Book Description

Research stimulated by curiosity brings out new pieces that make up the puzzle oflife and invention provides the tools to assemble and interpret it. The IndustrialRevolution of past centuries has brought innovations not accompanied by a farsightedvision of the consequences that are manifesting in this globalized twenty-firstcentury, particularly with an increase in energy demand and global warming. Theemerging biotechnology revolution, which applies technology to biological systems,could solve these problems without further deleterious effects if driven bysustainable development. Research and development institutes, subsidized bygovernments, are looking for renewable and sustainable energy resources that wouldreplace polluting fossil fuels nearly depleted.Recently the investigation of the marine microalgae's potential in biotechnologicalapplications is increasing by the realization that the ocean is a relatively untappedsource of energy biomass and novel biomolecules. Microalgae mainly represent thelast generation suitable feedstock for the transport sector, but due to theirbiochemical versatility are useful also for many others industrial fields such asmedical, pharmaceutical, food and cosmetic. Nowadays, biofuel production frommicroalgae biomass is still in progress; the efficiency of each step during the wholeprocess, from culturing to refining, needs to be improved to get yield economicallyreasonable. Coupling each other different industrial applications could lead toovercome the substantial investments with proper earnings making, hopefully in thenext future, this living energy source lucrative, therefore commercially feasible.In the last decades, researchers are focusing their attention on Diatoms, a taxon ofmicroalgae characterized by silica walls derived from secondary symbiotic event.Diatoms are affected by seasonal exponential growth called blooms that place themat the base of the oceans food chain, permit about 40% of atmospheric CO2 fixationand significant influence the biogeochemical cycle of the macronutrients: silicon(Si), nitrogen (N), phosphorus (P). This microalgae's group is a promising candidatefor biodiesel production because of their great lipid accumulation like reserve storagecompound mainly in the form of triacylglycerols (TAG), converted into biodieselthrough a reaction of trans-esterification.The aim of this thesis were the evaluation of the growth curves and biochemicalcomposition (lipids, carbohydrates and proteins) of the marine diatom CyclotellaCryptica grown in batch system by administering the average of the standard mediumf/2 daily or only the day of the inoculation. The growth curve were obtained bymonitoring daily the cellular density (cells/mL) with an optical microscope combinedwith a Bürker chamber. The biological macromolecules quantification, lipids,carbohydrates, and proteins were realized by Folch modified – MTBE, Dubois andLowry methods, respectively. Furthermore, the lipids composition werecharacterized both by Thin Layer Chromatography (TLC) and Nuclear MagneticResonance (NMR)-Eretic method.The results shows that the daily supply of the medium f/2 induce high cell density(2250000±77567 cells/mL) and biomass dry weight (1441.79±148.35 mg/L) thatmainly consist of proteins (88%) and lipid fraction is predominantly composed byphospholipids (PL). Conversely, administering the medium f/2 only the first day letthe diatoms in a starvation condition defined by a little cell density (192222 ± 26851)and biomass dry weight (205.90±22.24 mg/L) with a significant increase in therelative amount of storage compounds: carbohydrates (19%) and lipid (33%)predominantly in form of triacylglycerols (TAG).Typically, microalgae are growth at first in laboratories under strict controlledcondition in closed photobioreactors and then transferred to open-pounds for largescaleproduction.