Showing papers in "Critical Reviews in Biotechnology in 1983"
TL;DR: Several studies have indicated that upon immobilization, yeast cells performing ethanol fermentation exhibit more favourable physiological and metabolic properties, indicative of the fact that future developments in the production of ethanol and alcoholic beverages will be directed towards the use of immobilized cell systems.
Abstract: The application of immobilized cell systems for the production of ethanol has resulted in substantial improvements in the efficiency of the process when compared to the traditional free cell system. In this review, the various methods of cell immobilization employed in ethanol production systems have been described in detail. Their salient features, performance characteristics, advantages and limitations have been critically assessed. More recently, these immobilized cell systems have also been employed for the production of ethanol from non-conventional feedstocks such as Jerusalem artichoke extracts, cheese whey, cellulose, cellobiose and xylose. Ethanol production by immobilized yeast and bacterial cells has been attempted in various bioreactor types. Although most of these studies have been carried out using laboratory scale prototype bioreactors, it appears that only fluidized bed, horizontally packed bed bioreactors and tower fermenters may find application on scale-up. Several studies have indicated that upon immobilization, yeast cells performing ethanol fermentation exhibit more favourable physiological and metabolic properties. This, in addition to substantial improvements in ethanol productivities by immobilized cell systems, is indicative of the fact that future developments in the production of ethanol and alcoholic beverages will be directed towards the use of immobilized cell systems. 291 references.
107 citations
TL;DR: A vast number of potential applications are already known, and one of the most interesting applications may be in continuous fermentation such as ethanol production by immobilized living microorganisms.
Abstract: Although the application of the natural attraction of many microorganisms to surfaces has been applied in vinegar production since the early 1980s, and has long been utilized in waste water purification, the development of microbial cell immobilization techniques for special applications dates back only to the early 1960s. The immobilization may involve whole cells, cell fragments, or lysed cells. Whole cells may retain their metabolic activity with their complex multienzyme systems and cofactor regeneration mechanisms intact, or they may be killed in the process with only a few desired enzymes remaining active in the final biocatalyst. Cells may also be coimmobilized with an enzyme to carry out special reactions. Although relatively few industrial scale applications exist today, some are of very large scale. Current applications vary from relatively small scale steroid conversions to amino acid production and high fructose syrup manufacture. A vast number of potential applications are already known, and one of the most interesting applications may be in continuous fermentation such as ethanol production by immobilized living microorganisms. 373 references.
78 citations
TL;DR: In this paper, the effects of ethanol on the temperature profile of growth and thermal death of S. cerevisiae were reviewed and the underlying mechanisms are many and include the irreversible denaturation14 and the hyperbolic noncompetitive inhibition15 of glycolytic enzymes, the exponential non-competitive inhibition of the glucose transport system,16 the depression of the optimum and the maximum temperatures for growth,17 and the enhancement of thermal death.
Abstract: During alcoholic fermentation in batch by Saccharomyces cerevisiae and other yeasts, the increasing concentration of ethanol adversely affects the state and the activities of the yeast population including its specific growth rate, its specific rate of fermentation, and its viability.1“13 With increasing process temperature some of these effects may become more severe.1,8,12,13The underlying mechanisms are many and include the irreversible denaturation14 and the hyperbolic noncompetitive inhibition15 of glycolytic enzymes, the exponential noncompetitive inhibition of the glucose transport system,16 the depression of the optimum and the maximum temperatures for growth,17 and the enhancement of thermal death.19 Here we'll review the effects of ethanol on the temperature profile of growth and thermal death of S. cerevisiae. (For basic treatments of temperature profiles of yeasts see van Uden and Madeira-Lopes.-20,22)
52 citations
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49 citations
TL;DR: Recently, there has been much interest in this field and the results are promising although no commercial process is available as of yet.
Abstract: The search for renewable raw materials to replace fossile fuel has directed research towards the utilization of various cellulosic materials. Cellulosic plant materials consist of three main components: cellulose, hemicellulose, and lignin. In order to develop an economically feasible process, it is necessary to utilize all these materials. Cellulose and hemicellulose can be decomposed either by enzymatic or acid hydrolysis to yield sugars. In the case of both hardwoods and annual plants the main part of the hemicellulose consists of pentosans yielding xylose on hydrolysis (Table 1). The hydrolysate thus contains mainly glucose and xylose which must be fermented to ethanol in order to obtain a combustible motor fuel. Glucose can easily be fermented by conventional yeasts or by some bacteria, e.g., Zymo-monas, but xylose presents a more difficult problem. Recently, there has been much interest in this field and the results are promising although no commercial process is available as of yet.
31 citations
TL;DR: Zymomonas cultures grow anaerobically and, unlike yeasts, do not require the controlled addition of oxygen to maintain viability at high cell concentrations, and there are significantly higher specific rates of sugar uptake and ethanol production compared to those found for yeasts.
Abstract: The bacterium Zymomonas mobilis, which is used in the tropics to make pulque and alcoholic palm wines, appears to have considerable potential for industrial alcohol fermentations. Some of the advantages of the Zymomonas process reported in studies from our laboratory1-24 are1. There are significantly higher specific rates of sugar uptake and ethanol production compared to those found for yeasts.2. Considerably higher volumetric ethanol productivities found in continuous cell recycle systems (up to 120 to 200 g/hr).3. There are higher ethanol yields and lower biomass production than for yeasts. The lower biomass concentrations would seem to be a consequence of the lower metabolic energy available for growth. Zymomonas metabolize glucose via the Entner-Doudoroff pathway while yeasts convert glucose to ethanol via glycolysis.4. Zymomonas cultures grow anaerobically and, unlike yeasts, do not require the controlled addition of oxygen to maintain viability at high cell concentrations.5. The ethanol tol...
30 citations
TL;DR: The uses of ethanol can be divided into a number of categories: (1) potable ethanol in beer, wine, sake, cider, and perry, a variety of fermented fruit juices, and distilled beverages such as whiskey, gin, vodka, brandy, rum, and liquors; (2) solvent ethanol in the laboratory, in pharmaceutical preparations such as tonics and cough syrups, as a solvent for hop constituents, and in cosmetics; (3) as a cosurfactant in oil-water microemulsions; (4) as an
Abstract: The production of ethanol by microorganisms as a result of the fermentation of substrates such as sugars or starch is a process that predates recorded history. The uses of ethanol can be divided into a number of categories: (1) potable ethanol in beer, wine, sake, cider, and perry, a variety of fermented fruit juices, and in distilled beverages such as whiskey, gin, vodka, brandy, rum, and liquors; (2) solvent ethanol in the laboratory, in pharmaceutical preparations such as tonics and cough syrups, as a solvent for hop constituents, and in cosmetics; (3) as a cosurfactant in oil-water microemulsions; (4) as an antiseptic and sterilant; and (5) as a fuel in automobiles either en its own or more usually admixed with gasoline. It should not be forgotten that by far the largest volume of ethanol produced via fermentation is employed for potable purposes. Consequently, brewing, viticulture, and enology and distilled beverages are biotechnological industries that make a significant contribution to the ...
30 citations
TL;DR: In this paper, large scale industrial enzyme production is discussed and the authors present a review of the literature on large scale enzymes production in a large-scale industrial setting.
Abstract: (1983). Large Scale Industrial Enzyme Production. Critical Reviews in Biotechnology: Vol. 1, No. 1, pp. 59-85.
19 citations
TL;DR: A little over a year ago the author edited a textbook on alcohol production and titled it “Gasohol – Fuel Alcohol A Step to Energy Independence”.
Abstract: A little over a year ago the author edited a textbook on alcohol production and titled it “Gasohol – Fuel Alcohol A Step to Energy Independence”.1 Many changes have occurred since the concept for the textbook originated amidst the great euphoria of interest in alcohol in 1979 and 1980. It is, hence, very appropriate to perhaps review what has happened in the interim period.
9 citations
TL;DR: The development of interest in other species with the ability to convert xylose to ethanol or to ferment at high temperatures indicates that no existing strain of Saccharomyces or Zymomonas meets the specifications for all current and future uses.
Abstract: Ethanol-Producing MicrorganismsA wide variety of microbial species are known to produce ethanol as a product of carbohydrate fermentation.1 Organisms which have received attention in recent studies include a wide range of yeasts, some molds, and a number of specialized bacteria (Table 1). Traditionally, yeasts, particularly Saccharomyces cerevisiae, have been used for producing fermentation ethanol or alcoholic beverages in large-scale processes. In Table 1, Zymomonas mobilis, the predominant organism in fermentations producing Mexican “pulque” or palm wine,34-46 is the only bacterium of current economic significance. However, the development of interest in other species with the ability, for example, to convert xylose to ethanol or to ferment at high temperatures indicates that no existing strain of Saccharomyces or Zymomonas meets the specifications for all current and future uses. Certainly the use of alternative organisms, or even mixed cultures,4245 warrants investigation. However, this revie...
7 citations
TL;DR: This data indicates that biomass production from biomass has been of great interest in several countries since the mid 70s due to its potential use as a fuel, particularly for mixture with gasoline up to a ratio of 25%.
Abstract: Alcohol production from biomass has been of great interest in several countries since the mid 70s due to its potential use as a fuel. This idea, together with internal combustion engines (Otto engines), was born towards the end of the last century. Well into this century several countries used ethanol for mixture with gasoline up to a ratio of 25%. When World War II was over, alcohol lost markets, fossil fuels such as petroleum being economically more viable.