Xylanase is the key enzyme to degrade xylan that is a major component of hemicellulose. The enzyme has potential industrial applications in the food, feed, paper and flax degumming industries. The use of xylanases becomes more and more important in the paper industry for bleaching purposes. Xylanases used in the pulp bleaching process should be stable and active at high temperature and alkaline pH. Thermophilic and alkalophilic xylanases could be obtained by screening the wild type xylanases or engineering the mesophilic and neutral enzymes. In this paper, we reviewed recent progress of screening of the thermophilic and alkalophilic xylanases, molecular mechanism of thermal and alkaline adaptation and molecular engineering. Future research prospective was also discussed.
Endo-1,4-beta Xylanases ; chemistry ; Enzyme Stability ; Hot Temperature ; Hydrogen-Ion Concentration ; Paper ; Protein Engineering

Thermophilic and alkalophilic xylanases have great potential in the pulp bleaching industry. In order to improve the thermal stability of an alkaline family 11 xylanase Xyn11A-LC, aromatic residues were introduced into the N-terminus of the enzyme by rational design. The mutant increased the optimum temperature by 5 degrees C. The wild type had a half-time of 22 min at 65 degrees C and pH 8.0 (Tris-HCl buffer). Under the same condition, the mutant had the half-time of 106 min. CD spectroscopy revealed that the melting temperature (T(m)) values of the wild type and mutant were 55.3 degrees C and 67.9 degrees C, respectively. These results showed that the introduction of aromatic residues could enhance the thermal stability of Xyn11A-LC.
Endo-1,4-beta Xylanases ; chemistry ; Enzyme Stability ; Hydrogen-Ion Concentration ; Protein Engineering ; Temperature

Objective To review and analyse the CT distinguishing features of pulmonary cryptococcosis (PC)for improving the level of image diagnosis of the disease.Methods CT images and clinical details of 19 patients with biopsy or surgery pathology con-firmed PC were reviewed and analysed.Results Nodules or masses were presented in 10 cases,in which most casescases were nod-ules,lesions ranged in diameter from 1 cm to 2.5 cm.Multiple nodules were easy to fuse.Consolidation were presented in 6 cases,with high attenuation and clear border.3 cases were mixed type,with nodule,mass consolidation and ground glass attenuation.The lesions were mostly located in the inferior lobes(47%)and peripheral lung(68%).The features of pleural thickening,air bronchus sign,halo sign and cavitations were observed in 42%,36%,26%,21% of patients respectively.Conclusion CT findings of PC are diversity.The lesions are mostly located in the inferior and peripheral lung.Lesions are mild to moderate enhanced.Pleural thickening,air bronchus sign,halo sign,cavitations will be useful for the diagnosis.

Objective To compare radiation dose and image quality between prospective and retrospective ECG gating CT coronary angiography (CTCA) with 64-slice CT scanner. Methods Sixty patients with suspected coronary artery disease were selected, and randomly devided into two groups. Thirty patients in research group (average body-mass index [BMI]:[25.30±3.15] kg/m~2, heart rate ≤65 beats per minute [bpm]) underwent CTCA using prospective ECG-gating (120 kV, mA tailored to weight), while the rest 30 patients in control group (average BMI:[25.40±3.00] kg/m~2, heart rate ≤65 bpm) underwent CTCA using retrospective ECG-gating (120 kV, 650 mA). The average effective dose (ED) and standardizing radiation dose (ED_(Sd)) which was standardized by 12 cm length were respectively calculated, and statistical analysis was then conducted, meanwhile image quality was evaluated. Results The average ED of research group and control group was (5.97±1.04) mSv and (26.25±2.36) mSv, respectively (t_(A,B)=43.13, P<0.05). The ED_(Sd) of two groups was (5.49±0.45) mSv and (23.77±1.64) mSv (t_(Sd)=59.00, P<0.05). ED_(Sd) decreased by 76.62% in research group compared with that of control group. No significant difference of image quality was found between two groups (χ~2=4.26, P=0.235). Conclusion Prospective ECG-gating CTCA can effectively reduce radiation dose without compromising image quality.

The fermentation of ?-mannanase from an alkaliphilic Bacillus sp. has been studied in 16L tank. The optimum ventilation quantity and agitation speed were 1:1 vvm and 500r/min respectively. The fermentation cycle was 40 h and the highest ?- mannanase activity was 300 u/ml.

Inefficient degradation of lignocellulose is one of the main barriers for the utilization of renewable plant biomass for biofuel production. The bottleneck of the biorefinery process is the generation of fermentable sugars from complicated biomass polymers. In nature, the main microbes of lignocelluloses deconstruction are fungi. Therefore, elucidating the mechanism of lignocelluloses degradation by fungi is of critical importance for the commercialization of lignocellulosic biofuels. This review focuses on the progress in lignocelluloses degradation pathways in fungi, especially on the advances made by functional genomics studies.
Biofuels ; Fungi ; genetics ; metabolism ; Genetic Engineering ; Genome, Fungal ; genetics ; Industrial Microbiology ; Lignin ; metabolism

The background of developing cell factories for biorefinery was reviewed. Seventeen papers published in this special issue, covering the molecular mechanism of sugar utilization, genome-scale metabolic and regulative networks, the construction technologies, and the optimization of cell factories for biorefinery, were introduced.
Biofuels ; analysis ; Biotechnology ; methods ; Industrial Microbiology ; methods ; Metabolic Engineering ; methods ; Metabolic Networks and Pathways

Biomimetics ; trends ; Biotechnology ; trends ; China ; Conservation of Natural Resources ; methods ; trends ; Genetic Engineering ; Industry ; trends

Lactic acid has a wide range of uses in the chemical, pharmaceutical and food industry. With rapid development of poly (lactic acid) industry, the demand for polymer-grade L-lactic acid is continuously increasing. Developing low-cost, non-food-biomass-lactic-acid fermentation process and the fermentation-separation coupled technology are trends to reduce polymer-grade L-lactic acid production cost. This review summarized the most recent advances in low-cost L-lactic acid fermentation based on the use of non-food biomass, followed by addressing the key issue that might be strategically important for future development of polymer-grade L-lactic acid production in industry.
Biomass ; Biotechnology ; trends ; Cellulose ; metabolism ; Fermentation ; Insulin ; metabolism ; Lactic Acid ; metabolism ; Manihot ; metabolism ; Polymers ; metabolism

Lignocellulose is the most abundant natural biomass. Bioconversion of lignocelluloses becomes a bottleneck for biorefinery, because of its complex structures and heterogeneous composition. Besides screening or engineering approach for single free enzymes with improved properties, an alternative approach is to study synergistic pattern with hydrolysis systems or mimic natural cellulosome for better performance in cellulolytic substrate degradation. Besides, bacterial co-cultures provide another synergistic cellulolytic system. Engineered strains with modified metabolic network could facilitate consolidated bioprocess by increasing yields as well as reducing costs.
Bacteria ; genetics ; metabolism ; Biomass ; Cellulase ; genetics ; metabolism ; Cellulosomes ; genetics ; metabolism ; Enzymes ; metabolism ; Fermentation ; Lignin ; metabolism ; Metabolic Networks and Pathways