Assessment Of Heavy Metal Resistance And Bioremediation Potential Of Important Microalgal Strains

In the modern world of biology,microalgae play an important role in the environmental science and engineering for wastewater and soil bioremediation due to their sustainable production in low cost and eco-friendly nature.Heavy metals removal from soil and water and degradation of toxic chemicals are critical,as these pollutants may not only kill the aquatic&nonaquatic species but also enter the food web to cause severe disasters for human beings.Bioremediation of contaminated environment has attracted increasing interests in the research community for environmental biotechnology.In this thesis work,I have evaluated twenty two stains of microalgae for removal of heavy metals(Mercury(Hg2+),Cadmium(Cd2+),Lead(Pb2+),Copper(Cu2+),Aluminum(Al2+),and Iron(Fe2+)in aqueous solutions as a single metal species at concentration of Hg,Cd,5 ppm,Pb,Cu,10 ppm A1 and Fe 30 ppm,respectively.Five out of 22 strains were selected for their comparatively tolerance to one or more of the heavy metals.Further characterizations and heavy metal removal efficiency were successfully measured using the selected strains for aforementioned heavy metals by a different technique like OD,ICP Mass,SEM,and confocal Microscopy etc.It was found that the 5 selected stains could maintain normal growth under 10 ppm of(Hg,Cd),on 20 ppm of(Pb,Cu),and on 50 ppm of(Al,Fe),the growth became inhibited when the concentration of heavy metals went higher than 15 ppm for(Hg,Cd),20 ppm for(Pb,Cu),and 50 ppm for(Al,Fe),respectively.Removal efficiencies of Hg,Cd,Pb,Cu,A1 and Fe on aforementioned concentrations were 92,97,94,98,97,and 99.5%,respectively,while those for soil was 68,71,68,73,70 and 75%,respectively.A slight increase was observed in leakage of protein and nucleic acid with the passage of time.With a short time on desired concentration 2nd,stage morphology isthe samecontrol and 3rd stage with longtime compared little effect occurs on morphology compared with the untreated First stage.From above evidence is cleared that these heavy metals are toxic like as Hg>Cd>Pb>Cu>Al>and Fe.Another part of thesis work was about the synthesis and characterization of Gold(Au)and Silver(Ag)NPs their applications on pathogenic bacteria and their anticancer activity using HeLa cell line.Gold and silver NPs were fabricated by green synthesis process from the mixture of HAuCl and AgN03 solution and the cyanobacteria LeptolyngbyaJSC-1 extract.Detailed characterization of the NPs was carried out using UV-Vis spectroscopy,Dynamic Light Scattering(DLS)particle size analysis,Scanning Electron Microscopy(SEM),Transmissions electron microscopy(TEM),X-Ray Diffraction(XRD)analysis and FTIR.From Dynamic Light Scattering(DLS)particle size and SEM image analysis,we found that the average particle size to be 90 nm and 50 nm for gold and silver NPs respectively.We have further confirmed the formation of NPs by the analysis of XRD pattern,UV-VIS spectroscopy,and FTIR.Antibacterial assays of synthesized Au and Ag NPs was carried out both in liquid and solid growth medium against two pathogens(Escherichia coli,and Staphylococcusaureus).The resultant AuNPs was seen to have the antibacterial activities against E.coli(18 ± 2 mm)and S.aureus(14 ± 2 mm).It has been determined that AuNPs caused bacterial membrane damage thereby induced the production of intracellular reactive oxygen species(ROS).The finding reveals that biochemically capped AuNPs are the promising antibacterial agents that will induce oxidative stress for the two bacteria and cause their membrane disruption leading to cell death.On the other hand,AgNPs were observed to significantly inhibit the proliferation of HeLa cells by lower dose while severe cytotoxicity and higher intracellular uptake were observed after applying a high concentration of AgNPs.Efficient inhibition zones(17±2 and 21 ±2 mm)were produced at the maximum concentration used(100 ?l from lmg.ml-1 stock)for S.aureus and E.coli respectively.Our findings reveal that bio fabricated AgNPs have strong antibacterial activity and the ability to induce apoptosis in cancer cell line HeLa.