Novel applications of oxygenic photosynthetic organisms

dissertation

Danijel Stojković (Author), Matjaž Valant (Mentor), Elsa Fabbretti (Mentor)

Abstract

Inspired by natural microorganisms that possess a rigid cell wall to protect them in harsh conditions, individual cells of Chlamydomonas reinhardtii were artificially encapsulated with different materials and hydrogen production was enhanced. The first attempt was to cover the cells with hydrated silicon dioxide, which is naturally formed by diatoms. The cells covered with silica were not able to produce hydrogen, but the improved TiO2-encapsualtion of Chlamydomonas reinhardtii was found to positively affect their hydrogen production under sulfur-deprived conditions. It was shown that incubation of the cells in the dark before exposure to light was necessary in order to overcome the toxic effects of the (RKK)4D8 catalytic peptide that is essential for TiO2 formation. The TiO2-encapsulated cells were able to produce H2 with about double efficiency during 5-day period compared to non-encapsulated cells. The light-to-H2 conversion efficiency of TiO2-encapsulated Chlamydomonas reinhardtii system was estimated to be more than 4 % under optimized conditions. The encapsulation with platinum led us to discover the bioreductive properties of Chlamydomonas reinhardtii. Beside the homogeneous Pt reduction carried out by the algae, the most surprising discovery was the possibility to use algae culture for targeted heterogeneous nucleation. An important discovery was that is possible to control the nucleation mechanism and redirect predominantly homogeneous into fully heterogeneous nucleation.

Keywords

photosynthesis;H2 production;TiO2;encapsulation;Chlamydomonas reinhardtii;platinum reduction;

Data

Language:	English
Year of publishing:	2015
Source:	Nova Gorica
Typology:	2.08 - Doctoral Dissertation
Organization:	UNG FPŠ - Graduate School
Publisher:	[D. Stojković]
UDC:	577
COBISS:	3839739
Views:	7388
Downloads:	295
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary title:	Nove aplikacije oksigenih fotosinteznih organizmov
Secondary abstract:	Po navdihu mikroorganizmov iz narave, ki imajo trdno celično steno za zaščito pred neugodnimi zunanjimi dejavniki, sem celice alg Chlamydomonas reinhardtii obdal z različnimi materiali. Na ta način je bila izboljšana njihova proizvodnja vodika. Najprej sem celice prekril s hidriranim silicijevim dioksidom, iz katerega imajo svoje ogrodje diatomejske alge. Celice, ki so bile prekrite s silicijevim dioksidom, niso bile sposobne proizvajati vodika. Po drugi strani pa je enkapsulacija Chlamydomonas reinhardtii s TiO2 pozitivno vplivala na njihove sposobnosti proizvodnje vodika v pogojih brez žvepla. Pri tem sem ugotovil, da je inkubacija celic v temi, preden jih izpostavimo svetlobi, potreben pogoj, da se izognemo toksičnim učinkom (RKK)4D8 katalitičnega peptida, ki je potreben za tvorbo TiO2. S TiO2 modificirane celice so bile v petih dneh, v primerjavi z nemodificiranimi celicami, sposobne proizvajati H2 s približno dvakratno učinkovitostjo. Ocena potencialne učinkovitosti za pretvorbo svetlobe v H2 je pokazala, da bi bile v optimalnih pogojih, s TiO2 oblečene celice Chlamydomonas reinhardtii, sposobne preseči vrednost 4 %. Enkapsulacija s platino je vodila do odkritja bioredukcijskega potenciala, ki ga imajo alge Chlamydomonas reinhardtii. Poleg homogene redukcije Pt, ki je bila dosežena, je bilo najbolj presenetljivo odkritje zmožnosti alg za usmerjeno heterogeno nukleacijo. Odkrili smo, da je možno kontrolirati nukleacijski mehanizem in preusmeriti pretežno homogeno v heterogeno nukleacijo.
Secondary keywords:	fotosinteza;proizvodnja H2;TiO2;enkapsulacija;Chlamydomonas reinhardtii;disertacije;
URN:	URN:SI:UNG
Type (COBISS):	Doctoral dissertation
Thesis comment:	Univ. v Novi Gorici, Fak. za podiplomski študij
Pages:	XVI, 105 str.
ID:	9063268