Biosorption of low concentration levels of Lead (II) and Cadmium (II) from aqueous solution by Saccharomyces cerevisiae: Response surface methodology

Sustainable approaches for removing toxic heavy metal from contaminated water: A comprehensive review of bioremediation and biosorption techniques

In this comprehensive study, highlights emerging environmentally friendly methods to eliminating hazardous heavy metals from contaminated water, with an emphasis on bioremediation and biosorption. Breakthroughs, such as the combination of biological remediation and nanotechnology to improve the elimination of metals effectiveness and the use of genetically modified microbes for targeted pollutant breakdown. Developing biosorption materials made from agricultural waste and biochar, this indicates interesting areas for future research and emphasizes the necessity of sustainable practices in tackling heavy metal contamination in water systems. There seems to be a surge in enthusiasm for the utilization of biological remediation and biosorption methods as sustainable and viable options for eliminating heavy metals from contaminated water in the past couple of decades. The present review intends to offer an in-depth review of the latest understanding and advances in the discipline of biological remediation methods like bioaccumulation, biofiltration, bio-slurping, and bio-venting. Biosorption is specifically explained and includes waste biomass as biosorbent with the removal mechanisms and the hindrances caused in the process are detailed. Advances in biosorption like microbes as biosorbents and the mechanism involved in it. Additionally, novel enhancement techniques like immobilization, genetic modification, and ultrasound-assisted treatment in microbial sorbent are clarified. However, the review extended with analyzing the future advances in the overall biological methods and consequences of heavy metal pollution.

Applying circular economy principles and life cycle assessment: A novel approach using vine shoots waste for cadmium removal from water

This research investigates the potential of utilizing vine shoots, a byproduct of the viticulture industry, as biosorbent for cadmium removal from aqueous solutions. The Spanish wine industry, one of the most influential sectors, produces two to three million tons of vine shoots. By using vine shoots as biosorbent, this study contributes to the circular economy paradigm, transforming waste materials into valuable resources and minimizing environmental impacts associated with waste generation and disposal. The research underscores the significance of vine shoots in biosorption due to its high lignocellulosic content. By experimental analysis, the efficacy of vine shoots in cadmium biosorption is evaluated, considering factors such as environmental impact or energy consumption. This study examines the effect of six key input parameters on cadmium removal efficiency and power consumption, identifying optimal conditions for maximum removal with minimal energy consumption. The findings suggest that vine shoots offer promising biosorption capabilities, promoting sustainability in wastewater treatment and environmental remediation efforts. By employing the response surface method alongside desirability functions, the study determined the optimal variables for two distinct optimization scenarios. Notably, in the second optimization scenario, a cadmium removal rate of 99.23 % was achieved while consuming 25.6 W of power. The input parameters for this achievement should be set as follows: initial cadmium concentration of 100 ppm, pH level of 8, stirring time of 75 min, stirring speed of 100 rpm, temperature of 26 °C, and a dose of vine shoots of 0.1 g.

Investigation of the simulated microgravity impact on heavy metal biosorption by Saccharomyces cerevisiae

Heavy metals are one of the most dangerous environmental pollutions, and their elimination is one of the health system's priorities. Microorganisms have been introduced as a safe absorber of such pollution and this ability is related to the characteristics of their surface layers. There are reports about some bacteria's increment of cell envelope thickness in space conditions. Therefore, this study investigated SMG effect on heavy metals biosorption using Saccharomyces (S.) cerevisiae. Furthermore, the stability of complex, isotherm, and kinetic absorption models has been investigated. The results showed that the SMG positively affected the biosorption of mercury (Hg) 97% and lead (Pb) 72.5% by S. cerevisiae. In contrast, it did not affect cadmium (Cd) and arsenic (As) biosorption. In gastrointestinal conditions, Hg, Cd, and As-yeast complexes were stable, and their biosorption increased. In the case of the Pb-yeast complex, in simulated gastric exposure, the binding decreased at first but increased again in simulated intestinal exposure in both SMG and normal gravity (NG). The metals' biosorption by yeast followed the pseudo-second-order kinetic and the Langmuir isotherm models for all metals (As) matched with Langmuir and Freundlich. The current research results demonstrate that microgravity provides desirable conditions for heavy metal biosorption by S. cerevisiae. Furthermore, the biosorbent-heavy metal complex remains stable after simulated gastrointestinal conditions. Altogether, the results of this study could be considered in detoxifying food and beverage industries and maintaining astronauts' health.

Evaluation of Residual Yeast from Brewery Industry for Inactive Biosorption of Selenium from Industrial Wastewater: a Case Study

In this study, the second-life application of Saccharomyces cerevisiae obtained from brewery wastewater was evaluated in the biosorption of Se(IV) (Na2SeO3) sorbate in residue generated from a fine chemical industry. Biosorption experiments were carried out with different Se(IV) concentrations (A = 7.5 to 30.0 mg L-1 dissolved in deionized water or industrial effluent) and different biosorbent concentrations (B = 2.0 to 52.5 g L-1, dry mass). Inactive microbial biomass was evaluated in a wet and dehydrated state. The highest selenium removal efficiency (biosorption efficiency-R = 97.5%) was achieved with the same concentrations of sorbate in deionized water, using 24.0 g L-1 of wet cells. In contrast, the industrial effluent treatment showed lower biosorption efficiency (R = 83.3%) due to a large amount of other salts in the medium, mainly sulphur. Overall, the use of smaller amounts of biosorbent had a biosorption capacity of approximately five times greater than when 24.0 g L-1 in industrial effluent treatment was used. However, as reducing the concentration of the contaminant contained in the wastewater is the primary goal of this study, a more significant amount of biosorbent is recommended.

Saccharomyces cerevisiae additions normalized hemocyte differential genes expression and regulated crayfish (Procambarus clarkii) oxidative damage under cadmium stress

Because China produces the most crayfish in the world, safe solutions must be improved to mitigate the risks of ongoing heavy metal stressors accumulation. This study aimed to use Saccharomyces cerevisiae as a bioremediation agent to counteract the harmful effect of cadmium (Cd) on crayfish (Procambarus clarkia). Our study used three concentrations of S. cerevisiae on crayfish feed to assess their Cd toxicity remediation effect by measuring total antioxidant capacity (TAC) and the biomarkers related to oxidative stress like malondialdehyde (MDA), protein carbonyl derivates (PCO), and DNA-protein crosslink (DPC). A graphite furnace atomic absorption spectroscopy device was used to determine Cd contents in crayfish. Furthermore, the mRNA expression levels of lysozyme (LSZ), metallothionein (MT), and prophenoloxidase (proPO) were evaluated before and following the addition of S. cerevisiae. The results indicated that S. cerevisae at 5% supplemented in fundamental feed exhibited the best removal effect, and Cd removal rates at days 4th, 8th, 12th, and 21st were 12, 19, 29.7, and 66.45%, respectively, which were significantly higher than the basal diet of crayfish. The addition of S. cerevisiae increased TAC levels. On the other hand, it decreased MDA, PCO, and DPC, which had risen due to Cd exposure. Furthermore, it increased the expression of proPO, which was reduced by Cd exposure, and decreased the expression of LSZ and MT, acting in the opposite direction of Cd exposure alone. These findings demonstrated that feeding S. cerevisiae effectively reduces the Cd from crayfish and could be used to develop Cd-free crayfish-based foods.

Biodegradation of crystal violet dye by Saccharomyces cerevisiae in aqueous medium

Crystal violet (CV) is an azo dye with cationic nature, belonging to the triphenylmethane group. This study was designed to optimize CV removal by S. cerevisiae from aqueous solutions using BBD model. Harvested cells of S. cerevisiae were locally obtained from Iran Science and Technology Research Organization (ISTRO). The decolorization tests were performed in a laboratory container containing a 100 cc of reaction solution under different variables, including yeast dose (0.5-1.5 g/L), pH (4-10), dye concentration (10-100 mg/L), and the reaction time of 24 h. After stirring with a magnetic shaker at a speed of 400 rpm, 10 cc of each sample was taken and centrifuged at 4000 rpm for 10 min to separate the biomass from dye solution. Then, the supernatant was filtered and finally the remaining CV was measured by a spectrophotometer at λmax 590 nm. After the optimization of the factors mentioned above, the removal efficiency of this dye was investigated at the reaction times of 0.5-72 h. The findings indicated that CV removal ranged from 53.92 to 84.99%. The maximum CV removal was obtained at the CV concentration of 100 mg/L, the pH of 7, and the S. cerevisiae dose of 1.5 g/L. The findings showed that the elimination efficiency is directly related to the initial CV concentration, pH, and S. cerevisiae dose. However, during the reaction time, the elimination efficiency decreased slightly. The findings of this study proved that CV can be removed from aqueous solutions with an easy and low-cost method based on the use of indigenous microorganisms.

Kinetic and isotherm of competitive adsorption cadmium and lead onto Saccharomyces cerevisiae autoclaved cells

Heavy metal pollution has been regarded as a significant public health hazard during the industrialization, which also have exhibited various types of toxicological manifestations. Moreover, due to the high cost and toxic by-products, some conventional remediation methods were limited to heavy metals pollution control. In this work, autoclaved Saccharomyces cerevisiae was used as a biosorbent for the removal of Cd2+ and Pb2+ from single and binary ions aqueous solution system. The kinetics and isotherm of Cd2+ and Pb2+ were studied in different ion systems. The results showed that the competitive adsorption ability of S. cerevisiae to Pb2+ was stronger than that to Cd2+ in binary ions solution. To all the single ion solution of Cd2+ or Pb2+ and binary ions solution of Cd2+-Pb2+, there always existed that the adsorption of metal ions on S. cerevisiae fitted well with pseudo-second-order kinetic model and Langmuir isotherms model. The adsorption quantity qt in different solutions followed the sequence as qt (Cd2+-Pb2+) > qt (Pb2+-single) > qt (Pb2+-binary) > qt (Cd2+-single) > qt (Cd2+-binary). The autoclaved S. cerevisiae used in this research was one kind of rapid and favourable biosorbent for Pb2+ and Cd2+. In Pb2+ and Cd2+-containing solutions, sites competition and jointed toxicity of Pb2+ and Cd2+ on S. cerevisiae cells were the key to the total adsorption effect, and further researches were necessary in the next work. Thus, the current research presented that the autoclaved S. cerevisiae could be applied as an effective biosorbent for heavy metal adsorption from water environment and the design of eco-friendly technologies for the treatment of waste liquor.

Investigation of cadmium and nickel biosorption by Pseudomonas sp. via response surface methodology

The environmental contamination of heavy metals has grown over the last several decades along with global industrialization and now constitutes a serious threat to human health. In this research, high cadmium (Cd) and nickel (Ni) resistant bacteria that were chosen for heavy metal biosorption were isolated from the Industries Factory in Sari, Mazandaran, Iran. Pseudomonas aeruginosa was recognized as the isolated bacterium based on its morphological, physiological, biochemical, antibiotic resistance testing, and 16S rRNA sequences. The bacteria had the highest concentrations of resistance to Cd (up to 1600 ppm) and Ni, according to the Minimum Inhibition Concentration (MIC) test (up to 2000 ppm). Single-factor studies in single and binary systems were used to examine the effects of temperature, contact duration, pH value, starting Cd and Ni concentration, and biomass dose on the Cd and Ni adsorption by P. aeruginosa. The Cd and Ni biosorption in binary solutions was optimized using the response surface methodology (RSM) based on Central Composite Design (CCD). The investigation revealed that at pH 7.0, 45 °C, and 1.5 gL^-1 biomass dose, the greatest biosorption efficiency for Cd and Ni was 92.43 percent and 88.45 percent, respectively. According to the adsorption of Cd and Ni in urban water, under these similarly extreme conditions, Cd adsorption drops to 54% and Ni to 60%. Analysis Potential functional groups involving interactions between cells and metal ions were identified using Fourier transform infrared spectroscopy (FTIR). Different compounds and heavy metal ions were found to have been adsorbed to the surface of the biosorbent by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). It was determined that P. aeruginosa had a high rate of Cd and Ni adsorption and that variations in pH level had a greater impact than other parameters. The findings imply that P. aeruginosa biomass may be an effective, economical, and environmentally friendly method for removing Cd and Ni from contaminated settings. It also has a reasonable capacity for biosorption in both a natural environment and a laboratory environment.

Bioremediation of Wastewater Using Yeast Strains: An Assessment of Contaminant Removal Efficiency

The main goal of wastewater treatment is to significantly reduce organic compounds, micronutrients (nitrogen and phosphorus) and heavy metals and other contaminants (pathogens, pharmaceuticals and industrial chemicals). In this work, the efficiency of removing different contaminants (COD, NO₃^-, NO₂^-, NH₄⁺, PO₄^3-, SO₄^2-, Pb²⁺, Cd²⁺) from synthetic wastewater was tested using five different yeast strains: Kluyveromyces marxianus CMGBP16 (P1), Saccharomyces cerevisiae S228C (P2), Saccharomyces cerevisiae CM6B70 (P3), Saccharomyces cerevisiae CMGB234 (P4) and Pichia anomala CMGB88 (P5). The results showed a removal efficiency of up to 70% of COD, 97% of nitrate, 80% of nitrite, 93% of phosphate and 70% of sulfate ions for synthetic wastewater contaminated with Pb²⁺ (43 mg/L) and Cd²⁺ ions (39 mg/L). In contrast, the results showed an increase in ammonium ions, especially in the presence of Pb²⁺ ions. The yeast strains showed a high capacity to reduce Pb²⁺ (up to 96%) and Cd²⁺ (up to 40%) ions compared to the initial concentrations. In presence of a crude biosurfactant, the removal efficiency increased up to 99% for Pb²⁺ and 56% for Cd²⁺ simultaneously with an increase in yeast biomass of up to 11 times. The results, which were obtained in the absence of aeration and in neutral pH conditions, proved a high potential for practical applications in the biotreatment of the wastewater and the recovery of Pb and Cd ions, with a high benefit-cost ratio.

A Green Approach Used for Heavy Metals 'Phytoremediation' Via Invasive Plant Species to Mitigate Environmental Pollution: A Review

Heavy metals (HMs) normally occur in nature and are rapidly released into ecosystems by anthropogenic activities, leading to a series of threats to plant productivity as well as human health. Phytoremediation is a clean, eco-friendly, and cost-effective method for reducing soil toxicity, particularly in weedy plants (invasive plant species (IPS)). This method provides a favorable tool for HM hyperaccumulation using invasive plants. Improving the phytoremediation strategy requires a profound knowledge of HM uptake and translocation as well as the development of resistance or tolerance to HMs. This review describes a comprehensive mechanism of uptake and translocation of HMs and their subsequent detoxification with the IPS via phytoremediation. Additionally, the improvement of phytoremediation through advanced biotechnological strategies, including genetic engineering, nanoparticles, microorganisms, CRISPR-Cas9, and protein basis, is discussed. In summary, this appraisal will provide a new platform for the uptake, translocation, and detoxification of HMs via the phytoremediation process of the IPS.

Impact of simulated microgravity on bioremoval of heavy-metals by Lactobacillus acidophilus ATCC 4356 from water

There are several reports about the effect of gravity removal on some characteristics of microorganisms due to possible change in surface layer thickness and adherence properties. In this study, bioremoval efficiency of Lactobacillus acidophilus ATCC 4356 from water under simulated microgravity conditions was investigated. Furthermore, pretreatment effects (untreated, NaOH, and heat pretreated) of L. acidophilus ATCC 4356 on heavy metal removal was evaluated on microgravity, as our previous research showed impact of pretreatment on adherence properties of probiotics to environmental metals. The results showed that ability of L. acidophilus for arsenic adsorption enhanced following heat-pretreatment in simulated and normal gravity. Moreover, in both conditions of simulated microgravity and normal gravity NaOH-treated L. acidophilus increased the removal of cadmium and lead. In none of the conditions, pretreatment of lactobacillus affects mercury removal. Evaluation of stability of binding of L. acidophilus-heavy metal was investigated to check irreversibility of complex formation between microorganisms and metals in simulated gastrointestinal conditions. Data showed release of heavy metals from complex in normal gravity. Obtained results of this research show the favorable potential of simulated microgravity condition to increase bioremoval capacity of L. acidophilus for heavy metals.

Potential probiotic strains with heavy metals and mycotoxins bioremoval capacity for application in foodstuffs

Heavy metals and mycotoxins in foodstuffs are one of the major concerns of our world nowadays. Food decontamination with the help of microbial biomass is a cheap, easy, efficient, and green method known as bioremoval. Probiotics are able to reduce the availability of heavy metals and toxins in food products. The purpose of this review is to summarize the probiotics and potential probiotics' interesting role in food bio-decontamination. After a brief glance at the definition of potential probiotic strains with bioremoval ability, LABs (lactic acid bacteria) are described as they are the most important groups of probiotics. After that, the role of the main probiotic and potential probiotic strains (Bacillus, Lactobacillus, Lactococcus, Enterococcus, Bifidobacterium, Pediococcus, Propionibacterium, Streptococcus, and Saccharomyces cerevisiae) for heavy metals and mycotoxins bioremoval are described. Additionally, the bioremoval mechanism and the effect of some factors in bioremoval efficiency are explained. Finally, the investigations about probiotic and contaminant stability are mentioned. It is worth mentioning that this review article can be exerted in different food and beverage industries to eliminate the heavy metals and mycotoxins in foodstuffs.

Risk of low stability Saccharomyces cerevisiae ATCC 9763-heavy metals complex in gastrointestinal simulated conditions

The biosorption of heavy metals by microorganisms has attracted the interest of food researchers as the last approach to reduce the risk of their absorption in the human body. But the stability of yeast-metal complexes under simulated gastrointestinal conditions has not been investigated. In this study stability of complex as well as isotherm and kinetic models of biosorption have been studied. Also, the impact of some pretreatment on yeast biosorption was studied to check the possible impact of different environmental conditions in food processing. Data showed a risk of heavy metal release in simulated gastrointestinal conditions. The best biosorption of metals from aqueous solutions by Saccharomyces (S.) cerevisiae may be achieved after NaOH pretreatment for Mercury (Hg) 92.7%. While biosorption of Lead (Pb) 37.48%, Arsenic (As) 19.44%, and Cadmium (Cd) 39.9% by untreated yeast were better. In gastrointestinal conditions, Hg and Cd-yeast complexes were more stable and biosorption of Cd and Pb increased. Bonds of As and Hg-yeast complexes in digestion conditions were reversible. The metals biosorption by untreated yeast followed the pseudo-second-order kinetic and the Langmuir isotherm model for Hg, Pb, and Cd and Freundlich for As. Results showed that biosorption of heavy metals by S. cerevisiae, although may decrease metal bioavailability in fermented foods, the complex is not enough stable in gastrointestinal conditions.

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Biodecontamination of heavy metals from multi-metallic aqueous solutions using Saccharomyces cerevisiae.

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Stability assessment of metal-yeast complex after simulated gastrointestinal condition.

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Usingpretreatment strategies to increase bioremoval efficiency and stability.

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Indicating reversible bonds of heavy metal-yeast complexes.

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The Langmuir isotherm model was the best-predicting biosorption model.

Plants-Microorganisms-Based Bioremediation for Heavy Metal Cleanup: Recent Developments, Phytoremediation Techniques, Regulation Mechanisms, and Molecular Responses

Rapid industrialization, mine tailings runoff, and agricultural activities are often detrimental to soil health and can distribute hazardous metal(loid)s into the soil environment, with harmful effects on human and ecosystem health. Plants and their associated microbes can be deployed to clean up and prevent environmental pollution. This green technology has emerged as one of the most attractive and acceptable practices for using natural processes to break down organic contaminants or accumulate and stabilize metal pollutants by acting as filters or traps. This review explores the interactions between plants, their associated microbiomes, and the environment, and discusses how they shape the assembly of plant-associated microbial communities and modulate metal(loid)s remediation. Here, we also overview microbe-heavy-metal(loid)s interactions and discuss microbial bioremediation and plants with advanced phytoremediation properties approaches that have been successfully used, as well as their associated biological processes. We conclude by providing insights into the underlying remediation strategies' mechanisms, key challenges, and future directions for the remediation of metal(loid)s-polluted agricultural soils with environmentally friendly techniques.

Bacterial Biosorbents, an Efficient Heavy Metals Green Clean-Up Strategy: Prospects, Challenges, and Opportunities

Rapid industrialization has led to the pollution of soil and water by various types of contaminants. Heavy metals (HMs) are considered the most reactive toxic contaminants, even at low concentrations, which cause health problems through accumulation in the food chain and water. Remediation using conventional methods, including physical and chemical techniques, is a costly treatment process and generates toxic by-products, which may negatively affect the surrounding environment. Therefore, biosorption has attracted significant research interest in the recent decades. In contrast to existing methods, bacterial biomass offers a potential alternative for recovering toxic/persistent HMs from the environment through different mechanisms for metal ion uptake. This review provides an outlook of the advantages and disadvantages of the current bioremediation technologies and describes bacterial groups, especially extremophiles with biosorbent potential for heavy metal removal with relevant examples and perspectives.

Assessment of resistance and biosorption ability of Lactobacillus paracasei to remove lead and cadmium from aqueous solution

Since heavy metals have been regarded as ubiquitous environmental pollutants, the exploitation of bacterial biosorption has been suggested as an applicable method for being employed for heavy metal depletion. The present study aimed to characterize the function of Lactobacillus paracasei in the presence of Pb (II) and Cd (II). The simultaneous effect of pH, initial metal concentration, and inoculum size demonstrated the Pb (II) removal of 85.77% at the lowest pH, while the inoculum size was enhanced to 45 CFU/100 ml. The maximum Cd (II) removal was obtained at a high level of pH and inoculum size, while the metal concentration was reduced to 30 ppb. The addition of Cd (II) concentration in access led to the 10% drop in Cd (II) removal efficiency attributed to the metal toxicity and pH. Additionally, the slight variation in the amount of inoculum size caused the decreasing trend in the Cd (II) removal. According to the obtained results, the benefit of L. paracasei in the biosorption of heavy metals was well-recognized, which could be suggested as an alternative candidate. PRACTITIONER POINTS: Strain of Lactobacillus paracasei as potential probiotics was tested for biosorption. A successful response surface method was proposed. L. paracasei showed a good efficiency for the lead and cadmium biosorption. Biosorption process was effective in removing low metal level from drinking water. The maximum biosorption was found to be 85.77% for Pb (II) obtained from the experiment.

The synergy of mercury biosorption through Brevundimonas sp. IITISM22: Kinetics, isotherm, and thermodynamic modeling

This research experiment was conducted to investigate the potential of Brevundimonas species IITISM22 to remove mercury by using live biomass of bacterial cells at 298, 308, and 318 K. Characterization of bio-sorbent was done by FT-IR and SEM-EDX. The prime functional groups accountable for binding Hg were OH, -NH₂, -CH, -SH and -COO. The deformed bacterial structure was seen after Hg adsorption over the bacterial cell. Influences of different experimental factors, such as pH, temperature, contact time, Hg concentration, and biomass dose was examined. IITISM22 exhibited the highest Hg absorption at pH 6.5, contact time of 4 h, and showed an increased adsorption capacity while increasing the concentration of Hg. Kinetics were recommended by pseudo-second-order for adsorption process and isotherm was adequately defined by the Linear Langmuir isotherm model (K_L) = 1.4, 1.2, 0.9 mg/l; (R_L) = 0.020, 0.015, 0.013, respectively than Freundlich isotherm model. The Activation energy (E_a) of biosorption calculated were (131.10 KJ/mole) by using Arrhenius equation, and the thermodynamic parameters were ΔG⸰ (-41.03, -16.33, -16.12 KJ/mol), ΔH⸰ (-36.87 KJ/mol) and ΔS⸰ (-194.03 J/mol), respectively. These findings suggest that the removal process was based on chemisorption and the biosorption was exothermic. The result of the current experiment indicated that the IITISM22 could be an authentic biosorbent for Hg detoxification.

Characterization, mechanism of cypermethrin biosorption by Saccharomyces cerevisiae strains YS81 and HP and removal of cypermethrin from apple and cucumber juices by inactive cells

Cypermethrin is a common food contaminant and environmental pollutant that cause health threats to animals and humans. In this study, the characterization, mechanism, and application of cypermethrin removal by Saccharomyces cerevisiae were investigated. The binding of cypermethrin by the strains S. cerevisiae YS81 and HP was rapid and reached equilibrium at 2-8 h. The removal efficiency was dependent on incubation temperature and yeast concentration, whereas cypermethrin binding was not affected by pH. Heat and acid treatments enhanced the binding ability. Both strains survived in simulated digestion juices and removed cypermethrin effectively under simulated gastrointestinal conditions. Among the strains tested, the YS81 strain was the better candidate for cypermethrin concentration reduction. For the two S. cerevisiae strains, the biosorption kinetics and isotherm followed the pseudo-second-order model and Langmuir model well. The cell walls and the protoplasts were the main yeast cell components involved in cypermethrin binding. Fourier transformed infrared spectroscopy analysis revealed that -OH, -NH, -C-N, -COO^-, and -C-O played a major role in binding cypermethrin. Inactive cells effectively removed cypermethrin from apple and cucumber juices and did not affect the physico-chemical properties. Therefore, S. cerevisiae strains YS81 and HP may be used for cypermethrin reduction in food or feed.

Effective removal of lead (II) using chitosan and microbial adsorbents: Response surface methodology (RSM)

The ability of chitosan (1% w/v), Bifidobacterium longum (10⁸ CFU mL-¹) and Saccharomyces cerevisiae (10⁸ CFU mL-¹) separately or in combination (chitosan/B. longum, chitosan/S. cerevisiae, B. longum/S. cerevisiae) was assessed for lead (II) removal from aqueous solutions. The results showed chitosan/B. longum adsorbent had higher adsorption percentage in comparison with other adsorbents (p < 0.05). It was selected as the most efficient adsorbent and the effect of process variables including initial metal concentration (0.01-5 mg L^-1), contact time (5-180 min), temperature (4-37 °C) and pH (3-6) on the its removal efficiency was evaluated with a Box-Behnken design. Twenty-seven test runs were performed and the optimal conditions for metal adsorption was observed at metal concentration of 2.5 mg L^-1, contact time of 180 min, temperature of 37 °C and pH 4.5. The maximum lead (II) adsorption yield under optimal conditions was 97.6%. The foreign ions didn't diminish lead (II) adsorption by chitosan/B. longum and it had high selectivity toward the lead (II). Adsorption behavior was analyzed using the Freundlich and the Langmuir isotherms. The correlation coefficients (R²) demonstrated the Langmuir model had a better description on metal adsorption process. Overall, isotherms revealed chemisorption and physisorption were probably involved in metal adsorption on adsorbent.

The Biosorption Capacity of Saccharomyces Cerevisiae for Cadmium in Milk

This study aimed to evaluate the capacity of Saccharomyces cerevisiae for Cadmium absorption in milk. Nowadays, one of the most serious problems of the industrialized world is heavy metal pollution. Applying microorganisms as novel biotechnology is very useful, especially in foodstuffs. Among the biosorbents used for heavy metal removal, Saccharomyces cerevisiae has received increasing attention due to its popularity in the food industry. In this regard, the effects of some important factors such as the initial metal concentration, biomass concentration and contact time on the biosorption capacity of Saccharomyces cerevisiae were studied. The biosorption was analyzed by the inductively coupled plasma mass spectrometer (ICP-MS). The maximum cadmium (Cd) removal (70%) was at 80 μg/L of Cd concentration in milk samples containing 30 × 108 CFU Saccharomyces cerevisiae at the end of storage time (the 4th day). There were no significant differences in the sensory and physicochemical properties (pH, acidity and density) of milk samples during storage (p < 0.05). The isotherm studies were followed by two popular models, Langmuir and Freundlich, and the results showed a better fit to the Langmuir isotherm. Altogether, the results of this study demonstrate that the approach of using this valuable yeast could be applied for food detoxification and producing healthier foodstuffs.

Sorption Mechanism and Optimization Study for the Bioremediation of Pb(II) and Cd(II) Contamination by Two Novel Isolated Strains Q3 and Q5 of Bacillus sp

The use of bacterial strains as agents in bioremediation processes could reduce the harmfulness of potential toxic elements (PTEs) from water and soil with low or even no impact on the natural ecosystems. In this study, two new metal resistant-bacterial strains (Q3 and Q5) of Bacillus sp. were isolated from a sulfurous spring and their potential (as pure cultures or mixed) to remove Pb(II) and Cd(II) from an aqueous matrix was evaluated and optimized using response surface methodology (RSM). The optimal conditions for Cd(II) removal from all tested strains combinations were observed at an initial pH 5, a temperature of 38 °C, and an initial Cd(II) concentration of 50 mg L-1, while the performance of bacterial strains on Pb(II) removal was strongly correlated to initial pH and temperature conditions. Moreover, the efficiency of bacterial strains in removing both PTEs, Pb(II) and Cd(II), from an aqueous matrix was considerably higher when they were used as a mixed culture rather than pure. According to field emission SEM (FESEM) and EDS analysis, the two bacterial strains showed different mechanisms in removing Cd(II): Bacillus sp. Q5 bio-accumulated Cd(II) in its periplasmic space, whereas Bacillus sp. Q3 bio-accumulated Cd(II) on its cell surface. On the other hand, Pb(II) is removed by chemical precipitation (lead sulfide) induced by both Bacillus sp. Q3 and Q5. This study discloses new aspects of Pb(II) and Cd(II) bioremediation mechanisms in Bacillus species that can be extremely useful for designing and operating novel PTEs bioremediation processes.

Enhanced adsorption of Cr(VI), Ni(II) ions from aqueous solution using modified Eichhornia crassipes and Lemna minor

The environment is seriously affected by the release of hazardous heavy metals from the industries. The transformation of aquatic weeds into valuable nanosorbent has been considered as effective and efficient material in the wastewater treatment process. The aim of the study is to analyze the potential of nano-EC and nano-LM for the removal of chromium(VI) and nickel(II) ions. The characteristics of nanosorbent were analyzed using Fourier transform infrared spectroscopy (FTIR), Brunauer Emmett-Teller analysis (BET), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and thermo gravimetric analysis (TGA), respectively. Adsorptive performance of nanosorbent was studied with respect to pH, contact time, nano adsorbent dosage, and metal ion concentration. The maximum monolayer adsorption capacity of Cr(VI) and Ni(II) with respect to nano-EC was found to be 79.04 mgg^-1 and 85.09 mgg^-1, respectively. Adsorption isotherm and kinetic studies were performed and it was reported that adsorption isotherm follows Langmuir model with regression coefficient R² > 0.9 for nano-EC and nano-LM respectively. The pseudo-second order model was found to fit well with experimental data. Experimental results suggested that nano-EC can be considered as a suitable nanosorbent for the removal of Cr(VI) and Ni(II) ions from effluents.

Phlebia gigantea cells immobilized on renewable biomass matrix as potential ecofriendly scavenger for lead contamination

A novel biomaterial was prepared by the immobilization of Phlebia gigantea cells in the medium containing lignocellulosic waste and used for the first time in the bioremediation purpose. The developed new biocomposite possesses higher Pb(II) retention potential when compared with the free microbial cells. It could remove Pb(II) up to 74.11% at a biosorbent dosage of 4.0 g L^-1. Surface characterization was carried out through zeta potential, EDX, SEM, and IR studies to understand the metal-biocomposite interactions. The biosorption amount at equilibrium slightly decreased with the increase of the solution temperature. Kinetic data indicated Pb(II) biosorption onto suggested biocomposite fits well with the pseudo-first-order model. Biosorption equilibrium data suited Langmuir model with the highest coefficient of determination values. The immobilized material reached to maximum monolayer Pb(II) retention capacity (1.449 × 10^-4 mol g^-1) within the short equilibrium time (10 min). The designed biocomposite was also adapted to continuous flow mode sorption process. Regeneration tests by dynamic flow mode confirmed reutilization potential of biocomposite.

Adsorption of bivalent lead ions from an aqueous phase system: Equilibrium, thermodynamic, kinetics, and optimization studies

Punica granatum carpellary membrane powder (PGCM) and its surface modified form (MPGCM) with 2,4-dinitrophenylhydrazine (2,4-DNP) were used as adsorbents for removal of bivalent lead ions from aqueous phase system. Batch mode experiments using various parameters were carried out to assess the adsorption isotherms and dynamics of the process. Langmuir isotherm was well-fitted model for experimental data. Langmuir adsorption capacity using PGCM and MPGCM at pH of 7 was found to be 169.49 and 196.07 mg/g, respectively. Rate constant and thermodynamic parameters were calculated to evaluate the kinetic model and temperature dependence nature of adsorption. Box-Behnken design was applied to optimize the adsorption process of bivalent lead ions for PGCM and MPGCM using pH (3.0-9.0), initial bivalent lead ions concentration (20-100 mg/L), contact time (20-180 min), and temperature (20-60°C) parameters. The optimum conditions for maximum removal of bivalent lead ions on PGCM were found to be at pH of 6.99, initial bivalent lead ions concentration of 98.95, contact time of 176.05, and temperature of 21.20°C and on MPGCM at pH of 6.51, initial bivalent lead ions concentration of 99.99, contact time of 177.89, and temperature of 20.02°C, respectively. PRACTITIONER POINTS: Adsorption of bivalent lead from water using Punica granatum carpellary membrane powder and its modified form MPGCM is discussed. Batch mode experiments using various parameters were carried out to assess the adsorption isotherms and dynamics of the process. Langmuir adsorption capacity using PGCM and MPGCM at pH of 7 was found to be 169.49 and 196.07 mg/g, respectively. Box-Behnken design was applied to optimize the adsorption process of bivalent lead ions.

Detoxification of Heterocyclic Aromatic Amines by Probiotic to Inhibit Medical Hazards

Cancer is the second leading factor of human death in the world. Long-term consumption of cooked red meat brings about various types of cancers like colorectal cancer due to the formation of Heterocyclic Aromatic Amines (HAAs) during the heating process of meat. There are various solutions for the reduction of these toxicants. The aim of this article is to describe probiotic as one of the possible strategies for bioremoval of these carcinogenic and mutagenic substances and change food to functional one as well. The mechanism of biodetoxification is binding by probiotics, which depends on some variables including the probiotic characteristics, kind and content of the mutagens, as well as some properties of media. In this article, after introducing detoxification ability of probiotics and listing of all reported probiotics in this field, the influencing variables are surveyed and finally, opportunities and problems of HAA bioremoval by probiotics are described.

Evaluation of Oxalobacter formigenes DSM 4420 biodegradation activity for high oxalate media content: An in vitro model

Oxalate is a common component of many foods typically present as a salt of oxalic acid, which will be excreted in the urine. Hyperoxaluria is known to be a considerable risk factor for urolithiasis, and formation of oxalate kidney stone. Oxalate degradation by the probiotic anaerobic bacterium Oxalobacter formigenes DSM 4420 has high yield and efficiency both in the human colon helping to prevent hyperoxaluria and disorders such as the development of kidney stones and as a novel approach in reducing the high concentration of foodstuff oxalate content such as tea, coffee, and nuts. For determining the effective factors to enhance high concentration oxalate biodegradation activity of Oxalobacter formigenes DSM 4420 Plackett-Burman screening design was applied to evaluate the impact of 10 process variables. After determining the main factors by screening design, a response surface methodology was used to find suitable treatment combination for oxalate biodegradation by this probiotic. A second-order quadratic model estimated that the highest biodegradation of 60.2% was achieved in presence of 1.35 (g/L) inulin, 36.56 (g/L) glucose, 26 (mmol/L) ammonium oxalate, and pH 6. In other word, the optimum point showed that in the above condition the high concentration of ammonium oxalate content of 26 mmoL/L will reach to 9.95 mmoL/L. Reconfirmation experiment showed the validity of predicted optimum conditions. A surface model using the RSM and optimizing this model using the GA technique, resulted in a useful method of finding an optimal set of process parameters.

Optimization of cadmium biosorption by Shewanella putrefaciens using a Box-Behnken design

Microbial adsorption of heavy metals has been attracted more interest in the recent years. However, there are very few studies in investigating the biosorption of heavy metals by Shewanella putrefaciens, which is a metal reducing bacterium. Firstly, the effects of contact time, pH value, temperature, biomass dosage and initial cadmium concentration on the cadmium adsorption by Shewanella putrefaciens were studied by single factor experiments. Then, the response surface methodology (RSM) based on Box-Behnken design was used to optimize the cadmium adsorption by Shewanella putrefaciens. The results showed that the empirical model was suitable for experimental data, and the maximum cadmium removal efficiency by Shewanella putrefaciens was 86.54% under the optimum conditions of contact time 4.0 days, pH value 5, initial cadmium concentration of 20 mg/L, which was further verified by experiments. In addition, scanning electron microscope - Energy Dispersive Spectrometer (SEM-EDS) analysis showed that the bacteria were seriously deformed, and a "bamboo" shape was observed on the surface which consisted of cadmium according to the EDS analysis. Fourier transform infrared spectroscopy (FT-IR) analysis was used to evaluate the possible functional groups involving in interaction between cells and metal ions. The results showed that the distribution of cadmium on the cell surface was related to the carboxyl, amide, hydroxyl and phosphoric acid groups of Shewanella putrefaciens. These studies can provide a comprehensive understanding of the process and mechanism of microbial removal of heavy metals, and theoretical support for the follow-up practice of using biological adsorbents to remediate heavy metal contaminated soil.

Greener Method for the Removal of Toxic Metal Ions from the Wastewater by Application of Agricultural Waste as an Adsorbent

The presence of inorganic pollutants such as metal ions (Ni2+, Pb2+, Cr6+) in water, probably by long-term geochemical changes and from the effluents of various industries, causes diseases and disorders (e.g., cancer, neurodegenerative diseases, muscular dystrophy, hepatitis, and multiple sclerosis). Conventional methods for their removal are limited by technical and economic barriers. In biosorption, low-cost and efficient biomaterials are used for this purpose. In this study, Brassica Campestris stems from the agriculture waste and has been used for the removal of Ni2+, Cr6+ and Pb2+ ions from an aqueous solution containing all the ions. Effect of different parameters, e.g., pH, contact time, metal ion initial concentration, adsorbent dose, agitation rate and temperature were analyzed and optimized. The adsorbent worked well for removal of the Pb2+ and Cr6+ as compared to Ni2+. The atomic absorption spectrophotometer (AAS) and FTIR investigation of adsorbent before and after shows a clear difference in the adsorbent capability. The highest adsorption percentage was found at 98%, 91%, and 49% respectively, under the optimized parameters. Furthermore, the Langmuir isotherm was found better in fitting to the experimental data than that of the Freundlich isotherm.