Banca de DEFESA: ANDRÉA LÔBO MIRANDA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ANDRÉA LÔBO MIRANDA
DATA : 18/06/2019
HORA: 13:30
LOCAL: Instituto de Ciências da Saúde/ UFBA, auditório da Congregação, 2° andar
TÍTULO:

INVESTIGATION OF THE CONDITIONS OF CULTURE AND COMPOSITION OF Xanthomonas CALCIDES FOR IDENTIFICATION OF MARKERS OF PRODUCTIVITY AND QUALITY OF XANTANAS

PALAVRAS-CHAVES:

Viscosity; Molecular mass; FAME; Unsaturated fatty acids; X. campestris; X. axonopodis.

PÁGINAS: 93
GRANDE ÁREA: Outra
ÁREA: Tecnologia e Inovação
RESUMO:

Xanthan gum is a microbial exopolysaccharide with various functions in Xanthomonas and a wide variety of industrial applications due to its high water solubility, emulsifiability, suspensibility and thickening. Although xanthan gum is one of the main polysaccharides of microbial origin marketed worldwide, it presents wide heterogeneity in composition and molecular mass, and consequently in the resulting properties. Thus, in this study, the composition of cell fatty acids and the effect of different strains and time of Xanthomonas culture were investigated in order to identify productivity markers, reproducibility, composition and quality of xanthan gums obtained. Xanthomonas axonopodis pv. manihotis 290, Xanthomonas campestris pv. mangiferaeindicae 645 and Xanthomonas campestris pv. campestris 1155 strains were monitored for 168 h of culture. At 24 h, cell and gum samples were analyzed by FTIR, XRD, apparent viscosity, molecular mass, TGA, sugars and acids, as well as determination of cell growth and substrate consumption. The three Xanthomonas strains presented qualitative profiles of cellular fatty acids similar throughout the culture, with the acids 16: 1ω7 and 16: 0 being the major ones. For all strains studied, significant correlations were obtained between the ratios of these fatty acids and xanthan gum production. It was also verified the influence of the intrinsic characteristics of the strains on the properties, production and composition of the polymer. The strain X. campestris pv. campestris 1155 showed higher productivity in 24 hours of cultivation, but with limited properties for industrial application. On the other hand, the strain Xanthomonas axonopodis pv. manihotis 290 presented an inverse behavior. There was not direct association between the composition of fatty acids and the synthesized gums characteristics. Based on the evaluation of some kinetic parameters of the culture, it was possible to define the Xanthomonas strain and the culture time associated with the quality of the resulting exopolymer. For the first time, a direct relationship between unsaturated / saturated cellular fatty acids (I / S) and the xanthan gum production was identified, which allows the identification of a possible chemical marker of productivity of this biopolymer.

MEMBROS DA BANCA:
Externo ao Programa - 3725209 - CAROLINA OLIVEIRA DE SOUZA
Externo à Instituição - DENILSON DE JESUS ASSIS - UNIFACS
Presidente - 1350842 - JANICE IZABEL DRUZIAN
Externo ao Programa - 3053917 - KARINA TEIXEIRA MAGALHAES GUEDES
Externo ao Programa - 1980101 - MARCELO ANDRES UMSZA GUEZ