Cloning, expression and properties of trehalase from Pectobacterium cypripedii / 生物工程学报

Trehalase is widely used in industrial fermentation, food, medicine and other fields. There is a lack of industrial varieties of trehalase with excellent performance in China. Moreover, the applied research on trehalase was not well conducted. In this study, a strain of Pectobacterium cypripedii was screened from nature, and the gene PCTre encoding an acidic trehalase was cloned and expressed in E. coli BL21(DE3). The highest enzyme activity reached 4130 U/mL after fermenting in a 5 L fermenter for 28 h. The enzymatic properties study showed that PCTre hydrolyzed trehalose specifically. The optimum pH and temperature were 5.5 and 35 ℃, respectively. 80% of the enzyme activity was retained after being treated at pH 4.0, 4.5, and 5.0 for 8 h, showing good acid tolerance. Moreover, it has good tolerance to organic solvents, 60% enzyme activity was retained after being treated with 20% (V/V) ethanol solution for 24 h. Furthermore, trehalose could be completely hydrolyzed within 16 h in a simulated fermentation system containing 20% (V/V) ethanol and 7.5% trehalose, with 500 U/L PCTre added. This indicated a good application potential for industrial ethanol fermentation.

Application of next generation sequencing in studying food microorganisms-a review / 生物工程学报

Next generation sequencing technology has revolutionized studies in fermentation process, in particular, to explore the mechanism by which food microorganisms, including physiology, metabolic pathways, diversity and dynamic changes of microbial community. In addition, phylogenetic characteristics of different species or strains of the food microorganisms are disclosed. All these aspects will help explain how the microbes are interacting and responding to environmental factors. Bioinformatics analysis of genome and metagenome sequence data of food microorganisms could provide essential clues to improve fermentation process and function of microbes as well as control and prevention of foodborne disease outbreak. In this review, we summarized recent genomics and metagenomics studies on food microorganisms. The impact of next generation sequencing for the development and trends of food microorganism researches were discussed in details.

Screening, identification and culture optimization of a newly isolated aromatic nitrilase-producing bacterium--Pseudomonas putida CGMCC3830 / 生物工程学报

Microbial nitrilases have attracted increasing attention in nitrile hydrolysis for carboxylic acid production in recent years. A bacterium with nitrilase activity was isolated and identified as Pseudomonas putida CGMCC3830 based on its morphology, physiological and biochemical characteristics, as well as 16S rRNA gene sequence. The nitrilase production was optimized by varying culture conditions using the one-factor-at-a-time method and response surface methodology. Glycerol 13.54 g/L, tryptone 11.59 g/L, yeast extract 5.21 g/L, KH2PO4 1 g/L, NaCl 1 g/L, urea 1 g/L, initial pH 6.0 and culture temperature 30 degrees C were proved to be the optimal culture conditions. It resulted in the maximal nitrilase production of 36.12 U/mL from 2.02 U/mL. Investigations on substrate specificity demonstrate P. putida nitrilase preferentially hydrolyze aromatic nitriles. When applied in nicotinic acid synthesis, 2 mg/mL P. putida cells completely hydrolyzed 20.8 g/L 3-cyanopyridine into nicotinic acid in 90 min. The results indicated P. putida CGMCC3830 displayed potential for industrial production of nicotinic acid.

Clinical research on finger lateral veins anastomosis for restoring venous return of severed fingertip / 中华骨科杂志

Objective To investigate effect of finger lateral veins anastomosis for restoring venous return of severed fingertip.Methods From March 2008 to December 2012,36 patients underwent finger lateral veins anastomosis,including 21 males and 15 females,aged from 15 to 52 years (average,29.5±6.6 years).The thumb was involved in 3 cases,the index finger in 9 cases,the middle finger in 9 cases,the ring finger in 7 cases,and the little finger in 8 cases.The causes of injury included crush injury in 12 cases,electric saw injury in 8 cases,and incised injury in 16 cases.According to type of fingertip injury,there were 14 cases of type Ⅰ,5 cases of type Ⅱ,10 cases of type Ⅲ,and 7 cases of type Ⅴ.The ratios of anastomotic artery and veins were 1∶1,1∶2 or 2∶2 (average,1∶2).Results Thirty-six fingertips survived completely and no venous return obstruction happened,arterial crisis occurred in 3 cases after operation,which were cured after operative and medication treatment.Thirty patients were successfully followed up for 6 to 24 months (average,12.4±2.8 months).The fingers' appearances were satisfactory,finger pulps were plump with good flexibility,and no obvious atrophy of finger was found.The nails were nearly smooth,and the length of nails ranged from 10.5 to 18.9 mm (average,14.4±3.2 mm).The motion of distal interphalangeal joints,the two point discrimination,and the results of sensation measurement ranged from 0° to 70° (average,63°±5°),4.2 to 6.0 mm (average,4.6±0.4 mm),and S3 to S4,respectively.According to Tamai's classification,Tamai score increased from 68 to 100 at final follow-up,the results were excellent in 28 cases,good in 2 cases,with an excellent and good rate of 100％.Conclusion The finger lateral veins anastomosis is an effective method for restoring venous return of severed fingertip,which can avoid venous return obstruction,promote growth of nail,and restore motion and sensation of fingers.