Utilizable Energy Source Research Articles

Ensiling characteristics, physicochemical structure and enzymatic hydrolysis of steam-exploded hippophae: Effects of calcium oxide, cellulase and Tween

To find a comprehensive way to enhance the utilizability of steam-exploded hippophae, calcium oxide (CaO) preimpregnation, cellulase-added storage and saccharification with addition of Tween 20 were investigated in this study. Both CaO preimpregnation and cellulase addition promoted the ensiling fermentation of anaerobically stored steam-exploded hippophae indicated by lower cellulose proportion and higher organic acids content, but led to the decrease of saccharification yield by 11.83% and 46.77–51.22%, respectively. When taking into account of organic acids being utilizable energy source, storing with addition of cellulase enhanced the utilizability of the materials in whole. Moreover, the addition of Tween 20 enhanced saccharification yield of the steam-exploded hippophae by 26.69–45.25%. Additionally, FTIR and XRD spectra clearly illustrated the structural alteration during storage. It is concluded that storing with addition of cellulase and hydrolyzing with addition of Tween 20 can enhance the utilizability of steam-exploded hippophae.

Synergistic Effects of Cellulase-Producing Microorganisms for Future Bioconversion of Lignocellulosic Biomass

Lignocellulosic biomass can nowadays be bioconverted to value-added biofuels by numerous cellulases purified from diverse microbes. In nature, complex microbial communities produce multifunctional cellulase systems with broader substrate utilization and act sequentially in the synergistic action by subsequently converting cellulose into an utilizable energy source and glucose. This research was to apply cellulase producing isolates based on their possible synergistic action to degrade complex cellulose containing biomass. In the study, the microorganism species, isolated species from durian peels after macerated for 3 days and shown for their high biodegradation activity, Bacillus spp. (B12, B13, and B16) and Pseudomonas spp., (B23 and B55), could express high cellulase activity on carboxymethylcellulose (CMC) and filter paper (FP). Bacillus spp. B13 and B16 showed high cellulase activity on soluble cellulose of CMC while B12 and B55 displayed high cellulase activity on crystalline insoluble cellulose of FP. To observe the synergistic effect of the cellulase-producing consortia, co-cultures of B12,B23 and F23 were grew well on both CMC and FP. Therefore, these findings of synergistic effects of microbial consortia could bring us a future work to develop high efficient cellulase producing systems for further industry application.

Oxidation of medium-chain and long-chain fatty acids by polka dot grouper Cromileptes altivelis

In this study we tested the hypotheses that higher fat diets will promote greater fat oxidation, and that medium-chain fatty acids (MCFA) will be more readily oxidized than long-chain fatty acids (LCFA). The oxidation of dietary MCFA (coconut oil labelled with 14C-octanoic acid) and LCFA (olive oil labelled singly with 14C-palmitic acid and 14C-oleic acid) was measured in a metabolic chamber. MCFA and LCFA were included in the respective diets at 150 and 300 g kg−1. Polka dot grouper fed diets containing MCFA had a significantly higher (P < 0.05) respiration rate [2.4 mmol CO2 BW (kg)−0.79 h−1] and proportion of radioactivity in the respired CO2 (49.5%) than those fed diets containing LCFA [1.2 mmol CO2 BW (kg)−0.79 h−1 and 12.8%, respectively]. The amount of dietary fat did not significantly affect either of these two response attributes. The radioactivity in faeces and regurgitated material was low with diets containing MCFA, but was significantly higher with diets containing LCFA, and increased with increasing LCFA content, suggesting a decrease in digestibility. These results show that MCFA provide this species with a more readily utilizable source of energy than LCFA. Moreover, raising the amount of lipid in the diet above 150 g kg−1 did not increase the oxidation of fatty acids for energy.

The Clearance of Carbon-14-Fructose, Carbon-14-Glucose, and Carbon-14-Sorbitol by Calves at Birth and 7 Days of Age

Prior to birth, the calf is solely dependent on maternal energy sources. Dramatic changes in blood concentrations of carbohydrates, hormones, and enzymes occur, enabling the neonate to achieve homeostasis. Many of these changes are not well understood. This study was to monitor the metabolism and disappearance of labeled carbohydrates in conjunction with endogenous fructose and glucose. Calves were infused intravenously with 100 μCi of [U-14C]D-fructose, -glucose, or -sorbitol within 12min of birth and at 7 d of age. Close-interval blood and urine samples were collected until 720min postinfusion. Radiolabel from the three carbohydrates was separated into parent compound fractions by HPLC. Concentrations of cortisol, insulin, glucose, and fructose were determined from blood. Serum cortisol concentration was 3 to 10 times higher in calves at birth than at 7 d of age. Serum insulin concentrations increased postfeeding in newborn and 7-d-old calves. Insulin concentrations were related to plasma glucose. Endogenous plasma fructose was 63 mg/dl (SE=7) at birth and was undetectable after 14h. Glucose was 60 mg/dl (SE=1) and 92 mg/dl (SE=8) at birth and at 7 d, respectively. Clearance of radiolabel from glucose at birth and for all the carbohydrates at d 7 was similar. Fructose and sorbitol were cleared more slowly at birth. Radiolabel from fructose at birth was converted very slowly to glucose, but this conversion was rapid at d 7. Sorbitol was converted to fructose at birth but changed quickly to glucose at d 7. The 24-h excretion of radiolabel in urine was less than 4% for fructose and glucose at birth and at d 7. The label from sorbitol appeared in urine at birth (32%) and at d 7 (10%). A source of fructose may provide a slowly utilizable energy source until blood glucose concentrations become stable in the newborn calf.

Influence of starvation at low temperatures on utilization of energy reserves, appetite recovery and growth character in sea bass,Dicentrarchus labrax

The effect of starvation at selected low temperatures was studied in sea bass,Dicentrarchus labrax. The work focused on proximate chemical constituents and blood glucose. Appetite and growth of starved, refed specimens were also examined. Two experimental sets were designed. In one set the fish were exposed to 3 °C, 7 °C and 11 °C and in the other to 3 °C, 8 °C and 13 °C. Survival of the fish in the experimental conditions was 99.7%. Appreciable loss in body weight occurred. The reduction was more marked in the first week. No significant difference in chemical composition occurred in the first two weeks of starvation. Prolongation of food deprivation resulted in decline of lipid content with a corresponding increase in water content. This trend was the more marked at high temperature. Liver glycogen was the most readily utilizable source of energy. Lipid yielded energy after which proteins were mobilized to save further loss of lipid. Lipid exerted a sparing role for glycogen. The preference for different energy sources depended on exposure temperature and duration of starvation, Lipid chiefly supplied the energy needs of the 3 °C test groups, whereas liver glycogen provided the calorific requirements of fish at 7 °C, 8 °C, 11 °C and 13 °C. In the 3 °C test groups gluconeogenesis occurred after 2 weeks. The products of lipid breakdown may have served as substrates for glycogen biosynthesis. High tolerance of sea bass to low temperature was attributed to high fat content and hyperglycemia. The study also pointed to the involvement of some organs other than liver in generating glucose from their glycogen stores following exhaustion of hepatic glycogen. Starvation stress at the lowest temperatures adversely affected the return of the fish's appetite and growth characters. Compensatory growth occurred in sea bass refed after starvation. The findings have implications for aquaculture management procedures.

Inhibition of DNA Synthesis in Saccharomyces cerevisiae by Yeast Killer Toxin KT28

Treatment of sensitive cells of Saccharomyces cerevisiae with killer toxin KT28 affected cell viability after 2 h: the effect was dependent upon the availability of a utilizable energy source. Treatment led to an interruption of cell growth. The mother cells contained nuclear DNA, whereas their daughter buds did not. Using a killer-toxin-sensitive thymidine auxotroph of S. cerevisiae carrying a temperature-sensitive thymidylate uptake mutation, it was shown that the incorporation of dTMP at the permissive temperature was inhibited within 30 min of the addition of KT28. When cells labelled at the permissive temperature were incubated at the restrictive temperature, the level of radioactivity declined in the absence but not in the presence of KT28. No other effects of KT28 were observed within 2 h of its addition, and it is concluded that the inhibition of DNA synthesis is an early effect of the action of KT28.

Review: Neonatal Parenteral Nutrition with Medium‐Chain Triglycerides: Rationale for Research

With the advances in technology stable fat emulsions containing medium-chain triglycerides (MCT) became available. Intravenous MCT are readily utilizable energy source because they reach the liver rapidly and their medium-chain fatty acids (MCFA) are oxidized through carnitine-independent mechanisms. However the MCFA can also be deviated to alternative oxidation pathways which results in urinary excretion of metabolites. The metabolic effects of intravenous MCT containing fat emulsions are discussed and emphasis is given in the possible role of these fats in parenteral nutrition of preterm infants, who are carnitine depleted. Directions of future research are speculated.

Energy and protein sources for development of pig embryos cultured beyond hatching in vitro

The effects of supplementation of synthetic culture media with different energy and protein sources on in vitro development of pig embryos beyond the 4–8-cell stage have been explored. Minimal Essential Medium (MEM) supplemented with glucose (1 mg/ml) proved superior to Krebs-Ringer Bicarbonate (KRB) supplemented with glucose (1 mg/ml) in its capacity to support embryonic development to the expanded blastocyst stage ( P < 0.05). Inclusion of pyruvate (0.25 m M) or lactate (25 m M) in either MEM or KRB based media inhibited embryonic development. As pyruvate and lactate are important and readily utilizable energy sources for development of most other mammalian embryos in vitro, it is suggested that the observed inhibitory effects of these substrates reflect comparatively lower critical ranges of concentrations of pyruvate and lactate for optimum development of pig embryos in vitro. As a supplementary protein source to MEM, heat inactivated (HI) human serum (10% υ/υ) was superior ( P < 0.05) to HI-pig serum (10% υ/υ), HI-foetal calf serum (10% υ/υ) or bovine serum albumin (5 mg/ml). The proportion of 4–8-cell pig embryos which developed beyond hatching in MEM supplemented with HI-human serum (> 56%) was higher than any other reported for in vitro culture of pig embryos through the same developmental period and this medium is recommended for future studies on in vitro development of pig embryos from the four-cell through the hatched/expanded blastocyst stages.

Biological nitrogen fixation in the terrestrial environment of a high Arctic ecosystem (Truelove Lowland, Devon Island, N.W.T.).

Arranged in descending order of nitrogen-fixing (acetylene-reducing) potential the sites examined were mesic meadow and peat polygon troughs (equal rank), transition zone between mesic meadow and gravel ridge, gravel ridge, polar dessert, and peat polygon tops. The dominant nitrogen-fixing microorganisms, as in other Arctic areas, were blue-green bacteria, especially those epiphytic on Arctic mosses. The epiphytic association exhibited an optimum temperature for fixation of 20 degrees C. Other bacteria potentially able to fix nitrogen were present in the soils examined but their activity was severely restricted by low soil temperatures and lack of readily utilizable energy sources. These bacteria included members of the genera Klebsiella (the most numerous), Bacillus, Clostridium, and Beijerinckia (scarce). Also present at many of the sites was an unidentified yellow-pigmented fixer which was not Mycobacterium flavum. All fixers were psychotrophic rather than psychrophilic, having an optimum temperature greater than 20 degrees C but capable of slow growth at 5 degrees C or lower. The rate of acetylene reduction by the epiphytic system increased with the number of successive exposures to acetylene, a phenomenon of some significance in any calculations designed to measure the amount of nitrogen fixed in certain ecosystems.

Factors affecting genetic transformation of Neisseria gonorrhoeae.

Piliated gonococci were competent in genetic transformation in all stages of growth in minimal and enriched media, but nonpiliated cells were almost totally incompetent. Uptake of deoxyribonucleic acid into a deoxyribonuclease-insensitive state was observed only in competent piliated cells. Competence was not affected by washing of competent cells or treatment of competent cells with proteolytic enzymes. Expression of competence required presence of any of several different monovalent or divalent cations, as well as a utilizable source of energy. Efforts to produce genotypically or phenotypically competent derivatives of nonpiliated cells were unsuccessful. These experiments are consistent with the idea that pili may play a role in the irreversible uptake of transforming deoxyribonucleic acid by the gonococcus, but fail to provide evidence for other types of competence factors.

Effects of stress on carbohydrate metabolism in the teleost Notopterus notopterus (Pallas)*

The effects of different types of stre35 on carbohydrate metabolism in N. notopterus were investigated. Starvation alone brings about a signifiant increse in the glycogen content of the saccus vasculosus and a significant decrease in the brain glycogen concentration. The increased glycogen concentration in the saccus vasculosus may be a device to safeguard the brain against glucose deficiency during starvation stress. Rapid depletion of the muscle glycogen following fasting shows that the muscle glycogen IS the readily utilizable source of energy during starvation.Exposure of N. noropierus to air brought about an increaSe in the liver glycogen and blood glucose levels but did not affect other paramcters studied.Physical exhaustion of N. notopierus is noticed within 1–2 min of exercise. The readily available source of energy for exercise is the muscle glycogen. and the lactic acid produced is probably metabolized in the muscle itself. Saccus vasculosus glycogen. though inde‐pendent of changes in the blood glucose levels, may possibly be controlled by variations in the brain glycogen.

Energy expenditure is obligatory for the downhill transport of galactosides

Galactoside permease-containing cells of Escherichia coli have been depleted of energy reserves to such a low level that uptake of α-methyl-glucoside and cellular hydrolysis of o-nitrophenyl-β- d-galactopyranoside (ONPG) no longer take place. In all previous studies these transport processes had been found to be resistant to energy poisons and starvation. The cells' energy supplies can be sufficiently depleted by inducing the glucose permease and then making the cells pump α-methyl-glucoside to exhaustion in the absence of a utilizable energy source and in the presence of azide. Such cells recover their measured transport capabilities when a utilizable energy source is added back. The recovery is sufficiently fast and takes place in the presence of protein synthesis inhibitors which eliminates the possibility that protein synthesis is needed for recovery. Since the cellular hydrolysis assay of ONPG is dependent on permease, but constitutes a transport process from the outside region of high concentration to the inside where the concentration is very low, transport even down a thermodynamic electrochemical potential requires energy expenditure. I must therefore retract the concepts previously proposed (Koch, 1964); I now conclude that permease-mediated transport per se is dependent on energy and that energy coupling to transport, even down a gradient, is obligatory.

The rapid loss of viability of Azotobacter in aqueous solutions.

When a low number ofAzotobacter vinelandii 12837 log phase vegetative cells (2 × 103 cells/ml) were removed from the culture liquid to water of the same temperature, a rapid loss of viability occurred depending on the procedure of washing and suspending. Death was not accompanied by visible lysis and the rate of loss of viability was less at lower temperatures, and in the presence of salts or cell-free filtrates from heavy cell suspensions in water. The die-off was erratic at increased cell concentrations and was accelerated by utilizable energy sources. Cells standing in a favorable ionic solution (0.1% NaCl) do not lose their viability while cells washed by a series of centrifugations with the same ionic solution show a progressive loss of viability with each washing. Phospholipids were found to leach from the cells into the aqueous solutions. Such cell death suggests instability of the cell membrane and the loss of osmotic or ionic control in the cells.

Chemotaxis in bacteria.

Motile Escherichia coli placed at one end of a capillary tube containing an energy source and oxygen migrate out into the tube in one or two bands, which are clearly visible to the naked eye and can also be demonstrated by photography, microscopy, and densitometry and by assaying for bacteria throughout the tube. The formation of two bands is not due to heterogeneity among the bacteria, since the bacteria in each band, when reused, will form two more bands. If an anaerobically utilizable energy source such as galactose is present in excess over the oxygen, the first band consumes all the oxygen and a part of the sugar and the second band uses the residual sugar anaerobically. On the other hand, if oxygen is present in excess over the sugar, the first band oxidizes all the sugar and leaves behind unused oxygen, and the second band uses up the residual oxygen to oxidize an endogenous energy source. The essence of the matter is that the bacteria create a gradient of oxygen or of an energy source, and then they move preferentially in the direction of the higher concentration of the chemical. As a consequence, bands of bacteria (or rings of bacteria in the case of agar plates) form and move out. These results show that E. coli is chemotactic toward oxygen and energy sources such as galactose, glucose, aspartic acid, threonine, or serine. The full repertoire of chemotactic responses by E. coli is no doubt greater than this, and a more complete list remains to be compiled. The studies reported here demonstrate that chemotaxis allows bacteria to find that environment which provides them with the greatest supply of energy. It is clearly an advantage for bacteria to be able to carry out chemotaxis, since by this means they can avoid unfavorable conditions and seek optimum surroundings. Finally, it is necessary to acknowledge the pioneering work of Englemann, Pfeffer, and the other late-19thcentury biologists who discovered chemotaxis in bacteria, and to point out that the studies reported here fully confirm the earlier reports of Beijerinck (4) and Sherris and his collaborators (5,6) on a band of bacteria chemotactic toward oxygen. By using a chemically defined medium instead of a complex broth, it has been possible to study this band more closely and to demonstrate in addition the occurrence of a second band of bacteria chemotactic toward an energy source. Beijerinck (4) did, in fact, sometimes observe a second band, but he did not offer an explanation for it.

The roles of inducer and catabolite repressor in the synthesis of β-galactosidase by Escherichia coli

The mechanism of the induction of β-galactosidase in Escherichia coli at 30°C was investigated by separating the phase of enzyme induction from the phase of enzyme production. This separation was accomplished by removing the inducer by filtration after 3 to 4 min of contact with the cells, that is before enzyme had been formed; the cells then produced the enzyme in inducer-free medium at an exponentially declining rate for approximately 10 min. It was found that interference with the synthesis of normal RNA by 5-fluorouracil during the phase of enzyme induction largely prevents the subsequent production of normal enzyme and causes the formation of an altered protein serologically related to β-galactosidase; on the other hand, such an interference with RNA synthesis during the phase of enzyme production does not affect the formation of the enzyme by previously induced cells. Conversely, interference with protein synthesis by starvation for an amino acid or by chloramphenicol during the phase of induction does not prevent the subsequent production of normal enzyme; but such an interference with protein synthesis during the phase of enzyme production inhibits the formation of the enzyme by previously induced cells to the same extent as that of other protein. These results indicate that during the induction phase a messenger RNA specific for β-galactosidase is produced which directs the subsequent synthesis of the enzyme in the inducer-free medium. No additional β-galactosidase messenger RNA is formed after removal of the inducer and that present in the cell decays exponentially with a half-life of approximately 2·5 min. The rate of this decay is independent of the rate of protein synthesis or the rate of energy metabolism. An excess of intracellular catabolites, produced either by the rapid catabolism of glucose or by the restriction of protein synthesis in the presence of a utilizable energy source, inhibits the induction of the enzyme but does not affect the production of the enzyme by previously induced cells. Apparently, the catabolite repressor inhibits and the inducer stimulates the synthesis of the unstable messenger RNA specific for β-galactosidase.

The effects of thymine and of phosphate deprivation on enzyme synthesis in Escherichia coli

Abstract The ability of a thymine-requiring mutant of Escherichia coli to form the inducible enzyme β-galactosidase in media of different composition and at different stages of thymine starvation was investigated. The differential rate of synthesis of this enzyme in a medium containing casamino acids but no readily utilizable energy source, is the same whether or not protein synthesis is restricted by the omission of inorganic phosphate. Addition of a readily utilizable energy source, glycerol, reduces the differential rate of synthesis of the enzyme slightly when phosphate is present, but greatly when phosphate is absent. Apparently, catabolites derived from glycerol accumulate in the cell when the rate of protein synthesis is restricted by the lack of phosphate and repress the formation of enzymes sensitive to catabolite repression. The lack of thymine is initially without effect on the synthesis of β-galactosidase. When thymine starvation is sufficiently prolonged to cause the death of the cell, the rate of protein synthesis is reduced and glycerol almost completely represses the synthesis of β-galactosidase. The extensive thymine starvation reduces the cell's capacity to form the enzyme β-galactosidase in the absence of glycerol somewhat more than its capacity to synthesize proteins.

The effects of thymine and of phosphate deprivation on enzyme synthesis in Escherichia coli

The ability of a thymine-requiring mutant of Escherichia coli to form the inducible enzyme β-galactosidase in media of different composition and at different stages of thymine starvation was investigated. The differential rate of synthesis of this enzyme in a medium containing casamino acids but no readily utilizable energy source, is the same whether or not protein synthesis is restricted by the omission of inorganic phosphate. Addition of a readily utilizable energy source, glycerol, reduces the differential rate of synthesis of the enzyme slightly when phosphate is present, but greatly when phosphate is absent. Apparently, catabolites derived from glycerol accumulate in the cell when the rate of protein synthesis is restricted by the lack of phosphate and repress the formation of enzymes sensitive to catabolite repression. The lack of thymine is initially without effect on the synthesis of β-galactosidase. When thymine starvation is sufficiently prolonged to cause the death of the cell, the rate of protein synthesis is reduced and glycerol almost completely represses the synthesis of β-galactosidase. The extensive thymine starvation reduces the cell's capacity to form the enzyme β-galactosidase in the absence of glycerol somewhat more than its capacity to synthesize proteins.

House Fly Nutrition. II. Comparative Survival Values of Sucrose and Water

House flies maintained on lactose, wheat flour, milk powder, or 1-arabinose die within 48 hours, as they do if deprived of all food. A utilizable energy source such as sucrose takes precedence over water in fly survival. On sucrose alone, flies live about 50 percent longer than on water alone. Under conditions ranging from partial to complete inanition or dehydration, females prove more hardy and live more than 35% longer than males. Powdered food produces an avoidance reaction in the fly which is counterbalanced by its hunger drive. The fly's position at the edge of the food is a resultant of these two forces.