Cellulose bead entrapped microbial cells for biotechnical applications

Immobilization of intact or pretreated microbial cells instead of partially purified enzymes offers several advantages. A novel method has been applied to entrap Actinoplanes missouriensis, Bacillus coagulans, Kluyveromyces fragilis, K. lactis, Saccharomyces cerevisiae, Serratia sp., and Streptomyces albus cells within α-cellulose beads, with activity recoveries of about 22 to 85%. The best results were obtained with S. albus for glucose isomerase and with S. cerevisiae for invertase. The application of entrapped glucose isomerase-active A. missouriensis cells to increase the sweetness of β-galactosidase-hydrolysed dairy products was investigated in detail. Pressure drop across the column reactor bed was negligible; the stability of the entrapped enzyme was highest at pH 7.5 in the presence of both Mg²⁺and Co²⁺, although Co²⁺could be omitted with little effect on performance; and the activity was drastically affected by Ca²⁺content of substrate due to competition with Mg²⁺. The reactor was successfully operated for more than 5 weeks for the isomerization of demineralized concentrated whey hydrolysate of 8% lactose, 23% galactose, and up to 36% added glucose to obtain a syrup of sweetness approaching that of sucrose.     

Circulating chromogranin B levels in patients with acute respiratory failure: data from the FINNALI Study

Purpose: Circulating chromogranin B (CgB) levels are increased in situations characterized by systemic and myocardial stress, but whether CgB provides prognostic information in patients with acute respiratory failure (ARF) is unknown.

Methods: We included 584 patients with ARF, defined as ventilatory support?>6?h, and with blood samples available on Intensive Care Unit (ICU) admission and day 3 (n?=?479). CgB levels were measured by radioimmunoassay and follow-up was 90 days.

Results: One-hundred-sixty-nine patients (29%) died during follow-up. Admission CgB levels separated non-survivors from survivors: median 1234 (Q1-3 989–1742) vs. 917 (753–1224) pmol/L, respectively, p?<?0.001. CgB levels on ICU admission (logarithmically transformed) were associated with time to death after adjustment for established risk indices available on ICU admission, including N-terminal pro-B-type natriuretic levels: HR 2.62 (95%C.I. 1.82–3.77), p?<?0.001. Admission CgB levels also improved prognostication on top of SOFA and SAPS II scores as assessed by Cox regression analyses and the category-free net reclassification index. The area under the curve (AUC) for admission CgB levels to separate survivors and non-survivors was 0.72 (95%CI 0.67–0.76), while the AUC on day 3 was 0.60 (0.54–0.66).

Conclusions: CgB levels measured on ICU admission provided additional prognostic information to established risk indices in ARF patients.     

Characterization of the cellulose-binding ability of Geotrichum sp. M111 cells and its application to dehydration of the distilled waste of sweet potato shouchu.

The cellulose-binding ability of Geotrichum sp. M111 cells was investigated by the micro-tube method which gives an indication of the binding ability of M111 cells. The optimum pH value and temperature were 3-7 and below 50 degrees C, respectively, from measurement of the aggregation height for a mixture of cellulose powder and M111 cells. The binding constant of 0.3% for M111 cells to cellulose powder was obtained in a 20 mm citrate buffer of pH 5.0 at 30 degrees C. Aggregation was inhibited by such surfactants as sodium dodecylsulfate. The binding ability of M111 cells to cellulose fiber disappeared after a treatment with Driselase or Pronase E. This suggests that the binding ability might be related to the cell surface proteins. The dehydration rate of the distilled waste of sweet potato shouchu was accelerated by the addition of M111 cells. The analysis of dehydration by a linear viscoelastic model suggests that the acceleration effect might have been due to the space increase between cellulose fibers with the cell addition.     

Conformational change in the activation of lipase: an analysis in terms of low-frequency normal modes.

The interfacial activation of Rhizomucor miehei lipase (RmL) involves the motion of an alpha-helical region (residues 82-96) which acts as a "lid" over the active site of the enzyme, undergoing a displacement from a "closed" to an "open" conformation upon binding of substrate. Normal mode analyses performed in both low and high dielectric media reveal that low-frequency vibrational modes contribute significantly to the conformational transition between the closed and open conformations. In these modes, the lid displacement is coupled to local motions of active site loops as well as global breathing motions. Atomic fluctuations of the first hinge of the lid (residues 83-84) are substantially larger in the low dielectric medium than in the high dielectric medium. Our results also suggest that electrostatic interactions of Arg86 play an important role in terms of both the intrinsic stability of the lid and its displacement, through enhancement of hinge mobility in a high dielectric medium. Additional calculations demonstrate that the observed patterns of atomic fluctuations are an intrinsic feature of the protein structure and not dependent on the nature of specific energy minima.     

The Effect of Obesity on Pediatric Tibia Fractures

BackgroundChildhood obesity affects nearly one fifth of all children in the United States. Understanding the unique injury characteristics and treatment of tibia fractures in this population has become increasingly important. This study aims to explore the different injury characteristics between tibia fractures in obese and non-obese children.Methods215 skeletally immature children aged 2-18 who sustained tibia fractures between 2007.2019 were retrospectively reviewed. Patients were analyzed by weight group: underweight, normal weight, overweight, and obese as defined by body mass index (BMI) percentile based upon age. Analyses were performed on dichotomized groups: underweight and normal weight versus overweight and obese. Chi-square or Fisher’s exact test was used to compare differences in categorical outcome between the 2-category BMI class variables; Wilcoxon test was used to compare continuous outcomes. A multivariate logistic regression model was used to evaluate BMI associations while controlling for age, sex, race, and mechanism of injury.ResultsDistribution of BMI in the cohort included 6.5% underweight, 45.6% normal weight, 16.7% overweight and 31.2% obese. Overweight and obese children sustained fractures from low energy mechanisms at more than double the rate of normal and underweight children (20.5% versus 9.7%, p=0.028). Overweight and obese children sustained physeal fractures at a rate of 54.4% in comparison with 28.6% in their normal and underweight peers (p<0.0001, OR 2.50 (95% CI, 1.26-4.95)). Overweight and obese children sustained distal 1/3 tibia fractures at a higher rate of 56.9% compared to under and normal weight children at 33.9% (p=0.003, OR 2.24 (95% CI, 1.17-4.30)). Overweight and obese children underwent unplanned changes in treatment at a lower rate than normal and underweight children at 1% versus 8% rates of treatment change, respectively (p=0.013, OR 0.076 (95%CI, 0.009-0.655)). No significant differences were found in the rates of operative treatment, repeat reduction, post treatment complications, or physical therapy.ConclusionOverweight children sustain tibia fractures from low energy mechanisms at higher rates than their peers. Similarly, obese and overweight patients have higher rates of physeal injuries and higher rates of distal 1/3 tibia fractures. Complication rates are similar between obese and non-obese children undergoing treatment for tibia fractures. Level of Evidence: III     

Hydrolysis of xylan and fermentation of xylose to ethanol

The focus in the development of pulping processes has usually been exclusively on cellulose. However, hemicellulose could serve as a valuable source of hexose and pentose sugars. Consequently, it should not be destroyed in a process designed for very high cellulose fibre yields. Novel procedures developed for production of ethanol by the fermentation of pentoses as well as hexoses provide new possibilities of hemicellulose utilization.

Many fungi produce extracellular hemicellulases. In the present work the production of xylanase and β-xylosidase with strains of Aspergillus and Trichoderma was studied. The enzymes were used for the hydrolysis of xylan. Xylose was fermented to ethanol by the mold Fusarium oxysporum.     

Itaconic acid production by immobilized Aspergillus terreus with varied metal additions

Summary The effect of trace and alkaline metals on itaconic acid production by polyurethane-foam-immobilized Aspergillus terreus was examined in repeated shake-flask cultures according to a statistical experimental design. An increase in the glucose or copper concentration increased the need for earth alkaline metals. The experimentally obtained highest itaconic acid concentration of 51 g/l from 15% glucose with a total productivity of 3.67 g/l per day was reached during the first 14-day batch fermentation. In the fourth batch the calculated highest itaconic acid concentration of 19 g/l was reached with 25% glucose, 5 g/l of magnesium sulphate, 13 mg/l of copper sulphate and 10 g/l of calcium chloride. The immobilization of the mycelium increased the itaconic acid concentration obtained by as much as eightfold.Offprint requests to: H. Kautola     

Production of mold lactase

A process for production of mold lactase was developed. Tests were carried out in pilot and industrial scale with an Aspergillus niger strain selected after screening a number of molds.A computer coupled autoanalyzer system was used for monitoring enzyme formation in the pilot fermentor. Lactase production was investigated using different pH- and temperature-profiles. A. niger lactase has an acid pH optimum, a high temperature optimum and good stability. It does not require any metal ions. It is suitable for immobilization for hydrolysis of lactose in acid whey.Three-fold enhancement of lactase production was obtained by mutagenizing A. niger using NTG as mutagenic agent.The lactases produced by the mutants have the same pH and temperature optima and stability but the growth properties of the mutants were different from those of the original strain.Sufficient specific activity of the enzyme preparation for immobilization was obtained by purifying the enzyme by selective adsorption on Na-Ca-silicate.     

Itaconic acid production by immobilizedAspergillus terreus from xylose and glucose

Summary Aspergillus terreus NRRC 1960 spores were entrapped in calcium alginate gel beads or alternotely the fungal mycelium was immobilized either on Celite R-626 or in agar gel cubes, and the biocatalyst was employed both in repeated batch and in continuous column reactors to produce itaconic acid from D-xylose or D-glucose. The highest itaconic acid yield obtained in a submerged culture batch fermentation was 54.5% based on total initial glucose (55 g/l) with a volumetric productivity of 0.32 g/l h, and 44.8% from xylose (67 g/l) with a productivity of 0.20 g/l h. In a repeated batch fermentation mycelium immobilized in agar gel had a productivity of 0.112 g/l h, and mycelium grown from spores immobilized in calcium alginate gel 0.06 g/l h, both from xylose (60 g/l). With the best immobilized biocatalyst system used employing Celite R-626 as a carrier, volumetric productivities of 1.2 g/l h from glucose and 0.56 g/l h from xylose (both at 60 g/l) were obtained in continuous column operation for more than 2 weeks.     

Continuous production of gluconic acid by immobilized Gluconobacter oxydans cell bioreactor

Summary Living Gluconobacter oxydans cells were attached on fibrous nylon carrier. Free gluconic acid was directly continuously produced in an aerated tubular immobilized-cell bioreactor for at least 6 months, with a volumetric productivity of at least 5 g/lh at 100 g/l substrate glucose and about 80 g/l product gluconic acid concentrations. The highest volumetric productivity in respect to glucose concentration was obtained with 175 g/l glucose, with about 120 g/l product gluconic acid level. With self-directing optimization procedure in respect to maximum product gluconic acid level, productivities as high as about 12–15 g/lh were obtained at relatively high substrate feed rate of 0.166 l/lh and relatively low aeration rate of 0.5 l/lmin. The highest glucose conversion of about 96% was obtained with a long residence time, at the lowest substrate feed rate used at a relatively low aeration rate, resulting however in a significant increase in ketogluconic acid production.