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Doctoral Thesis
DOI
https://doi.org/10.11606/T.75.2020.tde-28082020-152400
Document
Author
Full name
Mirelle Takaki
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2020
Supervisor
Committee
Berlinck, Roberto Gomes de Souza (President)
Crnkovic, Camila Manoel
Forim, Moacir Rossi
Palma, Mario Sergio
Rodrigues Filho, Edson
Title in Portuguese
Estudo metabolômico de fungos do gênero Colletotrichum e de organismos marinhos produtores de tambjaminas
Keywords in Portuguese
Colletotrichum
fungos endofíticos
fungos fitopatogênicos
metabolômica
organismos marinhos
tambjaminas
Abstract in Portuguese

O presente trabalho descreve o estudo metabolômico de fungos do gênero Colletotrichum e de organismos marinhos produtores de tambjaminas Virididentula dentata, Tambja stegosauriformis, Tambja brasiliensis e Roboastra ernsti. Fungos do gênero Colletotrichum causam doenças em uma grande variedade de plantas de diversas famílias. Metabólitos secundários produzidos por estes micro-organismos podem constituir parte do processo de virulência associada à sua fitopatogenicidade. Apesar de muitos metabólitos de linhagens de Colletotrichum já terem sido isolados e identificados, a fitopatogenicidade associada a fungos deste gênero ainda não está bem estabelecida. Com o intuito de se investigar a diferença no metabolismo de linhagens endofíticas e fitopatogênica de Colletotrichum spp., 25 isolados de Colletotrichum foram investigados, dentro os quais 16 eram endofíticos e 9 fitopatogênicos. Os extratos dos meios de cultivo foram fracionados e analisados por UPLC-IMS-QToF-HRMS. Os dados brutos foram processados empregando-se ferramentas in-house e molecular networking. A avaliação dos resultados permitiu concluir que linhagens endofíticas e fitopatogênicas de Colletotrichum spp. possuem metabolismo consideravelmente diferente. Linhagens endofíticas produzem compostos que são comuns à varias linhagens do grupo; já linhagens fitopatogênicas produzem compostos mais específicos a cada um dos isolados. O processo de desreplicação dos resultados de molecular networking utilizando-se uma biblioteca in-house de compostos isolados de Colletotrichum spp. permitiu a identificação de 5 compostos que apresentam atividade fitotóxica nas amostras relacionadas às linhagens fitopatogênicas. Tais resultados são forte indicativo de que a fitopatogenicidade de linhagens de Colletotrichum podem estar associada à produção de compostos fitotóxicos. Tambjaminas são um grupo de alcalóides quimicamente relacionados à prodigiosina e prodigionina, isoladas de bactérias e organismos marinhos como ascídias, briozoários e nudibrânquios. Além de apresentarem atividades biológicas diversificadas, as tambjaminas estão possivelmente relacionadas à mecanismos de defesa dos organismos a partir dos quais são isoladas. Diversos estudos de organismos marinhos produtores de tambjaminas envolvidos em relações presa-predador demonstraram que estes alcalóides foram detectados nos extratos tanto das presas quanto dos predadores. Nesse sentido, foram obtidos os extratos de V. dentata, T. stegosauriformis, T. brasiliensis e R. ernsti. A partir da análise dos extratos orgânicos e aquosos dos organismos marinhos por HPLC-UV-ELSD-MS e UPLC-QToF-MS/MS, foi possível confirmar a presença de 6 tambjaminas conhecidas: tambjaminas A, C, D e K e os aldeídos das tambjaminas A e B. A quantificação do conteúdo de tambjaminas nas amostras de diferentes invertebrados por HPLC com detector de fluorescência demonstrou que T. stegosauriformis e T. brasiliensis possuem conteúdo de tambjaminas de 8 e 14 vezes superiores à sua presa V. dentata, enquanto que R. ernsti possui concentração de tambjaminas entre 3 e 5 vezes superiores à suas presas T. brasiliensis e T. stegosauriformis. Adicionalmente, análises metabolômicas não-direcionadas do extrato do manto de R. ernsti permitiram verificar a presença de 6 novas tambjaminas. A síntese, purificação e caracterização das novas tambjaminas permitiu confirmar a estrutura de 1 das tambjaminas inéditas.

Title in English
Metabolomic study of fungi of the genus Colletotrichum and tambjamines- producing marine organisms
Keywords in English
Colletotrichum
endophytic fungi
marine organisms
metabolomics
phytopathogenic fungi
tambjamines
Abstract in English

The present study describes the metabolomic investigation of fungi of the genus Colletotrichum and tambjamine-producing marine organisms Virididentula dentata, Tambja stegosauriformis, Tambja brasiliensis and Roboastra ernsti. Fungi belonging to the genus Colletotrichum cause disease in a wide variety of plants from different families. Secondary metabolites produced by these microorganisms can be part of the virulence process associated with their phytopathogenicity. Although many metabolites of Colletotrichum spp. have already been isolated and identified, the phytopathogenicity associated with fungi of this genus is not yet well established. In order to investigate the metabolic differences between endophytic and phytopathogenic strains of Colletotrichum spp., culture media produced by twenty-five isolates of Colletotrichum spp. were investigated, 16 of which were endophytic and 9 were phytopathogenic. The culture media were fractionated and analyzed by UPLC-IMS-QToF-HRMS. The raw data were processed using in-house tools and Molecular Networking. The evaluation of the results allowed us to conclude that endophytic and phytopathogenic strains of Colletotrichum spp. have considerably different metabolism. Endophytic strains produce compounds that are common to several strains in the group; phytopathogenic strains produce compounds more specific to each isolate. Dereplication of the GNPS exported results using an in-house library of compounds isolated from Colletotrichum fungi combined with in-silico fragmentation tools allowed the identification of 5 compounds in samples related to phytopathogenic strains. Those compounds display phytotoxic activity. Such results are a strong indication that the phytopathogenicity of Colletotrichum fungi may be associated with the production of phytotoxic compounds. Tambjamines are a group of alkaloids chemically related to prodigiosin and prodiginine, isolated from bacteria and marine organisms such as ascidians, bryozoans and nudibranchs. In addition to presenting diversified biological activities, tambjaminas are possibly related to the defense mechanisms of the organisms from which they are isolated. Several studies of tambjamine-producing marine organisms involved in prey-predator relationships have shown that these alkaloids were detected in extracts from both prey and predators. In this sense, extracts of V. dentata, T. stegosauriformis, T. brasiliensis and R. ernsti were obtained. The analysis of organic and aqueous extracts from marine organisms by HPLC-UV-ELSD-MS and UPLC-QTOF-MS/MS allowed us to confirm the presence of 6 known tambjamines: tambjamines A, C, D and K, and the aldehydes of the tambjamines A and B. The quantification of tambjamine content in samples from different invertebrates performed by HPLC with a fluorescence detector demonstrated that T. stegosauriformis and T. brasiliensis have tambjamines content 8 and 14 times higher than their prey V. dentata, while R. ernsti has tambjamines concentration between 3 and 5 times higher than their prey T. brasiliensis and T. stegosauriformis. Additionally, non-targeted metabolomic analyzes of the extract from the mantle of R. ernsti allowed to verify the presence of 6 new tambjamines. The synthesis, purification and characterization of the new tambjamines allowed to confirm the structure of 1 of the unprecedented tambjamines.

 
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Publishing Date
2020-09-01
 
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