The technique of double-layered plate was developed for screening the library of mutant endoglucanase III from Trichoderma reesei generated by the method of directed evolution.The enzyme activity was determined according to the velocity of the formation of halos on the plates.Several mutants with higher activity than the wild type at low temperature or alkaline pH were obtained by using this strategy under different screening conditions.Further results of spectrophotometric determination of the activities of these mutants were consistent with the results of plate screening.The establishment of such strategy will broaden the applications of the directed evolution methods for improving the existing proteins to obtain useful enzymes with new properties for industrial applications.

A white-rot fungi Rigidoporus sp.W-1 which could produce laccase was isolated. The fermentation conditions in shaking flasks were investigated. The optimal carbon source was wheat bran and (NH 4) 2SO 4 was the optimal nitrogen source. The components of the medium were optimized by orthogonal experiment. When W-1 was cultured under the optimum conditions, the activity of laccase could get to 7.1U/mL in 7 days.A great amount of crude laccase could be obtained by adding fresh medium to the 7 days old mycelium.

This paper discusses the mechanism of cellobiose in fungal cellulase induction a nd repression, and its inhibition of cellulases hydrolytic activity. Depending on the research result of cellulose binding domain, our hypothesis is that the main function of Exo-1,4-?-glucanase is to destroy th e crystal structure of cellulose to facilitaty hydrolyzing of ?-1,4 glucosidic bonds. A new strategy for the efficient transformation of cellulose material is advanced at t he end.

Objective: To investigate the protective factors and risk factors of nosocomial infection of severe acute respiratory syndrome (SARS) among health care workers (HCWs) , and thus provide the scientific basis for prevention and control of nosocomial infection. Methods: With the case-control study,a standardized questionnaire was used for data collection in three general hospitals where nosocomial infection had occurred. Univariate analysis was done at first. All concerned factors about SARS infection were scanned by using Chi-square test and Fisher' s exact test one by one, and determined as to whether they were risk factors or protective factors according to odd ratio (OR) score. Then, multivariate unconditional logistic regression analysis was used to re-analyze the picked-out factors for finding out which factors played independent roles. Results: Twenty-two factors (nineteen protective factors and three risk factors), among the total fifty-six factors, were significantly associated with SARS infection. Multivariate unconditional logistic regression revealed that factors such as double exposure suits ( OR = 0.053 ), education ( OR =0.072), gloves ( OR =0.102), hands sterilized by iodine ( OR =0.231 ), room air ventilation (OR = 0.32), were significantly protective; conversely, tracheal intubation ( OR = 30.793 ) was a significant risk factor. Conclusion: Strict defense and antisepsis measures were pivotal in preventing SARS infection among high-risk medical personnel. Education about associated knowledge and effective air ventilation were also important factors.

The effects of pretreatment of supercritical carbon dioxide (SC-CO2) on the supramolecular structure of cellulose and the cellulase catalyzed reaction were investigated. The cellulase activity was not affected when it was treated with SC-CO2 at 10MPa and at 50 degrees C for 30 min. But when the cellulase was treated by SC-CO2 in the presence of cellulose, the catalytic activity of the cellulase was lost. The cellulose pretreated with or without cellulase under the same SC-CO2 condition was then hydrolyzed with tresh crude cellulase. The final reducing sugar yield from the hydrolysis of the cellulose pretreated with cellulase was higher than that of the cellulose pretreated without cellulase. It was also found that the improvement of the enzymolysis had a direct relevance with the amount of cellulase used during the SC-CO2 pretreatment. The moisture content of cellulose before SC-CO2 pretreatment had an obvious influence on the subsequent enzymolysis. When the moisture content of cellulose was 60% (W/W), the reducing sugar yield was higher than when the moisture content was over 100% (W/W). The FT-IR spectra showed that the structure of the cellulose pretreated with cellulase under the SC-CO2 condition was different from that of the cellulose pretreated without cellulase. In the presence of the enzyme, the strength of the hydrogen bonds and the I beta phase at 710cm(-1) in the crystalline cellulose was weakened. These results suggest that the change in the cellulose structure induced by the SC-CO2 treatment favous the subsequent enzymolysis.
Carbon Dioxide ; chemistry ; Cellulase ; chemistry ; metabolism ; Chromatography, Supercritical Fluid ; methods ; Spectroscopy, Fourier Transform Infrared

Lignin peroxidase (LiP) hosted in Brij 30/cyclohexane/water nonionic reversed micelle could express its catalytic activity, but in Triton X-100/n-pentanol/cyclohexane/water nonionic reversed micelle LiP didn't show any catalytic activity. Some key factors that affected the catalytic activity of LiP in Brij 30 reversed micelle were studied at 20 degrees C. The optimum conditions were:omega0 = 8.5, pH = 2.2, [Brij30] = 600 mmol/L; under these conditions the half time of LiP was ca. 50 hours. As compared with the properties of LiP in aqueous solution, the activity of LiP hosted in Brij 30 reversed micelle dropped, but its stability improved greatly. To reveal the role of normal alcohol, which was a necessary component for forming Triton X-100 reversed micelles, the effect of n-pentanol on the catalytic activity of LiP in Brij 30 reversed micelle was investigated. Results indicated that high concentration of the alcohol deactivated LiP. So it was deduced that the phenomenon that LiP hosted in the Triton X-100 reversed micelles could not express its activity was mainly due to the alcohol co-surfactant.
Catalysis ; Cyclohexanes ; chemistry ; Enzyme Activation ; drug effects ; Micelles ; Octoxynol ; chemistry ; Pentanols ; chemistry ; Peroxidases ; metabolism ; Surface-Active Agents ; chemistry

Adult ; Culture Media ; classification ; Female ; Humans ; Male ; Mycoplasma Infections ; microbiology ; Mycoplasma hominis ; growth & development ; Ureaplasma Infections ; microbiology ; Ureaplasma urealyticum ; growth & development ; Urethra ; microbiology ; Vaginal Smears

OBJECTIVETo study the prevalence rate of upper respiratory tract group A Streptococcus (GAS) carriage in school-age children from Xinjiang Province.

METHODSA total of 478 children at age of 9-12 years from Tulufan City and Buerjin County of Xinjiang Province were enrolled by random cluster sampling. Throat swab cultures were performed once each season for the determination of presence of GAS.

RESULTSIn the 1 827 samples, 196 GAS strains were isolated, with a GAS carrier rate of 10.7%. The prevalence rate of GAS carrier in Tulufan City ranged from 3.7%-16.5% compared with 4.7%-21.4% in Buerjin County (P < 0.05). The prevalence rate of GAS carrier in winter is the highest, followed by in autumn, spring and summer in both regions. There were significant differences in the GAS carriage rate in autumn between the two regions. There were no significant differences in the GAS carriage rate between boys and girls. Of the 196 GAS strains, 133 from Han, 22 from Uygur and 41 from Hazakh children. There were significant differences in the prevalence rate of GAS carriage among children with different ethic groups.

CONCLUSIONSThe prevalence rate of GAS carriage is high in school-age children from Tulufan and Buerjin of Xinjiang Province. The GAS carrier rate is associated with the season and ethic group. The children from Buerjin County present a higher GAS carrier rate than those from Tulufan City.

Carrier State ; microbiology ; Child ; China ; Female ; Humans ; Male ; Prevalence ; Respiratory System ; microbiology ; Streptococcus pyogenes ; isolation & purification

ObjectiveTo investigate the current status of Kaschin-Beck disease in Shandong province, and to provide a scientific basis for decision-making in controlling the disease. Methods According to the National Monitoring Program of Kaschin-Beck disease requirements, historical serious villages of Kaschin-Beck disease in Qingzhou of Shandong province were selected annually; children aged 7 to 16 were chosen to receive clinical examination and children aged 7 to 12 were taken X-ray examination. Clinical and X-ray diagnosis was carried out according to the Diagnostic Criteria of Kashin Beck Disease(GB 16003-1995). Results From 1996 to 2010, in 53 diseased villages, three thousand three hundred and eighteen school children aged 7 to 16 were clinically diagnosed, and child Kaschin-Beck disease of degree Ⅰ and above were not detected; three thousand and ninety-one school children aged 7 to 12 were examined by X-ray, forty cases were found positive, and the total positive rate was 1.29％(40/3091 ). The year with the highest positive rate was 2002, and the rate was 3.49％(13/372) ; the positive rate was 0 in 1996 and 2008. The difference of the X-ray positive rate between each year was statistically significant(x2 =31.54, P ＜ 0.01 ). ConclusionsChild Kashin-Beck disease in Qingzhou is basically under control.Since etiology of Kashin-Beck disease is still unclear, surveillance of the disease still needs to be strengthened.

Objective To investigate the pathogenic characteristics and use of antibiotics in children with acute osteomyelitis,and to provide evidence for rational drug use in the clinic.Methods The clinical data of 266 children with acute osteomyelitis admitted to the Department of Orthopedics,Children's Hospital Affiliated to Zhengzhou University from January 2019 to December 2022 were retrospectively analyzed,and the basic information,pathogenic microorganisms,drug sensitivity test results,and antibacterial drug use of the children were statistically analyzed.Results In 266 cases of pediatric acute osteomyelitis,all underwent pathogen examination,and 148 cases were cultured for pathogens with a positive detection rate of 55.64％.A total of 154 strains of bacteria were detected.The top three pathogens were Staphylococcus aureus(104 strains,67.53％),Staphylococcus epidermidis(8 strains,5.19％),and Staphylococcus hominis(7 strains,4.55％).The detection rate of methicillin-resistant Staphylococcus aureus(MRSA)was 33.65％.Compared with methicillin-sensitive Staphylococcus aureus(MSSA),there was no significant difference in disease severity and prognosis of infection with MRSA.The utilization rate of antibiotics was 100.00％;227 cases of empirical antibiotics were used alone,accounting for 85.34％,primarily using ceftriaxone.Combination therapy was used in 39 cases,accounting for 14.66％,mainly ceftriaxone combined with vancomycin;the average course of intravenous drugs was 40.20 days.After receiving the drug sensitivity test results in 148 cases,76 cases(51.35％)continued the original treatment plan due to effective treatment.In 37 cases(25.00％),treatment was adjusted based on the drug sensitivity results due to poor treatment outcomes;the drug sensitivity results indicated sensitivity,but the clinical effect was not good in 25 cases accounting for 16.89％,which changed the drug treatment.In 10 cases(6.76％),clinical treatment was effective,leading to a switch to narrow-spectrum antibiotics or a change from combination therapy to monotherapy based on drug sensitivity results.Conclusion Empiric antibacterial therapy can cover common pathogens in children with acute osteomyelitis,and medication regimens can be adjusted according to clinical efficacy and drug sensitivity.However,the course of intravenous antibiotic treatment is too long,so it is necessary to further optimize the timing of transitioning from intravenous to oral administration.