Muthusamy Govarthanan

Significance of autochthonous Bacillus sp. KK1 on biomineralization of lead in mine tailings.

The aim of the study was to isolate and characterize potential autochthonous bacteria for biomineralization of Pb in mine tailings. A total of four bacteria were isolated from the soil samples and assayed for tolerance to Pb and other heavy metals. Isolate KK1 exhibited maximum Pb resistance and was subsequently identified as Bacillus sp. based on the partial 16S rRNA gene sequences. The isolate KK1 reduced the Pb ions and did not harbor pbrT gene. Selective sequential extraction of bioaugmented soil revealed that the isolate significantly reduced (26%) the exchangeable fraction and increased (38%) the carbonate fraction of Pb. X-ray diffraction studies confirmed the role of bacterially induced calcite precipitation in the bioremediation of mine tailings. A significant increase in the urease (334%), DHO (dehydrogenase) (14%), and phosphatase (37%) activity was observed in the bioaugmented mine soil.

Sunroot mediated synthesis and characterization of silver nanoparticles and evaluation of its antibacterial and rat splenocyte cytotoxic effects.

A rapid, green phytosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of Helianthus tuberosus (sunroot tuber) was reported in this study. The morphology of the AgNPs was determined by transmission electron microscopy (TEM). Scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS) and X-ray powder diffraction (XRD) analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy (FTIR) analysis revealed that biomolecules in the tuber extract were involved in the reduction and capping of AgNPs. The energy-dispersive spectroscopy (EDS) analysis of the AgNPs, using an energy range of 2–4 keV, confirmed the presence of elemental silver without any contamination. Further, the synthesized AgNPs were evaluated against phytopathogens such as Ralstonia solanacearum and Xanthomonas axonopodis. The AgNPs (1–4 mM) extensively reduced the growth rate of the phytopathogens. In addition, the cytotoxic effect of the synthesized AgNPs was analyzed using rat splenocytes. The cell viability was decreased according to the increasing concentration of AgNPs and 67% of cell death was observed at 100 μg/mL.

Bioleaching characteristics, influencing factors of Cu solubilization and survival of Herbaspirillum sp. GW103 in Cu contaminated mine soil.

This study was aimed at assess the potential of diazotrophic bacteria, Herbaspirillum sp. GW103, for bioleaching of Cu in mine soil. The strain exhibited resistance to As (550mgL(-1)), Cu (350mgL(-1)), Zn (300mgL(-1)) and Pb (200mgL(-1)). The copper resistance was further confirmed by locating copA and copB genes. The survival of the isolate GW103 during bioleaching was analyzed using green fluorescent protein tagged GW103. Response surface methodology based Box-Behnken design was used to optimize the physical and chemical conditions for Cu bioleaching. Five significant variables (temperature, incubation time, CaCO3, coconut oil cake (COC), agitation rate) were selected for the optimization. Second-order polynomials were established to identify the relationship between Cu bioleaching and variables. The optimal conditions for maximum Cu bioleaching (66%) were 30°C, 60h of incubation with 1.75% of CaCO3 and 3% COC at 140rpm. The results of Cu sequential extraction studies indicated that the isolate GW103 leached Cu from ion-exchangeable, reducible, strong organic and residual fractions. Obtained results point out that the isolate GW103 could be used for bioleaching of Cu from mine soils.

Eco-friendly biosynthesis and characterization of silver nanoparticles using Tinospora cordifolia (Thunb.) Miers and evaluate its antibacterial, antioxidant potential

Abstract The present study reports an eco-friendly, rapid and easy method for synthesis of silver nanoparticles (AgNPs) using Tinospora cordifolia as a reducing and capping agent. The different factor such as silver nitrate (AgNO3) concentration, fresh weight of T. cordifolia leaf, incubation time, and pH affecting silver reduction was investigated using Response surface methodology based Box–Behnken design (BBD). The optimum conditions were AgNO3 (1.25 mM), incubation time (15 h), Temperature (45 °C) and pH (4.5). T. cordifolia leaf extract can reduces silver ions into AgNPs within 30 min after heating the reaction mixture (60 °C) as indicated by the developed reddish brown color. The UV-Vis spectrum of AgNPs revealed a characteristic surface plasmon resonance (SPR) peak at 430 nm. AgNPs were characterized X-ray diffraction (XRD) revealed their crystalline nature and their average size of nanoparticles was 30 nm as determined by using Scherrers equation. Fourier transform infrared (FTIR) spectroscopy affirmed the role of T. cordifolia leaf extract as a reducing and capping agent of silver ions. Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) showed spherical shaped and confirming presence of elemental silver. The synthesized AgNPs was found higher antioxidant activity than plant extract by dot plot assay. In addition, antibacterial activity against Staphylococcus sp. (NCBI-Accession: http://ncbi-n:KC688883.1) and Klebsiella sp. (NCBI-Accession: http://ncbi-n:KF649832.1), showed maximum zone of inhibition of 13 mm and 12.3 mm, respectively, at 10 μg/mL of AgNPs. From the results it is suggested that the synthesized AgNPs showed higher antioxidant and antibacterial activity than the plant extract, thus signification of the present study is the production of biomedical products.

Biosynthesis and characterization of silver nanoparticles using panchakavya, an Indian traditional farming formulating agent

Synthesis of silver nanoparticles (AgNPs) with biological properties is of vast significance in the development of scientifically valuable products. In the present study, we describe simple, unprecedented, nontoxic, eco-friendly, green synthesis of AgNPs using an Indian traditional farming formulating agent, panchakavya. Silver nitrate (1 mM) solution was mixed with panchakavya filtrate for the synthesis of AgNPs. The nanometallic dispersion was characterized by surface plasmon absorbance measuring 430 nm. Transmission electron microscopy showed the morphology and size of the AgNPs. Scanning electron microscopy–energy-dispersive spectroscopy and X-ray diffraction analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy analysis revealed that proteins in the panchakavya were involved in the reduction and capping of AgNPs. In addition, we studied the antibacterial activity of synthesized AgNPs. The synthesized AgNPs (1–4 mM) extensively reduced the growth rate of antibiotic resistant bacteria such as Aeromonas sp., Acinetobacter sp., and Citrobacter sp., according to the increasing concentration of AgNPs.

Process optimization of cellulase production from alkali-treated coffee pulp and pineapple waste using Acinetobacter sp. TSK-MASC

The aim of this study was to assess the mixed combination of coffee pulp waste (CPW) and pineapple waste (PW) residues for cellulase production using newly isolated Acinetobacter sp. TSK-MASC in solid state fermentation. Response surface methodology based Box–Behnken design (BBD) was employed to optimize variables such as pH, incubation time, concentrations of CPW and PW. The BBD design investigation showed a sound adjustment of the quadratic model with the experimental statistics. Statistics based 3-D plots were generated to evaluate the changes in the response surface and to understand the relationship between the enzyme yield and culture parameters. The higher production (888 U mL−1) was achieved after 60 h of incubation with 3.0 g L−1 of CPW and PW at pH 7.0.

STATISTICAL OPTIMIZATION OF ALKALINE PROTEASE PRODUCTION FROM BRACKISH ENVIRONMENT Bacillus sp. SKK11 BY SSF USING HORSE GRAM HUSK

Protease production by Bacillus sp. SKK11 isolated from brackish environment was studied by solid-state fermentation with horse gram husk. Response surface methodology-based Box–Behnken design (BBD) was used to optimize the variables such as pH, maltose, and MgSO4. The BBD design analysis showed a reasonable adjustment of the quadratic model with the experimental data. Statistics-based contour and three-dimensional (3-D) plots were generated to evaluate the changes in the response surface and to understand the relationship between the enzyme yield and the culture conditions. The maximum yield of the enzyme was observed at pH 9.0.

Lead biotransformation potential of allochthonous Bacillus sp. SKK11 with sesame oil cake extract in mine soil

The potential of allochthonous Bacillus sp. SKK11 and sesame oil cake extract for the immobilization of Pb in mine soil was investigated in this study. The isolate SKK11, isolated from a brackish environment and identified as Bacillus sp. based on partial 16S rDNA sequencing, exhibited maximum resistance to Pb (750 mg L−1). Growth kinetic studies revealed that the presence of oil cake extract (2%) increased the biomass of the isolate SKK11. Transmission electron microscopy and X-ray diffraction studies showed that isolate SKK11 transformed Pb either intracellularly or extracellularly. Selective sequential extraction studies showed that the bioremediation decreased 24.9% of the exchangeable fraction in the mine soil in 3 days. However, 75.1% of the exchangeable fraction was not immobilized in the soil. An X-ray diffractogram of the bioremediated soil showed a major decrease (79.0%) in the intensity of the plagioclase mineral peak. Urease, dehydrogenase, amylase, invertase, cellulase, and alkaline phosphatase enzyme activities were increased in the bioremediated mine soil. These results suggest that the isolate Bacillus sp. SKK11 in combination with sesame oil cake extract could be employed for the immobilization of bioavailable Pb in contaminated soil.

Acorus calamus rhizome extract mediated biosynthesis of silver nanoparticles and their bactericidal activity against human pathogens

Silver nanoparticle (AgNP) synthesis and characterization is an area of vast interest due to their broader application in the fields of science and technology and medicine. Plants are an attractive source for AgNP synthesis because of its ability to produce a wide range of secondary metabolites with strong reducing potentials. Thus, the present study describes the synthesis of AgNPs using aqueous rhizome extract of Acorus calamus (sweet flag). The AgNP formation was evaluated at different temperatures, incubation time and concentrations of AgNO3 using Response surface methodology based Box–Behnken design (BBD). The synthesized AgNPs were characterized by UV–Visible spectroscopy, Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS). The surface plasmon resonance found at 420 nm confirmed the formation of AgNPs. SEM images reveal that the particles are spherical in nature. The EDS analysis of the AgNPs, using an energy range of 2–4 keV, confirmed the presence of elemental silver without any contamination. The antibacterial activity of synthesized AgNPs was evaluated against the clinical isolates Staphylococcus aureus and Escherichia coli and it was found that bacterial growth was significantly inhibited in a dose dependent manner. The results suggest that the AgNPs from rhizome extract could be used as a potential antibacterial agent for commercial application.

Low-cost and eco-friendly synthesis of silver nanoparticles using coconut (Cocos nucifera) oil cake extract and its antibacterial activity

Abstract The present study reports the simple, inexpensive, eco-friendly synthesis of silver nanoparticles (AgNPs) using coconut oil cake extract. Scanning electron microscopy–energy dispersive spectroscopy peak at 3 keV confirmed the presence of silver. Transmission electron micrograph showed that nanoparticles are mostly circular with an average size of 10–70 nm. The results of the X-ray powder diffraction analysis (2θ = 46.2, 67.4 and 76.8) indicated the crystal nature of the AgNPs. Fourier transform infrared spectroscopy analysis indicates that proteins present in the oilcake extract could be responsible for the reduction of silver ions. The synthesized AgNPs (1–4 mm) reduced the growth rate of multi-antibiotic-resistant bacteria such as Aeromonas sp., Acinetobacter sp. and Citrobacter sp. isolated from livestock wastewater.