Isolation, identification and heavy metals biosorption of a lead and cadmium-tolerant strain / 生物工程学报

Adding biological passivation agent during composting is one of the most effective ways to reduce the toxicity of heavy metals in contaminated livestock manure. To further improve biological passivation, we obtained a strain with high-heavy metal compounds tolerance to passivate heavy-metal contaminated manure and to characterize heavy-metal biosorption. High-tolerance microorganisms for lead and cadmium were isolated and screened from swine manure composting samples. The strain was identified by its morphology and molecular biology. After the influence of different pH, temperature and salt concentrations on growth of the strain were investigated, the optimal growth conditions were obtained for further analysis of its biosorption characteristics of lead and cadmium. The bacterium with tolerance to lead and cadmium termed SC19 was obtained, whose lead resistance was 600 mg/L and cadmium resistance was 120 mg/L. The isolate was further identified as Cedecea sp., and then its optimum pH was 7.0, temperature was 37 °C, and salt concentration was 0.5%. Lead removal was highest after 30 min of adsorption by the SC19 strain cultured for the stationary phase 36 h, and the maximum removal rate and biosorption capacity of lead were 60.7% and 329.13 mg/g, respectively. Meanwhile, cadmium removal was highest after 30 min of adsorption by the strain cultured for the logarithmic phase 8 h, and the maximum removal rate and biosorption capacity of cadmium were 51.0% and 126.19 mg/g, respectively. Fourier Transform InfraRed (FT-IR) results revealed that the biosorption process mainly happened on the surface of SC19 cell and many active groups on the cell surface could chelate the Pb²⁺ and Cd²⁺. By comprehensive comparison, it was showed that strain SC19 shared a certain capacity of Pb²⁺ and Cd²⁺ biosorption, and the bacterium provided precious microbial germplasm resources for biological passivation of heavy metal contaminated manure.

Expression, purification and activity verification of human norovirus NS6 protein / 中华实验和临床病毒学杂志

Objective@#To express the NS6 nonstructural protein of human norovirus (NoV) in Escherichia coli, and to detect its enzymatic activity after purification.@*Methods@#Human NoV NS6 gene was cloned into the prokaryotic expression vector pDE1 and then was transformed into E. coli BL21 for expression. NS6 protein was purified by Ni-NTA affinity chromatography and Superdex 200 pg column. The activity of NS6 protein was determined by digestion of fusion protein 15VP1-6P at 37 ℃.@*Results@#Human NoV NS6 protein was stably and highly expressed in E. coli. After purification, the expressed product reached a purity of more than 95%, and the relative molecular weight of NS6 protein was about 23×103 Da. NS6 protein could cleave the fusion protein containing rhinovirus 3C cleavage site.@*Conclusions@#The nonstructural protein NS6 of human NoV was successfully expressed in Escherichia coli, which laid a foundation for further study on the pathogenesis of human NoV.

The expression and purification of VP8* core protein of the rotavirus P 6 Genotype LL4260 / 中华实验和临床病毒学杂志

Objective@#The VP8* core protein of rotavirus P[6] genotype LL4260 was purified by prokaryotic expression, which is important for further study of protein structure and function.@*Methods@#The P[6] genotype LL4260 strain was obtained by PCR.The recombinant plasmid pET30 a-LL4260VP8*core was inserted into pET30 a vector and transformed into BL21 (DE3) competent cells with the correct recombinant plasmid. The expressed protein is purified by affinity chromatography and molecular sieve chromatography.@*Results@#The pET30 a-LL4260VP8* core region protein is soluble in the supernatant and proteins of approximately 22 kDa are identified by electrophoresis using purified proteins.@*Conclusions@#In this study, LL4260 containing pET30 a-LL4260VP8* core plasmid was successfully constructed and LL4260 strain VP8* protein was expressed.

Structure and function of human norovirus nonstructural proteins / 中华实验和临床病毒学杂志

Norovirus (NoV), a single stranded RNA virus, is the major causative agent of the global acute gastroenteritis in humans, and it has drawn more and more attention. Because of the lack of appropriate animal models and in vitro cell culture models, people have studied and understood more about the epidemiology and genetic variation of human viruses. The functional characteristics of the viral encoded protein and the pathogenesis of virus infection are poorly understood. In this paper, we summarize the progress in studies on characteristics of non-structural protein of norovirus, and hope that with the recent breakthrough in human cell culture model of human norovirus, it can be used as a tool for further research on the function of human norovirus non-structural protein.

Research progress of murine norovirus infection and immunity / 中华实验和临床病毒学杂志

Human norovirus (NoV) is a member of the calicivirus family, can cause nausea, vomiting, abdominal pain and diarrhea as the main clinical symptoms of acute gastroenteritis. Human norovirus infection can be popular in the world, all ages, causing serious burden of disease. Due to the lack of suitable small animal models, there is still a lack of understanding of human immune to norovirus infection and pathogenesis. Murine norovirus (MNV) was originally isolated in immune deficient mice, and causes infection and epidemic in mice. MNV provides an alternative model to study human norovirus infection and the host intestinal immune mechanism. This article will elaborate on two aspects of innate immunity and adaptive immunity.

The drug resistance and molecular mechanisms of human Campylobacter jejuni / 中华传染病杂志

Objective To analyze the characteristics of drug resistance to quinolones and erythromycin of clinical Campylobacter jejuni (C .jejuni) strains and to further investigate its molecular mechanisms .Methods A total of 193 clinical C .jejuni strains were isolated from feces of patients with diarrhea .Drug susceptibilities to ciprofloxacin (CIP ) , gentamycin (GEN ) , azithromycin (AZI ) , erythromycin (ERY) ,chloromycetin (CHL) ,doxycycline (DOX) and tetracycline (TET) were tested using standard agar dilution method . gyrA , gyrB and parC genes were amplified by polymerase chain reaction (RCR) and analyzed for molecular mechanisms of quinolones resistance ,and 23S rRNA , rplD and rplV genes for erythromycin resistance .Chi‐square test or Fisher′s exact two‐tailed tests were used to perform the statistical analysis .Results A total of 193 clinical C . jejuni strains were isolated during 1994—2010 ,among which 43 C .jejuni strains were isolated in 1994—1999 ,80 in 2000—2005 and 70 in 2006—2010 .The drug resistance rates for CIP increased significantly from 55 .8% in 1994—1999 to 95 .0% in 2000—2005 and 94 .3% in 2005—2010 (χ2=41 .94 ,P<0 .01) .The drug resistance rates for GEN were 0 in 1994—1999 ,11 .3% in 2000—2005 and 10 .0% in 2006—2010 ,but with no statistic difference (χ2=5 .078 , P=0 .08) .The drug resistance rates for AZI were 0 in 1994—1999 ,3 .8% in 2000—2005 and 4 .3% in 2006—2010 (χ2=1 .81 ,P=0 .40) .The drug resistance rates for ERY were 0 in 1994—1999 ,1 .3% in 2000—2005 and 4 .3% in 2006—2010 (χ2 = 2 .87 , P= 0 .24 ) . T he drug resistance rates for CHL were 2 .3% in 1994—1999 ,11 .3% in 2000—2005 and 20 .0% in 2006—2010 (χ2 =7 .82 ,P=0 .02) .The drug resistance rates for DOX were 60 .5% in 1994‐1999 ,86 .3% in 2000—2005 and 82 .9% in 2006—2010 (χ2 =12 .18 ,P<0 .01) .The drug resistance rates for TET were 74 .4%in 1994—1999 ,95 .0% in 2000—2005 and 94 .3% in 2006—2010 (χ2 = 15 .46 , P< 0 .01 ) .T he drug resistance rates for CIP‐DOX‐TET were 37 .2% in 1994—1999 ,83 .8% in 2000—2005 and 80 .0% in 2006—2010 (χ2 =33 .53 ,P<0 .01) .The drug resistance rates for CHL‐CIP‐DOX‐TET were 0 in 1994—1999 ,7 .5% in 2000—2005 and 20 .0% in 2006—2010 (χ2=12 .68 ,P<0 .01) .The drug resistance rates for GEN‐CIP‐DOX‐TET were 0 in 1994—1999 ,7 .5% in 2000—2005 and 8 .6% in 2006—2010 (χ2 =3 .74 ,P=0 .15) .All 163 CIP‐resistant C .jejuni strains had C257T mutation on gyrA gene .Mutations on gyrB gene were silent .ParC gene was absent in C .jejuni .Four ERY resistant C .jejuni strains had no mutation on rplD and rplV genes , but 3 of them had A2075G mutation on 23S rRNA gene . Conclusions The antimicrobial resistance rates for C .jejuni increase remarkably over the periods .C257T mutation on gyrA gene and A2075G mutation on 23S rRNA gene are main mechanisms for quinolones resistance and erythromycin resistance ,respectively .

Genotype of Rotavirus Vaccine Strain LLR in China is G10P15 / 病毒学报

Rotavirus is the leading causal agent of severe acute gastroenteritis in children aged <5 years. A specific pharmacologic agent for the treatment of rotavirus-infected children is lacking. In China, only the Luo Tewei oral vaccine (Lanzhou Institute of Biological Products, Shanghai, China), which is produced from Lanzhou lamb rotavirus vaccine (LLR), is available. Studies have hypothesized that the genotype of LLR is G10P[12], To identify the genotype of LLR by reverse transcription-polymerase chain reaction, we showed that the VP7 and VP4 genotypes of LLR were G10 and P[15], respectively, based on sequencing, alignment and phylogenetic analyses. In conclusion, we identified the genotype of rotavirus strain LLR to be G10P[15].