Sustainable rehabilitation can be compromised by the inability of vegetation to survive in hostile mine wastes on a long-term basis. The adverse chemical and physical properties of mine wastes, together with extreme pH conditions and lack of nutrients, provide poor growth conditions for vegetation during seed development and germination. This raises concern for the long-term survival of vegetation through means of seed production when under stress from the punitive properties of mine wastes. Seed vigour is a function of a variety of factors to which the parent plant is subjected during seed formation and maturation. Environmental conditions experienced by the maternal plant during the growth season plays a significant role in determining subsequent germination rates in seeds. Traits of offspring seed depend on the abiotic environment attributed by the growth medium during seed development and maturation The general aim of this study was to determine the viability of seed produced by a previous generation of grass species established in eight different mine wastes and two soils (namely: gypsum wastes; gold tailings with low pyrite content; gold tailings with high pyrite content; platinum tailings; kimberlite mine waste; fluorspar mine waste; andalusite mine waste; coal discard; red soil; and vertic soil) in order to identify suitable species for specific mine wastes to ensure long-term survival through means of seed production. The species selected included: Eragrostis curvula; Eragrostis tef; Cenchrus ciliaris; Eragrostis curvula; Digitaria eriantha; Cynodon dactylon; Chloris gayana; Hyparrhenia hirta; and Sorghum bicolor. The progeny seed‟s viability and ability to germinate were determined through a pot trial study and additional germination testing at the laboratory of Advance Seed (Pty) Ltd. (AS). The germination results were correlated with the growth media analyses by statistical non-parametric correlations which indicated several significant correlations among the growth media properties themselves, and with the germination of the progeny seed. C. gayana (Rhodes grass) seed had poor germination percentages, especially seed harvested from Rhodes grass grown in acidic wastes. Seed harvested from each of the E. curvula grasses grown in various mine wastes, had excellent germination percentages. According to the Repeated Measures ANOVA statistical analysis, there was a significant influence of the growth media in which the parent grass were grown as a variable on the germination of the progeny seed batches from S. bicolor, C. ciliaris, C. gayana, and D. eriantha, indicating that the environmental factors as attributed by the growth media, i.e. the eight different mine waste materials and two soils, and experienced by the maternal plant, did indeed influence the germination of progeny seed. However, it was found that significant correlations between the properties of the growth media and the germination of the progeny seed, was species dependent. The second general aim for this study was to evaluate above-ground re-growth of parent plants after cutting in the mine waste materials and soil types mentioned above. The ability of established grasses to re-grow after a cutting event was determined by cutting the above-ground biomass of the parent grasses, after which it was scored according observable above-ground growth in the following growth season. The measurement of re-growth was subjectively done by scoring the grasses according to observable above-ground biomass. Re-growth was observed for all the perennial grass species. This can be ascribed to the grasses showing resilience to stress factors attributed by the growth media; or new grasses which emerged from seed that collected in the pots, being mistaken for re-growth; or new emerging grasses from the nodes of stolons and/or rhizomes being mistaken for re-growth. However, the emergence of new grasses was an indicator of good health, as biomass allocation to rhizomes and stolons is reduced under low nutrient availability and stress conditions. Therefore the emergence of new grasses is indicative that the plant is either tolerant to stress conditions or that the plant adapted to the restriction of growth due to the roots being bound to the size of the pot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Sustainable rehabilitation can be compromised by the inability of vegetation to survive in hostile mine wastes on a long-term basis. The adverse chemical and physical properties of mine wastes, together with extreme pH conditions and lack of nutrients, provide poor growth conditions for vegetation during seed development and germination. This raises concern for the long-term survival of vegetation through means of seed production when under stress from the punitive properties of mine wastes. Seed vigour is a function of a variety of factors to which the parent plant is subjected during seed formation and maturation. Environmental conditions experienced by the maternal plant during the growth season plays a significant role in determining subsequent germination rates in seeds. Traits of offspring seed depend on the abiotic environment attributed by the growth medium during seed development and maturation The general aim of this study was to determine the viability of seed produced by a previous generation of grass species established in eight different mine wastes and two soils (namely: gypsum wastes; gold tailings with low pyrite content; gold tailings with high pyrite content; platinum tailings; kimberlite mine waste; fluorspar mine waste; andalusite mine waste; coal discard; red soil; and vertic soil) in order to identify suitable species for specific mine wastes to ensure long-term survival through means of seed production. The species selected included: Eragrostis curvula; Eragrostis tef; Cenchrus ciliaris; Eragrostis curvula; Digitaria eriantha; Cynodon dactylon; Chloris gayana; Hyparrhenia hirta; and Sorghum bicolor. The progeny seed‟s viability and ability to germinate were determined through a pot trial study and additional germination testing at the laboratory of Advance Seed (Pty) Ltd. (AS). The germination results were correlated with the growth media analyses by statistical non-parametric correlations which indicated several significant correlations among the growth media properties themselves, and with the germination of the progeny seed. C. gayana (Rhodes grass) seed had poor germination percentages, especially seed harvested from Rhodes grass grown in acidic wastes. Seed harvested from each of the E. curvula grasses grown in various mine wastes, had excellent germination percentages. According to the Repeated Measures ANOVA statistical analysis, there was a significant influence of the growth media in which the parent grass were grown as a variable on the germination of the progeny seed batches from S. bicolor, C. ciliaris, C. gayana, and D. eriantha, indicating that the environmental factors as attributed by the growth media, i.e. the eight different mine waste materials and two soils, and experienced by the maternal plant, did indeed influence the germination of progeny seed. However, it was found that significant correlations between the properties of the growth media and the germination of the progeny seed, was species dependent. The second general aim for this study was to evaluate above-ground re-growth of parent plants after cutting in the mine waste materials and soil types mentioned above. The ability of established grasses to re-grow after a cutting event was determined by cutting the above-ground biomass of the parent grasses, after which it was scored according observable above-ground growth in the following growth season. The measurement of re-growth was subjectively done by scoring the grasses according to observable above-ground biomass. Re-growth was observed for all the perennial grass species. This can be ascribed to the grasses showing resilience to stress factors attributed by the growth media; or new grasses which emerged from seed that collected in the pots, being mistaken for re-growth; or new emerging grasses from the nodes of stolons and/or rhizomes being mistaken for re-growth. However, the emergence of new grasses was an indicator of good health, as biomass allocation to rhizomes and stolons is reduced under low nutrient availability and stress conditions. Therefore the emergence of new grasses is indicative that the plant is either tolerant to stress conditions or that the plant adapted to the restriction of growth due to the roots being bound to the size of the pot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

The reduction of pathogenic microorganisms is essential to minimize human health risks associated with the reuse, reclamation, and recycling of wastewater and the land application of biosolids (sewage sludge). The most advanced treatment technologies, as well as, the most representative methods and indicator organisms are necessary to ensure public safety. The goal of this dissertation is to assess advanced Bardenpho wastewater treatment technologies in regards to virus removal, suggest the most appropriate viral indicators of human fecal contamination and/or treatment process controls, and develop an updated method for enumerating Ascaris ova viability in land applied biosolids. Appendix A evaluates the incidence of 11 different virus types in sewage throughout a 12-month time period, and their subsequent reduction via advanced Bardenpho treatment processes. This study showed that wastewater treatment facilities utilizing advanced Bardenpho for secondary treatment are more effective at reducing viruses in wastewater than facilities utilizing conventional aeration basin and trickling filter processes. Appendix B develops a new method for determining the viability of Ascaris ova in land applied biosolids. In this method, early development stages prior to larval-development, are included in the estimation of potential viability. Comparisons between viability enumerations suggests that the conventional microscopy method, in which only ova containing motile larva are considered viable, underestimates the number of eggs that may progress to an infectious stage. Whereas, the method based on early-to-late stage development, considers the potential viability of all eggs, providing a more conservative approach.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / Thesis submitted in partial fulfilment for the degree of Master of Science (polymer science) at Stellenbosch University / ENGLISH ABSTRACT: The goal of this study was to synthesize hybrid hydrogels via a chemical crosslinking mechanism through use of chain end functional poly(N-vinyl pyrrolidone)(PVP) with various topologies. The crosslinking chemistries should be benign in nature i.e. at physiological pH ranges and at 37 °C. The degradation products should be biologically tolerable and renal clearance should be possible (< 30 000 g/mol PVP0. PVP of various topologies, controlled molar mass and quantitative chain end functionality was obtained via Reversible Addition Fragmentation chain Transfer (RAFT) mediated polymerization (PDI = 1.1- 1.4). The synthesized polymers were chain end functionalized to introduce thiol or aldehyde moieties. Thiol chain ends were obtained through post polymerization modification of xanthate functional PVP with either aminolysis or reduction. The aldehyde moiety was obtained by post polymerization modification of xanthate end functional PVP with sequential hydrolysis and thermolysis. Thiol functional four arm star PVP was reacted with acrylate difunctional poly(ethylene glycol) (DIAC PEG) crosslinker under standard Michael addition conditions. In order to obtain thioether crosslinked hydrogels from tetra functional star PVP molecules it was found that a minimum thiol functionalization of 30% and a molar ratio of acrylate:thiol of 1:1.1 is required. The Schiff base reaction was used to synthesize imine or secondary amine (after reduction) crosslinks with the lysine residues on either lysozyme or bovine serum albumin (BSA) or the primary amines of bis-(2-amino ethyl)amine). Hydrogels were obtained from aldehyde functionalized PVP molecules with a fraction of functional aldehyde chain ends of 0.88 for difunctional molecules and 0.50 for tetra functional star PVP molecules with lysozyme or BSA crosslinkers. The reaction rate was favoured by lowered pH (<6.0) and an optimum molar ratio of amine : aldehyde of 1:0.8. Hydrogels were analyzed by equilibrium swelling calculations to determine the molar mass between crosslinks and the estimated pore size. In both crosslinking systems the properties of the formed hydrogels were seen to be affected by molar ratio used and by the topology of the crosslinking agent. PVP BSA and PVP PEG hydrogels were tested for 24 h and 48 h cell viability by using H9C2 myoblast cells. A concentration range of 0.25 x 10(2) to 0.01 g/mL was studied. Cell mortality was tested by Trypan blue staining and results were verified with MTT assay. A very low cell death precentage (<37%)was observed. Cells even appeared to experience a stimulatory effect after 48 h of exposure at low concentrations of PVP PEG hydrogel treatments. The properties of the formed hydrogel could be tuned by the molar mass ratios of PVP and crosslinker. The functionality of the crosslinker directly affects the molar mass between crosslinks and thus indirectly the degradation profile. It was concluded that PVP molecules with various topologies, well-defined molar masses and chain end functionality could be obtained via RAFT mediated polymerization. Obtained polymers were successfully modified and crosslinked to obtain hydrogels with stoichiometrically tuneable properties i.e. initial swelling ratio, degradation time, molar mass between crosslinks. The hydrogels had very positive cell viability results that would definitely justify further research into these materials as “tissue-mimetic” materials. / AFRIKAANSE OPSOMMING: Die doel van die studie is om poli(N-viniel pirollidoon) (PVP) gebaseerde hibried hidrogelle te sintetiseer deur middel van kovalente kruisbindings met toepaslike kruisverbinder molekules. Die chemiese reaksies betrokke in die vorming van hierdie kovalente kruisbindings moet gematig van aard wees, by fisiologiese pH en by 37 °C plaasvind. Die degradasieprodukte van die hibried-hidrogel moet biologies verdraagsaam en ook uitskeibaar deur die endokrinologiese sisteem wees. PVP van verskillende topologieë, beheerde molêre massa en kwantitatiewe kettingendfunksionaliteit is berei deur ‘n omkeerbare addisie-fragmentasiekettingoordrag (OAFO)-beheerde polimerisasieproses (PDI = 1.1-1.4). Xantaat-kettingend-PVP is aangepas na thiol of aldehied kettingendfunksies. Thiolendfunksies is verkry deur middel van ‘n aminolisasie-reaksie. Xantaat kettingend-PVP is stapsgewys gemodifiseer deur hidroliese en verhittingstappe om die aldehied ketting-endfunksionaliteit te bekom. Thiol ketting-endfunksionele vier-armige ster-PVP is kovalent gebind aan difunksionele poly(etileen glikol) deur middel van die Michael-addisiereaksie. PVP PEG hidrogelle het slegs gevorm met vier-armige ster-PVP molekules wat oor ‘n minimum van 30 % thiol-funksionaliteit beskik het en ‘n optimale molêre massa verhouding van 1:1.1 vir ankrilaat to thiol. Die Schiff-basisreaksie is gebruik om hidrogel te sintetiseer wat met imiene of amiene (na redusering) kovalente bindings gekruisbind is. In hierdie sisteme het hidrogel slegs gevorm as die aldehied-PVP molekules oor ‘n fraksie funksionele kettingend-waarde van 0.88 vir dialdehied-PVP molekules en 0.5 vir vier armige ster-PVP molekules beskik het. Die reaksie snelheid van die Schiff-basis kovalente bindings is bevoordeel deur die pH te verlaag (≤ 6.0) en ‘n gunstige molêre massa verhouding van 1:0.8 vir die nukleofiel teen oor die akseptor molekule is waargeneem. Ewewigswel berekeninge is gebruik om die molêre massa tussen kruisbindings en die gemiddelde benaderde porieë binne die drie-dimensionele interne struktuur van die hydrogel te bepaal. Die seltoksisiteit van PVP-BSA en PVP-PEG hidrogelle is oor 24 h en 48 h in die teenwoordigheid van H9c2 mioblast-selle getoets. Die hydrogel behandelings is uitgevoer in ‘n konsentrasie reeks van 0.25 x 10(2) tot 0.01 g/mL. Selmortaliteit is getoets deur ‘n Trypan-blou verkleuringstudie. Hierdie resultate is ondersteun deur MTT sel-lewensvatbaarheidstoetse. ‘n Lae selmortaliteit (≤ 37 %) is waargeneem en, opspraakwekkend, het van die selle na 48 h verhoogde vitaliteit getoon in die teenwoordigheid van lae konsentrasies PVP-PEG hidrogelle. Dit is bevind dat hidrogel eienskappe deur stoichiometriese molêre massa verhoudings asook die keuse in die topologie van kruisverbinder beïnvloed word. Hierdie eienskappe het ‘n direkte effek op die degradasieprofiel van die gevormde hidrogel. Samevattend dus is PVP molekules met ‘n variasie van topologieë, spesifieke molêre massas en kettingfunksionalitete deur middel van OAFO-gemedieerde polimerisasies gesintetiseer. Xantaatkettingendfunksionele PVP-molekules kon suksesvol omgeskakel word na die kettingendfunksionaliteit van ons keuse om ‘n hibriedhidrogel met stoichiometries-manupileerbare eienskappe te sintetiseer. Die positiewe sel-lewensvatbaarbheidstudie resultate staaf verdere ondersoeke in hierdie PVPgebaseerde hibried hidrogelmateriaal as ‘n weefsel nabootsingsmateriaal.

Canadian Prairie agriculture, in general, is expected to benefit under climate change with increasing mean temperatures projected for the immediate future. However, a number of knowledge gaps still exist. Foremost among these is the measurement of the effects of extreme climate events in a given year as well as their long-term impact on the supply of agricultural products, and also the financial situation of farms. In addition, the economic impacts of climate change on livestock operations are relatively under-studied. In particular, knowledge of the impacts on Prairie beef cattle remains more guesswork than research-based evidence. This dissertation assesses the impact of changes in the normal climate as well as the impact of climate extremes by including projected inter-annual climate variability. The economic impact of these changes on crops, beef cattle activities and the viability of farms in mixed operation settings is measured. Correspondingly, this work presents alternative adaptation measures and their likely use in managing mixed farm operations for future extreme weather events. For the analysis, two study sites are selected: (1) the Oldman River Basin of Alberta, called Pincher Creek, and (2) the Swift Current Creek Basin of Saskatchewan, called Swift Current. This study is a part of a larger project entitled “Vulnerability and Adaptation to Climate Extremes in the Americas” and the study sites are intended to represent the project catchment areas in the provinces of Alberta and Saskatchewan. I develop what I call a MF-CCE model (Mixed Farm model for the economic impact assessment of Climate Change and Extremes). The MF-CCE is a whole farm simulation model that integrates models of beef cattle production, crop production and climate changes into farm level economic decisions. Simulations are conducted over a 30-year period in each climate scenario: the first of these is a baseline climate scenario from 1971-2000, and I also simulate future climate change impacts for the 2041-2070 era. The modelled farms produce enough crops, hay and pasture to support the beef cattle feed demand. Pasture demand and supply are linked by specific pasture requirements and productivity. Beef herd feed grain demand and on-farm supply are linked by a linear programming optimization algorithm. Crop mix for the market is selected through the development of a multi-year linear programming problem that maximizes the present value of gross margins. Crop and hay productivity are estimated through the Food and Agriculture Organization’s (FAO’s) AquaCrop (version 3) modeling framework, while annual pasture productivity is estimated using the Forage Calculator for Native Rangeland obtained from the Saskatchewan Research Council (SRC). The AquaCrop is a water-driven crop simulation model, termed a crop water productivity (WP) model which simulates the yield response of herbaceous crops to water availability and use. The model is believed to be superior in simulating crop yield in the conditions where water is a key limiting factor in crop production (FAO, 2011). Summarizing the results of the simulation, prairie crop production is expected to benefit under the simulated climate change scenario. Increases in crop productivity generate about 60% higher profits in the Pincher Creek site and about 57% more for the Swift Current site. Due to increases in grain and hay productivity, more area is made available to produce grain for the market. This effectively doubles the crop net return at the Pincher Creek site and triples the crop return at the Swift Current site. A consideration of future pasture response to the climate change scenario is important in estimating climate change consequences for live beef production as well as on the economic return of a mixed farm. If the pasture productivity decreases, as assumed under the regular pasture yield scenario in the study, appropriate adaptation is necessary for the farm to benefit from future climate change. Under this scenario, beef production activities in the future are projected to gain by 50% in Pincher Creek and 40% in Swift Current compared to the baseline scenario. If pasture productivity under the future scenario increases in a manner similar to crop yield increases, existing pastureland will be enough to maintain beef herds into the future. In turn, this strategy will mitigate the cost of beef herd adaptation during climate extremes, and instead gains from beef cattle production would be 35% higher in Swift Current and 6% higher in Pincher Creek relative to gains under regular pasture yield conditions. At the farm level, with beef cattle and crop production combined, substantial gains are projected for both of the study sites. Farm net profit is estimated to increase by more than 35% at the Pincher Creek site and more than 140% at the Swift Current site under the future scenario. Income risk will also be lower in this scenario, as highlighted by a lower coefficient of variation of net farm profit. Farm financial indicators tracked in this study – farm cash flow, family cash flow, and farm net worth – all indicate that the farm’s financial position will be much better in the future climate scenario. At the Pincher Creek site, a few problematic liquidity events are forecasted under the future climate scenario, but in light of significant improvements in other economic indicators, overall, this effect is negligible. The appropriate choice of adaptation strategies for managing beef herds during extreme climate events plays an important role in determining the profitability of not only beef cattle activities, but also the financial position at the whole farm level. However, the choice of adaptations is contextual: the preference of adaptation strategy differs across activities, farms and period of study. For beef cattle activities, maintaining the beef herd without any compromise on herd size and implementing a regular feeding plan is preferred to other adaptation alternatives. At the whole farm level for the Pincher Creek site, culling the herd is preferred under the baseline scenario, while the purchasing feed option is preferred under the future climate scenario. At the Swift Current site, culling the herd is the preferred strategy under both scenarios. Commodity prices and the cost of farm inputs profoundly affect the economic position of the farm under the future climate change scenario. If commodity prices and cost of production remain the same as under the baseline scenario, future farm net profit is estimated to be 50% higher for the Pincher Creek site and about 25% higher for the Swift Current site, compared to profits under projected future prices. This result implies that the pure effect of climate change could be much higher if costs and prices do not change. Results of this dissertation indicate that average Prairie mixed farms, as represented by these study farms, remain economically viable under both the baseline and future scenarios. The results also suggest that the overall gain to these farms under a future climate change scenario would be positive. The potential severity of extreme climate events in the future, at least for the future scenario period simulated in this study, would not be significant enough to threaten the future economic viability of Prairie agriculture. However, the research also highlights the importance of policies that support farmers when they endure losses in years of extreme climate events. Further research on evaluating different Best Management Practices (BMPs) in dealing with droughts, for example, would be helpful in taking advantage of future climate change. Policy development to enhance the longer-term adaptive capacity of Prairie farmers, such as development of early warning systems for climate extremes, or the development of drought tolerant cultivars of crops and forages, would be most helpful in coping with climate extremes in the future.

<p>The increasing number of patients undergoing treatment with assisted reproductive techniques (ART) during the past years have led to the need of developing different methods for separation of spermatozoa that can be used for different fertilisation procedures and for freezing. Cryopreservation of spermatozoa includes preparation, freezing, storage and thawing.</p><p>In this study two different cryomedia (Cryo Protec I and Cryo Protec II) for human spermatozoa were compared. The main outcome was spermsurvival rate for spermatozoa after freezing. Sperm viability was assessed using the Hypo-osmotic swelling test which is based on osmolality.</p><p>A total of 86 samples of semen were used in this study (Cryo Protec I=38, Cryo Protec II=48). The survival rate between the two cryomedia did not differ much but Cryo Protectant I showed a small increase in survival for the spermatozoa after freezing. The Hypo-osmotic swelling test also showed similar values of viable spermatozoa for the two cryomedia both before and after freezing.</p>

Guayule (Parthenium argentatum Gray) is one of two major plants in the world grown for natural rubber and therefore, is of potential importance to the U.S. One area of research interest relates to methods of enhancing production of viable seeds. Therefore, studies were conducted in 1984, 1985, and 1986, in Tucson, Arizona to determine the effect of honey bee pollination on: seed set; seed weight; total seed yield; percentage of seed germination; yield and percentage of rubber and resin content. This experiment involved four guayule cultivars and four pollination treatments: plants caged with bees; plants caged without bees; plants open-pollinated; and plants individually covered with Delnet bags. All four cultivars responded positively to honey bee pollination. Plots with bees produced at least 195% more seeds than plots from which bees were excluded. However, there were no qualitative differences in the seed weights between the treatments. The percentage of seed germination from plots serviced by bees was significantly greater (65%) than from plots without bees (50%). Highest seed germination rates were obtained when seeds were collected in May (80%) and September (76%). June, July, and August seed collections resulted in lower seed germination rates (40%, 26%, and 63%, respectively). The plots in which bees were present gave a higher rubber yield (323 kg/ha) than plots without bees (255 kg/ha). However, there were no quantitative differences in the percentage of resin content between the treatments. These studies demonstrated that (1) honey bees can increase seed yield, seed germination, and rubber content in guayule, and (2) seeds produced during summer months had poorer germination rates and lower yields.

A study was conducted to optically determine the viability of the Gram +, endospore-forming bacterial genera Bacillus using a hyperspectral reflectance spectrometer. Endospores are a dormant, differentiated cellular capsule form taken by select bacteria to ensure survival when environmental conditions become unfavorable. Two species of Bacillus were used for this study, Bacillus megaterium and Bacillus subtilis. These endospores were killed using a chemical treatment of sodium hypochlorite or a physical treatment of heat and pressure in an autoclave. The treated samples along with viable samples were lyophilized to form a powder. A reflectance spectrometer measuring 350 nm to 2500 nm (UV to shortwave infrared) was used to collect optical data on bulk powders. The resulting spectra were analyzed using several different methods, including integration and a Support Vector Machine (SVM) to obtain optimal separability of viable and nonviable endospores. Results of this study demonstrated the significant spectral separability of live and dead endospores with a level of confidence <0.05 in both species.

Aquatic hypoxia, or low dissolved oxygen, is a growing environmental concern and has detrimental effects on many fishes. Research on fish responses to hypoxia includes whole animal studies as well as organ culture systems. In this thesis, the gulf killifish, Fundulus grandis, was used to determine the interaction between hypoxic exposure and four common euthanasia techniques on selected blood and gill variables and to develop an in vitro gill incubation system. Euthanasia techniques had differential effects on blood and gill, with the common fish anesthetic MS-222 having the greatest effects, but none altered the response to hypoxia. During the development of gill culture, the highest gill viability was measured in isosmotic seawater medium and shorter incubation times. This study provides insight into the applicability of different euthanasia techniques in hypoxia research, as well as preliminary observations on an incubation system for isolated gills.

As leveduras são de relevante importância dentro da agroindústria sucroalcooleira devido sua participação no processo fermentativo de produção de álcool. Deste modo, faz-se necessário o conhecimento deste agente fermentativo com destaque para Saccharomyces cerevisiae, principal gênero. O objetivo deste trabalho foi estudar a linhagem de levedura S. cerevisiae Y904, exposta a condições não proliferantes, após fermentação em meio que sofreu adição de óleo vegetal e sua possível correlação com manutenção da viabilidade celular. Foram realizadas análises para contagem de unidades formadoras de colônias, viabilidade celular, concentração celular, nitrogênio total na levedura e no meio, carboidratos totais, trealose e glicogênio. As leveduras submetidas a condições não proliferantes apresentaram menores teores de carboidratos totais, com destaque para trealose e glicogênio, em relação às leveduras comerciais. Saccharomyces cerevisiae sofreu queda de viabilidade acentuada após 24 h em solução fisiológica, em condições não proliferantes, sob agitação de 90 rpm e temperatura de 30 ± 1°C, seguida de uma acentuada autólise a partir de 120 h (5°dia), provavelmente, devido ao teor de carboidratos de reserva da célula que se encontravam em valores extremamente baixos, da ordem de 0,15 mg de trealose em 100 mg da matéria seca e 4 mg de glicogênio em 100 mg da matéria seca. A partir desse ponto entraram em total desorganização celular. / Yeast is highly important in sugar and alcohol agroindustry due to its role in the fermentative process of alcohol production. Thus, it is necessary to know this microorganism, most specially the Saccharomyces cerevisiae, the main species. The objective of this work was to study the strain Y904 of the yeast Saccharomyces cerevisiae under non-proliferating conditions after fermentation in a medium in which it was added vegetable oil and verify its possible correlation with the maintenance of the cellular viability. Analyses were performed in order to determine colony forming units, cellular viability, cellular concentration, total nitrogen in yeast and in medium, total carbohydrates and trehalose and glycogen contents. The yeast submitted to non-proliferating conditions presented a lower content of total carbohydrates, specially trehalose and glycogen, when compared to commercial yeasts. The viability of the yeast Saccharomyces cerevisiae Y904 markedly decreased after 24 hours in physiological solution under non-proliferating conditions in a shaker for 90 rpm at 30 ± 1°C. It was observed an accentuated autolysis from the 120 th hour (5 th day) on. This was probably because of the very low content of the carbohydrates of reserve in the cells, 0.15 mg of trehalose and 4.0 mg of glycogen in 100 mg of dry weight. From this point the cells began a total cellular disorganization.