O objetivo do presente trabalho foi estudar o efeito de diferentes limitações nutricionais sobre a produção de retamicina por Streptomyces olindensis ICB20. Realizaram-se cultivos contínuos empregando meios limitados em carbono, nitrogênio ou fosfato, variando-se a vazão específica de alimentação entre 0,025 e 0,075 h -1 . A análise dos dados dos cultivos mostrou que a produção de retamicina foi favorecida sob limitação por fosfato, resultando em velocidades específicas de produção (qRTM) da ordem de 9,2 mg/g.h em D=0,075 h -1 ; adicionalmente, qRTM variou linearmente com D, isto é, com a velocidade específica de crescimento, tal relação não foi observada sob limitação por carbono ou nitrogênio. O emprego de meio limitado em nitrogênio resultou nas menores velocidades específicas de produção, com valor máximo de 4,2 mg/g.h em D=0,043 h -1 . Cultivos empregando meio limitado em carbono levaram a valores intermediários de qRTM, variando entre 3,0 e 6,6 mg/g.h. Os maiores valores de fator de conversão glicose a célula (YX/GLC) foram obtidos em cultivos empregando meio limitado em carbono, aproximadamente, 0,40, enquanto que sob limitação por nitrogênio e fosfato, YX/GLC variou ao redor de 0,30. Para estudar o efeito de diferentes concentrações de glicose na alimentação, realizaram-se cultivos contínuos empregando meio limitado em fosfato com concentração de glicose variando entre 10 e 25 g/L. Os resultados mostraram que o emprego de concentrações de glicose superiores a 10 g/L levou a menor produção de retamicina, possivelmente devido à ocorrência de repressão catabólica. Os dados relativos à análise de imagens não indicaram nenhuma relação clara entre as diferentes limitações nutricionais e a morfologia nem entre as dimensões dos objetos e a produção. Entretanto, parece haver relação entre a porcentagem em área de diferentes classes morfológicas e a produção de retamicina, sendo que aparentemente, a produção é inversamente proporcional à porcentagem de clumps. / The aim of the present work was to assay the influence of different nutrient limitation on the production of retamycin by Streptomyces olindensis ICB20. A series of continuous cultures was performed using carbon-limited, phosphate-limited or nitrogen-limited media, varying the dilution rate (D) between 0.025 and 0.075 h -1 . The analysis of the cultures data showed that the production of retamycin was favored under phosphate limitation, resulting in values of specific production rate (qRTM) as high as 9.2 mg/g.h at D=0.075 h -1 , additionally, qRTM varied linearly with D, hence, with the specific growth rate; however such relationship was not observed in carbon-limited neither nitrogen-limited cultures. The use of nitrogen-limited medium led to the lowest production rates, with a maximum value of 4.2 mg/g.h at D=0.043 h -1 . Cultures using carbon-limited medium resulted in intermediary values of qRTM, varying between 3.0 and 6.6 mg/g.h. The highest values of biomass yield (YX/GLC) were obtained in cultures using carbon-limited medium, approximately 0.40, while under nitrogen and phosphate limitation, YX/GLC varied around 0.30. To study the effect of different glucose concentration in the feed medium, continuous cultures using phosphate-limited medium with glucose concentration varying between 10 g/L and 25 g/L were performed. The culture results showed that the use of glucose concentration higher than 10 g/L in the feeding medium led to lower production of retamycin, possibly due to catabolic repression. The data of image analysis showed no clear relation between nutrient limitation and morphology neither between objects dimensions and retamycin production. However, there seems to be a relation between the percentage in area of different morphological classes and retamycin production, apparently the production is inversely proportional to the percentage of clumps.

Wolbachia é uma bactéria intracelular obrigatória, de transmissão vertical, encontrada em tecidos reprodutivos de muitos artrópodes e nematóides. Ela manipula o ciclo reprodutivo de seus hospedeiros, induzindo partenogênese, feminização, morte de machos e incompatibilidade citoplasmática. No intuito de verificar a existência de alterações reprodutivas em mosquitos Culex quinquefasciatus infectados por Wolbachia (cepa B), tratamos com antibiótico uma colônia infectada e obtivemos uma colônia livre da infecção. Os mosquitos de nossas colônias apresentam o fenômeno de incompatibilidade citoplasmática. Paralelamente, a infecção causa redução do número de ovos e diminui a mortalidade de larvas e pupas, fazendo com que o número de adultos emergidos seja estatisticamente igual entre os animais infectados e não infectados. Além disso, observamos que mosquitos coletados na natureza, na cidade de São Paulo, Brasil, estão infectados pela mesma cepa da bactéria. / Wolbachia is an obligatory intracellular bacterium, maternally inherited, found in reproductive tissues of many arthropods and nematodes. It manipulates the reproductive behavior of their hosts, inducing parthenogenesis, feminization, male-killing and cytoplasmic incompatibility. In order to verify the existence of reproductive manipulation in Culex quinquefasciatus mosquitoes infected with Wolbachia (B strain), an infected population was treated with antibiotic to obtain a Wolbachia free colony. The mosquitoes of our colonies present the cytoplasmic incompatibility phenomenon. In parallel, infection causes reduction in the number of eggs and decreases the mortality of larvae and pupae, making the number of emerged adults statistically equal between the infected and uninfected animals. Furthermore, we observed that wild mosquitoes collected in Sao Paulo city, Brazil, are infected by the same strain of bacteria.

As endometrites representam um entrave à produção de bovinos leiteiros, à medida que a enfermidade diminui a fertilidade dos rebanhos e causa muitos prejuízos ligados ao custo de tratamento e perda produtiva. Este trabalho avaliou a validade e a eficiência do tratamento com Cefapirina, Ceftiofur e Oxitetraciclina. Para isso 120 animais diagnosticados com endometrite graus II e III pela técnica de histeroscopia fluida foram divididos em 4 grupos de 30 animais, sendo grupo controle (não tratado), um grupo tratado com 500 mg i.u. de Cefapirina, um grupo tratado com 6,6 mg/Kg de Ceftiofur e um grupo recebeu uma infusão de 4g de Oxitetraciclina i.u.. Os animais foram avaliados 4 vezes ou até alcançarem a cura. Avaliou-se o escore de condição corporal, a involução uterina por meio da mensuração dos diâmetros de cérvix e cornos uterinos, a presença e a característica do conteúdo uterino, o padrão hemodinâmico do útero, a resposta de citologia endometrial e a saúde endometrial por meio da histeroscopia. Os animais tratados com Cefapirina e Ceftiofur apresentaram diminuição da proporção de polimorfonucleares nas células recuperadas para citologia endometrial (P = 0,028). Todos os tratamentos apresentaram taxas de cura superior a do grupo controle, os tratamentos apresentaram taxa de cura pelo menos 23% superior a do controle (P = 0,042), porém não houve diferença entre os grupos. Não houve diferença na velocidade de cura entre os tratamentos. Em conclusão o emprego de tratamentos para endometrite é uma conduta aconselhável. Todos os tratamentos testados neste estudo obtiveram eficiência semelhante / Endometritis is a great barrier to the dairy production, as it diminishes fertility and causes economical losses with treatment costs and lowering production. This work has evaluated the value and the efficacy of the use of Cephapirin, Ceftiofur, and Oxitetracyclin for endometritis treatment. 120 animals were diagnosed with grade II and III endometrites trough hyteroscopic examination, and were allocated in four groups of 30 animals, control group (no treatment), Cephapin, that received i.u. Infusion of 500 mg of Cephapirin, Ceftiofur, received s.c. 6.6 mg/kg of Ceftiofur, and Oxitetracyclin, that got treated with i.u. Infusion of 4g of Oxitetracyclin. The animals were evaluated for four times or until they reached cure. Body condition score, Uterine involution assessed by ultrasound measurement of cervix and uterine horns, presence and the characteristic of uterine content, uterine hemodynamic patterns, cytology response, and uterine health response to treatment assessed by hysteroscopy were evaluated at each examination. Cows treated with Cephapirin and Ceftiofur presented a drop on the proportion of PMN retrieved at endometrial cytology examination (P = 0,028). All the treatments presented a bigger rate of cure than control group, at least 23% higher (P = 0,042); however, there was no difference among treatments. There was no difference on cure time among treatments. In conclusion, treating endometritis is an advisable conduct. All the treatments tested in this trial were equally efficient

The rapid emergence of multidrug resistant bacterial strains represents a major global healthcare issue. Amongst five known classes of membrane transporters, which play a huge role in multidrug efflux, primary-active ATP-binding cassette (ABC) transporters are ATP powered whilst secondary-active transporters utilize electrochemical ion gradients to drive substrate transport. Mechanistic insights into transport by these proteins can help with the design and development of novel therapeutic agents against multidrug resistance, and can increase our understanding of the physiological functions of these transporters. Although available crystal structures illustrate a common alternate access model for transport by ABC transporters, the mechanisms by which metabolic energy is coupled to the transport cycle is still elusive. This thesis presents a series of functional studies using whole cells as well as artificial phospholipid membranes to study the energetics of transport, and the influence of membrane phospholipids on substrate transport by the homodimeric Escherichia coli lipid A/multidrug ABC exporter MsbA. Current alternating access models for ABC exporters involve cycling between conformations with inward- and outward-facing substrate-binding sites in membrane domains (MDs) in response to engagement and hydrolysis of ATP at the nucleotide-binding domains (NBDs). Here we report that MsbA also utilizes another major energy currency in the cell by coupling substrate transport to a transmembrane electrochemical proton gradient. In this thesis, analogous substrate transport reactions are also studied for two other ABC exporters, the MsbA homologue LmrA and the human multidrug transporter ABCG2. The dependence of ATP-dependent transport on proton coupling, and the stimulation of MsbA-ATPase by the chemical proton gradient highlight the functional integration of both forms of metabolic energy. It also raises questions about the role of NBDs in the transport process. Comparisons of drug transport and resistance in cells expressing MsbA-MD (truncated MsbA lacking the NBD) and full length MsbA (MsbA-WT) demonstrate increased transport efficiency of MsbA-WT compared to MsbA-MD. In addition, growth studies using E. coli WD2 cells, which are conditionally defective in MsbA’s essential activity in lipid A transport, show that lipid A transport can be restored by the expression of MsbA-WT but not MsbA-MD or ATP-hydrolysis impaired Walker A mutant (MsbA- ΔK382). Lastly, we also present biochemical experiments with proteoliposomes with a defined phospholipid composition, which suggest that cardiolipin is essential for the transport activity of MsbA. These techniques open the way to further explore lipid-proteins interactions and examine the physiological role(s) of MsbA. In conclusion, this thesis produces new insights in the mechanisms of transport and energy coupling in ABC exporters.

Wolbachia é uma bactéria intracelular obrigatória, de transmissão vertical, encontrada em tecidos reprodutivos de muitos artrópodes e nematóides. Ela manipula o ciclo reprodutivo de seus hospedeiros, induzindo partenogênese, feminização, morte de machos e incompatibilidade citoplasmática. No intuito de verificar a existência de alterações reprodutivas em mosquitos Culex quinquefasciatus infectados por Wolbachia (cepa B), tratamos com antibiótico uma colônia infectada e obtivemos uma colônia livre da infecção. Os mosquitos de nossas colônias apresentam o fenômeno de incompatibilidade citoplasmática. Paralelamente, a infecção causa redução do número de ovos e diminui a mortalidade de larvas e pupas, fazendo com que o número de adultos emergidos seja estatisticamente igual entre os animais infectados e não infectados. Além disso, observamos que mosquitos coletados na natureza, na cidade de São Paulo, Brasil, estão infectados pela mesma cepa da bactéria. / Wolbachia is an obligatory intracellular bacterium, maternally inherited, found in reproductive tissues of many arthropods and nematodes. It manipulates the reproductive behavior of their hosts, inducing parthenogenesis, feminization, male-killing and cytoplasmic incompatibility. In order to verify the existence of reproductive manipulation in Culex quinquefasciatus mosquitoes infected with Wolbachia (B strain), an infected population was treated with antibiotic to obtain a Wolbachia free colony. The mosquitoes of our colonies present the cytoplasmic incompatibility phenomenon. In parallel, infection causes reduction in the number of eggs and decreases the mortality of larvae and pupae, making the number of emerged adults statistically equal between the infected and uninfected animals. Furthermore, we observed that wild mosquitoes collected in Sao Paulo city, Brazil, are infected by the same strain of bacteria.

Resumo:O florfenicol é um antibiótico utilizado para o tratamento de doença respiratória em bovinos. Estudar e compreender a sua farmacocinética são ferramentas importantes para o controle eficaz e adequado dessas enfermidades, minimizando assim o aparecimento de cepas bacterianas resistentes. Por isso, este estudo teve por objetivo determinar o perfil farmacocinético do florfenicol em plasma bovino após aplicação intramuscular de duas doses e avaliar a sua eficácia contra bactérias sensíveis. No estudo, foram utilizados 8 bovinos que receberam duas aplicações de florfenicol por via intramuscular e na posologia de 20 mg/Kg com intervalo de 48 horas. A concentração plasmática foi determinada por cromatografia líquida de alta performance acoplada a um espectrofotômetro de massa. A concentração inibitória mínima foi realizada em um laboratório veterinário seguindo os padrões internacionais do Clinical and Laboratory Standard Institute. Os parâmetros farmacocinéticos calculados foram: Cmax = 1,21 ± 0,25 µg/mL, Tmax = 3,43 ± 2,23 h, AUC0-t = 34,16 ± 4,50 h.µg/mL, T½ = 63,46 ± 23,76 h; e Cmax = 1,17 ± 0,20 µg/mL; Tmax = 6,00 ± 0,00 h; AUC0-t = 52,37 ± 5,50 h.µg/mL; T½ = 77,74 ± 43,65 h, respectivamente para a primeira e segunda aplicação. Os níveis de florfenicol no plasma mantiveram-se acima da concentração inibitória mínima para as bactérias: Mannheimia haemolytica (0,75 µg/mL), Pasteurella multocida tipo capsular A (0,75 µg/mL) e Histophilus sommus (0,30 µg/mL). Estes resultados comprovam a eficácia do florfenicol contra bactérias que causam a doença respiratória dos bovinos / Abstract:The florfenicol is an antibiotic used for the treatment of respiratory disease in cattle. Study and understand its pharmacokinetics are important tools for effective control of these diseases and appropriate, thereby minimizing the appearance of resistant bacterial strains. Therefore, this study aimed to determine the pharmacokinetic profile of florfenicol in bovine plasma after intramuscular injection of two doses and evaluate their effectiveness against susceptible bacteria. In the study, we used eight cattle that received two applications of florfenicol and intramuscularly at a dose of 20 mg/kg at intervals of 48 hours. The plasma concentration was determined by high performance liquid chromatography coupled to a mass spectrometer. The minimum inhibitory concentration was performed in a veterinary laboratory following the international standards of the Clinical and Laboratory Standards Institute. Pharmacokinetic parameters were calculated: Cmax = 1.21 ± 0.25 µg/mL, Tmax = 3.43 ± 2.23 h, AUC0-t = 34.16 ± 4.50 h.µg/mL, T½ = 63.46 ± 23.76 h, and Cmax = 1.17 ± 0.20 µg/mL, Tmax = 6.00 ± 0.00 h, AUC0-t = 52.37 ± 5.50 h.µg/mL, T½ = 77.74 ± 43.65 h, respectively for the first and second application. The florfenicol levels in plasma remained above the minimum inhibitory concentration for bacteria: Mannheimia haemolytica (0.75 µg/mL), Pasteurella multocida capsular type A (0.75 µg/mL) and Histophilus sommus (0.30 µg/mL). These results indicate the effectiveness of florfenicol against bacteria that cause respiratory disease of cattle / Orientador:Luiz Cláudio Nogueira Mendes / Banca:Sérgio Diniz Garcia / Banca:Antonio de Queiroz Neto / Mestre

Metabólitos secundários produzidos por Streptomyces com atividade antibiótica apresentam relevante importância biotecnológica para as indústrias farmacêuticas e agroquímicas. Dentre estes metabólitos, podemos destacar a nigericina, um antibiótico poliéter usado como aditivo em ração animal atuando como promotor de crescimento e no tratamento de algumas doenças, como a malária, em carcinoma nasofaríngeo, a vaccínia, entre outras. Neste trabalho foram avaliadas duas cepas de actinobactérias potenciais produtoras de nigericina, a EUCAL 26 e a EUCAL 74. As duas actinobatérias foram fermentadas em cinco meios de cultivo diferentes (BD, Czapek, ISP2, M29 e TSB). A cepa EUCAL 26 foi a mais promissora na produção de nigericina em meio Czapeck. A partir da EUCAL 26, foi feito um estudo da máxima produção de nigericina em meio Czapek variando o pH do meio, temperatura de fermentação, e período de fermentação. As melhores condições encontradas foram em pH 7,0 a 25 °C por 27 dias. Foi realizado também um estudo de otimização de aumento de escala de fermentação, de um volume de meio Czapeck de 50 mL, para um volume de 4 L. Também foram avaliados dois resíduos agroindustriais (Farmal e Melaço de Soja) para a produção de nigericina. O meio de Melaço de Soja aumento a produção em aproximadamente 300x quando comparado com o meio Czapeck padrão. Os efeitos dos nutrientes do meio Czapeck também foram avaliados. A retida do K2HPO4 do meio produziu um aumento de 50x na produção de nigericina, quando comparado com o meio Czapeck controle. Também foi avaliado o efeito da adição de -butirolactonas sintéticas, moléculas de sinalização hormonal, para a produção de nigericina. Das 15 -butirolactonas testadas, a DP21A foi a mais eficiente, pois além de aumentar a produção de nigericina em 23x, também diminui o período máximo de sua produção. Todas as analises realizadas neste trabalho para o monitoramento da produção de nigericina, foram feitas empregando a espectrometria de massas sequencial acoplada à cromatografia liquida de ultra eficiência. / Secondary metabolites produced by Streptomyces with antibiotic activity have significant biotechnological importance for the pharmaceutical and agrochemical industries. Among them, nigericin stands out as an antibiotic polyether used as growth promoter in animal feed and for treatment of some diseases such as malaria, nasopharyngeal carcinoma, and vaccinia. In this study, two actinobacteria strains considered potential producers of nigericin named EUCAL 26 and 74 were tested. The two actinobacteria were fermented in five different culture media (BD, Czapek, ISP2, M29 and TSB). EUCAL 26 strain was the most promising in producing nigericin in amid Czapeck media. For EUCAL 26, a study of maximum production of nigericin in Czapek medium at varying the pH, fermentation temperature and fermentation period have been performed. As a result, the best conditions were pH 7.0, at 25 °C for 27 days. In addition, an optimization study for scale-up fermentation have been done, where a volume of 50 mL Czapeck medium have been expanded to 4 L, in order to obtain the highest production of nigericin. Two agroindustrial residues (FARMAL and Honey Soy) have also been evaluated for nigericin production. The honey soy medium increased nigericin production in the rate of 300 when compared with standard Czapeck medium. The effects of nutrients from Czapeck medium have also been evaluated. Removal of K2HPO4 from culture medium resulted in an increase of 50 times when compared with the control Czapeck medium. The effect of adding synthetics -butyrolactones (hormone signaling molecules) for the production of nigericin have also been evaluated. From 15 tested -butyrolactones, DP21A was the most efficient. In addition to increase nigericin yield in 23x it also reduced the period for its maximum production. All analyzes performed in this study to monitor the nigericin production were performed using tandem mass spectrometry coupled to ultra high performance liquid chromatography.

Rhodococcus equi is a soil-dwelling facultative intracellular pathogen that can infect many mammals, including humans. R. equi is most well known for its ability to cause severe pyogranulomatous disease in foals, primarily involving the lungs although other body systems may also be affected. The disease is endemic on many horse-breeding farms worldwide and poses a severe threat to the horse breeding industry because there is no vaccine available. Current prophylaxis is based on systematic preventative treatments with macrolides combined with rifampicin, which are also used to treat clinical cases of the disease in foals. In this thesis I have used a combination of wet laboratory and bioinformatic approaches to identify the molecular basis of emerging combined resistance to macrolides and rifampicin in R. equi foal isolates from the USA. The genomes of a selection of resistant and susceptible strains from across the USA were sequenced and assembled. Resistance genes were systematically searched by reciprocal best-match BLASTP comparisons to known antibiotic resistance determinants. This led to the discovery of a novel erythromycin ribosomal methylase (erm) gene, erm(46), in all resistant strains. Complementation analysis in a susceptible R. equi strain showed that erm(46) was sufficient to confer resistance to all macrolides, lincosamides, and streptogramin B. The erm(46) gene is carried by an integrative conjugative element (ICE) which is transferable between R. equi strains. The ICE is formed by two distinct parts, a class I integron associated with an IS6100 sequence and the erm(46) determinant carried by a sub-element which contains putative actinobacterial conjugative translocase apparatus and a transposase/integrase. All resistant strains also carry the same non synonymous point mutation in rpoB conferring rifampicin resistance. Thus, these strains are carrying double resistance to the most commonly used antibiotics to treat R. equi worldwide. Phylogenetic analysis based on the core genome demonstrated that all resistant strains are clonal. This indicates that although conjugal acquisition of the erm(46) conjugative element may occur at a high frequency, the need for the concurrent presence of a second rpoB mutation for survival in the macrolide and rifampicin dominated farm environment has effectively selected for the spread of a single clone. In the second section of this work, we sequenced a further 20 R. equi genomes from difference sources (equine, porcine, bovine, human), including representatives of each of the seven major genogroups previously defined in our laboratory based on pulsed field gel electrophoresis. I have used the newly acquired genetic information to study the genome of R. equi and analyse its diversity within and outwith its species group. This enabled us to explore the pan genome and define that R. equi is a genetically well-defined bacterial species. Our results provide definitive evidence that resolves the current dispute over R. equi classification, specifically they do not support the recent proposal (based on classical polyphasic bacterial taxonomical methods) that R. equi should be transferred to a new genus. Our core-genome phylogenomic analyses unambiguously show that the genus Rhodocococcus is monophyletic and that R. equi forms a clade together with the most recently described related environmental species R. defluvii that radiates from within the genus. Together with other shared biological and genetic characteristics, namely the unique niche-adaptive mechanism based on evolutionarily related extrachromosomal replicons, R. equi should be conseidered a bona fide member of the genus Rhodococcus. We also confirm that Rhodococcus spp. and Nocardia spp. are sufficiently distinct to warrant them belonging to different genera. In conclusion, this work used whole genome sequencing to characterize the molecular basis underlying the emergence and clonal spread of multi-resistant R. equi in horse breeding farms in the USA. This work also highlights the limitations of classical taxonomical approaches in bacterial systematics, and illustrates the importance of incorporating modern phylogenomic approaches to understand the evolutionary relationships between bacterial strains and their accurate taxonomic position.

TB remains a major health issue worldwide causing around 1.5 deaths each year. The recent phase III clinical trials of shortened TB treatment failed to show superiority compared to the current regimen and this mainly because of relapse. Relapse is thought to be caused by dormant bacteria. Dormancy in Mycobacterium species has been shown to be associated with the accumulation of intracellular lipids, defining two phenotypes: the lipid rich (LR) cells (associated with dormancy) and the lipid poor (LP) cells (non-dormant). LR cells were shown to have a higher phenotypic antibiotic resistance compared to LP cells. Studying these two phenotypes is therefore central in tuberculosis research to understand better the disease and also potentially start to reveal the bacteriology of relapse. We investigated the power of Raman spectroscopy, a label-free and non-destructive technique, to discriminate LR and LP bacteria both in-vitro and ex-vivo. This represents the first Raman spectroscopy study that tries to discriminate the phenotypes of M. tuberculosis and investigate them directly at the site of the disease. Using total lipid extract of M. tuberculosis, we showed the location of the main lipid bands in the Raman spectrum. The two major lipid peaks were located around 1300 cm⁻¹ and 1450 cm⁻¹. Raman spectroscopy can discriminate LR and LP cells with high sensitivity and specificity. The main differences between the two groups are located in the two major Raman lipid peaks, the lipid band A (1300 cm⁻¹) and lipid band B (1440 to 1450 cm⁻¹). The two phenotypes were successfully discriminated in TB infected guinea pig lung tissue sections also from in-vitro culture using wavelength modulated Raman (WMR) spectroscopy combined with fluorescence imaging. We developed a protocol to perform both Raman spectroscopy and immunohistochemistry on the same tissue sample. We studied the evolution of LR and LP proportion in mycobacterial population as the growth conditions changed and showed that LR cells could rapidly convert to LP cells as they face favourable growth conditions. The results presented in this thesis showed that LR M. tuberculosis cells could be predominant at the site of infection. This would suggest that drug sensitivity testing should be performed on culture presenting both LR and LP cells in high proportion.

Efficient delivery into cells is essential for many applications. However, cellular access of “cell-impermeable” molecules, such as drugs, sensors, proteins and oligonucleotides, can often be severely limited due to the plasma membrane which protects cells from unregulated influx of hydrophilic materials. In order to solve this issue, several physical techniques and bio-chemical products are today available. One of them is called peptoids (N-alkylglycines). These compounds are peptidomimetics which are resistant to enzymatic degradation, non-immunogenic and are readily prepared by an Fmoc chemical approach. Peptoids based on the "TAT"-peptide (RKKRRQRRR) offer rapid cellular uptake/delivery and low cytotoxicity. In this thesis, based on previous works using fluorescein-cationic peptoids, various fluorescent N-substitued glycines (lysine-like) were prepared by the monomer method followed by solid-phase synthesis. Their cellular uptakes in vitro into several cell lines (such as HeLa, B16F10, HEK293T and primary immune cells) were examined via flow cytometry and microscopy. The cellular delivery of small molecules mediated by the 9mer polymer achieved an efficient and rapid penetration. These results open up a vast number of applications for delivery of macromolecules using nonalysine-like peptoid. In order to demonstrate this ability, the nonalysinelike carrier was used to deliver various biopolymer molecules such as peptides, GFP protein and DNA (in collaboration with Dr. Stefano Caserta). In addition, thanks to the non-cytotoxicity of this cellular transpoter (MTT assays); experiments were carried out in vivo in mice using peptoids labelled near-infrared dyes. The first results have shown that the peptoid is not toxic for the mouse and does not block cell movements. These results allowed the use of 9mer-peptoid as a cellular tracking agent. Based on the development on antimicrobial peptides, the polylysine-like peptoid was also tested as an antibiotic. Recent experiments carried out in collaboration with Dr. Kevin Dhaliwal have revealed a new antimicrobial property of the peptoids. In vitro and in vivo studies have been carried out using both gram positive and negative bacteria. These results present a promising alternative to conventional antibiotics and antimicrobial peptides (AMPs).