Combined strategies for improving production of a thermo-alkali stable laccase in Pichia pastoris

Background: Laccases are copper-containing enzymes which have been used as green biocatalysts for many industrial processes. Although bacterial laccases have high stabilities which facilitate their application under harsh conditions, their activities and production yields are usually very low. In this work, we attempt to use a combinatorial strategy, including site-directed mutagenesis, codon and cultivation optimization, for improving the productivity of a thermo-alkali stable bacterial laccase in Pichia pastoris. Results: A D500G mutant of Bacillus licheniformis LS04 laccase, which was constructed by site-directed mutagenesis, demonstrated 2.1-fold higher activity when expressed in P. pastoris. The D500G variant retained similar catalytic characteristics to the wild-type laccase, and could efficiently decolorize synthetic dyes at alkaline conditions. Various cultivation factors such as medium components, pH and temperature were investigated for their effects on laccase expression. After cultivation optimization, a laccase activity of 347 ± 7 U/L was finally achieved for D500G after 3 d of induction, which was about 9.3 times higher than that of wild-type enzyme. The protein yield under the optimized conditions was about 59 mg/L for D500G. Conclusions: The productivity of the thermo-alkali stable laccase from B. licheniformis expressed in P. pastoris was significantly improved through the combination of site-directed mutagenesis and optimization of the cultivation process. The mutant enzyme retains good stability under high temperature and alkaline conditions, and is a good candidate for industrial application in dye decolorization.

Bacillus anthracis isolates analysis by multiple-locus variable-numbers of tandem repeats analysis,Liaoning,China / 中国人兽共患病学报

The epidemic characteristics and genotype of Bacillus anthracis strains in Liaoning Province ,China was analyze in this study .Six Bacillus anthracis strains from 2001 to 2011 were studied with multiple‐locus variable‐number tandem repeat analysis (MLVA) .BioNumerics4 .0 software was used to analyze the DNA fingerprint of statistics ,and cluster analysis results were obtained .Clustering analysis found that the 6 strains could be divided into two genotypes .For anthrax outbreaks ,the ge‐netic markers of multiple‐locus variable‐number tandem repeat were highly similar .It's suggested that MLVA is quite useful for investigation of strain relatedness in regions of outbreaks .

Prevalence of malaria in Liaoning Province,2008 to 2013 / 中国血吸虫病防治杂志

Objective To understand the trend and epidemiologic characteristics of malaria prevalence so as to provide the evidence for further control of the disease in Liaoning Province. Methods The data of registered cases of malaria in Liaoning Province from 2008 to 2013 were collected and analyzed with the descriptive epidemiological methods. Results A total of 202 ma-laria cases were reported from 2008 to 2013. There was no epidemic outbreak ,and the average annual incidence was 0.08/100 000. Totally 17 P. v. cases of local infection were reported,and 185 imported malaria cases were reported(P.v. 33 cases,P.f. 113 cases,P.v.&P.f. 13 cases,P.o. 3 cases,and unspecified 23 cases). The ratio of male to female was 5.91:1,the populations aged 31-45 years were the most(47.52%),and the main occupation was exported labors(46.04%). The 179 imported cases were infected in Africa and Southeast Asia,6 imported cases were infected in Anhui Province,Yunnan Province and Hongkong,and 16 local cases were infected in the border area of Dandong City. Conclusions Although the annual incidence of malaria in Liaon-ing Province is lower than 1/10 000,the incidence shows an increasing trend because the exported labors are increased. There-fore,the epidemic monitoring and health education should be strengthened,especially for the exported labors who have returned.

Optimization of beta-carotene production by a newly isolated Serratia marcescens strain

beta-carotene is a commonly used food colorant. In this work, a novel beta-carotene producing strain, Serratia marcescens RB3, was isolated and identified by physiological and biochemical tests, as well as 16S rDNA sequence analysis. The production of beta-carotene by S. marcescens RB3 was identified through HPLC analysis. The cultivation conditions for beta-carotene production by S. marcescens RB3 were optimized as 2.0 percent lactose, 2.0 percent peptone, 0.3 percent beef extract, 1.0 percent NaCl supplemented with 0.05 percent Fe2+, pH 6.0 and 30ºC. Under the optimal conditions, the yield of beta-carotene achieved 2.45 ug/mL.

Preparation and Quality Control of Thermosensitive Meloxicam Hydrogel / 中国药房

OBJECTIVE: To prepare thermosensitive meloxicam hydrogel and establish its quality control method.METHODS: The hydrogel was prepared with poloxamer 407 and poloxamer 188 as base.The content of meloxicam in the thermosensitive gel was determined by UV spectrophotometry.RESULTS: The thermosensitive meloxicam hydrogel was yellowish or flavovirens in color,with its identification and tests all in conformity with the related specification stated in Chinese Pharmacopeia(2005 edition).The linear response range of meloxican was 1.956～19.56 mg?L-1(r=0.999 7).The average recovery was 98.42%(RSD=1.53%).CONCLUSION: The preparative technique is simple,and the quality of the preparation is controllable.

Drug Resistance of Pathogens in Pediatric Intensive Care Unit / 中华医院感染学杂志

OBJECTIVE To investigate the drug resistance of pathogens in pediatric ICU and discuss how to treat infections caused by these resistant strains.METHODS After genus identification,bacterial susceptibility test was carried out using Kirby-Bauer disk method.RESULTS A total of 270 clinical isolates were analyzed including 194(72%) strains of Gram-negative bacilli and 76(28%) strains of Gram-positive cocci.From them 182(67%) strains were isolated from sputum,78(29%) strains from blood and 10(4%) strains from secretion.The most common bacilli were Klebsiella spp,coagulase negative Staphylococcus,Escherichia coli,Enterococcus spp and Pseudomonas aeruginosa.About 66.7% of E.coli and 91.1% of Klebsiella spp isolates produced ESBLs,the isolating rate of MRCNS was 83.9%.CONCLUSIONS The characteristics of pathogen distribution and drug resistance surveillance must be understood in order to use antibiotics rationally,to control the increasing trend of drug resistance pathogens and to forbid the break out of nosocomial infections.