Effects of temperature on microbial ethanol production. III. The influence of the temperature on the relation existing between the specific ethanol formation rate of the yeast Saccharomyces cerevisiae Sc 5 and the ethanol concentration in the culture medium

The ethanol-inhibitory behaviour of the yeast Saccharomyces cerevisiae Sc 5 was found to be characterized by a continual-linear relation between the specific ethanol formation rate and the ethanol concentration. Therefore the simple equation could be applied for it. It is shown that this model is correct only then, if all of the process parameters are in their optimum. Out of the optimum temperature range the characteristics of the function ν = f(P) change in such a way that in regard to the ethanol concentration P twc linear relations exist for each suboptimum temperature: and a non-linear equation is current for each superoptimum temperature: where b_T is also a function of the temperature and always less than 1. Taking as a basis these equations the specific ethanol formation rate of the used strain can be calculated for the whole biokinetic P/T-sphere of ethanol production.     

A kinetic study of the alcoholic fermentation of grape juice

The alcoholic fermentation of grape juice by a wine yeast was studied batchwise at pH 3.6 and 4.05 to develop kinetic equations relating cell concentration, N, to product concentration, P. In the exponential growth phase where A, B, and C are constants, and μ is the specific growth rate. In the stationary phase, where the cell population is constant, was found to apply. This equation, which incorporates a stoichiometric constant, P_m, predicted correctly the operation of a continuous fermentor at pH 3.6 and at 4.05. To study more fully the effect of alcohol concentration on yeast growth, a continuous fermentor was used in which the grape juice feed was supplemented with pure alcohol. At pH 3.6 the specific growth rate varied as, There was no growth inhibition below an alcohol concentration of 2.6 g./100 cc., but inhibition was complete above 6.85 g./100 cc. This is a modified form of the relation suggested by Hinshelwood.¹ The data suggest that growth in batch culture was limited not only by alcohol but also by some other factor, probably a nutritional deficiency.     

Inhibition-threshold substrate concentrations

A proposed substrate inhibition model (M. C. Tseng and M. Wayman, Can. J. Microbiol., 21 , 994 (1975)), ((1)) ((2)) derived from yeast growth rates has been applied to data for bacterial growth: Pseudomonas methanica grown on methanol and Arthrobacter AK19 grown on n-butanol. The model represents the experimental data very well.     

Buoyant densities of natural and synthetic DNA's in CsCl and Cs2SO4 considered as sequence-dependent properties

The buoyant densities of natural and synthetic DNA's can be accurately interrelated if second-neighbor influences are taken into account. We derive the following expressions, based partly on the buoyant densities of six synthetic DNA's, for the buoyant densities ρ (g/cm³) of DNA's having random sequences. In CsCl, and in Cs₂SO₄, . In these equations, H_G is the mole fraction of G : C base pairs in the DNA and the buoyant densities are calculated relative to densities for E. coli DNA of 1.703 and 1.426 (g/cm³) in CsCl and Cs₂SO₄, respectively.     

The effects of some ions on the membrane potential of the giant axon of Myxicola

The effects of various ions on the resting membrane potential of the giant axons of Myxicola were determined. The mean resting potential in artificial sea water is 69 mv, inside negative. The membrane potential decreases with incresing external potassium concentrations, while changes in the sodium and chloride concentrations have little or no effect. For potassium concentrations greater than 50 mM/L the relation between membrane potential and concentration approximates that of a perfectly selective potassium electrode. The data for the whole range of concentrations examined can be well fitted by the equation: It was pointed out that the Myxicola giant axons can be studied under space voltage clamp and can be made available in the laboratory for 12 months out of the year. Myxicola then should become a very useful preparation for the study of membrane phenomena.     

Beyond growth rate 0.6: Corynebacterium glutamicum cultivated in highly diluted environments

Fast growth of industrial microorganisms, such as Corynebacterium glutamicum, is a direct amplifier for the productivity of any growth coupled or decoupled production process. Recently, it has been shown that C. glutamicum when grown in a novel picoliter bioreactor (PLBR) exhibits a 50% higher growth rate compared to a 1 L batch cultivation [Grünberger et al. (2012) Lab Chip]. We here compare growth of C. glutamicum with glucose as substrate at different scales covering batch cultivations in the liter range down to single cell cultivations in the picoliter range. The maximum growth rate of standard batch cultures as estimated from different biomass quantification methods is ${\hat {\mu }} = 0.42\pm 0.03\,{\rm h}^{- 1} $ even for microtiter scale cultivations. In contrast, growth in a microfluidic perfusion system enabling analysis of single cells reproducibly reveals a higher growth rate of ${\hat {\mu }} = 0.62\pm 0.02\,{\rm h}^{- 1} $ . When in the same perfusion system cell‐free supernatant from exponentially grown shake flask cultures is used the growth rate of single cells is reduced to ${\hat {\mu }} = 0.47\pm 0.02\,{\rm h}^{- 1} $ . Likewise, when fresh medium is additionally supplied with 5 mM acetate, a growth rate of ${\hat {\mu }} = 0.51\pm 0.01\,{\rm h}^{- 1} $ is determined. These results prove that higher growth rates of C. glutamicum than known from typical batch cultivations are possible, and that growth is definitely impaired by very low concentrations of byproducts such as acetate. Biotechnol. Bioeng. 2013; 110: 220–228. © 2012 Wiley Periodicals, Inc.     

Growth kinetics of a yeast grown on glucose or hexadecane

The kinetics of growth of a Torulopsis sp. was investigated in a continuous culture with glucose or hexadecane as the carbon source; growth was limited by either carbon or nitrogen. The relationship between the concentration of the limited substrate and the steady-state growth rate of the organism was examined and tested against various models of growth. No existing model was found to describe the growth accurately and a new model has been proposed: It is postulated that this behavior would result from a simple first order reaction between the reactants of the rate-limiting enzymic reaction of the organism's metabolism.     

Conformational aspects of polypeptides. XVII. Synthesis of oligomers and co-oligomers derived from L-alanine and L-glutamic acid

A series of oligomers was synthesized of the form: Where Z is the benzyloxycarbonyl group and n = 2, 3, 5, 10. We encountered difficulty in dissolving the decamer in any solvent except strong organic acids. We therefore prepared co-oligomers of the type: where (a) w = x = y = 1; (b) w = 0, x = y = 3; and (c) w = x = y = 3. A series of model compounds composed of glycine L -alamine and γ-methyl-L -glutamate were also prepared. We converted manyof the benzyloxycarbonyl oligopeptides into their corresponding acetyl derivatives. Some of these peptides were synthesized by mixed anhydride and active ester techniques while others were prepared via azide coupling techniques using the tert-butoxycarbonylhydrazide blocking group. All reactions proceeded with retention of configuration.     

Growth characteristics of a thermotolerant strain of lodderomyces elongisporus grown on sucrose

A thermotolerant yeast species of Lodderomyces elongisporus EH 60 was isolated and physiologically characterized. This yeast possesses a high specific growth rate with μ_max = 0.61 h^?1. The dependence of the specific growth rate and cell yield on temperature, dilution rate, sucrose concentration and pH-value is investigated. Sucrose concentrations greater than 10 g/l inhibit the growth velocity. The specific growth rate μ can be calculated by a simple combination equation in the form: . The total optimum values for a sucrose-based continuous growth process with regard to the optimum cell yeild are: Y_S = 0.50 g DM/g S. T_opt. = 38,6 °C and D_opt. = 0,35 h^?1. The function Y_S = f(D, T) is represented by a total model.     

Oxygen mass transfer and gas holdup in a bubble column bioreactor with biosynthesis liquids

The influence of the rheology of some antibiotic biosynthesis liquids produced by Streptomyces aureofaciens, Nocardia mediterranei and Penicillium chrysogenum on the volumetric liquid phase oxygen transfer coefficient, k_La, and gas holdup, ε_G, together with the influence of superficial gas velocity, were studied in a bubble column bioreactor, using samples of fermentation liquids taken from industrial stirred tank fermenters, at 30-hour intervals during fermentation batch. The results were compared to those of previous studies from literature on non-Newtonian homogeneous fluids, such as CMC-Na, xanthan and starch solutions, respectively. In the heterogeneous broths, ε_G and k_La decreased with increasing apparent viscosity of the broth and increased with increasing superficial velocity. The experimental data were correlated using non-linear regression with correlation coefficients above 0.85.     

A Measure of Plankton Community Similarity Utilizing Variable Weighting of Total Density and Taxonomic Proportionality

Four commonly used formulae for measuring percentage similarity (PS) of biological communities were tested for their usefulness in relating to two plankton community properties, species proportional differences and total density differences. The formula best combining species proportionality and total density in the expression of PS is new: where min (xi,yi) is the lesser percentage (doubly standardized) of a species in two samples X and Y and where 2 q, 2xi and 2yi are the total quantities of all species in samples 8,X and Y, where \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_i {z_i } ,\,\sum\limits_i {x_i } \,and\sum\limits_i {y_i } $\end{document} are the total quantities of all species in samples Z, X and Y, respectively. Sample 2 contains the highest density of all species in the set; \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_i {z_i \, > \,(\sum\limits_i {x_i ,\,} \sum\limits_i {y_i } )} $\end{document}. The new expression of PS is simple to use and has the additional advantage of offering the analyst an unlimited choice of weighting factors or importance values for proportionality of species content and total density. The method has been applied to data from Gravenhurst Bay (Ontario) and effectively demonstrates the consequences of phosphorus loading reductions for phytoplankton communities.     

Abundance trends of American martens in Michigan based on statistical population reconstruction

Estimating the dynamics of furbearer populations is challenging because their elusive behavior and low densities make observations difficult. Statistical population reconstruction is a flexible approach to demographic assessment for harvested populations, but the technique has not been applied to furbearers. We extended this approach to furbearers and analyzed 8 yr of age-at-harvest data for American marten (Martes americana) in the Upper Peninsula of Michigan. Marten abundance estimates showed a general downward trend from an estimate of = 1,733.3 animals in 2000 to = 1,163.9 in 2007. The harvest probability of martens increased nearly 5-fold from 0.0542 in 2000 to 0.2637 in 2007, which corresponded to a 5-fold increase in trap-nights. Continued monitoring of martens in the Upper Peninsula, Michigan, and a reassessment of current harvest regulations are necessary given the estimated decreases. Moreover, we do not encourage the use of harvest indices as the sole technique to assess the status and trends of marten and fisher populations. Auxiliary studies in the Upper Peninsula, Michigan, will allow for continued use and improvement in the application of these models. © 2011 The Wildlife Society.     

Photon correlation spectroscopy of hemoglobin: Diffusion of Oxy-HbA and Oxy-HbS

Translation diffusion coefficients have been measured for oxyhemoglobin A and oxyhemoglobin S over the concentration range 0.1–37 g/dl by means of photon correlation spectroscopy. The solutions were 0.1 M in KCl and in each case the pH was adjusted to the isoelectric point of the hemoglobin species present. No significant differences were found between the HbA and HbS results; and after correction to water at 20°C, the diffusion coefficients could be described by the equation where D_o = (6.93 ± 0.06) × 10^?7 cm²/sec and c ids the concentration in units of g/dl. No evidence was found for the aggregation of oxy-HbS at high concentrations which was reported by Lindstrom et. al. [(1976) Biophys. J. 16 , 679–689].     

The role of predator removal,density-dependence,and environmental factors on mallard duckling survival in North Dakota

Duckling survival is an important component of mallard (Anas platyrhynchos) recruitment and population growth, yet many factors regulating duckling survival are poorly understood. We investigated factors affecting mallard duckling survival in the drift prairie of northeastern North Dakota, 2006–2007. Mammalian meso-predators were removed by trapping on 4 92.3 km² study sites and another 4 study sites served as controls. We monitored 169 broods using telemetry and periodic resighting, and we modeled cumulative survival to 30 days of age using the nest survival module in Program MARK. Duckling survival was not affected by predator removal ( , 85% CI: 0.182–0.234; , 85% CI: 0.155–0.211) and was only weakly negatively correlated with duckling density. Duckling survival was higher in 2007 ( , 85% CI: 0.193–0.355) than 2006 ( , 85% CI: 0.084–0.252) and increased with total seasonal and semipermanent wetland area and declined with perennial cover in the surrounding landscape. Broods that hatched earlier in the season (especially in 2006) and ducklings that were heavier at hatch also had higher survival. Our estimates of duckling survival are among the lowest reported for mallards and contradict previous research in Saskatchewan that found predator removal increased duckling survival. However, our results are consistent with other studies suggesting that earlier hatch date, increased wetland availability, and better duckling condition lead to increased survival. Management actions that increase wetland density, improve nest success early in the season, and potentially target brood-specific predators such as mink (Neovison vison) would likely lead to higher duckling survival. © 2011 The Wildlife Society.     

Conformational dependence of the vicinal proton coupling constant for the Cα?Cβ bond in peptides

We use the nmr data concerning the C^αH? C^βH fragment in eight peptides with rigid side chains to parametrize a Karplus correlation between the vicinal proton J_αβ coupling constant and the dihedral angle θ. When considering molecules containing the fragment C^αH^α? C^βH^βH^β′, the three-dimensional structure of the model peptides does not need to be known with accurate precision, since each set of J_αβ and J_αβ′ coupling constants is then related to the coefficients of the Karplus equation. A good correlation is observed with the Karplus equation, which is in substantial agreement with the J_αβ coupling constants reported for rigid as well as rotating C^α? C^β bonds in peptides.     

Einfluß extracellulärer Konzentrationen auf die spezifische Wachstumsrate von Mikroorganismen

The influence of extracellular concentrations of hydrogen ion and C-substrates on the specific growth rate of different microorganisms is investigated. A general relationship in the form can be used to describe the inhibition effect of H^Plus;- or substrate concentration (c_i) on the growth rate. Different examples are demonstrated and the adequate specific constants K₁ and K₂ calculated.     

Hydrogen-tritium exchange of the random chain polypeptide

The Hydrogen–tritium exchange character of poly-D ,L -alanine was studied in detail as a model for the hydrogen exchange behavior of the unhindered, polymeric peptide group. The random chain nature of poly-D ,L -alanine was evident in the uniformity of exchange rate of all its hydrogens and in the similarity between this rate and that of random chain poly-D ,L -lysine and other known, unhindered secondary amide groups. An equilibrium isotope effect favoring the binding of tritium over protium to the extent of 21% was measured. Specific acid and base catalysis of the exchange and the absence of detectable general catalysis were demonstrated. Apparent energy of activation is 17 kcal/mole for deprotonation, largely due to dependence of K_w on temperature, and 15 kcal/mole for protonation, which correlates with the extreme apparent pK. The hydrogen –tritium exchange half-time rate; of poly-D ,L -alamine at any pH and temperature (T: °C) is given by the equation:      

Occupancy and abundance of wintering birds in a dynamic agricultural landscape

Assessing wildlife management action requires monitoring populations, and abundance often is the parameter monitored. Recent methodological advances have enabled estimation of mean abundance within a habitat using presence–absence or count data obtained via repeated visits to a sample of sites. These methods assume populations are closed and intuitively assume habitats within sites change little during a field season. However, many habitats are highly variable over short periods. We developed a variation of existing occupancy and abundance models that allows for extreme spatio-temporal differences in habitat, and resulting changes in wildlife abundance, among sites and among visits to a site within a field season. We conducted our study in sugarcane habitat within the Everglades Agricultural Area southeast of Lake Okeechobee in south Florida. We counted wintering birds, primarily passerines, within 245 sites usually 5 times at each site during December 2006–March 2007. We estimated occupancy and mean abundance of birds in 6 vegetation states during the sugarcane harvest and allowed these parameters to vary temporally or spatially within a vegetation state. Occupancy and mean abundance of the common yellowthroat (Geothlypis trichas) was affected by structure of sugarcane and uncultivated edge vegetation (occupancy = 1.00 [ = 0.96–1.00] and mean abundance = 7.9 [ = 3.2–19.5] in tall sugarcane with tall edge vegetation versus 0.20 [ = 0.04–0.71] and 0.22 [ = 0.04–1.2], respectively, in short sugarcane with short edge vegetation in one half of the study area). Occupancy and mean abundance of palm warblers (Dendroica palmarum) were constant (occupancy = 1.00, = 0.69–1.00; mean abundance = 18, = 1–270). Our model may enable wildlife managers to assess rigorously effects of future edge habitat management on avian distribution and abundance within agricultural landscapes during winter or the breeding season. The model may also help wildlife managers make similar management decisions involving other dynamic habitats such as wetlands, prairies, and even forested areas if forest management or fires occur during the field season. © 2011 The Wildlife Society.     

A posteriori Investigation of Spatial Arrangements in Gnathostomulida and Copepoda

Copepods at MHTL and gnathostomulids from MHTL to sublittoral sands were studied in 162 samples from Tucker's Town Cove beach, Bermuda. Species were analyzed for mean density (X̄), mean crowding ( ), and patchiness ( /X) using Lloyd's a posteriori statistic for mean crowding. Diversity was computed using the Shannon-Wiener Index (H′). Copepoda were found to be nearly three times more abundant than Gnathostomulida at the MHSL site. 74% of the copepods were found in the surface cm of sediment while 87% of the gnathostomulids were located between 1–4 cm deep and within the RPD layer. Similar gnathostomulid distributions were found at MSL and sublittorally. Mean density and mean crowding were highly variable for the numerically dominant species in each group, whereas patchiness was relatively constant with values ranging between /X̄ = 1.50 to 2.73 for P = 0.05. Such consistency in patchiness between two diverse taxa having distinctly different vertical distributions may suggest that there exists an optimum degree of patchiness for interstitial fauna and that the optimum values may lie within a range similar to that of the numerically dominant Copepoda and Gnathostomulida. Overall patchiness was slightly higher in the gnathostomulids and in the rarer species as predicted by Lloyd's statistic. Diversity was higher in the Copepoda, attributable primarily to species richness.     

Polarized fluorescence in an electric field. A model calculation with application to the geometry of the 2-hydroxy-4,4′-diamidinostilbene–DNA complex

Theoretical expressions are derived for the change in the polarized components of the fluorescence, resulting from the orientation of a rigid molecule bearing a chromophore with arbitrary angles for the absorption and transition moments \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _a $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _e $\end{document} with respect to the molecular axis. The break in the symmetry relation H_V = V_H is related to the tilt angle between \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _a $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _e $\end{document}. The theory is applied to a sonicated DNA–2-hydroxy-4,4′-diamidinostilbene complex, in the blue and red emission bands of this peculiar dye. Simultaneous measurements of linear dichroism and fluorescence lead to the determination of an angle of 47° between a fluorescent bound dye and the DNA axis, with no difference for the blue- and red-emitting species, but confirm the presence of nonfluorescent bound dye in a more perpendicular arrangement.