Identificación y caracterización de rickettsia sp. y sus posibles artrópodos vectores en el estado de Nuevo León y Veracruz, México.

Tesis (Doctorado en Ciencias con Acentuación en Entomología Médica) UANL, 2012.

Identification de composés naturels contre Saprolegnia sp., un champignon pathogène en aquaculture

La saprolégniose est une maladie fongique causée par le champignon aquatique Saprolegnia sp. qui affecte les poissons sauvages et ceux provenant des piscicultures. L’apparition de touffes cotonneuses semblables à de la ouate de couleur blanche à grise est souvent la première indication de l’infection. Ce saprophyte ubiquitaire se nourrit habituellement des œufs de poissons morts, mais peut se propager rapidement aux œufs sains causant la mort de ces derniers. La saprolégniose est souvent une infection secondaire, mais des souches virulentes peuvent facilement se développer sur les salmonidés ayant subi un stress ou une mauvaise manipulation. De grandes pertes économiques associées à la saprolégniose sont rapportées chaque année à travers le monde surtout dans l’industrie de la pisciculture. Jusqu’en 2002, le contrôle de la saprolégniose pouvait se faire par l’utilisation du vert de malachite, un colorant organique ayant une grande activité antifongique. Malheureusement, cette molécule a été bannie à cause de ses propriétés cancérigènes. Aucun composé aussi efficace n’est actuellement disponible pour traiter les infections de la saprolégniose. Des molécules ou extraits naturels ayant un potentiel antifongique ont donc été testés à l’aide de deux techniques (par graines de chanvre et par cylindre d’agar). Les molécules d’un extrait de propolis (cire de ruches d’abeilles) démontrant de l’activité anti-Saprolegnia ont été identifiées. De plus, une bactérie, Pseudomonas aeruginosa, pouvant être retrouvée dans le même environnement que Saprolegnia sp. a démontré un effet antagoniste au champignon. Une molécule de signalisation intercellulaire produite par P. aeruginosa, 4-hydroxy-2-heptylquinoline (HHQ), a été identifiée comme responsable de l’effet antagoniste contre Saprolegnia sp.

Perception d’effort et de mise en charge et asymétrie motrice lors du passage assis à debout chez le sujet hémiparétique

L’asymétrie de mise en charge (MEC) lors du passage assis à debout (PAD) chez les personnes hémiparétiques est une observation clinique connue mais peu expliquée. Ce projet visait donc le développement de connaissances sur les facteurs explicatifs de l’asymétrie de MEC chez cette clientèle en s’intéressant plus spécifiquement au lien entre la distribution des efforts aux genoux lors du PAD et l’asymétrie de MEC observée ainsi qu’à la perception de ces deux éléments lors de cette tâche. Ainsi, les objectifs généraux étaient de : 1) déterminer si l’exécution spontanée asymétrique du PAD des sujets hémiparétiques est expliquée par une distribution des efforts symétriques aux genoux en quantifiant ces efforts par le Taux d’utilisation musculaire électromyographique (TUMEMG) et, 2) déterminer si les individus hémiparétiques sont conscients des stratégies motrices qu’ils utilisent en évaluant leurs perceptions de MEC et d’efforts aux genoux durant le PAD. La première étude a évalué la capacité des personnes hémiparétiques à percevoir leur distribution de MEC aux membres inférieurs lors du PAD. Par rapport aux participants sains, leur distribution de MEC fut davantage asymétrique et leurs erreurs de perception plus élevées. La deuxième étude a quantifié la distribution des efforts aux genoux chez les sujets sains et hémiparétiques lors du PAD spontané. Les deux groupes ont montré une association entre leur distribution de MEC et leur distribution d’effort. Toutefois, la relation était plus faible chez les patients. Le classement des participants hémiparétiques en sous-groupes selon leur degré d’asymétrie de force maximale des extenseurs des genoux (faible, modéré, sévère) a révélé une similarité des efforts aux genoux parétique et non parétique chez le groupe ayant une atteinte sévère. La troisième étude a déterminé si la perception de la distribution des efforts aux genoux des sujets hémiparétiques était reliée à leur distribution réelle d’effort mesurée lors de PAD exécutés dans différentes positions de pieds. En plus d’être incapables de percevoir les changements de distribution d’effort induits par les différentes positions de pieds, leurs erreurs de perception d’effort furent plus élevées que celles de MEC. Par le biais du test fonctionnel assis-debout de cinq répétitions, la dernière étude a déterminé l’influence du nombre de répétitions du PAD sur les distributions de MEC et d’efforts aux genoux chez les sujets sains et hémiparétiques. Contrairement aux contrôles, les distributions des sujets hémiparétiques furent plus asymétriques à la première répétition du test fonctionnel que lors de l’exécution spontanée unique du PAD. En somme, les résultats de cette thèse ont démontré que la distribution des efforts aux genoux doit être considérée parmi les facteurs explicatifs de l’asymétrie de MEC des individus hémiparétiques lors du PAD et qu’il y a un besoin de mieux documenter la perception des personnes hémiparétiques lorsqu’elles exécutent des tâches fonctionnelles.

Évaluation de l'impact de l'utilisation de tylosine et de virginiamycine sur les profils de résistance aux antimicrobiens chez enterococcus SP. et Escherichia coli isolés de porcs

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Développement d'un outil d'évaluation de l'équilibre assis chez les individus ayant une lésion à la moelle épinière: Une étude exploratoire

Travail d'intégration réalisé dans le cadre du cours PHT-6113.

L-Glutaminase production by an immobilized marine Pseudomonas sp. BTMS -51

The present study is about the Pseudomonas sp. BTMS-51 isolated from the marine sediments of Cochin Coast. In the present study, it is concluded that marine bacteria are ideal candidates for immobilization using either Ca-alginate entrapment or physical adsorption on to synthetic inert supports and the process of immobilization does not negatively influence them. Thus, Ca-alginate entrapment of the bacteria was found to be well suited for reuse of the biomass and extended operational stability during continuous operation. Adherence of the bacterium to inertsupports was observed to be strong and it imparted minimal stress on the immobilized bacterium and allowed detachment and relocation on the supports which enabled the formation of a dynamic equilibrium maintaining a stable cell loading. This is particularly desirable in the industry for extended operational stability and maintenance of consistently higher outputs. Marine Pseudomonas sp. BTMS-51 is ideal for industrial production of extra cellular L-glutaminase and immobilization on to synthetic inert support such as polyurethane foam could be an efficient technique, employing packed bed reactor for continuous production of the enzyme. Temperature and glutamine concentration had significant effects on enzyme production by cells immobilized on polyurethane foam (PUF).

Process Optimization for Mass Production of Marine Yeast Candida sp. S 27 and its Nutritional Characterization

The main source of protein for human and animal consumption is from the agricultural sector, where the production is vulnerable to diseases, fluctuations in climatic conditions and deteriorating hydrological conditions due to water pollution. Therefore Single Cell Protein (SCP) production has evolved as an excellent alternative. Among all sources of microbial protein, yeast has attained global acceptability and has been preferred for SCP production. The screening and evaluation of nutritional and other culture variables of microorganisms are very important in the development of a bioprocess for SCP production. The application of statistical experimental design in bioprocess development can result in improved product yields, reduced process variability, closer confirmation of the output response to target requirements and reduced development time and overall cost.The present work was undertaken to develop a bioprocess technology for the mass production of a marine yeast, Candida sp.S27. Yeasts isolated from the offshore waters of the South west coast of India and maintained in the Microbiology Laboratory were subjected to various tests for the selection of a potent strain for biomass production. The selected marine yeast was identified based on ITS sequencing. Biochemical/nutritional characterization of Candida sp.S27 was carried out. Using Response Surface Methodology (RSM) the process parameters (pH, temperature and salinity) were optimized. For mass production of yeast biomass, a chemically defined medium (Barnett and Ingram, 1955) and a crude medium (Molasses-Yeast extract) were optimized using RSM. Scale up of biomass production was done in a Bench top Fermenter using these two optimized media. Comparative efficacy of the defined and crude media were estimated besides nutritional evaluation of the biomass developed using these two optimized media.

Production of Alkaline Protease by Free and Immobilised Cells of VIBRIO sp. Under Different Fermentation Systems and Its Application on Deproteinisation of Prawn Shell Waste for Chitin Recovery

This thesis presents a detailed account of a cost - effective approach towards enhanced production of alkaline protease at profitable levels using different fermentation designs employing cheap agro-industrial residues. It involves the optimisation of process parameters for the production of a thermostable alkaline protease by Vibrio sp. V26 under solid state, submerged and biphasic fermentations, production of the enzyme using cell immobilisation technology and the application of the crude enzyme on the deproteinisation of crustacean waste.The present investigation suggests an economic move towards Improved production of alkaline protease at gainful altitudes employing different fermentation designs utilising inexpensive agro-industrial residues. Moreover, the use of agro-industrial and other solid waste substrates for fermentation helps to provide a substitute in conserving the already dwindling global energy resources. Another alternative for accomplishing economically feasible production is by the use of immobilisation technique. This method avoids the wasteful expense of continually growing microorganisms. The high protease producing potential of the organism under study ascertains their exploitation in the utilisation and management of wastes. However, strain improvement studies for the production of high yielding variants using mutagens or by gene transfer are required before recommending them to Industries.Industries, all over the world, have made several attempts to exploit the microbial diversity of this planet. For sustainable development, it is essential to discover, develop and defend this natural prosperity. The Industrial development of any country is critically dependent on the intellectual and financial investment in this area. The need of the hour is to harness the beneficial uses of microbes for maximum utilisation of natural resources and technological yields. Owing to the multitude of applications in a variety of industrial sectors, there has always been an increasing demand for novel producers and resources of alkaline proteases as well as for innovative methods of production at a commercial altitude. This investigation forms a humble endeavour towards this perspective and bequeaths hope and inspiration for inventions to follow.

Alkaline Protease from a Non-toxigenic Vibrio sp.(V26) and its Applications

The thesis presents a detailed account of the alkaline protease produced by Vibrio sp.(V26) a mangrove isolate,and the application of this enzyme in different fields.The protease producer strain was identified on the basis of biochemical characteristice,putative virulence traits and 16S rRNA gene sequencing.The purification and characterization of the protease has been carried out. Along with this, an attempt has been made to identifiy the protease gene. The physical parameters as well as the media components influencing protease production were optimized using Response Surfce Methodology(RSM).The scale up of the application of the protease from Vibrio sp.(V26) in the dissociation of cells in animal cell culture,in the recovery of silver from used X-ray films as well as an ingredient in commercial detergents were investigated.

Pigment production by marine Serratia sp. BTWJ8

The marine microorganisms are yet to be exploited as a source of natural pigments for probable utilization in various industries. Hence, in this study focus was made only on pigment producing marine bacteria for pigment production and evaluation of the same for some application besides development of an ideal bioprocess for subsequent indigenous production of the pigment using the same organism towards ultimate industrial application.

Physicochemical and molecular characterization of bacteriophages ΦSP-1 and ΦSP-3, specific for pathogenic Salmonella and evaluation of their potential as biocontrol agent

This thesis entitled Physicochemical and molecular characterization of bacteriophages ΦSP-1and ΦSP-3, specific for pathogenic Salmonella and evaluation of their potential as biocontrol agent . Salmonella were screened using standard methodologies from various environmental samples including chicken caecum. Salmonella strains, which were previously isolated and stocked in the lab, were also included in this study as host, for screening Salmonella specific lytic phages. The Salmonella strain in this study designated as S49 which helped in phage propagation by acting as host bacteria was identified as Salmonella enterica subsp. enterica by 16S rRNA gene analysis and serotyping . A total of three Salmonella specific phage named as ΦSP-1, ΦSP-2 and ΦSP-3 were isolated from chicken intestine samples via an enrichment protocol employing the double agar overlay method. ΦSP-1 and ΦSP-3 showing consistent lytic nature were selected for further study and were purified by repeated plating after picking of single isolated plaques from the lawns of Salmonella S49 plates. Both the phages produced small, clear plaques indicating their lytic nature. ΦSP-1 and ΦSP-3 were concentrated employing PEG-NaCl precipitation method before further characterization. The focus of present study was to isolate, characterize and verify the efficacy of lytic bacteriophages against the robust pathogen Salmonella, capable of surviving under various hostile conditions. Two phages, ΦSP-1 and ΦSP-3, belonging to two families, Podovoridae and Siphoviridae were isolated.

Characterization of polyhydroxyalkanoates accumulating vibrios from marine benthic environments and production studies of polyhydroxyalkanoates by Vibrio sp. BTKB33

The present work deals with the characterization of polyhydroxyalkanoates accumulating vibrios from marine benthic environments and production studies of polyhydroxyalkanoates by vibrio sp.BTKB33. Vibrios are a group of (iram negative, curved or straight motile rods that normally inhabit the aquatic environments.The present study therefore aimed at evaluating the occurrence of PHA accumulating vibrios inhabiting marine benthic environments; characterizing the potential PHA accumulators employing phenotypic and genotypic approaches and molecular characterization of the PHA synthase gene. The study also evaluated the PHA production in V:'hri0 sp. strain BTKB33, through submerged fennentation using statistical optimization and characterized the purified biopolymer. Screening for PHA producing vibrios from marine benthic environments. Characterization of PHA producers employing phenotypic and genotypic approaches.The incidence of PHA accumulation in Vibrio sp. isolated from marine sediments was observed to be high, indicating that the natural habitat of these bacteria are stressful. Considering their ubiquitous nature, the ecological role played by vibrios in maintaining the delicate balance of the benthic ecosystem besides returning potential strains, with the ability to elaborate a plethora of extracellular enzymes for industrial application, is significant. The elaboration of several hydrolytic enzymes by individuals also emphasize the crucial role of vibrios in the mineralization process in the marine environment. This study throws light on the extracellular hydrolytic enzyme profile exhibited by vibrios. It was concluded that apart from the PHA accumulation, presence of exoenzyme production and higher MAR index also aids in their survival in the highly challenging benthic enviromnents. The phylogenetic analysis of the strains and studies on intra species variation within PHA accumulating strains reveal their diversity. The isolate selected for production in this study was Vibrio sp. strain BTKB33, identified as V.azureus by 16S rDNA sequencing and phenotypic characterization. The bioprocess variables for PHA production utilising submerged fermentation was optimized employing one-factor-at-a-time-method, PB design and RSM studies. The statistical optimization of bioprocess variables revealed that NaCl concentration, temperature and incubation period are the major bioprocess variables influencing PHA production and PHA content. The presence of Class I PHA synthase genes in BTKB33 was also unveiled. The characterization of phaC genes by PCR and of the extracted polymer employing FTIR and NMR analysis revealed the presence of polyhydroxybutyrate, smallest known PI-IAs, having wider domestic, industrial and medical application. The strain BTKB33 bearing a significant exoenzyme profile, can thus be manipulatedin future for utilization of diverse substrates as C- source for PHA production. In addition to BTKB33, several fast growing Vibrio sp. having PHA accumulating ability were also isolated, revealing the prospects of this environment as a mine for novel PHA accumulating microbes. The findings of this study will provide a reference for further research in industrial production of PHAs from marine microorganisms .

Investigations on Phaeocystis sp., A Harmful Bloom- Forming Alga Isolated from Cochin Estuary

Considering the importance of diversity of micro algae in our ecosystem and new invasion of many organisms, an attempt was made to monitor the Cochin estuary along the south west coast of India for the qualitative distribution of phytoplankton and to study the growth kinetics and allelopathic effect of the phaeocystis sp. Isolated from the cochin estuary. Phaeocystis blooms are common only in high latitude environments and they rarely occur in low latitude environments such as tropics and subtropics. As phaeocystis is grouped under harmful alga ,in the present study the factors causing the blooms formation in the ecosystem. The nutrient concentration of the water body along with other physiochemical parameters that includes temperature salinity and ph play an important role in triggering the bloom of phaeocystis .The phaeocystis harbor specific bacterial flora associated with it and they exert an important role in the growth ,haemolytic activity and the bloom phases of the alga. The harmful alga mainly depends on the production of alleopathic compounds for the establishment of bloom in the marine environments .These physiological properties of the phaecystis were considered for the study, along with the role of nutrients in the allelopathic and hemolytic activity

Studies on L-glutamic acid Production using Brevibacterium sp.

The thesis comprises a set of experiments mainly focused on the improvement of L-glutamic acid fennentation. Much attention has been given to use of locally available raw materials, culturing the organism on inert solid substrates and also immobilization of the bacterial cells from the view point of long term utilization of biocatalyst and continuous operation of the stabilized system. Studies were also carried out for the down stream processing for the extraction and purification of L-glutamic acid. An attempt was made to study the morphological features of the microorganism including the cell premeability. In relation with the accumulation of glutamic acid within the cells an approach was made to study the behaviour of the Brevibacterium cells when they are exposed to hyper osmotic environment. Attempts were also made to study the requirement of iron and production of siderophores by this microbial strain. The search for a suitable nitrogen source for glutamate fermentation ended with a promising result that they got a potent urease activity and it can be utilized for many biotransfonnation studies. The entire thesis is presented in three sections, viz. introductory section, experimental section and the concluding section

Fermentation Of Rice And Related Products By Bacillus Sp.

Recently’ recognition cnf immobilization ‘technology for the rapid conversion of several substrates into metabolites and repeated reuse of the biocatalysts have drawn the attention of the fermentation scientists and technologists to try these new technologies for the rapid production of pnxkmt and enhancement of the efficiencies of the systems Hence in the present study rice was selected,as a substrate since it is a rich source of starch, available and cultivated throughout the year almost in all part of our country. Rice although known for its use as a staple food in many forms as rice, idli, dosai etc., has not been used in industry extensively. However, it ii; a potential resource for’ the production of alcohol, high protein food anui for sugar and sugar syrups as it is evidenced by the few reports mentioned in the review of literature. Of the several microorganisms available, Bacillus sp, is a known candidate for the production of amylases. Hence in the present study Bacillus sp, was desired for its known efficiencies in starch conversion