Arabitol

About: Arabitol is a research topic. Over the lifetime, 388 publications have been published within this topic receiving 8398 citations. The topic is also known as: D-(+)-Arabitol & D-arabitol.

Contribution of fungal spores to particulate matter in a tropical rainforest

Abstract: The polyols arabitol and mannitol, recently proposed as source tracers for fungal spores, were used in this study to estimate fungal contributions to atmospheric aerosol. Airborne particulate matter (PM2.5 and PM10) was collected at Jianfengling Mountain, a tropical rainforest on Hainan Island situated off the south China coast, during spring and analyzed for arabitol and mannitol by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The average concentrations of arabitol and mannitol exhibited high values with averages of 7.0 and 16.0 ng m − 3 respectively in PM2.5 and 44.0 and 71.0 ng m − 3 in PM10. The two tracers correlated well with each other, especially in the coarse mode aerosol (PM2.5 − 10), indicating they were mainly associated with coarse aerosol particles and had common sources. Arabitol and mannitol in PM10 showed significant positive correlations with relative humidity, as well as positive correlations with average temperature, suggesting a wet emissions mechanism of biogenic aerosol in the form of fungal spores. We made estimations of the contribution of fungal spores to ambient PM mass and to organic carbon, based on the observed ambient concentrations of these two tracers. The relative contributions of fungal spores to the PM10 mass were estimated to range from 1.6 to 18.2%, with a rather high mean value of 7.9%, and the contribution of fungal spores to organic carbon in PM10 ranged from 4.64 to 26.1%, with a mean value of 12.1%, implying that biological processes are important sources of atmospheric aerosol.

Low-temperature-induced changes in trehalose, mannitol and arabitol associated with enhanced tolerance to freezing in ectomycorrhizal basidiomycetes (Hebeloma spp.).

Abstract: Ectomycorrhizal fungi have been shown to survive sub-zero temperatures in axenic culture and in the field However, the physiological basis for resistance to freezing is poorly understood In order to survive freezing, mycelia must synthesise compounds that protect the cells from frost damage, and certain fungal-specific soluble carbohydrates have been implicated in this role Tissue concentrations of arabitol, mannitol and trehalose were measured in axenic cultures of eight Hebeloma strains of arctic and temperate origin grown at 22, 12, 6 and 2°C In a separate experiment, mycelia were frozen to –5°C after pre-conditioning at either 2°C or 22°C For some, especially temperate strains, there was a clear increase in specific soluble carbohydrates at lower growth temperatures Trehalose and mannitol were present in all strains and the highest concentrations (close to 25% and 05% dry wt) were recorded only after a cold period Arabitol was found in four strains only when grown at low temperature Cold pre-conditioning enhanced recovery of mycelia following freezing In four out of eight strains, this was paralleled by increases in mannitol and trehalose concentration at low temperature that presumably contribute towards cryoprotection The results are discussed in an ecological context with regard to mycelial overwintering in soil

Intramolecular esterification by lipase powder in microaqueous benzene: Factors affecting activity of pure enzyme

Abstract: Various factors affecting the catalytic activity of pure lipase of Pseudomonas fluorescens in microaqueous benzene were investigated with respect to lactonization of 15-hydroxypentadecanoic acid. Without deposition of the enzyme or of the enzyme plus activity enhancer (additive) on celite powder, the pure enzyme was very poorly dispersed in the microaqueous benzene, resulting in very low activity. The enzyme immobilized on celite powder exhibited the highest activity at a free water content of ca. 0.083%. When a sugar alcohol such as erythritol, arabitol, or sorbitol was added before lyophilization with approximate proportion of 3 g/g enzyme, marked increases in the enzyme activity were observed at a shifted optimal free water content, i.e., 0.04%. Inclusion of phosphotidylcholine resulted in a somewhat higher activity than in the system of enzyme plus celite only. Addition of lactose, bovine serum albumin, casein, dextran, polyvinyl alcohol, phosphate, or NaCl all caused a decrease in the enzyme activity. From the effects of the additives examined, it is deduced that the following three factors are required for a pure enzyme to exhibit its full activity in a water-immiscible organic solvent: (1) optimum moisture content, (2) disperser (support particles having enough surface area on which the enzyme is thinly deposited), and (3) activity enhancer (additive) at optimum concentration The importance of noting the purity of the enzyme preparation is emphasized when its catalysis in an organic solvent is investigated.

Microbial Water Relations: Features of the Intracellular Composition of Sugar-Tolerant Yeasts

Abstract: Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast. One such factor was the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism. In such cases (lactose and glycerol), the sugar-tolerant species had a much lower capacity for the solute than did the nontolerant species. Sucrose uptake was consistently different between all sugar-tolerant strains on the one hand and all nontolerant strains on the other. The difference was attributable in part to metabolism of sucrose by the nontolerant yeasts. The major difference between the two types of yeast, however, was the presence of one or more polyhydric alcohols at high concentrations within each of the sugar-tolerant strains but none of the nontolerant strains. In most cases the major polyol was arabitol. The solute concentration (and, hence, water availability) of the growth medium affected both the amount of arabitol produced by Saccharomyces rouxii and the proportion retained by the yeast after brief washing with water at 0 C. When the yeast was suspended in a buffer at 30 C, the polyol leaked out at a slow, constant, reproducible rate. The polyene antibiotic amphotericin B caused rapid release of polyol by the yeast, the rate being proportional to amphotericin concentration. Contact of the yeast with glucose (1 mM) caused an extremely rapid ejection of polyol which lasted less than 40 s. Some implications of these results are discussed, as is the role of the polyol as a compatible solute in determining the water relations of the yeast.

Fermentation of corn fibre sugars by an engineered xylose utilizing Saccharomyces yeast strain

Abstract: The ability of a recombinant Saccharomyces yeast strain to ferment the sugars glucose, xylose, arabinose and galactose which are the predominant monosaccharides found in corn fibre hydrolysates has been examined. Saccharomyces strain 1400 (pLNH32) was genetically engineered to ferment xylose by expressing genes encoding a xylose reductase, a xylitol dehydrogenase and a xylulose kinase. The recombinant efficiently fermented xylose alone or in the presence of glucose. Xylose-grown cultures had very little difference in xylitol accumulation, with only 4 to 5g/l accumulating, in aerobic, micro-aerated and anaerobic conditions. Highest production of ethanol with all sugars was achieved under anaerobic conditions. From a mixture of glucose (80g/l) and xylose (40g/l), this strain produced 52g/l ethanol, equivalent to 85% of theoretical yield, in less than 24h. Using a mixture of glucose (31g/l), xylose (15.2g/l), arabinose (10.5g/l) and galactose (2g/l), all of the sugars except arabinose were consumed in 24h with an accumulation of 22g ethanol/l, a 90% yield (excluding the arabinose in the calculation since it is not fermented). Approximately 98% theoretical yield, or 21g ethanol/l, was achieved using an enzymatic hydrolysate of ammonia fibre exploded corn fibre containing an estimated 47.0g mixed sugars/l. In all mixed sugar fermentations, less than 25% arabinose was consumed and converted into arabitol.