influence of Carbon Source on the Production of Extracellular Polymeric Substance by Bacteria for the Bioremediation of Heavy Metals in Santo Amaro City

The city of Santo Amaro (Bahia, Brazil) gained visibility among the scientific community due to the contamination of the Subaé River by lead and cadmium from the PLUMBUM Mineração e Metalurgia Ltda industry, on the banks of the river in 1956, which produced lead ingots The present work aimed to investigate the adsorption capacity of heavy metals (Pb and Cd) of EPS produced by bacterial species from the Subaé River, for possible future application of these biopolymers in bioremediation processes in areas impacted by the aforementioned heavy metals. Subaé river water was collected for physical-chemical analysis and bacterial isolation. It was verified that all isolated bacteria produced an expressive amount of Exopolysaccharide (EPS). Thus, the optimization of this production in different sugars (sucrose, glucose, and mannitol) and in three different pHs: 5.5; 6.5, and 7.5. All bacteria produced EPS in large quantities and the best sugar was sucrose at pH 7.5. In order to use the EPS for the bioremediation area, the adsorption test of lead and cadmium was carried out by the isolated EPS. 0.5 g of the EPS was dissolved in 50 ml of deionized water, then the solutions of metals, lead acetate, and cadmium sulfate (procedure performed separately) were incubated at 28 °C for 16 h after that period, and were centrifuged. Samples were filtered to separate the insoluble EPS and the filtrates obtained were used in the quantification of the metals by atomic absorption (FAAS- Flame Atomic Absorption Spectrometry). Bacillus spp., Bacillus cereus, Staphylococcus spp., and Serratiamarcescens, all showed tolerance to the tested metals, due to the efficiency in the adsorption capacity of the EPS, and it was possible to distinguish seven genera, Klebsiella pneumonia, Pseudomonas aeruginosa, Lysinibacillus spp. to be used in the bioremediation of environments contaminated with heavy metals.

Advancements in biosurfactant production using agro-industrial waste for industrial and environmental applications.

The adverse effects of waste generation on the environment and public health have raised global concerns. The utilization of waste as a raw material to develop products with enhanced value has opened up novel prospects for promoting environmental sustainability. Biosurfactants obtained from agro-industrial waste are noteworthy due to their sustainability and environmental friendliness. Microorganisms have been employed to generate biosurfactants as secondary metabolites by making use of waste streams. The utilization of garbage as a substrate significantly reduces the expenses associated with the process. Furthermore, apart from reducing waste and offering alternatives to artificial surfactants, they are extensively employed in bioremediation, food processing, agriculture, and various other industrial pursuits. Bioremediation of heavy metals and other metallic pollutants mitigated through the use of bacteria that produce biosurfactants which has been the more recent research area with the aim of improving its quality and environmental safety. Moreover, the production of biosurfactants utilizing agricultural waste as a raw material aligns with the principles of waste minimization, environmental sustainability, and the circular economy. This review primarily focuses on the production process and various types of biosurfactants obtained from waste biomass and feedstocks. The subsequent discourse entails the production of biosurfactants derived from various waste streams, specifically agro-industrial waste.

Penicillium oxalicum-mediated the green synthesis of silica nanoparticles: characterization and environmental applications

AbstractIn terms of biocompatibility, environmental friendliness, scalability, and cost-effectiveness, green nanoparticle (NP) synthesis is a modern area of nanotechnology that performs better than physical and chemical methods. The utilization of endophytic Penicillium oxalicum for the biogenesis of silica nanoparticles is the goal of the current work. The structural and optical properties of the fungal produced silica nanoparticles were investigated utilizing transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), x ray diffraction (XRD) and dynamic light scattering (DLS). All of the investigated parameters and their interactions were found to have a significant effect on the crystallite size, according to the results. The average diameter size of the biosynthesized SiO2-NPs was ranged between 20 -50 nm. The size of the biosynthesized SiO2-NPs was 28.7 nm, and their crystalline nature was confirmed by XRD, according to characterization results. A surface plasmon resonance spectrum of silica nanoparticles was obtained at 280 nm. Under UV light, Ribazol black b and Crystal violet dyes were photocatalytically degraded utilizing biosynthesized SiO2 nanoparticles. The highest decolorization percentage of Crystal violet and Ribazol black b was 94.1% ± 1.2% and 85.1% ± 0.93%, respectively after 90 and 120 min, for both crystal violet and Ribazol black b of incubation at 50.0 mg mL─1 of SiO2 nanoparticles. Furthermore, SiO2-NPs were successfully used more than once for biodegradation and that was regarded as its efficacy. Silica nanoparticles were used to remove Co, Pb, Cd, and Zn with percentages of 99.9% ± 1.2%, 99.9% ± 1.3%, 99.9% ± 1.3%, and 99.4% ± 1.4%, respectively. The phytotoxicity test was investigated by using Zea mays L seed which the root length increases to (28 ± 0.35) and (21 ± 0.51) cm, respectively when subjected tothe treated CV and Ribazole black b effluent... In conclusion, endophytic Penicillium oxalicum was used to successfully biosynthesize SiO2-NPs, which showed, phytotoxicity, heavy metal bioremediation, and photocatalytic activity against CV and Ribazol black b dye.

Beneficial role of Burkholderia cepacia in heavy metal bioremediation in metal-polluted soils and enhance the tomato plant growth

Plant rhizospheric microbes have good potential for tolerating the stress environment. In such, heavy metal tolerating soil bacteria were isolated from the tomato plant rhizosphere. The isolated bacterial strain was molecularly (16S rRNA) identified as Burkholderia cepacia. The B. cepacia showed many kinds of characteristics such as, phosphate solubilization at the range of 337.4 μg ml−1 in broth medium; metal resistance effect up to 4 mM; solubilization of Cd and Pb at 3319 and 1170.6 μg l−1; and also produced plant growth regulators such as HCN, siderophores, and IAA. Furthermore, the B. cepacia exhibited antifungal activity against the phytopathogenic fungi, Rhizoctonia solani (7.8 mm) and Fusarium oxysporum (6.5 mm) by significantly inhibiting fungal development. The Germination experiments indicate that when compared to control, B. cepacia-treated seeds showed the maximum level of germination within 4 days (MGT – 3.02). The bacterial strain B. cepacia with different concentrations of cadmium (Cd) and lead (Pb) metal-treated seeds increases the germination rate compared to un-inoculated metal treatments (46 % Cd, 48 % Pb). In the pot experiment, the soil application of bacterial inoculation significantly increases plant height (146.2 cm), and biomass (278 g FW). B. cepacia also induces enzyme activities such as peroxidase (PO), polyphenol oxidase (PPO), β-1,3-glucanase, and phenols in plants with various concentrations of Cd and Pb. The present study suggests that B. cepacia partially decreased the Cd and Pb toxicity in soils and controlled phytopathogens on tomato plants by integrating numerous pathways that improved the plant response.

LITERATURE REVIEW: METALLOTHIONEIN SEBAGAI PROTEIN PENGIKAT LOGAM UNTUK BIOREMEDIASI LOGAM BERAT

Background: The purpose of bioremediation is to remove or reduce dangerous compounds to improve environmental quality, one of which is heavy metals. Metal-binding proteins can minimize the impact of heavy metal pollution from the environment. This metal binding protein can accumulate metals by microorganisms. One of the known metal-binding proteins is metallothioneins (MTs). This protein can minimize the effects of heavy metals in the environment by creating protein-metal ion complex bonds. This review article provides a comprehensive insight into the role of metallothionein as a metal-binding protein for heavy metal accumulation, and the mechanisms involved in heavy metal bioremediation Methods: The method used is a literature review using reputable national and international journals. Results: Based on the results of a literature review, metallothionein can be found in many organisms such as bacteria, humans, plants, invertebrates, and mammals. Metallothionein can accumulate heavy metals that contain highly conserved cysteine residues. These residues allow MTs to bind, transport, and store various essential (Zn and Cu) and non-essential (Cd and Hg) heavy metals via thiolate bonding. Conclusion: Heavy metals are dangerous for the survival of living things and can cause damage to vital functions. One of the metal-binding proteins is metallothionein, which is involved in the organism's tolerance to heavy metal content and can accumulate it, so that the effects of heavy metals can be minimized.

Toxic heavy metal bioremediation potential of Pleurotus ostreatus fruit bodies grown in sugarcane bagasse supplemented substrate

Toxic heavy metal bioremediation potential of Pleurotus ostreatus fruit bodies grown in sugarcane bagasse supplemented substrate

Reproductive strategy response of the fungi Sarocladium and the evaluation for remediation under stress of heavy metal Cd(II)

Cadmium (Cd) is documented as one of the most lethal metals and poses a major threat to all life forms in the environment due to its toxic effects. Bioremediation of hazardous metals has received considerable and growing interest over the years. The functional fungi with tolerance to the heavy metal Cd were screened from the mining soil samples. Two fungi isolates from coal mine soil were characterized as Sarocladium sp. M2 and Sarocladium sp. M6 based on morphological and partial ITS sequencing analysis. M2 and M6 exhibited high levels of resistance to cadmium, and they were investigated for their micro-morphology and application in heavy metal removal with different concentration Cd(II) (0, 50, 100, 150 and 200 mg/L). The colony morphology of M2 and M6 gradually become very similar to that of bacteria with the increase of cadmium concentration (150–200 mg/L). Micro-morphological studies showed that Cd(II) exposure caused the disappearance of conidial heads and the occurrence of hyphae breakage (100–200 mg/L Cd(II), which is consistent to the colony morphology results. The surface/volume ratio of the spores decreased with the presence of Cd(II). The removal potential of fungi for cadmium was quantified by atomic absorption spectrometry. M2 and M6 showed great potential as bioremediators for highly Cd(II)-contaminated environment. The highest Cd(II) biosorption capacity was 5.13 ± 0.21 mg/g for M2 and 6.04 ± 0.21 mg/g for M6. The highest heavy metal sorption by M2 removed 57.11% ± 4.45% Cd(II) while that of M6 removed 48.35% ± 1.44% Cd(II) in 200 mg/L initial concentration Cd(II). To the best of our knowledge, this is the first report that cadmium induced the change of reproduction mode of the Sarocladium, from conidia to arthrospores, which made the colony morphological modifications, from the fungi colony morphology to the bacteria colony morphology. The arthrospore-modified (hyphae breakage) seemed to accumulate greater amounts of heavy metals than filamentous hyphae formation.

Ionomic analysis of Prosopis laevigata response to heavy metals: phytoremediation potential determined by wavelength-dispersive X-ray fluorescence

Prosopis laevigata (mesquite) plants can tolerate drought, thermal stress, alkalinity, salinity, and toxicity of heavy metals, making them attractive for phytoremediation. Nonetheless, most of these features have been studied under controlled laboratory conditions. In this work, the bioaccumulation of heavy metals in a free-living population of P. laevigata trees growing in a heavily metal-contaminated site (aluminum, chromium, iron, titanium, copper, and zinc) was analyzed. Furthermore, crystal phases of mineral nutrients and trace elements found in P. laevigata tissues were determined by X-ray diffraction. P. laevigata trees accumulated 705 (± 17), 47,064 (± 1459), 14,800 (± 401) and 30,000 (± 1719) mg/kg of Cu, Zn, Fe and Al, confirming the potential of these plants to hyper-accumulate metals. The X-ray diffraction analysis showed that P. laevigata trees can chelate Al3+ with phosphates to form orthorhombic crystals of aluminum phosphate (AlPO4) in the tissues. This aluminum chelation was probably a mechanism of tolerance used by the plant. The inoculation of seedlings with the endophytic Bacillus cereus MH778713 did not prevent Cr-accumulation in the plant but increased metal tolerance and seedling development. These results highlight the use of P. laevigata and B. cereus MH778713 together as tools for heavy metal bioremediation, particularly on arid and semiarid soils.

Microbial diversity in polyextreme salt flats and their potential applications.

Recent geological, hydrochemical, and mineralogical studies performed on hypersaline salt flats have given insights into similar geo-morphologic features on Mars. These salt-encrusted depressions are widely spread across the Earth, where they are characterized by high salt concentrations, intense UV radiation, high evaporation, and low precipitation. Their surfaces are completely dry in summer; intermittent flooding occurs in winter turning them into transitory hypersaline lakes. Thanks to new approaches such as culture-dependent, culture-independent, and metagenomic-based methods, it is important to study microbial life under polyextreme conditions and understand what lives in these dynamic ecosystems and how they function. Regarding these particular features, new halophilic microorganisms have been isolated from some salt flats and identified as excellent producers of primary and secondary metabolites and granules such as halocins, enzymes, carotenoids, polyhydroxyalkanoates, and exopolysaccharides. Additionally, halophilic microorganisms are implemented in heavy metal bioremediation and hypersaline wastewater treatment. As a result, there is a growing interest in the distribution of halophilic microorganisms around the world that can be looked upon as good models to develop sustainable biotechnological processes for all fields. This review provides insights into diversity, ecology, metabolism, and genomics of halophiles in hypersaline salt flats worldwide as well as their potential uses in biotechnology.