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The effects of metal oxide nanoparticles on yeasts of the genus Rhodotorula


Author: Beșliu Alina
Degree:doctor of biology
Speciality: 03.00.23 - Biotechnology
Year:2020
Scientific adviser: Agafia Usatîi
doctor habilitat, professor, Institute of Microbiology and Biotechnology of the ASM
Institution:

Status

The thesis was presented on the 24 September, 2020
Approved by NCAA on the 23 December, 2020

Abstract

Adobe PDF document – 0.98 Mb / in romanian
Adobe PDF document – 1.06 Mb / in english

Thesis

CZU 507. 663.12/. 604.2: 620.3

Adobe PDF document 6.88 Mb / in romanian
185 pages

Keywords

ZnO, Fe3O4 nanoparticles, Rhodotorula gracilis, viability, morphological characters, carbohydrates, proteins, carotenoid pigments, catalase, superoxide dismutase

Summary

The thesis consists of an introduction, five chapters, general conclusions and recommendations, 361 of bibliographic sources, 12 appendices, main text 129 pages, 55 figures, 19 tables. The results were published in 46 scientific papers.

Objectives of the paper: Validation of microbiological and biochemical tests in the context of ensuring the qualification and quality of the methods used to evaluate the effects of nanoparticles of metal oxides; Establishing the particularities of the action of ZnO and Fe3O4 nanoparticles with different dimensions on yeasts of the genus Rhodotorula; Elaboration of the procedures for the use of ZnO and Fe3O4 nanoparticles in the biotechnology of yeast cultivation; Obtaining the chitosan-zinc and chitosan-iron nanocomposites and appreciating the perspectives of their use in the biotechnology of pigmented yeasts.

Scientific novelty and originality. For the first time, microbiological and biochemical tests are validated and the cellular functional groups of pigmented yeasts of the genus Rhodotorula have been identified, involved in the response to the action of the nanoparticles. For the first time is elucidated the action character of ZnO and Fe3O4 nanoparticles on viability, biomass production, cellular and colonial morphological characteristics, protein content, carbohydrates, carotenoids, antioxidant enzymes in yeasts of the Rhodotorula genus depending on size and concentration. It has been shown that ZnO nanoparticles, used in concentrations 1-20 mg/L in Rh. gracilis cultivation, positively influence the processes of protein multiplication and biosynthesis, carbohydrates and carotenoid pigments. It has been shown that Fe3O4 nanoparticles induce in Rh.gracilis significant changes in biosynthetic processes and antioxidant defense system, which is manifested by decreased carotenoid content and catalase enzyme. For the first time, the character of action of chitosan-zinc and chitosan-iron nanocomposites on yeasts of the genus Rhodotorula is elucidated. Two new procedures have been developed to increase the quantity and quality of proteins with the use of ZnO nanoparticles and to evaluate the toxicity of Fe3O4 nanoparticles with the use of Rh. gracilis as a model. The processes are confirmed by a 2 patents and patent application.

The important scientific problem solved in the paper. The effects of nanoparticles of ZnO and Fe3O4 metal oxides on yeasts of biotechnological interest in the genus Rhodotorula have been established, which has contributed to the elucidation of some mechanisms of action, which has allowed to appreciate the prospects for use in bionanotechnologies. Theoretical significance. The particularities of action of the ZnO and Fe3O4 nanoparticles, based on their size and concentration, and of the chitosan-zinc and chitosan-iron nanocomposites on the microbiological and biochemical indices in yeasts of the genus Rhodotorula, have been argued, which served as a basis for the elucidation of some of action and elaboration of the procedures for use in the biotechnology of yeast cultivation.

The applicative value. It is proposed for recovery: a process for increasing the protein content of Rh. gracilis strains with the use of ZnO nanoparticles; a new process for testing the harmfulness of Fe3O4 nanoparticles with the use as a model of pigmented yeasts of the genus Rhodotorula; a new process for making chitosan-zinc and chitosan-iron nanocomposites with biotechnological perspectives.

Implementation of results. The results of the research are applied within the Institute of Electronic Engineering and Nanotechnologies “D. Ghițu”, and the practical work in the soil microbiology laboratory, the Institute of Microbiology and Biotechnology.