Banca de DEFESA: SAMANTHA SERRA COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : SAMANTHA SERRA COSTA
DATA : 24/04/2019
HORA: 09:00
LOCAL: Auditório da Congregação, 2º andar do Instituto de Ciências da Saúde - UFBA
TÍTULO:

PRODUCTION, EXTRACTION AND CHARACTERIZATION OF MICROALGAS BIOMASS POLYHYROXIALCANOATES (PHAs)

PALAVRAS-CHAVES:

cyanobacteria; biopolymers; microalgae; molecular mass

PÁGINAS: 107
GRANDE ÁREA: Outra
ÁREA: Multidisciplinar
RESUMO:

The growing use of conventional plastics has generated concern about the large accumulation in the environment, arising the need for production and use of biodegradable polymers to replace them. Polyhydroxyalkanoates (PHAs) are biopolymers synthesized intracellularly by various microorganisms as a form of energy storage. Microalgae are promising sources of PHAs, as they are the only microorganisms that accumulate PHAs through photosynthesis, using light and CO2 as main sources of energy, reducing production costs, which constitutes the biggest obstacle to its commercialization. Thus, the objective of this work was to produce and characterize PHAs of the biomass of different microalgae, evaluating the extraction methods and cultivation strategies for greater biopolymer accumulation. Initially, the efficacy of six methods of PHA extraction from Spirulina sp. LEB-18 was evaluated considering the extraction yield, purity and properties (FTIR, molecular mass, crystallinity index and monomer composition) of the polymers. After 30 days of cultivation, 1.02 g L-1 of biomass was obtained, yielding between 6.10 and 9.80% of PHAs and degrees of purity between 63.5 and 93.6%, depending on the extraction method used. The use of sodium hypochlorite in the initial extraction stage contributed to increased yield, and the use of methanol at the end of the process contributed to increase the purity of the biopolymers. The molecular mass, the crystallinity index and the composition of the PHAs varied with the extraction methods, demonstrating interference of the extraction process in the properties of the polymers. An indirect relationship (R2 = 0.80) was found between the percentage of the 11-hydroxyhexadecanoate monomer and the degree of crystallinity of the PHAs, suggesting that the increase of medium and long chains in the PHA structure contributes to this. In the second stage, the influence of the nitrogen availability of the culture medium on the production and composition of biomass (chlorophyll, proteins, lipids and fatty acids) and PHA production and properties (FTIR, crystallinity index, TGA and DSC). Chlorella minutíssima, Synechococcus subsalsus and Spirulina sp. LEB-18 were grown in "standard" medium and in medium with reduction of 70% of nitrogen. The cellular growth of microalgae was reduced in the limited nitrogen medium, as well as the biochemical composition of the biomass, with higher storage of carbonaceous molecules such as lipids and PHAs. C. minutissima did not synthesize PHA even in a limited nitrogen environment, unlike S. subsalsus (16% m m-1 dry biomass) and Spirulina sp. (12%). The PHAs presented different thermal and physical properties, evidencing the influence of the strain on the properties of the polymer, formed mainly by long chain monomers (C14 to C18). This composition is a scientific novelty, since it was not registered in PHAs synthesized by other microalgae. The PHAs obtained by the two microalgae can be used in several areas, with potential for the development of packages due to low crystallinity. S. subsalsus accumulated more PHA, with more attractive properties, proving to be more promising to obtain the biopolymer

MEMBROS DA BANCA:
Externo à Instituição - DENILSON DE JESUS ASSIS - UNIFACS
Interno - 1919894 - FABIO ALEXANDRE CHINALIA
Externo ao Programa - 2897782 - ICARO THIAGO ANDRADE MOREIRA
Interno - 1350842 - JANICE IZABEL DRUZIAN
Externo à Instituição - JOSIANE DANTAS VIANA BARBOSA - Senai