Purification and properties of mycodextranase from Bacillus circulans NHB-1

A Gram-positive bacterium, Bacillus circulans, isolated from soil was found to produce an enzyme hydrolyzing nigeran (mycodextran, alternating α-1,3- and α-1,4-linked glucan). The molecular weight of the purified enzyme was 120,000 and its isoelectric point was 8.30. The optimum pH and temperature for the enzyme activity were 6.0 and 50°C, respectively. The enzyme was stable in the pH range from 6.0 to 7.0 and up to 50°C. The K_m (mg/ml) for nigeran was 1.37. The enzyme specifically hydrolyzed the nigeran into nigerose and nigeran tetrasaccharide by an endo-type action, indicating that it is a mycodextranase (EC 3.2.1.61) cleaving only the α-1,4-glucosidic linkages in nigeran. The N-terminal amino acid sequence of the purified enzyme of B. circulans (APTVYEAESAAKTGGV) was different from that of the mycodexstranase purified from Streptomyces sp. J-13-3 (XDPGDPTDPDPSGVGATLPF).     

Oil pollution in the North Sea—a microbiological point of view

In this study we determined oil degradation rates in the North Sea under most natural conditions. We used the heavy fuel oil, Bunker C, the major oil pollutant of the North Sea, as the model oil. Experiments were conducted in closed systems with water sampled during winter and repeated under identical conditions with water collected during summer. No nitrogen or phosphorous was added and conditions were chosen such that neither oxygen nor nutrients, present in the water, would become limiting during the experiments. We detected a fourfold increased degradation rate for water samples taken in summer (18°C water temperature) as compared to water sampled in winter (4°C water temperature). Under the assumption that biodegradation of oil can be regarded as a Michaelis-Menten type kinetic reaction, the kinectic constants V_max and K_M were determined for oil biodegradation at 4°C and 18°C. At both temperatures K_M was about 40 ppm, whereas V_max was 3–4 times higher at 18°C. From both V_max and the results of fermentation studies, we determined the maximum rates of Bunker C oil degradation in the North Sea as ∼20 g m⁻³a⁻¹ at 4°C in winter and 60–80 g m⁻³a⁻¹ at 18°C in summer. Furthermore, while over 25% of the oil was degraded within 6 weeks in summer, only 6.6% of the oil was degraded in winter. A higher incubation temperature in winter (18°C) increased both the rate and the percentage of oil degraded, but degradation did not reach the level obtained during the summer. While these data reflect the oxidation only of the hydrocarbons, we conducted experiments directly in the open sea to determine the contribution of abiotic factors to oil removal. Approximately 42% of the oil was lost within 6 weeks under these conditions in summer and 65% in winter. However, GC-MS analysis of the recovered oil showed no significant change in the alkane pattern that would indicate enhanced degradation. Thus, mainly abiotic factors such as erosion and dispersion rather than degradation were responsible for enhanced oil removal. Especially the high loss during winter can be attributed to frequent storms resulting in greater dispersion. In conclusion, the higher oil degrading potential of the microbial population in the North Sea was represented by a four times faster oil degradation during the summer. In-situ experiments showed that abiotic factors can have an equal (summer) or even higher (winter) impact on oil removal.     

Solid–Liquid Equilibrium of Maltitol Aqueous Solutions—Implications on the Crystallization Behavior and Process

The solubility of maltitol in pure water and industrial syrup was measured in a temperature range from 10 to 90 °C. Maltitol is highly soluble in water, and this yields high viscosity values for the saturated aqueous solutions at different temperatures. In addition, solubility of maltitol in ethanol/water mixtures was followed at 30, 35, 45, and 55 °C. Results show that maltitol solubility is highly dependent on water content in the solvent mixture. Moreover, it increases monotonically with temperature. The logarithm of viscosity changes linearly against the mole fraction of maltitol in the aqueous solutions up to saturation. The saturated solutions showed a Newtonian behavior in a temperature range from 20 to 90 °C. Maltitol is also characterized in supersaturated solutions by a narrow metastable zone, which slightly increases as temperature is raised. The density of aqueous solutions of maltitol was measured as a function of molality up to saturation at 20 °C, and results show that density can be correlated with concentration according to a linear relation. The obtained results were used to explain maltitol crystallization, which exhibits a high nucleation rate and a slow growth leading to small size crystals.     

Purification and Properties of Mycodextranase from Streptomyces sp. J-13-3

An enzyme hydrolyzing nigeran (alternating α-l,3-and α-l,4-linked glucan) was purified from the culture filtrate of Streptomyces sp. J-13-3, which lysed the cell wall of Aspergillus niger, by precipitation with ammonium sulfate and column chromatographies on DEAE-Sephadex A-50, CM-Sephadex C-50, chromatofocusing, and Sephadex G-I00. The final preparation was homogenous in polyacrylamide gel electrophoresis (PAGE). The molecular weight of the enzyme was 68,000 by SDS–PAGE and gel filtration. The optimum pH and temperature for the enzyme activity were 6.0 and 50°C, respectively. The enzyme was stable in the pH range from 6.0 to 8.0 and up to 50°C. The enzyme activity was inhibited significantly by Hg⁺, Hg²⁺, and p-chloromercuribenzoic acid. The K_m (mg/ml) for nigeran was 3.33. The enzyme specifically hydrolyzed nigeran into nigerose and nigeran tetrasaccharide by an endo-type of action, indicating it to be a mycodextranase (EC 3.2.1.61) that splits only the α-l,4-glucosidic linkages in nigeran.     

Visualization of freezing damage. II. Structural alterations during warming

There is a growing amount of indirect evidence which suggests that the loss in viability of rapidly cooled cells is due to recrystallization of intracellular ice. This possibility was tested by an evaluation of the formation of morphological artifacts in rapidly cooled cells to determine whether this process can account for the loss in viability. Samples of the common yeast Saccharomyces cerevisiae were frozen at 1.8 or 1500 °C/min, and the structure of the frozen cells was examined by the use of freeze-fracturing techniques. Other cells cooled at the same rate were warmed to temperatures ranging from ?20 ° to ?50 °C and then rapidly cooled to ?196 °C, a procedure that should cause small ice crystals to coalesce by the process of migratory recrystallization. Cells cooled at 1500 °C/min and then warmed to temperatures above ?40 °C formed large intracellular ice crystals within 30 min, and appreciable recrystallization occurred at temperatures as low as ?45 °C. Cells cooled at 1.8 °C/min and warmed to temperatures as high as ?20 °C underwent little structural alteration. These results demonstrate that intracellular ice can cause morphological artifacts. The correlation between the temperature at which rapid recrystallization begins and the temperature at which the cells are inactivated indicates that recrystallization is responsible for the death of rapidly cooled cells.     

Distribution and conformation of crystalline nigeran in hyphal walls of Aspergillus niger and Aspergillus awamori.

Hyphal walls of Aspergillus awamori containing increased amount of the alpha-glucan, nigeran, became correspondingly more opaque when viewed in the electron microscope as shadowed preparations. However, increased polymer deposition was not accompanied by any significant change in wall thickness. The nigeran of both A. awamori and Aspergillus niger occurred in situ in a crystalline conformation identical to that of single crystals prepared with pure polysaccharide. Furthermore, this polymer was the dominant crystalline material in the hyphae whether or not they were enriched in nigeran. Enzymic digestion of nigeran in A. niger and A. awamori revealed that the bulk of the polymer was exposed to the cell's exterior. However, a certain fraction was accessible to enzymic attack only after the wall was treated with boiling water. A third portion, detectable only by x-ray diffraction, was associated with other components and could not be extracted, even with prolonged boiling. It was removed by hot, dilute alkali and was associated in the wall with another glucan fraction. Dry heating of A. niger walls altered their susceptibility to enzymic digestion of nigeran in situ. It is proposed that this treatment introduces interstices in the crystal surface that facilitate attack.     

Response of rice plants to constant and cyclic submerged soil temperature regimes

Summary An experiment was conducted in controlled temperature water baths to compare the response of rice plant of variety Taichung (Native) 1 to cyclic soil temperature regime of 32°C/20°C and constant soil temperature regime of 26°C. These temperature regimes are reported to be highly favourable for rice growth and therefore selected for comparison. The plants growing at 32°C/20°C showed some superiority over those growing at 26°C in respect of root growth and tiller development. The grain yield at 32°C/20°C was higher which resulted from larger number of tillers and panicles than at 26°C, although the difference in other yield characteristics was not appreciable. NPK content of grains, straw and roots did not vary appreciably between 32°C/20°C and 26°C but the total uptake of these nutrients varied because of the difference in total dry matter production. The results suggest that the development of rice plants, particularly in reproductive phase, is practically as good at 26°C as at 32°C/20°C and there seems to be no sufficient ground for generalising the phenomenon of diurnal thermoperiodicity for rice plants.     

EFFECT OF TEMPERATURE AND GRAZING ON GROWTH AND REPRODUCTION OF FLOATING MACROCYSTIS SPP. (PHAEOPHYCEAE) ALONG A LATITUDINAL GRADIENT1

Macroalgal rafts frequently occur floating in coastal waters of temperate regions of the world’s oceans. These rafts are considered important dispersal vehicles for associated organisms with direct development. However, environmental factors may limit the floating potential of kelp and thereby the dispersal of associated organisms. To examine the effect of water temperature and grazing on growth, reproductive output, and survival of floating Macrocystis spp., experiments were conducted in outdoor tanks during austral summer 2006/2007 at three sites along the Chilean Pacific coast (20° S, 30° S, 40° S). At each site, Macrocystis spp. was maintained individually at three different water temperatures (ambient, ambient − 4°C, ambient + 4°C) and in the presence or absence of the amphipod grazer Peramphithoe femorata for 14 d. High water temperatures (>20°C) provoked rapid degradation of Macrocystis spp. rafts. At moderate temperatures (15°C–20°C), algal survival depended on the presence of associated grazers. In the absence of grazers, algal rafts gained in biomass while grazing caused considerable losses of algal biomass. Algal survival was the highest under cooler conditions (<15°C), where raft degradation was slow and grazer-induced biomass losses were compensated by continuing algal growth. Our results indicate that floating kelp rafts can survive for long time periods at the sea surface, but survival depends on the interaction between temperature and grazing. We suggest that these processes limiting the survival of kelp rafts in warmer temperatures may act as a dispersal barrier for kelp and its associated passengers.     

PHYSIOLOGICAL PERFORMANCE OF FLOATING GIANT KELP MACROCYSTIS PYRIFERA (PHAEOPHYCEAE): LATITUDINAL VARIABILITY IN THE EFFECTS OF TEMPERATURE AND GRAZING1

Rafts of Macrocystis pyrifera (L.) C. Agardh can act as an important dispersal vehicle for a multitude of organisms, but this mechanism requires prolonged persistence of floating kelps at the sea surface. When detached, kelps become transferred into higher temperature and irradiance regimes at the sea surface, which may negatively affect kelp physiology and thus their ability to persist for long periods after detachment. To examine the effect of water temperature and herbivory on the photosynthetic performance, pigment composition, carbonic anhydrase (CA) activity, and the nitrogen (N) and carbon (C) content of floating M. pyrifera, experiments were conducted at three sites (20° S, 30° S, 40° S) along the Chilean Pacific coast. Sporophytes of M. pyrifera were maintained at three different temperatures (ambient, ambient ? 4°C, ambient + 4°C) and in presence or absence of the amphipod Peramphithoe femorata for 14 d. CA activity decreased at 20° S and 30° S, where water temperatures and irradiances were highest. At both sites, pigment contents were substantially lower in the experimental algae than in the initial algae, an effect that was enhanced by grazers. Floating kelps at 20° S could not withstand water temperatures >24°C and sank at day 5 of experimentation. Maximal quantum yield decreased at 20° S and 30° S but remained high at 40° S. It is concluded that environmental stress is low for kelps floating under moderate temperature and irradiance conditions (i.e., at 40° S), ensuring their physiological integrity at the sea surface and, consequently, a high dispersal potential for associated biota.     

The effect of temperature on embryo survival and development in pallid sturgeon Scaphirhynchus albus (Forbes & Richardson 1905) and shovelnose sturgeon S. platorynchus (Rafinesque, 1820)

The thermal response of pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorynchus embryos was determined at incubation temperatures from 8 to 26°C and 8 to 28°C, respectively. The upper and lower temperatures with 100% (LT₁₀₀) embryo mortality were 8 and 26°C for pallid sturgeon and 8 and 28°C for shovelnose sturgeon. It was concluded that 12–24°C is the approximate thermal niche for embryos of both species. Generalized additive and additive‐mixed models were used to analyze survival, developmental rate and dry weight data, and predict an optimal temperature for embryo incubation. Pallid sturgeon and shovelnose sturgeon embryo survival rates were different in intermediate and extreme temperatures. The estimated optimal temperature for embryo survival was 17–18°C for both species. A significant interaction between rate of development and temperature was found in each species. No evidence was found for a difference in timing of blastopore, neural tube closure, or formation of an S‐shaped heart between species at similar temperatures. The estimated effects of temperature on developmental rate ranged from linear to exponential shapes. The relationship for rate of development to temperature was relatively linear from 12°C to 20°C and increasingly curvilinear at temperatures exceeding 20°C, suggesting an optimal temperature near 20°C. Though significant differences in mean dry weights between species were observed, both predicted maximum weights occurred at approximately 18°C, suggesting a temperature optimum near 18°C for metabolic processes. Using thermal optimums and tolerances of embryos as a proxy to estimate spawning distributions of adults in a river with a naturally vernalized thermal regime, it is predicted that pallid sturgeon and shovelnose sturgeon spawn in the wild from 12°C to 24°C, with mass spawning likely occurring from 16°C to 20°C and with fewer individuals spawning from 12 to 15°C and 21 to 24°C. Hypolimnetic releases from Missouri River dams were examined; it was concluded that the cooler water has the potential to inhibit and delay sturgeon spawning and impede embryo incubation in areas downstream of the dams. Further investigations into this area, including potential mitigative solutions, are warranted.     

Temperature acclimation alters cardiac performance in the lobster Homarus americanus

The American lobster is a poikilotherm that inhabits a marine environment where temperature varies over a 25°C range and depends on the winds, the tides and the seasons. To determine how cardiac performance depends on the water temperature to which the lobsters are acclimated we measured lobster heart rates in vivo. The upper limit for cardiac function in lobsters acclimated to 20°C is approximately 29°C, 5°C warmer than that measured in lobsters acclimated to 4°C. Warm acclimation also slows the lobster heart rate within the temperature range from 4 to 12°C. Both effects are apparent after relatively short periods of warm acclimation (3–14 days). However, warm acclimation impairs cardiac function at cold temperatures: following several hours exposure to frigid (<5°C) temperatures heart rates become slow and arrhythmic in warm acclimated, but not cold acclimated, lobsters. Thus, acclimation temperature determines the thermal limits for cardiac function at both extremes of the 25°C temperature range lobsters inhabit in the wild. These observations suggest that regulation of cardiac thermal tolerance by the prevailing environmental temperature protects against the possibility of cardiac failure due to thermal stress.     

Microcosm evaluation of bioaugmentation after field-scale thermal treatment of a TCE-contaminated aquifer

This paper investigates effects of combining thermal and biological remediation, based on laboratory studies of trichloroethene (TCE) degradation. Aquifer material was collected 6 months after terminating a full-scale Electrical Resistance Heating (ERH), when the site had cooled from approximately 100°C to 40°C. The aquifer material was used to construct bioaugmented microcosms amended with the mixed anaerobic dechlorinating culture, KB-1^TM, and an electron donor (5 mM lactate). Microcosms were bioaugmented during cooling at 40, 30, 20, and 10°C, as temperatures continually decreased during laboratory incubation. Redox conditions were generally methanogenic, and electron donors were present to support dechlorination. For microcosms bioaugmented at 10°C and 20°C, dechlorination stalled at cis-dichloroethene (cDCE) and vinyl chloride (VC) 150 days after bioaugmentation. However, within 300 days of incubation ethene was produced in the majority of these microcosms. In contrast, dechlorination was rapid and complete in microcosms bioaugmented at 30°C. Microcosms bioaugmented at 40°C also showed rapid dechlorination, but stalled at cDCE with partial VC and ethene production, even after 150 days of incubation when the temperature had decreased to 10°C. These results suggest that sequential bioremediation of TCE is possible in field-scale thermal treatments after donor addition and bioaugmentation and that the optimal bioaugmentation temperature is approximately 30°C. When biological and thermal remediations are to be applied at the same location, three bioremediation approaches could be considered: (a) treating TCE in perimeter areas outside the source zone at temperatures of approximately 30°C; (b) polishing TCE concentrations in the original source zone during cooling from approximately 30°C to ambient groundwater temperatures; and (c) using bioremediation in downgradient areas taking advantages of the higher temperature and potential release of organic matter.     

野生鸡枞菌种长期保存方法比较

野生鸡枞菌种质资源的有效保存是对野生鸡枞加以保护和利用的前提。以自行分离的5个野生鸡枞菌株作为研究对象,采用蒸馏水保藏法和-80°C冻结保藏法对野生鸡枞菌种长期保存的方法进行了实验研究,蒸馏水法分别保存于室温和4°C,-80°C冻结保藏同时采用程控降温法和泡沫盒降温法,保存20个月后对4种不同方法保存的5个菌株的保存效果进行比较。实验结果表明:蒸馏水室温保存法菌种存活率为100%,萌发期较短,为4-10 d,是一种简便、实用、有效而成本低廉的长期保存方法;-80°C冻结保藏法的存活率为56%-76%,萌发期7-16 d,泡沫盒降温法可以很好地控制降温速度,是一种简便有效的控温方法。     

Fatty Acid Levels in Apple Leaves of Different Age as Affected by Temperature

Relative electrical conductivity (RC) values and Tally acid levels were measured on apple leaves of different ages exposed to 0 and 20°C. RC values were measured at—3°C and high RC values indicate frost-sensitive tissue. A prolonged period at 0°C gave an increased RC value of the leaves, which indicates damage. At 20°C the RC values were lower in older leaves than in young leaves. The fatty acids level as well as the degree of saturation were different at different ages of the leaves. Young leaves showed a higher fatty acid level in plants held at 20°C than in plants at 0°C. The older leaves maintained the same level after 12 days at 20°C as after 3 days at 20°C. The fatty acid level decreased at 0°C. The linolenic acid level followed the same trend as total fatty acids, indicating that synthesis and degradation of linolenic acid can occur in the same plant depending on the age of the leaf and on the temperature. Cold resistance and linolenic acid levels were correlated in both old and young leaves at 20°C and in older leaves at 0°C. There was no correlation between cold resistance and levels of linotenic acid levels in young leaves at 0°C. Two hiosynthetic pathways for linolenic acid synthesis are discussed.     

A Simple Biosynthetic Method for Preparation of High Specific Radioactivity Phosphatidyl-choline

Chemical changes in lysozyme during heating at 150~250°C for 20min were investigated by means of IR, ESR, and CD spectroscopies and gel permeation chromatography, and further a tryptic hydrolysate from the lysozyme heated at 200°C was analyzed by ion exchange chromatography. At 150°C, polymerization through disulfide linkages was observed, and at180°C, both polymerization and degradation occurred. When the temperature was raised to 200°C, remarkable changes in the structure of lysozyme, such as cleavage and recombination of peptide bonds, occurred. Over 200°C, polymerization and degradation occurred more violently.     

Effects of water vapor absorption on the physical and chemical stability of amorphous sodium indomethacin

This study reports on the effects that water absorbed into amorphous sodium indomethacin (NaIMC) can have on simultaneous tendencies to crystallize to its trihydrate form and to undergo base-catalyzed hydrolysis because of the plasticizing effects of water on molecular mobility. Measurement of water vapor absorption at 30°C and powder x-ray diffraction patterns as a function of relative humidity (RH) reveal that upon exposure to 21% RH, NaIMC does not crystallize over a 2-month period. Measurements of the glass transition temperature as a function of such exposure reveals a change in T _g from 121°C, dry, to 53°C at 21% RH, such that T _g at 21% RH is ≈13°C above the highest storage temperature of 40°C used in the study. At 56% RH and higher, however, crystallization to the trihydrate occurs rapidly; although over the 2-month period, crystallization was never complete. Assessment of chemical degradation by high-performance liquid chromatography analysis revealed significant instability at 21% RH; whereas at higher RH, the extent of chemical degradation was reduced, reflecting the greater crystallization to the more chemically stable crystalline form. It is concluded that when amorphous forms of salts occur in solid dosage forms, the simultaneous effects of enhanced water vapor sorption on crystallization and chemical degradation must be considered, particularly when assessing solid-state chemical degradation at higher temperatures and RH (eg, 40°C 75% RH).     

The modelling of combined strategies to achieve thermophilic composting of sludge in cold region

Low ambient temperature presents a significant technical challenge for efficient operation of the composting facility located in cold region. In this study, mathematical model was used as a tool to develop the operational strategy to accomplish thermophilic composting of sewage sludge in the cold-climate environment. The correlations between composting temperature, water volatilization, heat loss rate, organics degradation and ambient temperature, feedstock temperature, sludge moisture and aeration rate were predicted and evaluated by using the numerical simulation method. The feasibility of optimizing air supply, adjusting feedstock moisture and elevating starting temperature in the low temperature surroundings was investigated. The results obtained from both mathematical modelling and pilot-scale composting experiments demonstrated that the combined strategies of the three approaches could preliminarily achieve material drying, pathogen inactivation and organics stabilization within 20 days at the ambient temperature as low as −24 °C. However, it seems difficult for anyone of these approaches to meet the requirement of thermophilic composting, independently.     

Degradation of Poliovirus Polypeptides <Emphasis Type="Italic">in vivo</Emphasis>

CELLS infected with attenuated type 1 poliovirus (LSc) at 39° C synthesize only 20% of the viral proteins produced at 35° C. Polyacrylamide gel electrophoresis of viral peptides shows that only four peptides (with molecular weights of 230,000, 212,000, 196,000 and 160,000) are produced at the restrictive temperature¹. It was suggested that the last three are cleavage products of the 230,000 molecular weight peptide. Furthermore, since smaller peptides were never observed it was suggested that proteolysis might eliminate them from infected cells at 39° C. Nonsense and deletion mutations cause degradation of incomplete peptides of β-galactosidase² and the lac repressor³. We have studied whether there is significant proteolysis of the peptides of attenuated poliovirus in vivo at 39° C. There is extensive degradation of viral peptides at the restrictive temperature and essentially no degradation at the permissive temperature. The peptides of wild type virulent virus are not degraded at either 35° C or 39° C.     

Temperature-limited Activity in the Garter Snake Thamnophis melanogaster (Colubridae)

Many garter snakes, Thamnophis melanogaster, at a desert pond first started foraging for tadpoles when mean water surface temperature was about 20 °C (at 0945–1015 h), and the number of snakes tripled when water temperature reached about 24 °C (at 1100–1130 h). In two years, snakes foraged in April and May, but not in March when water never reached 23 °C and only exceeded 20 °C for a few hours after the usual foraging hours. Snakes in the laboratory dedicated increasing amounts of time to underwater foraging as air and water temperatures increased from 9 °C to 29 °C, and their rate of attacks on fish increased steeply and progressively above an apparent threshold lying between roughly 19 °C and 24 °C, up to at least 29 °C. Temperature may limit T. melanogaster's foraging at the pond to the hours after roughly 0900 h and to the period after roughly March, despite evidence that prey abundance is maximal in March.