Banca de QUALIFICAÇÃO: JULIANA DE FÁTIMA DOS SANTOS SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : JULIANA DE FÁTIMA DOS SANTOS SILVA
DATA : 07/12/2021
HORA: 14:00
LOCAL: Defesa remota, via Google Meet
TÍTULO:

CHARACTERIZATION OF THE QUORUM SENSING (QS) MECHANISM IN Zymomonas mobilis IN RESPONSE TO THE TYPE 2 AUTO-INDUCTOR (AI-2)

PÁGINAS: 85
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
SUBÁREA: Biologia Molecular
RESUMO:

Zymomonas mobilis is a gram-negative facultative anaerobic bacterium, which is considered a microorganism of major potential for industrial applications, since it presents several important attributes that favor its use in alternative bioconversion processes. Z. mobilis has attracted the attention of the bioethanol industry for several years, especially for presenting some advantageous features regarding ethanol production, when compared to the yeast Saccharomyces cerevisiae. In addition, genetic manipulation techniques have been developed for this bacterium, which has been genetically modified and/or adapted to produce different high value-added products (as levan, sorbitol, lactate and 2.3-butanediol). Therefore, Z. mobilis possesses a number of desirable characteristics for the bioconversion industry and a better understanding of the mechanisms used to control gene expression in this bacterium can help in the development of new genetically manipulated strains, with high capacity of industrial production. This project aims to characterize the global transcriptional response of Z. mobilis to the process of Quorum Sensing (QS), a chemical communication process employed by bacteria to assess population density in their surrounding environment and synchronize behavior in a community scale. The activation of the QS response reduces cell growth, activating expression of genes involved with a series of alternative activities, such as biofilm formation, bioluminescence and production of pathogenicity factors, for example. Thus, QS-responsive promoters may be used to redirect cellular resources for the production of substances of interest in recombinant Z. mobilis strains. To characterize such promoters, RNA-seq libraries were constructed using RNA obtained from Z. mobilis cells at two phases of growth in minimal medium (MM): (i) cells growing at the exponential phase and (ii) cells in stationary phase. The libraries were sequenced using the Illumina NextSeq platform and the sequences obtained were processed by the Rockhopper software, using the reference genome of Z. mobilis ZM4. Comparisons involving these two transcriptomes demonstrated that the QS response induced expression of a total of 588 genes (q value ≤ 0.01), including 292 upregulated genes and 296 downregulated genes (32% of the bacterium genome). These studies led to the identification of chromosomal regions carrying QS-responsive promoter elements, which are currently being mapped and identified. Such inducible promoters may constitute an important tool for Z. mobilis manipulation, with possible application in a wide variety of industrial bioprocesses, allowing the expression of transgenes in this bacterium, under controlled and optimized conditions. 

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1674592 - TIAGO RODRIGUES
Membro Titular - Examinador(a) Interno ao Programa - 2605490 - SERGIO DAISHI SASAKI
Membro Titular - Examinador(a) Interno ao Programa - 1696841 - LUCIANO PUZER
Membro Suplente - Examinador(a) Interno ao Programa - 1675708 - DANIELE RIBEIRO DE ARAUJO