| dc.description.abstract | Focus on microalgae continues to grow for the production of biomass and various valueadded products including proteins, lipids, and pigments. The bioproducts from microalgae have found their applications not only in the field of petroleum industry but also in food and nutrition and pharmaceutical industries. However, due to several technical challenges associated with the inability to effectively dewater micro-algal biomass and extracting valuable compounds, microalgae-based bio-refinery is not yet economically feasible. To make the microalgae-based bio-refinery platform sustainable, less energy and resource intensive dewatering and harvesting techniques needs to be deployed. Part 1 of this dissertation focuses on a novel dewatering technique of microalgal biomass by using an amphiphilic polyelectrolyte, which upon adsorbing on the biomass, leads to formation of a net hydrophobic ensemble that consequently migrates into a hydrophobic organic solvent i.e., hexane. The technique also involves simultaneous separation of algal proteins by retaining them in the aqueous phase while migrating algal cellular debris to a hexane phase at the right system pH and polyelectrolyte concentration. Separation and recovery of microalgae from the aqueous medium that they reside in is difficult as a result of the nature of the algal cells, i.e., small cell size, density close to water, low concentration, and ability to stay suspended in water due to surface potential. This study has been divided into four sections: 1) separation studies on model algal particles; 2) separation of model proteins (egg albumin); 3) Simultaneous separation of model algal particles and models proteins in hexane and aqueous phase; and 4) separating algal proteins and cellular debris in aqueous and hexane phase respectively. The technique involves the addition of a positively charged electrolyte, Mono/Poly-(diallyl dimethyl ammonium chloride, DADMAC) which interacts with negatively charged particles to form hydrophobic ensembles. The resulting hydrophobic ensembles, upon addition of a hydrophobic organic solvent, migrate from aqueous phase to the hydrophobic organic solvent phase.
From the studies conducted onChlorella sorokiniana,the ability of polyDADMACtodewater and extract cellular debris, lipids, and pigments to the hexane phase while retaining protein fraction in the aqueous phase was investigated. It was observed that different components could be migrated from one phase to the other by modulating the system pH. Close to the isoelectric point, proteins can be retained in the aqueous phase while selectively migrating algal debris to the hexane phase via targeted binding of the polyelectrolyte. Approximately 80% of total proteins were retained in the aqueous phase at pH 4, and 90% of cellular debris were migrated to the hexane phase at pH 4.5. Results indicate the possibility of separating multiple components from microalgae in an aqueous-organic solvent two-phase system using polyDADMAC. Part 2 of this dissertation focuses on screening of highly specific RNA dependent RNA polymerase (RdRp) inhibitors for Tick-Borne encephalitis virus. Tick-Borne encephalitis virus (TBEV) in humans can be caused by direct tick bites or by consumption of nonpasteurized milk or milk products from TBEV- infected sheep, goats and cows. The TBEV genome encodes a single polyprotein, which is co/post-translationally cleaved into seven nonstructural proteins. Of the non-structural proteins, NS5 contains the RdRp domain and a methyltransferase (MTase) domain that are responsible for the replication of the viral genome. The focuses of this section was on screening for potential antivirals using a hybrid receptor and ligand-based pharmacophore search. For identification of pharmacophores, a mixture of small probe molecules and nucleotide triphosphates (NTPs) were used. The ligand/receptor interaction screenings of structures using ZINCPharmer search engine in ZINC database resulted in five compounds that bound to the RdRp domain with high affinity. Compounds Zinc 9662, and Zinc 9041hadsignificantlylower binding energies than native NTPs at the RdRp binding site. Experimental studies indicated that Zinc 7151 substantially inhibited viral growth at 30 µMconcentration while both Zinc 3677 and Zinc 7151 had antiviral activity at 100 µM. | |
