Efficient pullulan production by Aureobasidium pullulans using cost-effective substrates.

In this study, cost-effective substrates such as cassava starch, corn steep liquor (CSL) and soybean meal hydrolysate (SMH) were used for pullulan production by Aureobasidium pullulans CCTCC M 2012259. The medium was optimized using response surface methodology (RSM) and artificial neural network (ANN) approaches, and analysis of variance indicated that the ANN model achieved higher prediction accuracy. The optimal medium predicted by ANN was used to produce high molecular weight pullulan in high yield. SMH substrates increased both biomass and pullulan titer, while CSL substrates maintained higher pullulan molecular weight. Results of kinetic parameters, key enzyme activities and intracellular uridine diphosphate glucose contents revealed the physiological mechanism of changes in pullulan titer and molecular weight using different substrates. Economic analysis of batch pullulan production using different substrates was performed, and the cost of nutrimental materials for CSL and SMH substrates was decreased by 46.1% and 49.9%, respectively, compared to the control using glucose and yeast extract as substrates, which could improve the competitiveness of pullulan against other polysaccharides in industrial applications.

Pullulan gum production from low-quality fig syrup using Aureobasidium pullulans.

Pullulan is an important polysaccharide with several potential applications in food science, pharmaceutical and cosmetic industries, but high costs of pullulan production are the main limitation for commercial utilization. Therefore, a cost-effective process for pullulan production was developed using fig syrup as an exclusive nutrient source. In particular, the feasibility of using low quality fig syrup as a supplemental substrate for pullulan gum production by Aureobasidium pullulans was investigated. Fermentation was carried out over a range of fig syrup and sucrose degrees Brix (5-15%). Maximum pullulan gum production was observed after 96h using 12.5% fig syrup, yielding approximately14.06 g/L. This value of pullulan production (14.06 g/L) was higher than the amount of pullulan produced using sucrose as substrate (5.01 g/L). In conclusion, fig syrup was an effective substrate for pullulan production by Aureobasidium pullulans, and, therefore, this byproduct deserves attention for the cost-effective and environmentally friendly pullulan production.

Economic co-production of poly(malic acid) and pullulan from Jerusalem artichoke tuber by Aureobasidium pullulans HA-4D.

BACKGROUND: poly(L-malic acid) (PMA) is a water-soluble polyester with many attractive properties in medicine and food industries, but the high cost of PMA fermentation has restricted its further application for large-scale production. To overcome this problem, PMA production from Jerusalem artichoke tubers was successfully performed. Additionally, a valuable exopolysaccharide, pullulan, was co-produced with PMA by Aureobasidum pullulans HA-4D. RESULTS: The Jerusalem artichoke medium for PMA and pullulan co-production contained only 100 g/L hydrolysate sugar, 30 g/L CaCO3 and 1 g/L NaNO3. Compared with the glucose medium, the Jerusalem artichoke medium resulted in a higher PMA concentration (114.4 g/L) and a lower pullulan concentration (14.3 g/L) in a 5 L bioreactor. Meanwhile, the activity of pyruvate carboxylase and malate dehydrogenas was significantly increased, while the activity of α-phosphoglucose mutase, UDP-glucose pyrophosphorylase and glucosyltransferase was not affected. To assay the economic-feasibility, large-scale production in a 1 t fermentor was performed, yielding 117.5 g/L PMA and 15.2 g/L pullulan. CONCLUSIONS: In this study, an economical co-production system for PMA and pullulan from Jerusalem artichoke was developed. The medium for PMA and pullulan co-production was significantly simplified when Jerusalem artichoke tubers were used. With the simplified medium, PMA production was obviously stimulated, which would be associated with the improved activity of pyruvate carboxylase and malate dehydrogenas.

Overproduction of cellulase by Trichoderma reesei RUT C30 through batch-feeding of synthesized low-cost sugar mixture.

Cellulase is a prerequisite for the bioconversion of lignocellulosic biomass, but its high cost presents the biggest challenge. In this article, low-cost mixture was produced from glucose through the transglycosylation reaction catalyzed by ß-glucosidase for cellulase overproduction by Trichodema reesei RUT C30. As a result, cellulase titer of 90.3FPU/mL, which was more than 10 folds of that achieved with lactose as inducer, was achieved at 144h. Meanwhile, cellulase productivity was drastically increased to 627.1FPU/L/h, at least 3-5 folds higher than previously reported by the fungal species. The crude enzyme was further tested by hydrolyzing NaOH-pretreated corn stover with 15% solid loading, and 96.6g/L glucose was released with 92.6% sugar yield at 96h and 44.8g/L ethanol was obtained.

Novel peritoneal dialysis solutions--what are the clinical implications?

Novel low-glucose degradation products (GDP) peritoneal dialysis (PD) fluids have an improved biocompatibility profile as compared to standard fluids. Clinical studies suggest that their use may be associated with favorable clinical outcomes; however, large prospective randomized studies addressing clinical endpoints such as patient and technique survival are presently lacking. Nevertheless, as their only disadvantage is their cost, they are already being used as the standard treatment by many adult PD centers. This policy is also in line with the latest recommendations from the European Pediatric Dialysis Working Group which advises that conventional, single-chamber PD solutions should be replaced by PD solutions with reduced GDP content. The use of icodextrin, the glucose polymer PD solution, is recommended for patients with high or high-average peritoneal transport and/or ultrafiltration problems who otherwise would resort to hypertonic (3.86% glucose) exchanges.

A randomized comparison study of Aquacel Ag and Glucan II as donor site dressings with regard to healing time, cosmesis, infection rate, and patient's perceived pain: a pilot study.

This study was undertaken to compare pain, healing time, infection rate, and cosmetic outcome between Aquacel Ag (Convatec) and Glucan II (Brennan Medical) as donor site dressings. The authors performed a prospective, randomized, patient-controlled study. Eligible patients had two donor sites harvested. One site was dressed with Aquacel Ag and the other site with Glucan II. Patients were followed at set time points for 6 months to determine the rate of epithelialization, patient's perceived pain, infection rate, and the cosmetic outcome. A total of 20 patients were enrolled in the study. All patient data were collected through reepithelialization. The average time to wound healing for Aquacel Ag was 12.5 ± 2.07 days compared with Glucan II 12.7 ± 1.99 days. Perceived pain scores for each donor site were recorded. On postoperative day 5, patients reported significantly less pain with the Aquacel Ag site (Aquacel Ag 1.75 vs Glucan II 2.5, P = .02). Three donor sites showed clinical signs of infection (two Glucan II and one Aquacel Ag) prompting culture and dressing removal. There was no statistically significant difference in cosmetic outcomes of the donor sites at any time point. When comparing Aquacel Ag and Glucan II, our study has determined that there is no significant difference with regard to healing time, infection rates, and cosmetic outcomes. Both dressings are comparable with regard to ease of application and postoperative care.

[Medical and economic evaluation of new peritoneal dialysis solutions]. / Evaluation médico-économique des nouvelles solutions en dialyse péritonéale.

Conventional peritoneal dialysis solutions are mostly bioincompatible in relationship with a low pH, a high glucose and glucose degradation products (GDP) concentrations inducing anatomical and functional peritoneal membrane alterations. Use of icodextrin solution instead of glucose hypertonic solution preserves peritoneal membrane minimizing glucose exposure and its peritoneal absorption. Physiological fluids with a neutral pH and less GDP seem to have a positive effect on residual renal function which declines more slowly when they are early prescribed, before highly damaged and sclerotic kidneys. Preliminary data show that patients and technique survivals are better when physiological solutions are used either for diabetic and non diabetic patients. However, these new solutions do not improve peritonitis rates except for bicarbonate solutions but this fact must still be confirmed by other studies. In spite of a higher cost, physiological solutions must be proposed mainly for patients with a low comorbidity index and a high life expectancy.

Carbohydrates--the renewable raw materials of high biotechnological value.

Carbohydrates are the potential biomolecules derived from nature. Their molecular diversity has led to a bewildering variety of species, structures and characteristics all performing a large array of functions of great significance. Biologically they are vital as message (immunological) carriers, physiologically they are useful as energy (nutritional) reserves, and technologically they are needed for altering the texture and consistency (functional) of foods. Recent advances in glycobiology have opened up a new understanding of the role of sugars in biology and medicine. Noncellulosic beta-(1-3)-linked D-glucans, a group of polysaccharides found as constituents of fungi, algae, and higher plants, exhibit many interesting properties, depending on their molecular conformation. They are excellent 'biological response modifiers' and show significant immunomodulatory activities. They elicit a variety of host defense biological responses, for example, potent antitumor activity. On the other hand, the mixed-linkage ((1-3/1-4)-beta-linked) glucans are important constituents of cereal cell walls, where they perform properties of physiological importance, such as water holding capacity, porosity, and plasticity, which are useful at different stages of growth/development of plants. Of late, carbohydrate-based therapeutics are becoming the promise against many chronic diseases of today and tomorrow. Some of the characteristic features, structural attributes, functional significance, and applications of a selected few carbohydrate species are the subject matter of this review.

Cost savings from peritoneal dialysis therapy time extension using icodextrin.

Previous retrospective studies have reported that icodextrin may prolong peritoneal dialysis (PD) treatment time in patients with refractory fluid overload (RFO). Because the annual cost of PD therapy is lower than that of hemodialysis (HD) therapy in Australia, we prospectively investigated the ability of icodextrin to prolong PD technique survival in patients with RFO. We used a computer model to estimate the savings associated with that therapeutic strategy, based on annual therapy costs determined in a regional PD and HD costing exercise. Patients who met standard criteria for RFO and who were otherwise to be converted immediately to HD, were asked to consent to an open-label assessment of the ability of icodextrin to delay the need to start HD. Time to conversion to HD was measured. The study enrolled 39 patients who were followed for a mean period of 1.1 years. Icodextrin significantly increased peritoneal ultrafiltration by a median value of 368 mL daily. It prolonged technique survival by a mean period of 1.21 years [95% confidence interval (CI): 0.80-1.62 years]. Extension of PD treatment time by icodextrin was particularly marked for patients who had ultrafiltration failure (UFF, n = 20), defined as net daily peritoneal ultrafiltration < 1 L daily (mean extension time: 1.70 years; 95% CI: 1.16-2.25 years). Overall, annualized savings were US$3,683 per patient per year. If just the patients with UFF were considered, the savings increased to US$4,893 per year. Icodextrin prolongs PD technique survival in patients with RFO, permitting them to continue on their preferred therapy. In Australia, that practice is highly cost-effective, particularly in individuals with UFF.