Orientador: Odair Correa Bueno / Banca: Luiz Carlos Forti / Banca: Ana Paula Protti de Andrade Crusciol / Banca: Maria Santina de Castro Morini / Banca: Sulene Noriko Shima / Resumo: O presente trabalho teve como objetivo o estudo da evolução dos comportamentos de preparação do substrato, cuidado com a cria e cuidado com a rainha e alados em formigas cultivadoras de fungo. Estas formigas pertencem à tribo Attini, subfamília Myrmicinae, e ocorrem exclusivamente no continente americano. Esta tribo contém aproximadamente 230 espécies, porém pouco se conhece da biologia da maioria delas, graças ao fato de serem extremamente crípticas e de não apresentarem importância econômica, como as formigas cortadeiras, que são as mais estudadas. Foram utilizadas seis espécies, que representam bem os diversos níveis da filogenia da tribo: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus e Trachymyrmex sp. nov. Os comportamentos foram estudados em ninhos mantidos em laboratório, com o auxílio de micro-câmeras e um aparelho gravador de vídeo. Os comportamentos foram analisados, caracterizados e quantificados. Os resultados foram divididos em três capítulos de acordo com o tipo de comportamento. No capítulo sobre a evolução dos comportamentos de preparação do substrato foi observado que, basicamente, o processo evoluiu no sentido de aumentar a capacidade das operárias em decompor inicialmente o substrato. As espécies basais, A. pilosum, M. parallelus e Myrmicocrypta sp. apresentaram um processamento mais simples com um número menor de comportamentos e principalmente sem os comportamentos do tratamento químico, que é responsável pela fragmentação do substrato ao mesmo tempo em que ele é tratado com enzimas digestivas. As duas espécies do gênero Trachymyrmex apresentaram um processo mais complexo com grande participação do tratamento químico. Em A. disciger, que é uma cortadeira, há uma intensa especialização do sistema de castas para o aumento da eficiência... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work aims to study the evolution of the behaviors of substrate preparation, brood, queen and winged forms care in fungus growing ants. These ants are included in the tribe Attini, subfamily Myrmicinae, and occur exclusively in the american continent. This tribe contains approximately 230 species, but little is known about the biology of most of them, tanks to the fact that they show very cryptic habits and are not economically important, like the leaf cutting ants, which are the most studied. Six species were used in this work, which represent well all the levels of the phylogeny of the tribe: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus and Trachymyrmex sp. Nov. The behaviors were studied in laboratory nests, with a set of micro cameras and a video recording device. The behaviors were analyzed, characterized and quantified. The results were summarized and discussed in tree chapters, arranged by type of behavior. In the chapter about the evolution of the substrate preparation behaviors, basically it is assumed that this process evolved in order to develop the capacity of previously decompose the substrate by the workers. In the basal species, A. pilosum, M. parallelus and Myrmicocrypta sp. this process is very simple with a small number of behaviors and principally without the behaviors of chemical treatment, which are responsible for the fragmentation of the substrate as it is treated by with digestive enzymes. In the two species of the genus Trachymyrmex, the process became more complex and showed a greater participation of these behaviors. A. disciger, witch is a leaf cutting ant, showed an extensive specialization of physical castes in all the phases of the process which elevated it's efficiency. In the chapter about the evolution of the behaviors of brood care... (Complete abstract click electronic access below) / Doutor

All living organisms require food for growth and survival. Heterotrophs depend on autotrophs such as green plants which can synthesize their own food unlike heterotrophic animals. Among heterotrophs, only humans and some insects have the remarkable ability to cultivate crops for food. While humans cultivate plants, three insect lineages—ants, termites, and beetles—cultivate fungi inside their nests in obligate mutualistic exo-symbioses. Interestingly, just like human agriculture, insect fungus farms are also threatened by weeds and pests, e.g. the farms of fungus-growing termites which cultivate Termitomyces fungi can be overgrown by weeds such as the parasitic fungus Pseudoxylaria. Studies on ant and beetle fungus-farming systems have uncovered the important role of chemicals and behaviour in helping these insects to protect their crops from parasitic fungi. On the other hand, studies on the termite system till now, have only revealed the presence of antifungal compounds and actinobacteria which are largely non-specific and inhibitory to the mutualistic crop fungi. Antifungal behavioural mechanisms, if present, are yet to be discovered. Therefore, this thesis focuses on different anti-Pseudoxylaria mechanisms employed by fungus-growing termites, viz. role of nest abiotic factors, mechanism of fungal recognition by termite hosts, behavioural response of termite to Pseudoxylaria presence and coupling of this behaviour to anti-Pseudoxylaria activity. The present thesis has been divided into six chapters. CHAPTER 1 gives a brief literature review on fungus-farming insects and the different mechanisms which insects employ in order to keep their fungal farms safe from growth of parasitic fungi with specific reference to fungus-growing termites. The obligate mutualistic interaction between termites and the Termitomyces fungus is 19–49 My-old and is, therefore, a very ancient agriculture system. The mutualistic fungus is cultivated on partially digested plant matter called fungus comb inside the nest and harvested by termites for nutrition. At the same time, the weedy fungal parasite Pseudoxylaria can compete with the mutualistic fungus for nutrition leading to negative effects on the fungal farms. Termite hosts are believed to use abiotic factors, antibiotics and hygienic behaviours to keep their fungal gardens free from parasitic fungi such as Pseudoxylaria. However, the actual mechanisms used by termites against parasitic fungi are unclear. Unravelling the proximate mechanisms used in fungal cultivar protection is central to understanding the evolutionary stability of these farming mutualisms. CHAPTER 2 examines the diversity and population genetic structure of Termitomyces and Pseudoxylaria strains associated with the fungus-growing termite Odontotermes obesus. Genetic diversity of cultivar and parasite could have important implications for the stability of the mutualistic interaction, e.g. genetic clonality arising from monoculture is generally thought to make populations more prone to infection by parasites. Using molecular phylogenetic tools, within-nest genetic homogeneity was found in Termitomyces species but not in Pseudoxylaria species. Lower OTU but higher genotypic diversity (within the most abundant OTU) was found in the genus Termitomyces compared to Pseudoxylaria. Additionally, population genetics methods suggested a sexual population structure for Termitomyces and clonal propagation for Pseudoxylaria species. This is the first study to investigate the population genetics of the symbiotic fungi associated with the termite genus Odontotermes or any other termite species from India. In CHAPTER 3, the effect of nest micro-environment alone on the growth of the parasitic fungus Pseudoxylaria was examined. For this, seasonal changes in nest xiii temperature and CO2 were recorded and in situ and ex situ growth experiments were performed on Pseudoxylaria. The monthly pattern of mound temperatures was found to be similar to the outside—cycling from highs in summer to lows in winter—but characterised by dampened variation compared to high daily fluctuations outside. Moreover, the mound CO2 levels were found to be orders of magnitude above atmospheric levels and, unlike the outside, were characterised by daily and monthly fluctuations. With in situ experiments during summer and winter, the effect of these dissimilar conditions—inside and outside mounds—was examined on Pseudoxylaria growth. The growth of the parasite was found to be greater inside than outside the mound. Following this, the growth of different parasite isolates under controlled ex situ conditions was examined—spanning the variation in environmental conditions that mounds exhibit daily and seasonally. High CO2 levels decreased parasitic fungal growth in general but temperature had an isolate-dependent effect. Taken together, these results suggested that the parasite is adapted to survive in the mound. However, mound environmental conditions still seemed to exert a negative effect on parasite growth, even if they cannot inhibit Pseudoxylaria completely. These results shed light on the possible new role of termite-engineered structures in impacting parasitic fungus ecology, independent of any direct role of termites in suppressing parasite growth. This is the first study to investigate the effect of abiotic factors on Pseudoxylaria growth. In CHAPTER 4, whether termites can differentiate between Termitomyces and Pseudoxylaria was investigated. In a novel, laboratory-based choice assay, termites displayed a differential response towards the two fungi by burying the Pseudoxylaria with agar. Also, termites were found to be able to differentiate between the fungi using olfactory cues, i.e. smell, alone, for this task. The mutualistic and parasitic fungi were found to emit unique volatile bouquets which could help termites to distinguish between them. This is important because, whether termites use antifungal compounds or hygienic behaviours, it is crucial that they are able to differentiate between the parasitic and mutualistic fungi so that they can selectively use antifungal mechanisms—whether chemical or behavioural—against Pseudoxylaria. This is of special significance because, many actinobacteria and anti-Pseudoxylaria compounds isolated from this system till now, lack specificity and inhibit the mutualistic Termitomyces as well. Also, fungal grooming and weeding behaviours as displayed by fungus-growing ants have not yet been reported in termites. This is the first study to show that termites have the behavioural capacity to differentiate between the mutualistic and parasitic fungi in an ecologically relevant setting. In CHAPTER 5, whether the burying of Pseudoxylaria could affect its growth was investigated. It was found that termites can utilise agar, glass beads and soil for deposition over the offered fungal plugs but the use of agar and glass beads did not inhibit Pseudoxylaria growth effectively. On the other hand, soil deposition was found to decrease growth of both Pseudoxylaria and Termitomyces fungi post-burial. However, Pseudoxylaria was found to be affected more strongly than Termitomyces. Further, hypoxia acting alone seemed to decrease only Pseudoxylaria survival without any apparent effect on Termitomyces. Therefore, hypoxia induced by soil deposition may be the reason behind the decrease in Pseudoxylaria survival. However, presence of antifungal compounds can not be ruled out and they may be selectively applied in larger quantities on Pseudoxylaria with soil deposition. This study demonstrates an anti-Pseudoxylaria activity of this insect behaviour, unique to termites among fungus-farming insects, to the presence of the parasitic fungus. CHAPTER 6 concludes the findings of this thesis and suggests a working model for the mechanism of growth suppression of Pseudoxylaria inside a termite nest. In particular, focus is on the important role of abiotic factors when combined with termite behaviour in the apparent absence of Pseudoxylaria from termite nests. These results not only shed new light on how the ecology of these fungi is affected by their termite host but also reveal the mechanistic bases that may contribute fundamentally to the evolutionary stability of this ancient mutualism.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-14Bitstream added on 2014-06-13T20:46:50Z : No. of bitstreams: 1 diniz_ea_dr_rcla.pdf: 624691 bytes, checksum: 0bce2c8708444f08d4428ee602667889 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho teve como objetivo o estudo da evolução dos comportamentos de preparação do substrato, cuidado com a cria e cuidado com a rainha e alados em formigas cultivadoras de fungo. Estas formigas pertencem à tribo Attini, subfamília Myrmicinae, e ocorrem exclusivamente no continente americano. Esta tribo contém aproximadamente 230 espécies, porém pouco se conhece da biologia da maioria delas, graças ao fato de serem extremamente crípticas e de não apresentarem importância econômica, como as formigas cortadeiras, que são as mais estudadas. Foram utilizadas seis espécies, que representam bem os diversos níveis da filogenia da tribo: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus e Trachymyrmex sp. nov. Os comportamentos foram estudados em ninhos mantidos em laboratório, com o auxílio de micro-câmeras e um aparelho gravador de vídeo. Os comportamentos foram analisados, caracterizados e quantificados. Os resultados foram divididos em três capítulos de acordo com o tipo de comportamento. No capítulo sobre a evolução dos comportamentos de preparação do substrato foi observado que, basicamente, o processo evoluiu no sentido de aumentar a capacidade das operárias em decompor inicialmente o substrato. As espécies basais, A. pilosum, M. parallelus e Myrmicocrypta sp. apresentaram um processamento mais simples com um número menor de comportamentos e principalmente sem os comportamentos do tratamento químico, que é responsável pela fragmentação do substrato ao mesmo tempo em que ele é tratado com enzimas digestivas. As duas espécies do gênero Trachymyrmex apresentaram um processo mais complexo com grande participação do tratamento químico. Em A. disciger, que é uma cortadeira, há uma intensa especialização do sistema de castas para o aumento da eficiência... / This work aims to study the evolution of the behaviors of substrate preparation, brood, queen and winged forms care in fungus growing ants. These ants are included in the tribe Attini, subfamily Myrmicinae, and occur exclusively in the american continent. This tribe contains approximately 230 species, but little is known about the biology of most of them, tanks to the fact that they show very cryptic habits and are not economically important, like the leaf cutting ants, which are the most studied. Six species were used in this work, which represent well all the levels of the phylogeny of the tribe: Acromyrmex disciger, Apterostigma pilosum, Mycetarotes parallelus, Myrmicocrypta sp., Trachymyrmex fuscus and Trachymyrmex sp. Nov. The behaviors were studied in laboratory nests, with a set of micro cameras and a video recording device. The behaviors were analyzed, characterized and quantified. The results were summarized and discussed in tree chapters, arranged by type of behavior. In the chapter about the evolution of the substrate preparation behaviors, basically it is assumed that this process evolved in order to develop the capacity of previously decompose the substrate by the workers. In the basal species, A. pilosum, M. parallelus and Myrmicocrypta sp. this process is very simple with a small number of behaviors and principally without the behaviors of chemical treatment, which are responsible for the fragmentation of the substrate as it is treated by with digestive enzymes. In the two species of the genus Trachymyrmex, the process became more complex and showed a greater participation of these behaviors. A. disciger, witch is a leaf cutting ant, showed an extensive specialization of physical castes in all the phases of the process which elevated it’s efficiency. In the chapter about the evolution of the behaviors of brood care... (Complete abstract click electronic access below)

Orientador: Odair Correa Bueno / Resumo: Atualmente, a tribo Attini compreende 45 gêneros e entre eles estão as formigas-cortadeiras cultivadoras de fungo, pertencentes aos gêneros Atta e Acromyrmex, que causam grandes danos econômicos a agricultura devido ao intenso corte de materiais vegetais frescos para cultivo do seu fungo simbiôntico Leucogaricus gongylophorus. Essas formigas apresentam diferentes mecanismos de defesa para proteger seus ninhos contra organismos competidores. Dentre esses mecanismos está a defesa humoral e celular (inata e adquirida) do sistema imune interno e a defesa imune externa, que inclui qualquer característica atuando no ambiente capaz de melhorar sua proteção contra patógenos, sendo esta caracterizada em formigas pela remoção física de patógenos e pela secreção de compostos antimicrobianos advindos de glândulas exócrinas e simbiontes bacterianos. Poucos estudos buscam integrar os diferentes fatores envolvidos na capacidade defensiva das formigas a fim de compreender estratégias fisiológicas adquiridas para proteger a colônia. Diante disso, a presente pesquisa teve por objetivo investigar a defesa da formiga-cortadeira Atta sexdens contra patógenos. Para tanto, realizamos a revisão sistemática dos mecanismos de defesa das formigas discutidos na literatura, a qual nos direcionou para investigação da defesa química externa dessa espécie de formiga. Os ensaios conduzidos foram de atividade enzimática, análise cromatográfica e testes de inibição de fungos patógenos e antagonistas. Verificam... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Currently Attini tribe comprises 45 genera and among them are fungus-growing leaf-cutting ants belonging to the genera Atta and Acromyrmex. They cause great economic damage to agriculture due to the intense cutting of fresh plant material for cultivation of its symbiotic fungus Leucogaricus gongylophorus. These ants present different defense mechanisms to protect their nests against competing organisms. Among these mechanisms is the humoral and cellular defense (innate and acquired) of the internal immune system and the external immune defense. This last one includes any hereditary characteristic acting in the environment and being capable of improve its protection against pathogens. It is characterized in ants by the physical removal of pathogens and by secretion of antimicrobial compounds from exocrine glands and bacterial symbionts. Few studies have sought to integrate the different factors involved in ants' defensive capacity in order to understand physiological strategies acquired to protect the colony. In this way, the present research had the goal to investigate the defense of the ant-cutter Atta sexdens against pathogens. For this, we performed the systematic review of ant defense mechanisms discussed in the literature, which directed us to investigate the external chemical defense of this ant species. The tests carried out were of enzymatic activity, chromatographic analysis and tests of inhibition of pathogenic and antagonistic fungi. We have observed that secretion... (Complete abstract click electronic access below) / Mestre

No description available.

The fungus-growing ants have long provided a spectacular example of co-evolutionary integration between distantly related taxa. Their ecological success has been thought to depend largely on the evolutionary alignment of reproductive interests between ants and fungi, following vertical transmission and the ancient suppression of fungal sexuality. In my dissertation I explored the role of lateral cultivar switching on the evolution of the fungus-gardening ant mutualism. First, I provided the first evidence for sexual reproduction in the attine cultivars, together with evidence of extensive independent long-distance horizontal transmission of fungal genes. In fact, fungi have greater gene flow relative to their host ants, crossing the Gulf of Mexico between Latin America and Cuba, over which the ants cannot readily disperse. Second, for the special case of leaf-cutting ants, I show that the cultivar population was largely unstructured with respect to host ant species, and leaf-cutting ants interact largely with a single species of fungus. Finally, I examined the effect of post-glacial expansion on the population structure of the northern fungus-gardening ant Trachymyrmex septentrionalis and compared it with that of its two microbial mutualists: a community of lepiotaceous fungal cultivars and associated antibiotic-producing Pseudonocardia bacteria. This comparison allowed me to examine the effect of historical biogeographic forces, such as climate-driven range shifts, on the population structure of the ants and their microbial symbionts. While neither the cultivar nor the Pseudonocardia genetic structure was correlated with that of the ants, they were significantly, though weakly, correlated with each other. These results suggest that biogeographic forces may act differently on macro- and microscopic organisms, even in the extreme case where some microbial mutualists may be vertically transmitted from generation to generation and share the same joint ecological niche. Thus, binding forces that appear to enforce host fidelity are relatively weak and pairwise associations between cultivar lineages and ant species have little opportunity for evolutionary persistence. Taken together, my studies suggest that mechanisms other than long-term pairwise interactions between ants and fungi (so-called partner fidelity feedback) govern the evolution of the mutualism over evolutionary time. / text

Há uma simbiose quadripartida no ecossistema das formigas cultivadoras de fungos entre três mutualistas (Formiga da tribo Attini, jardim fúngico e actinomicetos simbiontes) e um parasita (fungo patogênico especializado Escovopsis sp). As actinobactérias associadas à formiga hospedeira produzem metabólitos secundários para inibir este patógeno, mas não o fungo mutualista. Produtos naturais interessantes foram relatados a partir destas bactérias com um amplo espectro de atividades biológicas. Portanto, várias actinobactérias foram isoladas do exoesqueleto e do jardim das formigas agricultoras para isolar compostos ativos contra diferentes alvos como Leishmania donovani e Escovopsis. Os antibióticos e compostos citotóxicos conhecidos griseorhodina A (1), griseorhodina C (2), griseorhodina G (3) e a dinactina (4) foram produzidos em cultivo sólido de ISP-2 por Streptomyces puniceus AB10, que foi isolada da formiga cortadeira Acromyrmex rugosus rugosus. As configurações absolutas de 1 e 2 foram inequivocamente estabelecidas como 6S,6aS,7S,8S e 6R,6aS,7S,8R, respectivamente, usando dicroísmo circular vibracional (VCD) e cálculos da Teoria do Funcional de Densidade (DFT). A bactéria Streptomyces puniceus AB10 produziu em meio-A líquido apenas uma familia de antibióticos como a dinactina (4). O composto 4 mostrou inibição contra Escovopsis e uma atividade maior contra L. donovani em promastigota e amastigota intracelular que a miltefosina. Dois estereoisômeros, strepchazolina A (5) e strepchazolina B (6), os antibióticos streptazolina (7), seu isômero-E (8), e o composto inorgânico octa-enxofre (9) foram produzidos em cultivo sólido de ISP-2 por Streptomyces chartreusis AC70, que foi isolada do jardim fúngico da formiga cortadeira Acromyrmex subterraneus brunneus. O composto 9 mostrou atividade antagonista contra o fungo patogênico especializado Escovopsis sp. Este é o primeiro relato de 8 como produto natural. As configurações absolutas de 5 e 6 foram inequivocamente estabelecida como 5S,6S,9R e 5S,6S,9S, respectivamente, usando dicroísmo circular vibracional (VCD) e cálculos da Teoria do Funcional de Densidade (DFT). A bactéria Candidatus Streptomyces philanthi ICBG292, isolada do exoesqueleto de operária de colônia de formiga Cyphomyrmex, produziu os antibióticos Mer-A2026B (10), piericidina-A1 (11) e nigericina (12). Os compostos 10-12 mostraram atividade contra Escovopsis sp e contra L. donovani. O composto 12 mostrou uma atividade maior contra L. donovani em promastigota e amastigota intracelular que a miltefosina. O composto 10 também foi ativo contra o fungo Trichoderma sp. Streptomyces sioyaensis ICBG311, isolada de machos alados de colônia de formiga Cyphomyrmex, produziu uma nova naftoquinona chamada cyphoquinona (13), dois novos compostos antifúngicos denominados cyphomycina (14) e epoxicyphomycina (15), e o antifúngico conhecido GT-35 (16). Os compostos 14-16 mostraram atividade contra diferentes linhagens de Escovopsis sp e Candida albicans K1 com MIC de 1.0, 0.5 e 0.25 ?g/mL, e uma atividade maior contra L. donovani em promastigota e amastigota intracelular que a miltefosina, enquanto 13 apresentou atividade baixa contra L. donovani. A cyphomycina (14) também mostrou uma potente atividade in vitro contra os patógenos humanos resistentes Aspergillus fumigatus 11628 (resistente à equinocandina), C. glabrata 4720 (resistente ao triazol), e C. auris B11211 (resistente à echinocandina, ao triazol, e à anfotericina B), com MIC de 0.5, 0.5 e 4 ?g/mL, respectivamente. Um estudo de dose única de cyphomycina (14) no modelo de camundongos neutropênicos de candidíase disseminada exibiu uma dose-resposta iv com um log de redução de 0.56 e 0.66 do carga infecciosa quando é tratado com 20 e 40 mg/kg da cyphomycina (14), respectivamente, e epoxicyphomycina (15) exibiu um log de redução de 0.53 com 40 mg/kg, demonstrando relevância clínica e eficácia de 14 e 15 neste modelo padrão da indústria de infecção por Candida. Por outro lado, GT-35 (16) matou os ratos 1 hora após a dose de 40 mg/kg. / There is a quadripartite symbiosis in the fungus-growing ant ecosystem between three mutualist (Attine ant, fungal garden and symbiotic actinomycetes) and one parasite (specialized pathogenic fungus Escovopsis sp). The actinobacteria associated to the ant host produce secondary metabolites to inhibit this pathogen but not the crop fungus. Interesting natural products have been reported from these bacteria with a wide spectrum of biological activities. In this thesis, several actinobacteria were isolated from the exoskeleton and garden of fungus-growing ants to isolate active compounds against different targets such as Leishmania donovani and Escovopsis. The known antibiotic and cytotoxic compounds griseorhodin A (1), griseorhodin C (2), griseorhodin G (3) and dinactin (4) were produced in solid ISP-2 culture by Streptomyces puniceus AB10, which was isolated from the leaf-cutter ant Acromyrmex rugosus rugosus. The absolute configurations of 1 and 2 were unambiguously established as 6S,6aS,7S,8S and 6R,6aS,7S,8R, respectively, using vibrational circular dichroism (VCD) and density functional theory (DFT) calculations. The bacterium Streptomyces puniceus AB10 produced in broth A-medium only one family of antibiotics as dinactin (4). Compound 4 showed inhibition against Escovopsis and a higher activity against L. donovani promastigotes and intracellular amastigotes than miltefosine. Two stereoisomers strepchazolin A (5) and strepchazolin B (6), the antibiotic streptazolin (7), its E-isomer (8), and the inorganic compound cyclooctasulfur (9) were produced in solid ISP-2 culture by Streptomyces chartreusis AC70, which was isolated from the fungal garden of the leaf-cutter ant Acromyrmex subterraneus brunneus. Compound 9 showed antagonist activity against the specialized pathogenic fungus Escovopsis sp. This is the first report of 8 as natural product. The absolute configurations of 5 and 6 were unambiguously established as 5S,6S,9R and 5S,6S,9S, respectively, using vibrational circular dichroism (VCD) and density functional theory (DFT) calculations. The bacterium Candidatus Streptomyces philanthi ICBG292, isolated from the exoskeleton of a worker of a Cyphomyrmex colony, produced the antibiotics Mer-A2026B (10), piericidin-A1 (11) and nigericin (12). Compounds 10-12 showed activity against Escovopsis sp and against L. donovani. Compound 12 showed higher activity against L. donovani promastigotes and intracellular amastigotes than miltefosine. Compound 10 was also active against the fungus Trichoderma sp. Streptomyces sioyaensis ICBG311, isolated from winged male ants of Cyphomyrmex colonies, produced a new naphtoquinone named cyphoquinone (13), two new antifungal compounds named cyphomycin (14) and epoxycyphomycin (15), and the known antifungal GT-35 (16). Compounds 14-16 displayed activity against several strains of Escovopsis sp and Candida albicans K1 with a MIC of 1.0, 0.5 and 0.25 ?g/mL, and a higher activity against L. donovani promastigotes and intracellular amastigotes than miltefosine, while 13 a weak activity against L. donovani. Cyphomycin (14) also showed potent in vitro activity against the resistant human pathogens Aspergillus fumigatus 11628 (echinocandin resistance), C. glabrata 4720 (triazole resistance), and C. auris B11211 (echinocandin, triazole, and amphotericin B resistance), with MIC of 0.5, 0.5 and 4 ?g/mL, respectively. A single-dose study of cyphomycin (14) in a neutropenic mouse disseminated candidiasis model exhibited a dose-like response with 0.56 and 0.66 log reduction of infectious burden when treated with 20 and 40 mg/kg cyphomycin (14), respectively, and epoxycyphomycin (15) exhibited 0.53 log ii reduction with 40 mg/kg, demonstrating clinical relevance and effectiveness of 14 and 15 in this industry-standard model of Candida infection. On the other hand, GT-35 (16) killed the mice 1 hr post dose at 40 mg/kg.

La diversité fongique des meules de plusieurs espèces de Macrotermitinae a été analysée au niveau taxinomique, fonctionnel et génétique à l’aide d’une approche polyphasique associant plusieurs techniques complémentaires. L’objectif étant d’évaluer la spécificité des taxons fongiques associés aux meules ainsi que les relations qu’ils entretiennent avec les termites champignonnistes. Une grande variété de phylotypes cultivables appartenant majoritairement au phylum des Ascomycètes a été obtenue par isolement et séquençage des ITS fongiques, et peu de séquences se sont révélées être spécifiques à un genre de Macrotermitinae particulier. Les profils physiologiques obtenus ont mis en évidence la nature saprophytique de la majorité des phylotypes et confirmé l’absence de taxons spécifiques. Par PCR-DGGE de l’ADN total de meules, 100% des phylotypes ITS et 28S fongiques identifiés étaient affiliés au genre Termitomyces. La technique Suicide Polymerase Endonuclease Restriction (SuPER) a été adaptée à la mycoflore des meules pour limiter l’impact de l’ADN majoritaire du Termitomyces symbiotique. Celle-ci a permis la détection de plusieurs autres populations fongiques. Les analyses phylogénétiques ont montré d’une part la spécificité des Xylaria associés aux meules de Macrotermitinae bien qu’aucune co-évolution n’ait été observée avec les termites hôtes et d’autre part leur affiliation dans un sous-genre spécifique. Une analyse préliminaire des facteurs d’inhibition a également révélé l’implication des termites dans la régulation des communautés fongiques des meules. Dans leur ensemble, nos résultats illustrent clairement l’influence des Macrotermitinae sur les communautés fongiques telluriques pendant leurs différentes activités. / Fungal diversity of several Macrotermitinae fungus combs was analyzed at taxonomic, functional and genetic levels using a polyphasic approach. The aim of this thesis was to evaluate the specificity of fungal strains from combs and to elucidate their relationship with fungus-growing termites. A large variety of culturable phylotypes mainly belonging to Ascomycota phylum was retrieved using conventional isolation techniques followed by sequencing of ITS1-5.8S-ITS2 region. Based on the obtained results, there is evidence for any speciesspecificity between these taxa and a given genus of Macrotermitinae. This finding was supported by the physiological profile of some representative phylotypes which revealed the saprophytic nature of most of the isolates. By PCR-DGGE analysis of fungal ITS and LSU, all of the sequences were belonged to Termitomyces genus. The Suicide Polymerase Endonuclease Restriction method was adapted to the analysis of comb mycoflora for restricting the impact of the dominant Termitomyces DNA. As expected, this latter technique revealed non-Termitomyces fungal populations. Phylogenetic analysis also showed the specificity of termiteassociated Xylaria although they do not evolved with termite hosts, and also their affiliation to a new genus or at least a specific sub-genus. Preliminary investigation revealed the implication of termite workers in fungal regulation in fungus combs. All in one, our results clearly underline the great impact of fungus-growing termite species on soil fungal community during their activities.

No description available.