An automatic,on-line glucose analyzer for feed-back control of fed-batch growth of Escherichia coli

Summary A computer-assisted on-line glucose analyzer was developed for feed-back control of cell growth. Using this system the glucose consumption rate for Escherichia coli was determined to be linear during batch culture at 0.37 g/hr. On-line feed-back control of glucose concentration at 1.5±0.5 g/L was used with fed-batch cultures to produce 31.2 g dry weight of E. coli cells/L in 12 h.     

Kinetics of alcohol production by zymomonas mobilis at high sugar concentrations

Summary Studies on the growth ofZ.mobilis revealed that high concentrations of glucose (10-25%) can be efficiently and rapidly converted to ethanol in batch culture. By comparison withS. carlsbergensis,Z.mobilis had specific glucose uptake rates and specific ethanol productivies several times greater than the yeast.Z.mobilis also had ethanol yields of up to 97% of a theoretical value.     

Production of ethanol and biomass from various carbohydrates byKluyveromyces fragilis

Summary Growth ofKluyveromyces fragilis NRC 2475 and the production of ethanol by the yeast were studied in the media containing one of the following sugars: glucose, lactose, galactose, or a glucose-galactose (50% 50%) mixture as a carbon source.The largest biomass yield and the lowest yield of ethanol were obtained in the medium containing glucose. The medium containing galactose gave the lowest yield of biomass and the largest yield of ethanol. When lactose was used for the growth and production of ethanol the obtained results for both biomass and ethanol were between those obtained with glucose and galactose.The ethanol productivities, expressed in terms of ethanol produced either per unit of cells, or per unit of cells and time, were the highest in the system with galactose and the lowest in that with glucose.     

Visual detection of β-fructofuranosidase (inulase) —Regulatory mutants ofKluyveromyces fragilis

Summary Inulase constitutive mutant cells of the yeastKluyveromyces fragilis were enumerated in continuous culture cell populations. After cloning and growth on glycerol agar plates, mutant colonies stained red when exposed to a mixture of sucrose and a chromogenic reagent for glucose.Mutants with improved inulase production on glucose were isolated from opaque agar plates containing undissolved inulin. Mutant colonies were surrounded with clearing zones. Attempts to isolate similar mutants by selection for 2-deoxyglucose resistance proved unsuccessful withK. fragilis.     

Glycerol production by immobilised cells of Pichia farinosa

Summary Cells ofPichia farinosa were immobilised in calcium alginate and K-Carrageenan and their ability to produce glycerol from glucose under aerobic conditions with acidic as well as alkaline pH was investigated. An average glycerol production rate of 0.07 g/l.h was obtained with immobilised cells (IMC) in shake flasks. Continuous glycerol production in a fluidised bed reactor (FBR) under steady state operation gave a glycerol concentration of 13.5 g/l in the product stream.     

Quinoprotein D-glucose dehydrogenases inAcinetobacter calcoaceticus LMD 79. 41: Purification and characterization of the membrane-bound enzyme distinct from the soluble enzyme

Acinetobacter calcoaceticus is known to contain soluble and membrane-bound quinoprotein D-glucose dehydrogenases while other oxidative bacteria such asPseudomonas orGluconobacter contain only membrane-bound enzyme. The two different forms were believed to be the same enzyme or interconvertible. Present results show that the two different forms of glucose dehydrogenase are distinct from each other in their enzymatic and immunological properties as well as in their molecular size.The soluble and membrane-bound glucose dehydrogenases were separated after French press-disruption by repeated ultracentrifugation, and then purified to nearly homogeneous state. The soluble enzyme was a polypeptide of 55 Kdaltons, while the membrane-bound enzyme was a polypeptide of 83 Kdaltons which is mainly monomeric in detergent solution. Both enzymes showed different enzymatic properties including substrate specificity, optimum pH, kinetics for glucose, and reactivity for ubiquinone-homologues. Furthermore, the two enzymes could be distinguished immunochemically: the membrane-bound enzyme is cross-reactive with an antibody raised against membrane-bound enzyme purified fromPseudomonas but not with antibody elicited against the soluble enzyme, while the soluble enzyme is not cross-reactive with the antibody of membrane-bound enzyme.Data also suggest that the membrane-bound enzyme functions by linking to the respiratory chain via ubiquinone though the function of the soluble enzyme remains unclear.     

Production of HBsAg by growth rate control with recombinantSaccharomyces cerevisiae in fed-batch

Summary To maintain a constant specific growth rate for a recombinantS.cerevisiae in fed-batch, the medium feeding rate has been controlled with respect to the hourly calculated glucose uptake rate. The recombinant yeast producing HBsAg showed the exponential production trend in proportion to the exponential cell growth. Total cell yield in fed-batch was about 0.402 g cells/g glucose, and HBsAg was produced about ten times more than in batch. Decrease of growth rate by HBsAg produced was not shown.     

Fermentation capabilities ofZymomonas mobilis glycolytic enzymes

Summary Cell-free extracts ofZymomonas mobilis were capable of fermenting glucose to ethanol and CO₂ when stimulated by arsenate to act as an ATP uncoupler. 2M glucose was completely converted resulting in a final concentration of 16.5 % w/v ethanol. 1 M glucose was completely converted at temperatures up to 50°C. The results demonstrate that the glycolytic enzymes are more resistant to temperature and ethanol than are the living cells.     

Production of 2-keto-3-deoxygluconate by immobilized cells of Sulfolobus solfataricus

Summary 2-Keto-3-deoxygluconate, an intermediate of glucose breakdown inSulfolobus solfataricus, was produced by enzymic dehydration of gluconate using whole cells of the micro-organism immobilized in crude egg white. The degradation of 2-keto-3-deoxygluconate to pyruvate and glyceraldehyde was avoided by inhibiting the aldolase activity in the cells by sodium borohydride treatment.     

Kinetic studies on alac-containing strain ofZymomonas mobilis

Summary Batch and continuous culture studies have been carried out on a strain ofZ.mobilis (ZM6306) which can convert lactose directly to ethanol. Previous strain development has established that thelac operon encoded on the transposon Tn951 can be expressed inZ.mobilis. Using a medium containing 80 g/l glucose and 40 g/l lactose, it was found that strain ZM6306 could convert about 13 g/l lactose to 4 g/l ethanol and 6 g/l galactose in continuous culture. Further lactose conversion is likely with increased cell concentration using a cell recycle system.     

Characterization of somatic embryogenesis and plant regeneration in cotton (Gossypium hirsutum L.)

Summary Seventeen cultivars of cotton (Gossypium hirsutum L.) were evaluated for callus initiation and maintenance using 3 initiation media and 3 maintenance media. After a series of transfers of a 3% glucose media, calli were placed on a 3% sucrose medium. After several weeks calli were observed for the presence of embryo-like structures. Cultivars Coker 201 and Coker 315 were identified as embryogenic. Embryogenic callus has since been routinely obtained within 6 weeks by initiating callus on glucose media for 3–4 weeks followed by transfer to sucrose media. Histological examination has shown that embryos are derived from isodiametric, densely cytoplasmic cells and follow predictable patterns of development. Upon maturity, transfer to auxin-free media with reduced sucrose levels results in embryo germination. Regenerated plants can be transferred to greenhouse within 90 days of callus initiation.The senior author is presently a Research Geneticist, USDA-ARS, and Assistant Professor Present address     

Production of fructose syrup by selective removal of glucose from hydrolyzed Jerusalem artichoke juice

Summary The study shows that the yeastSaccharomyces cerevisiae ATCC 36859 can be successfully used for the production of fructose syrup from glucose-fructose mixtures or from Jerusalem artichoke juice by the conversion of glucose to ethanol. During these processes fructose concentration was unchanged.Ethanol yield (Y_P/S), based on glucose consumed in Jerusalem artichoke juice, and ethanol concentration were 0.428 g/g and 1.7% (w/v) respectively. When the juice was supplemented with glucose higher ethanol concentrations were attained but with lower ethanol yields.     

A one step process for the conversion of cellulose to ethanol using anaerobic microorganisms in mono- and co-culture

Summary The reducing sugars, glucose, and ethanol produced during growth of the anaerobes Clostridium thermocellum and Acetivibrio cellulolyticus on cellulose were assayed. Zymomonas mobilis was grown under similar conditions and could ferment glucose to ethanol. The ethanol production by the cellulolytic bacteria alone and in co-culture with Zymomonas is described. Approximately 27% of a 1% cellulose substrate could be converted to ethanol by this co-culture.     

Photosynthetic ability in dark-grown Reboulia hemisphaerica and Barbula unguiculata cells in suspension culture

Suspension cultured cells of the liverwort, Reboulia hemisphaerica and of the moss, Barbula unguiculata were independently subcultured in the medium containing 2% glucose in the dark or in the light for more than one year, and the photosynthetic activities of the final cultures were determined. Throughout the culture period light-grown cells of both species contained high amount of chlorophyll (4 to 34 g mg^–1 dry weight) and showed a high photosynthetic activity (10 to 84 mol O₂ mg^–1 chlorophyll h^–1). Dark-grown cells of R. hemisphaerica showed the same level of chlorophyll content and photosynthetic O₂ evolving activity as light-grown cells. Although chlorophyll content in dark-grown B. unguiculata cells was ten-fold lower than that in light-grown cells, the photosynthetic activity of these dark-grown cells was higher than that of light-grown cells based on chlorophyll content.     

Could the improvements in the alcoholic fermentation of high glucose concentrations by yeast immobilization be explained by media supplementation?

Summary The maximal concentration of ethanol produced during the fermentation of 320 g/l glucose bySaccharomyces bayanus was higher when the yeast cells were immobilized either by adsorption on celite or by entrapment in k-carrageenan beads (from 10.5% with free cells up to 14.5% and 13.1% (v/v) respectively). This increase was due to medium supplementation with the compounds present in the immobilization supports.     

Development of an optimal heterotrophic growth medium for Chlorella vulgaris

Summary Final biomass yields of Chlorella vulgaris cultured heterotrophically in bristol medium amended with 0.1% (w/v) yeast extract (Difco) or 0.5% glucose (w/v) were 26 and 58 times higher, respectively, than yields obtained for autotrophically grown cells in the light. Similarly, final biomass increases were 35 and 138 fold for these organic substrates in the dark. The mixture of 0.1% yeast extract and 0.5% glucose was optimal and produced increases in final biomass of 70 and 140 times in the light and dark, respectively.     

Use ofClostridium acetobutylicum P262 for production of solvents from whey permeate

Summary The production of solvents from whey permeate in batch fermentation usingClostridium acetobutylicum P262 was examined. An overall reactor productivity of 0.24 g/l.h was observed, representing a marked improvement over reports using other strains of clostridia. Using a semi-synthetic medium galactose was shown to be as effective a substrate as glucose. When whey permeate was used in which the lactose was hydrolysed prior to fermentation, preferential uptake of glucose over galactose was observed, and such hydrolysis provided no advantage to the fermentation process.     

Sophorose lipid formation by resting cells of Torulopsis bombicola

Summary To produce glycolipids resting cells of the yeast Torulopsis bombicola were incubated in the presence of different mono-, di- and trisaccharides or hydrocarbon substrates. The main product was always a lactonic sophorose lipid containing a mono-unsaturated 17-hydroxyoctadecanoic acid. Using glucose pH and temperature optima were studied as well as growing and resting cells were compared.     

Glucose isomerase activity of streptomyces kanamyceticus

Summary Streptomyces kanamyceticus produces a significant level of intracellular glucose isomerase when grown in submerged culture. The optimum temperature for enzyme activity is 90°C, but the optimum pH is changed by the kinds of buffer solution used. The activity is higher at pH 7.0–9.5. Treatment of cells with cetyl trimethyl ammonium bromide extracts almost the same amount of the enzyme as ultrasonic treatment. The selection of the method of treatment for enzyme extraction depends, however, on the nature of cell growth in synthetic or complex medium.     

Production of citric acid from sugars present in wood hemicellulose usingAspergillus niger andSaccharomycopsis lipolytica

Summary One strain each of the fungus,Aspergillus niger, and the yeast,Saccharomycopsis lipolytica, were investigated for their ability to produce citric acid from the sugars present in hemicellulose hydrolysates.S. lipolytica produced citric acid as efficiently from mannose as from glucose, but failed to assimilate xylose, arabinose or galactose.A. niger readily assimilated mannose, xylose and arabinose, and produced citric acid from these sugars although the yields were lower than from glucose. A possible inhibitory effect of arabinose on citric acid production from other sugars was observed usingA. niger.