Environmental Microbiology and Engineering : Microalga Scenedesmus sp.: A Potential Low-Cost Green Machine for Silver Nanoparticle Synthesis

( Jaya Shree Jena ),( Nilotpala Pradhan ),( Rati Ranjan Nayak ),( Bishnu P Dash ),( Lala Behari Sukla ),( Prasanna K Panda ),( Barada K Mishra ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.4

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of Ag+ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of Ag+ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

Extraction of copper from copper slag: Mineralogical insights, physical beneficiation and bioleaching studies

Sandeep Panda,Srabani Mishra,Danda Srinivas Rao,Nilotpala Pradhan,Umaballava Mohapatra,Shivakumar Angadi,Barada Kanta Mishra 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.4

Copper slag was subjected to in-depth mineralogical characterization by integrated instrumental techniquesand evaluated for the efficacy of physical beneficiation and mixed meso-acidophilic bioleaching tests towardsrecovery of copper. Point-to-point mineral chemistry of the copper slag is discussed in detail to give better insight intothe association of copper in slag. Characterization studies of the representative sample revealed the presence of fayaliteand magnetite along with metallic copper disseminated within the iron and silicate phases. Physical beneficiation of thefeed slag (~0.6% Cu) in a 2 L working volume flotation cell using sodium isopropyl xanthate resulted in Cu beneficiationup to 2-4% and final recovery within 42-46%. On the other hand, a mixed meso-acidophilic bacterial consortiumcomprised of a group of iron and/or sulfur oxidizing bacteria resulted in enhanced recovery of Cu (~92-96%) from theslag sample. SEM characterization of the bioleached slag residue also showed massive coagulated texture with severeweathered structures. FE-SEM elemental mapping with EDS analysis indicated that the bioleached residues were devoidof copper.

Fe (III) reduction strategies of dissimilatory iron reducing bacteria

Jacintha Esther,Lala Behari Sukla,Nilotpala Pradhan,Sandeep Panda 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.1

Advances in applied and industrial microbial biotechnology have opened up many new avenues for appli-cation of several microorganisms. A group of certain metal reducers such as the dissimilatory iron reducing microor-ganisms possess an inherent potential to reduce oxidized metals under strict anaerobic/facultative anaerobic condition,thereby opening possibilities to combat environmental pollution. This unique property has invited researchers towardsunderstanding the metabolic regulatory pathways that enables the microbes to thrive under extreme environmentalconditions. Currently, dissimilatory iron reducing bacteria (DIRB) is in the focus of researchers to elucidate the specificmechanisms responsible for microbial metal reduction. The recent advances towards understanding the metabolism ofiron reduction in Shewanella and Geobacter , the model DIRB has been covered in this review. It is believed that themetabolic insights into the Fe (III) reduction systems of the model DIRB; Shewanella and Geobacter (as discussed inthe review) can be a basis for metabolic engineering to provide improved practical applications. With the advancementof our existing knowledge on the metabolic processes of the model iron reducers, applications ranging from laboratoryto field scale practices can be carried out. DIRB has gained immense interest for its application in the field of bioreme-diation, electrobiosynthesis, and bioelectronics in this decade. It can therefore be anticipated that the forthcoming yearswill see more applications of microbial iron reducers based on the existing as well as advanced metabolic informationsavailable in open source literature.

Recovery of copper from a surface altered chalcopyrite contained ball mill spillage through bio-hydrometallurgical route

Sandeep Panda,Pradeep Chandra Rout,Chinmaya Kumar Sarangi,Srabani Mishra,Nilotpala Pradhan,Umaballav Mohapatra,Tondepu Subbaiah,Lala Behari Sukla,Barada Kanta Mishra 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.3

Bioleaching studies for chalcopyrite contained ball mill spillages are very scarce in the literature. We developeda process flow sheet for the recovery of copper metal from surface activated (600 oC, 15 min) ball mill spillagethrough bio-hydrometallurgical processing route. Bioleaching of the activated sample using a mixed meso-acidophilicbacterial consortium predominantly A. ferrooxidans strains was found to be effective at a lixiviant flow rate of1.5 L/h, enabling a maximum 72.36% copper recovery in 20 days. Mineralogical as well as morphological changesover the sample surface were seen to trigger the bioleaching efficiency of meso-acidophiles, thereby contributing towardsan enhanced copper recovery from the ball mill spillage. The bio-leach liquor containing 1.84 g/L Cu was purified throughsolvent extraction using LIX 84I in kerosene prior to the recovery of copper metal by electrowinning. Purity of thecopper produced through this process was 99.99%.

Recovery of nickel from chromite overburden, Sukinda using Aspergillus niger supplemented with manganese

Lala Behari Sukla,Sunil Kumar Behera,Prangya Parimita Panda,Sandeep Kumar Saini,Nilotpala Pradhan,Barada Kanta Mishra 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.2

Oxalic acid is a prominent metabolite secreted by several fungi under specific conditions, which acts as a metal chelating agent. Amongst different fungal species, Aspergillus niger is favored as the best option for microbial production of oxalic acid. The present study deals with the oxalic acid over production by A. niger in response to manganese supplement to its growth medium, which in turn improves the recovery of nickel from pre-treated chromite overburden(COB) during fungal bioleaching. The metabolic pathway in oxalate bio-synthesis by A. niger involves one prominent cytoplasmic enzyme oxaloacetate acetylhydrolase (OAH), which catalyzes the breakdown of oxaloacetate metabolic intermediate to oxalate and acetate. Oxalic acid production was increased due to supplement of manganese to the culture medium of the A. niger. Manganese acts as cofactor for OAH enzyme; further, it enhances the catalytic activity of OAH to produce more oxalate. With oxalic acid production by A. niger, nickel recovery from pre-treated COB was improved. During the study, a maximum of nickel recovery was achieved up to 38.6% from pre-treated COB by adding 80 ppm of manganese to the culture media, whereas 24.0% of nickel was recovered without supplement of manganese (experiments were performed at 30 oC and the COB pulp density 2% w/v).

Bio-hydrometallurgical processing of low grade chalcopyrite for the recovery of copper metal

Sandeep Panda,Lala Behari Sukla,Chinmaya Kumar Sarangi,Nilotpala Pradhan,Tondepu Subbaiah,Barada Kanta Mishra,Gur Lal Bhatoa,Mullukutlashivram Prasad,Subrat Kumar Ray 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.6

A process flowsheet was developed to recover copper metal from the lean sulfide ore of copper available at Malanjkhand, Hindustan Copper Limited (HCL), India. Copper pregnant leach solution (PLS) obtained from bio-heap leaching of chalcopyrite containing 0.3% copper was purified through solvent extraction (SX) and the copper recovered by electrowinning (EW). The copper-free raffinate obtained from SX stripping unit was returned back to the bioleaching circuit. The purity of the electrolytic copper produced at pilot scale was found to be 99.96%. During electrowinning,the effect of flow rate of electrolyte on current efficiency and energy consumption was also studied.