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Recently electronic waste (e-waste) includes the fastest growing waste stream in the world. Nevertheless, it also contains about 40 different elements of the periodic table; hence it is a significant metal source. Generally, e-waste recycling is done by the pyrometallurgy and/or hydrometallurgy method. However, the use of microorganisms in hydrometallurgy called bioleaching is a good alternative for eco-friendly and cost-effective recycling of e-waste and recover metals. Leptospirillum-dominated consortium was used to generate ferric iron lixiviant by oxidizing ferrous iron. The resulting lixiviant was used for bioleaching of metals from waste cell phone printed circuit boards (WPCBs). The pretreatment of pulverized WPCB (p-WPCB) and unpulverized WPCB (up-WPCB) was done using 2 M NaOH to see the effect of pretreatment on metal extraction. Moreover, the effect of maintenance of pH of the system was also checked. The controlling of pH of the system to 2.0 ± 0.1 showed enhancement of Cu, Zn, and Ni solubilization. The highest solubilization of copper was 96.86%, which was achieved with pretreated up-WPCB; zinc was 90.69% with pretreated p-WPCB, whereas nickel was 93.65% with untreated up-WPCB. Ours is the first report for extraction of copper, zinc, and nickel from unpulverized mobile phone WPCBs at high pulp density. The solubilization of metals achieved with 100 g/L pulp density provides a promising indication to scale up the process. [ABSTRACT FROM AUTHOR]

Crude oil contamination of land and water leads to their abandonment after heavy oil recovery processes. Analogous to bioremediation, phytoremediation has provided an efficient solution towards land reclamation through enhancement of flora. The present work manifests significance of phytoremediation via reclamation of crude oil contaminated soil collected from Kalol, India. The collected soil was analyzed for pH, oxidation–reduction potential, electrical conductivity (EC), bulk density, particle size, moisture. The experimental work consists three batch units; pot A, pot B and pot C with crude oil contaminated soil, fresh soil and control respectively. While observing plant growth for 120 days, Total Petroleum Hydrocarbon (TPH) was measured at determined intervals for estimation of percentage degradation. After 90 days of pot observation, contaminated soil was inoculated with rhizospheric bacterial inoculum developed from pot A which forms new batch for microbial-remediation as an additional scope to this work. Gas chromatography mass spectroscopy (GC-MS-MS) was carried out for determination of naphthalene contamination. Crude oil degradation in pot A was estimated as 82.16% followed with the affirmation given by degradation kinetics whereas, 60.68% and 36.75% degradation was observed in pot C-control and new batch respectively. Cynodon sp. grown in pot A was confirmed by identification as reported. Statement of novelty This work signifies the potential of phytoremediation by Cynodon sp. grown in crude oil contaminated soil fertilized with cow dung and corn silk. Although studies in this context are present in literature, this study adds an affirmation to it. Also it differs in terms of contamination percentage removal which is better compared to previous studies but the only demerit is that specific specie could not be identified due to time limitation. Also, the use of corn silk as fertilizer is new to literature. Indigenous microorganisms vary based on substrates and conditions and this experiment was performed on sweet crude oil extracted from Gujarat, India which adds new information to the literature. [ABSTRACT FROM AUTHOR]

Molecular modeling is a rapidly growing field that uses new data and techniques to control access for trading with computational biology. To decipher the structural integrity of thermophilic amidases, an in silico approach was studied for 14 thermostable amidases from selected different thermophiles to perform the homology modeling. Results of the sequence based characterization showed the presence of higher glutamate and histidine in thermophilic aliphatic amidases as compared to mesophilic aliphatic bacterial amidase and they are conserved at specific position of 205-283. Presence of asparagine, glutamine and histidine along with cysteine in a hydrophobic core region provide more stability. These amino acids were found to be higher in amidase from Geobacillus sp. Catalytic triad was found at various helix, which is present in both the aliphatic amidases. These developed models have been considered for the molecular docking simulations to identify the binding affinity of amidases with selected targets (substrates). Malonamide, lactamide and valeramide possessed the minimum binding energy with all the thermophilic targets, which were in the range of 3 to 5 kcal.mol-1. Malonamide demonstrated higher specificity as compared to rest of the docked substrates and was further used for molecular dynamics (MD) simulations to evaluate the binding stability and conformational changes. After 1 nano second (ns) MD study with pre-defined parameters, the structural arrangements of individual atoms have been survived at higher temperature specifically for the Geobacillus sp. [ABSTRACT FROM AUTHOR]

Chemical leaching agents were compared for metal extractions from selected e-waste. Effect of iron, sulphur oxidizers and the formulated consortium were investigated for metals extraction from television printed circuit boards. The consortium showed maximum metal leaching efficiency. The bioleaching profile was studied as a function of pH, redox potential, acid consumed and the amount of Cu, Zn and Ni extracted. At 10 g/L of e-waste, 90%, 93% and 87% of Cu, Zn and Ni were extracted within 96 h. Ethylene diamine tetra acetic and pyrite were found beneficial. Two-step process resulted in more metal extraction even at 100 g/L pulp density. [ABSTRACT FROM AUTHOR]

Bioleaching of potassium from feldspar was optimized for five fungal and two bacterial isolates for carbon, nitrogen, agitation, pH and incubation time. Fungal isolates SDSR and SDS3 and bacterial isolate SDS1 released 34, 42 and 28 ppm K in sucrose-amended medium, respectively. Isolate SDS3 took 10 days for the highest K solubilization, whereas SDSR required 15 days under 150 rpm shaking condition. The pH of medium was found to decrease from 7.0 to 2.05 after the growth of the organisms. High-performance liquid chromatography analysis of the filtrate showed the presence of citric, tartaric and maleic acid, which could be responsible for the solubilization of potassium. [ABSTRACT FROM AUTHOR]