Synthesis of sugar fatty acid esters using a β-xylosidase from <Emphasis Type="Italic">Aspergillus awamori</Emphasis> for transxylosylation

Aspergillus awamori K4 β-xylosidase has broad acceptor specificity. It has been used to synthesize a sugar fatty acid ester via its transxylosylation activity. One xylosyl residue was initially transferred to hexamethylene glycol as a linker with a yield of 0.36 g/g xylobiose. Linoleic acid was subsequently linked to one terminal hydroxyl side of the transfer product hydroxyhexyl xyloside through an esterification reaction catalyzed by a lipase. The synthesis of hexyl linoleoyl xyloside was confirmed by TOF-MS analysis. The binding with a linker improved the esterification reaction because of the hydrophobic hexamethylene chain and also prevented steric hindrance by the xylosyl residue. This sugar fatty acid ester synthesis method using transglycosylation should facilitate the production of emulsifiers or surfactants with various functions.     

The production of acidic,O-acylated cyclosophorans [cyclic (1→2)-β-d-glucans] by Agrobacterium and Rhizobium species

Acidic cyclosophorans [cyclic (1→2)-β-d-glucans] containing methylmalonic acid, or succinic acid, or both, were isolated by DEAE-cellulose chromatography from culture filtrates and cells of some strains of Agrobacterium radiobacter, Rhizobium phaseoli, and R. trifolii. The evidence suggests that one carboxyl group of the dicarboxylic acid is in ester linkage with an hydroxyl group of a sugar unit.     

On the Frequency Distribution of a Product

Biometric interest often attaches to the product of two directly determined variables. In sugar production, for example, the yield of the desired commodity is the product of the total weight of cane or beet from unit area and the sugar content per unit weight. In crop and animal production, there are many analogous situations where experimental or other information may come from field plots or individual animals and the success of inferences or decisions is related to the frequency distribution of such a product. The voluminous published literature relating to frequency distributions appears to contain little that is directly relevant. It therefore seems worth placing on record results recently obtained for the third and fourth moments of a product in the simple case of both variables being Normally distributed.     

Chimeric tomato plants show that aphid resistance and triacylglucose production are epidermal autonomous characters.

Graft chimeras were generated using Lycopersicon pennellii and L. esculentum to determine the contribution of the three meristem layers (L1, L2, and L3) to trichome density, sugar ester production, and aphid resistance. Sugar esters, in the form of triacylglucoses, have been implicated in the aphid resistance of pennellii. One chimera possessed the epidermal layer (L1) of pennellii and the internal tissues (L2 and L3) of the aphid-susceptible esculentum. The second chimera had both the L1 and L2 of pennellii and the L3 of esculentum. Type IV trichome densities did not differ significantly among the chimeras and pennellii. Both chimeras accumulated sugar esters with similar sugar and fatty acid composition as pennellii. The concentration of epicuticular sugar ester on the chimeras was also comparable with that of pennellii. Leaf cage and feeding studies demonstrated that both chimeras are as resistant to aphids as is pennellii. The resistance could be reduced similarly on all three types of plants by removal of the type IV trichome exudate. These results indicate that the presence and density of the type IV trichomes and the amount and type of sugar esters produced are features determined by the genotype of the epidermis. These epidermal features are sufficient to account for the aphid resistance observed in pennellii.     

糖脂修饰的脂肪酶在有机溶剂中催化酯化反应

本文研究了不同糖脂化合物修饰的脂肪酶在有机溶剂中催化长碳链脂肪酸和脂肪醇的酯化反应,不同的脂肪酶经糖脂修饰后,催化活性均有不同程度的提高。在４种糖脂和６种脂肪酶中,以蔗糖酯ＳＥ－７修饰脂肪酶ＣＥＳ活性最高,本文还对ｐＨ、溶剂和温度等对修饰脂肪酶生的影响进行了研究。     

C-C bond formation at the 3'-position of nucleosides by the use of their enol esters

Nucleosides having an enol ester structure in the sugar portion were synthesized and their reaction with several types of electrophiles were carried out. This furnished a new method for constructing C-C bond at the 3'-position.     

A Fresh View of Glycolysis and Glucokinase Regulation: History and Current Status

This minireview looks back at a century of glycolysis research with a focus on the mechanisms of flux regulation. Traditionally, glycolysis is regarded as a feeder pathway that prepares glucose for further catabolism and energy production. However, glycolysis is much more than that, in particular in those tissues that express the low affinity glucose-phosphorylating enzyme glucokinase. This enzyme equips the glycolytic pathway with a special steering function for the regulation of intermediary metabolism. In beta cells, glycolysis acts as a transducer for triggering and amplifying physiological glucose-induced insulin secretion. On the basis of these considerations, I have defined a glycolytic flux regulatory unit composed of the two fructose ester steps of this pathway with various enzymes and metabolites that regulate glycolysis.     

Hydrocarbon emulsification and enhanced crude oil degradation by lauroyl glucose ester

Enzymatically synthesized lauroyl glucose emulsified different hydrophobic substrates when assayed spectrophotometrically. Stable emulsions were formed with triglycerides as well as with hydrocarbons. There was a linear relation between the concentration of lauroyl glucose (50-450 microg) and emulsification activity under the assay conditions when tested with aromatic and aliphatic hydrocarbons. This sugar ester was able to emulsify the aromatic hydrocarbons benzene, toluene and xylene. Long chain alkanes (n-decane and n-hexadecane) as well as brominated long chain alkanes (1-bromodecane and 1-bromohexadecane) were efficiently emulsified. The effect of lauroyl glucose ester on degradation of crude oil by a known oil-degrading Rhodococcus species was also investigated. The culture showed enhanced degradation of crude oil when lauroyl glucose ester was used as an emulsifier. It degraded 70% of the aliphatic fraction of Bombay High crude oil in the presence of the sugar ester at a concentration of 200mg l(-1) as compared to 50% without the emulsifier.     

High-resolution proton nuclear magnetic resonance characterization of seminolipid from bovine spermatozoa

The high-resolution one- and two-dimensional proton nuclear magnetic resonance (1H-NMR) characterization of seminolipid from bovine spermatozoa is presented. The 1H-NMR data was confirmed by gas-liquid chromatography-mass spectrometric analysis of the partially methylated alditol acetates of the sugar unit, mild alkaline methanolysis of the glyceryl ester, mobility on normal phase and diphasic thin-layer chromatography (HPTLC), and fast atom bombardment mass spectrometry (FAB-MS). The structure of the molecule corresponds to 1-O-hexadecyl-2-O-hexadecanoyl-3-O-beta-D-(3'-sulfo)-galactopyranosyl- sn-glycerol.     

Intrinsic nitric oxide regulates the taste response of the sugar receptor cell in the blowfly, Phormia regina

The taste organ in insects is a hair-shaped taste sensory unit having four functionally differentiated contact chemoreceptor cells. In the blowfly, Phormia regina, cGMP has been suggested to be a second messenger for the sugar receptor cell. Generally, cGMP is produced by membranous or soluble guanylyl cyclase (sGC), which can be activated by nitric oxide (NO). In the present paper, we electrophysiologically showed that an NO scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO), an NO donor, 1-hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC 7) or an NO synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) specifically affected the response in the sugar receptor cell, but not in other receptor cells. PTIO, when introduced into the receptor cells in a sensillum aided by sodium deoxycholate (DOC, pH 7.2), depressed the response of sugar receptor cells to sucrose but did not affect those of the salt or water receptor cells. NOC 7, given extracellularly, latently induced the response of sugar receptor cells; and L-NAME, when introduced into the receptor cells, depressed the response of sugar receptor cells. The results clearly suggest that NO, which may be produced by intrinsic NOS in sugar receptor cells, participates in the transduction cascade of these cells in blowfly.     

Degradation of chitosans with chitinase B from Serratia marcescens. Production of chito-oligosaccharides and insight into enzyme processivity

Family 18 chitinases such as chitinase B (ChiB) from Serratia marcescens catalyze glycoside hydrolysis via a mechanism involving the N-acetyl group of the sugar bound to the -1 subsite. We have studied the degradation of the soluble heteropolymer chitosan, to obtain further insight into catalysis in ChiB and to experimentally assess the proposed processive action of this enzyme. Degradation of chitosans with varying degrees of acetylation was monitored by following the size-distribution of oligomers, and oligomers were isolated and partly sequenced using (1)H-NMR spectroscopy. Degradation of a chitosan with 65% acetylated units showed that ChiB is an exo-enzyme which degrades the polymer chains from their nonreducing ends. The degradation showed biphasic kinetics: the faster phase is dominated by cleavage on the reducing side of two acetylated units (occupying subsites -2 and -1), while the slower kinetic phase reflects cleavage on the reducing side of a deacetylated and an acetylated unit (bound to subsites -2 and -1, respectively). The enzyme did not show preferences with respect to acetylation of the sugar bound in the +1 subsite. Thus, the preference for an acetylated unit is absolute in the -1 subsite, whereas substrate specificity is less stringent in the -2 and +1 subsites. Consequently, even chitosans with low degrees of acetylation could be degraded by ChiB, permitting the production of mixtures of oligosaccharides with different size distributions and chemical composition. Initially, the degradation of the 65% acetylated chitosan almost exclusively yielded oligomers with even-numbered chain lengths. This provides experimental evidence for a processive mode of action, moving the sugar chain two residues at a time. The results show that nonproductive binding events are not necessarily followed by substrate release but rather by consecutive relocations of the sugar chain.     

Comparison of the Baker's yeast process performance in laboratory and production scale

A 215 m³ industrial bubble column reactor for fedbatch production of Baker's yeast was sampled for sugar, to investigate the extent of concentration gradients. The results verify that such gradients exist: the concentration is higher closer to the feeding point. Effects of sugar heterogeneities at different scales were studied by 1)?performing a volumetric scale-down of the industrial process in a laboratory stirred tank reactor (STR); 2) performing the same scaled down process in a Scale-Down Reactor (SDR) with repeated short term exposure of the cells to high sugar concentrations. In this reactor about 10% of the Baker's yeast culture was intermittently exposed to high (0.45–1.9?g?l^?1) concentrations of sugar, for periods of 60 seconds. It was found that physiological parameters of glycolysis and respiration were affected by environmental heterogeneities: 1) A biomass yield reduction of about 6–7% was found, with both the production reactor and the SDR, as compared to the homogeneous reactor. The loss of yield is interpreted in terms of a metabolic by-pass via ethanol, where cells are consuming and producing ethanol with different yields. 2) The maximum respiration rate was higher in cells produced in the production unit and in the SDR. 3) The product quality, expressed as gassing power of the yeast in a dough, was increased for sweet and non-sugar doughs in the SDR, and for sweet doughs in the production reactor. Thus, the SDR, when run with defined glucose gradients, in some aspects resembles the large reactor. It could be regarded as a tool for scale-down and scale-up studies and may be useful in investigations on the scale-up sensitivity of a process.     

Effect of host-tree and environmental variables on honeydew production by scale insects (

Honeydew excreted by phloem-sap sucking scale insects (Ultracoelostoma sp.) living in the bark of beech (Nothofagus solandri:) trees growing at a high elevation (900 m) site in the Craigieburn range of Canterbury, New Zealand, was measured over four days during 1–10 May 1996. Average standing crop of honeydew sugar was 3.1 mg m-2, and ranged from 0.4 to 5.5 mg m-2. Daily production of honeydew sugar ranged from 0.2 to 1.5 mg insect-1 24 h-1, and 4.1 to 45.9 mg m-2 24 h-1. Honeydew production varied significantly between trees, and trees with the highest mean individual rates of production (mg sugar insect-1 24 h-1) tended to be those with the highest numbers of insects per unit bark area. Air temperature averaged over the 24 hours preceding each production sample explained 65% of the variability in 3-hourly honeydew production, showing that honeydew production is controlled by environmental and host-tree variables. Using this data, together with previously published estimates of carbon uptake and seasonal variability in honeydew standing crop, it was estimated that carbon contained in honeydew is equivalent to 1.8% of net primary production of beech trees at Craigieburn. Determining the effects of environmental variables on tree and insect physiology will allow formulation of an environmentally-driven process-based model of honeydew production.     

Effect of some alkaline phosphatase inhibitors on intestinal calcium transfer

1. There is a good correlation between the capacity of sugars to stimulate calcium transfer and their capacity to be phosphorylated by the intestinal alkaline phosphate with a part of the phosphate liberated from an ester phosphate. 2. On the sugar dependent and sugar independent calcium transfer, inhibitors of this enzyme act differently. 3. Phosphate, a competitive inhibitor suppresses both transfers. 4. Only the dependent sugar transfer was suppressed with phloridzin acting competitively at the sugar site, or with EDTA which could react close to the active site. 5. L-phenylalanine and phenobarbital, not competitive inhibitors does not act on either type of calcium transfer, the sugar dependent or the sugar independent.     

Linoleate-rich acylglucosylceramides of pig epidermis: structure determination by proton magnetic resonance

The structure of the linoleate-rich acylglycosylceramides isolated from pig epidermis has been reinvestigated. Gas-liquid chromatographic analysis of the alditol acetates produced from the sugar component indicated that 90% of the hexose is glucose while the remaining 10% is galactose. The predominance of the beta-D-glucosyl group was confirmed by 360 MHz proton magnetic resonance spectroscopy. The magnetic resonance method was also used to prove that the ester-linked linoleic acid is actually attached to the omega-hydroxyl group of the long chain hydroxyacid, not to the sugar as had been reported previously. A key spectral feature supporting this new structural assignment was a triplet at 3.82 ppm, which indicates methylene protons between another methylene and an ester linkage. After saponification, this signal moved to 3.33 ppm, a chemical shift expected for a methylene bearing a free hydroxyl group. Furthermore, all of the sugar ring protons could be accounted for both before and after acetylation. No evidence was found to suggest that an ester is attached to the sugar ring in the native material. It is concluded that the principal porcine epidermal acylglycosylceramide is 1-beta-D-glucosyl-N-(omega-O-linoleoyl)-triacontanoylsphingosine.     

Control of fructose 2,6-bisphosphate levels in rat macrophages by glucose and phorbol ester

The presence of fructose 2,6-bisphosphate (Fru 2,6-P2) in elicited peritoneal macrophages of rat was examined. These cells possess an active phosphofructokinase-2 which is diminished by citrate and only slightly inhibited by glycerol 3-phosphate. Phosphofructokinase-1 submaximal activity was increased 26-fold by the addition of 1 microM Fru 2,6-P2. Incubation of cells without glucose decreased the amount of Fru 2,6-P2 to zero, but further addition of 5 mM glucose increased the levels of the sugar ester 20-fold. In addition, the presence of phorbol ester potentiated the synthesis of Fru 2,6-P2. By contrast phenylisopropyladenosine or prostaglandin F2 alpha inhibited the production of Fru 2,6-P2.     

Alkali‐based AFEX pretreatment for the conversion of sugarcane bagasse and cane leaf residues to ethanol

Sugarcane is one of the major agricultural crops cultivated in tropical climate regions of the world. Each tonne of raw cane production is associated with the generation of 130 kg dry weight of bagasse after juice extraction and 250 kg dry weight of cane leaf residue postharvest. The annual world production of sugarcane is ～1.6 billion tones, generating 279 MMT tones of biomass residues (bagasse and cane leaf matter) that would be available for cellulosic ethanol production. Here, we investigated the production of cellulosic ethanol from sugar cane bagasse and sugar cane leaf residue using an alkaline pretreatment: ammonia fiber expansion (AFEX). The AFEX pretreatment improved the accessibility of cellulose and hemicelluloses to enzymes during hydrolysis by breaking down the ester linkages and other lignin carbohydrate complex (LCC) bonds and the sugar produced by this process is found to be highly fermentable. The maximum glucan conversion of AFEX pretreated bagasse and cane leaf residue by cellulases was ～85%. Supplementation with hemicellulases during enzymatic hydrolysis improved the xylan conversion up to 95–98%. Xylanase supplementation also contributed to a marginal improvement in the glucan conversion. AFEX‐treated cane leaf residue was found to have a greater enzymatic digestibility compared to AFEX‐treated bagasse. Co‐fermentation of glucose and xylose, produced from high solid loading (6% glucan) hydrolysis of AFEX‐treated bagasse and cane leaf residue, using the recombinant Saccharomyces cerevisiae (424A LNH‐ST) produced 34–36 g/L of ethanol with 92% theoretical yield. These results demonstrate that AFEX pretreatment is a viable process for conversion of bagasse and cane leaf residue into cellulosic ethanol. Biotechnol. Bioeng. 2010;107: 441–450. © 2010 Wiley Periodicals, Inc.     

Life cycle assessment of cane-sugar on the island of mauritius

Goal, Scope and Background  Agricultural production includes not only crop production, but also food processing, transport, distribution, preparation, and disposal. The effects of all these must be considered and controlled if the food chain is to be made sustainable. The goal of this case study was to identify and review the significant areas of potential environmental impacts across the whole life cycle of cane sugar on the island of Mauritius. Methods  The functional unit was one tonne of exported raw sugar from the island. The life cycle investigated includes the stage of cane cultivation and harvest, cane burning, transport, fertilizer and herbicide manufacture, cane sugar manufacture and electricity generation from bagasse. Data was gathered from companies, factories, sugar statistics, databases and literature. Energy depletion, climate change, acidification, oxidant formation, nutrification, aquatic ecotoxicity and human toxicity were assessed. Results and Discussion  The inventory of the current sugar production system revealed that the production of one tonne of sugar requires, on average, a land area of 0.12 ha, the application of 0.84 kg of herbicides and 16.5 kg of N-fertilizer, use of 553 tons of water and 170 tonne-km of transport services. The total energy consumption is about 14235 MJ per tonne of sugar, of which fossil fuel consumption accounts for 1995 MJ and the rest is from renewable bagasse. 160 kg of CO₂ per tonne of sugar is released from fossil fuel energy use and the net avoided emissions of CO₂ on the island due to the use of bagasse as an energy source is 932,000 tonnes. 1.7 kg TSP, 1.21 kg SO₂,1.26 kgNO_xand 1.26 kg CO are emitted to the air per tonne of sugar produced. 1.7 kg N, 0.002 kg herbicide, 19.1 kg COD, 13.1 kgTSS and 0.37 kg PO₄ ^3- are emitted to water per tonne of sugar produced. Cane cultivation and harvest accounts for the largest environmental impact (44%) followed by fertilizer and herbicide manufacture (22%), sugar processing and electricity generation (20%), transportation (13%) and cane burning (1%). Nutrification is the main impact followed by acidification and energy depletion. Conclusions  There are a number of options for improvement of the environmental performance of the cane-sugar production chain. Cane cultivation, and fertilizer and herbicide manufacture, were hotspots for most of the impact categories investigated. Better irrigation systems, precision farming, optimal use of herbicides, centralisation of sugar factories, implementation of co-generation projects and pollution control during manufacturing and bagasse burning are measures that would considerably decrease resource use and environmental impacts. Recommendation and Outlook  LCA was shown to be a valuable tool to assess the environmental impacts throughout the food production chain and to evaluate government policies on agricultural production systems.     

Efficient Acetone–Butanol–Ethanol Production from Corncob with a New Pretreatment Technology—Wet Disk Milling

Acetone–butanol–ethanol (ABE) production from corncob was achieved using an integrated process combining wet disk milling (WDM) pretreatment with enzymatic hydrolysis and fermentation by Clostridium acetobutylicum SE-1. Sugar yields of 71.3 % for glucose and 39.1 % for xylose from pretreated corncob were observed after enzymatic hydrolysis. The relationship between sugar yields and particle size of the pretreated corncob was investigated, suggesting a smaller particle size benefits enzymatic hydrolysis with the WDM pretreatment approach. Analysis of the correlation between parameters representing particle size and efficiency of enzymatic hydrolysis predicted that frequency 90 % is the best parameter representing particle size for the indication of the readiness of the material for enzymatic hydrolysis. ABE production from corncob was carried out with both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes using C. acetobutylicum SE-1. Interestingly, when considering the time for fermentation as the time for ABE production, a comparable rate of sugar consumption and ABE production in the SHF process (0.55 g/l·h sugar consumption and 0.20 g/l·h ABE production) could be observed when glucose (0.50 g/l·h sugar consumption and 0.17 g/l·h ABE production) or a mixture of glucose and xylose (0.68 g/l·h sugar consumption and 0.22 g/l·h ABE production) mimicking the corncob hydrolysate was used as the substrate for fermentation. This result suggested that the WDM is a suitable pretreatment method for ABE production from corncob owing to the mild conditions. A higher ABE production rate could be observed with the SSF process (0.15 g/l·h) comparing with SHF process (0.12 g/l·h) when combining the time for saccharification and fermentation and consider it as the time for ABE production. This is possibly a result of low sustained sugar level during fermentation. These investigations lead to the suggestion that this new WDM pretreatment method has the potentials to be exploited for efficient ABE production from corncob.     

Parameters Affecting Ethyl Ester Production by Saccharomyces cerevisiae during Fermentation

Volatile esters are responsible for the fruity character of fermented beverages and thus constitute a vital group of aromatic compounds in beer and wine. Many fermentation parameters are known to affect volatile ester production. In order to obtain insight into the production of ethyl esters during fermentation, we investigated the influence of several fermentation variables. A higher level of unsaturated fatty acids in the fermentation medium resulted in a general decrease in ethyl ester production. On the other hand, a higher fermentation temperature resulted in greater ethyl octanoate and decanoate production, while a higher carbon or nitrogen content of the fermentation medium resulted in only moderate changes in ethyl ester production. Analysis of the expression of the ethyl ester biosynthesis genes EEB1 and EHT1 after addition of medium-chain fatty acid precursors suggested that the expression level is not the limiting factor for ethyl ester production, as opposed to acetate ester production. Together with the previous demonstration that provision of medium-chain fatty acids, which are the substrates for ethyl ester formation, to the fermentation medium causes a strong increase in the formation of the corresponding ethyl esters, this result further supports the hypothesis that precursor availability has an important role in ethyl ester production. We concluded that, at least in our fermentation conditions and with our yeast strain, the fatty acid precursor level rather than the activity of the biosynthetic enzymes is the major limiting factor for ethyl ester production. The expression level and activity of the fatty acid biosynthetic enzymes therefore appear to be prime targets for flavor modification by alteration of process parameters or through strain selection.