Publications (16)31.6 Total impact
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Article: Coexpression of bile salt hydrolase gene and catalase gene remarkably improves oxidative stress and bile salt resistance in Lactobacillus casei.
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ABSTRACT: Lactic acid bacteria (LAB) encounter various types of stress during industrial processes and gastrointestinal transit. Catalase (CAT) and bile salt hydrolase (BSH) can protect bacteria from oxidative stress or damage caused by bile salts by decomposing hydrogen peroxide (H(2)O(2)) or deconjugating the bile salts, respectively. Lactobacillus casei is a valuable probiotic strain and is often deficient in both CAT and BSH. In order to improve the resistance of L. casei to both oxidative and bile salts stress, the catalase gene katA from L. sakei and the bile salt hydrolase gene bsh1 from L. plantarum were coexpressed in L. casei HX01. The enzyme activities of CAT and BSH were 2.41 μmol H(2)O(2)/min/10(8) colony-forming units (CFU) and 2.11 μmol glycine/min/ml in the recombinant L. casei CB, respectively. After incubation with 8 mM H(2)O(2), survival ratio of L. casei CB was 40-fold higher than that of L. casei CK. Treatment of L. casei CB with various concentrations of sodium glycodeoxycholate (GDCA) showed that ~10(5) CFU/ml cells survived after incubation with 0.5% GDCA, whereas almost all the L. casei CK cells were killed when treaded with 0.4% GDCA. These results indicate that the coexpression of CAT and BSH confers high-level resistance to both oxidative and bile salts stress conditions in L. casei HX01.Journal of Industrial Microbiology 08/2011; 38(8):985-90. · 1.80 Impact Factor -
Article: Correlations of fecal bacterial communities with age and living region for the elderly living in Bama, Guangxi, China.
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ABSTRACT: Bama County (Guangxi, China) is famous for its longevous population. In this study, intestinal microflora of 17 healthy elderly subjects of different ages and from different regions (rural and urban) in Bama, were analyzed by denaturing gradient gel electrophoresis (DGGE). Significant effects of age and living region on the whole intestinal bacterial communities were observed by redundancy analysis (RDA). A total of 11 bacterial strains that were correlated with age and living region were identified using a t-value biplot combined with band sequencing. Four bacterial strains were correlated with both age and living region of the elderly in Bama. Two Bacteroides strains and one Ruminococcaceae strain were abundant in the rural, younger elderly; conversely, one Desulfovibrio strain was high in the urban, older elderly. Another Bacteroidetes strain was only correlated with the participant's age, and its abundance increased with the age of the elderly. The richness of one Clostridium sordellii strain, which was only correlated with the elderly living region, was high in the urban elderly. The study also found five other novel bacterial strains that were correlated with the age or living region of the elderly in Bama. These results expand our understanding of age- and region-effects on the intestinal microflora of the elderly and raise the possibility of developing probiotics originating from centenarians.The Journal of Microbiology 04/2011; 49(2):186-92. · 1.10 Impact Factor -
Article: Coexpression of the superoxide dismutase and the catalase provides remarkable oxidative stress resistance in Lactobacillus rhamnosus.
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ABSTRACT: Lactic acid bacteria (LAB) are generally sensitive to oxidative stress caused by reactive oxygen species (ROS). Antioxidant enzymes, especially superoxide dismutase (SOD) and catalase (CAT), can protect against ROS by eliminating superoxide and H(2)O(2), respectively. Lactobacillus rhamnosus is a valuable probiotic starter culture but is deficient in both SOD and CAT, and is thus likely to suffer from oxidative stress in industrial fermentation. To confer high level of oxidative resistance on L. rhamnosus , the SOD gene sodA from Streptococcus thermophilus and CAT gene katA from L. sakei were coexpressed in L. rhamnosus AS 1.2466. The enzyme activities of SOD and CAT were 147.80 ± 1.08 U/mg protein and 2.53 μmol of H(2)O(2) /min/10(8) cfu, respectively, in the recombinant L. rhamnosus CS. After incubation with 10 mM H(2)O(2), the survival ratio of L. rhamnosus CS was 400-fold higher than that of L. rhamnosus CAT. In long-term aerated conditions, viable cells of L. rhamnosus CS remained ∼10(6) cfu/mL after incubation for 7 days, while no living cells of the control were detected. These results showed that the cooperation between SOD and CAT could significantly enhance oxidative resistance in L. rhamnosus . To our best knowledge, this is the first report of two synergistic antioxidant genes being coexpressed in the same Lactobacilli.Journal of Agricultural and Food Chemistry 03/2011; 59(8):3851-6. · 2.82 Impact Factor -
Article: Complete genome sequence of Bifidobacterium longum subsp. longum BBMN68, a new strain from a healthy chinese centenarian.
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ABSTRACT: Bifidobacterium longum subsp. longum BBMN68 was isolated from the feces of a healthy centenarian living in an area of BaMa, Guangxi, China, known for longevity. Here we report the main genome features of B. longum strain BBMN68 and the identification of several predicted proteins associated with the ecological niche of longevity.Journal of bacteriology 02/2011; 193(3):787-8. · 3.94 Impact Factor -
Article: Characterization of the cryptic plasmid pTXW from Lactobacillus paracasei TXW.
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ABSTRACT: A cryptic plasmid from Lactobacillus paracasei TXW isolated from koumiss, designated as pTXW, was sequenced and characterized. It is 3178 bp in length with a G+C content of 42.9%. The plasmid pTXW was predicted to encode 4 putative ORFs. RepB shared high homology with initiator proteins of plasmids from the rolling circle replication (RCR) pMV158 family. copG was predicted to encode a transcriptional repressor, which was involved in plasmid copy number control together with a putative antisense RNA. Mob putatively acts as a relaxase and belongs to the MOB(V) relaxase family. Sequence analysis revealed a double strand origin (dso) located upstream the repB gene, which contained the conserved nick sequence of the pMV158 family. A putative single strand origin (sso-like) consisting of successive inverted repeats was also detected. Mung bean nuclease analysis and Southern hybridization confirmed the presence of single-stranded DNA (ssDNA) intermediates, suggesting that pTXW replicates via the RCR mechanism. Furthermore, the relative copy number of pTXW was estimated to be 73.5±1.2 copies in each cell by real-time PCR. The new RCR plasmid would be valuable to construct vectors for application in food industry.Plasmid 01/2011; 65(1):1-7. · 1.52 Impact Factor -
Article: A novel vector for lactic acid bacteria that uses a bile salt hydrolase gene as a potential food-grade selection marker.
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ABSTRACT: A novel vector pM4aB for lactic acid bacterial was developed using a bile salt hydrolase gene from Lactobacillus plantarum as a potential food-grade selection marker. The 3.0-kb pM4aB consisted of the replicon of Lactobacillus plasmid pM4, a multiple cloning site and the bsh gene, which was constructed by elimination of a 5.5-kb non-food-grade DNA fragment from an 8.5-kb intermediate vector pBEmpM4aB. For electroporation into Lactobacillus paracasei X9, a high transformation efficiency of 4.0±1.0×10(4) CFU/μg plasmid DNA was yielded with 0.1% (wt/vol) glycodeoxycholic acid sodium selection. A high segregation stability of the vector was also observed as only 0.1% plasmid was lost after 50 generations of growth without selection pressure. The application potential of pM4aB was further confirmed by expression of a catalase gene from Lactobacillus sakei in L. paracasei. These results revealed that the novel vector pM4aB constructed in this study would be a useful tool for genetic modification of the industrially important LAB.Journal of biotechnology 01/2011; 152(1-2):49-53. · 2.88 Impact Factor -
Article: High-level expression of heme-dependent catalase gene katA from Lactobacillus Sakei protects Lactobacillus rhamnosus from oxidative stress.
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ABSTRACT: Lactic acid bacteria (LAB) are generally sensitive to hydrogen peroxide (H(2)O(2)), Lactobacillus sakei YSI8 is one of the very few LAB strains able to degrade H(2)O(2) through the action of a heme-dependent catalase. Lactobacillus rhamnosus strains are very important probiotic starter cultures in meat product fermentation, but they are deficient in catalase. In this study, the effect of heterologous expression of L. sakei catalase gene katA in L. rhamnosus on its oxidative stress resistance was tested. The recombinant L. rhamnosus AS 1.2466 was able to decompose H(2)O(2) and the catalase activity reached 2.85 mumol H(2)O(2)/min/10(8) c.f.u. Furthermore, the expression of the katA gene in L. rhamnosus conferred enhanced oxidative resistance on the host. The survival ratios after short-term H(2)O(2) challenge were increased 600 and 10(4)-fold at exponential and stationary phase, respectively. Further, viable cells were 100-fold higher in long-term aerated cultures. Simulation experiment demonstrated that both growth and catalase activity of recombinant L. rhamnosus displayed high stability under environmental conditions similar to those encountered during sausage fermentation.Molecular Biotechnology 03/2010; 45(2):155-60. · 2.17 Impact Factor -
Article: Characterization of a rolling-circle replication plasmid pXY3 from Lactobacillus plantarum XY3.
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ABSTRACT: The complete nucleotide sequence of cryptic plasmid pXY3 isolated from Lactobacillus plantarum strain XY3 has been determined. It consisted of a 2968-bp circular molecule with a G+C content of 39%. Sequence analysis of pXY3 revealed three putative open reading frames (ORFs). Based on sequence similarity, the Rep protein shared 89% and 88% identity with Rep proteins of pLF24 and pWCFS102, respectively, which belonged to the rolling-circle replication (RCR) pMV158 family. A ssoT-like single-strand origin (sso) and a typical pMV158 family double-strand origin (dso) located upstream of the rep gene. Southern blot analysis indicated pXY3 replicate via a rolling-circle (RC) mechanism. Furthermore, the relative copy number of pXY3 was estimated to be about 97 copies per chromosome equivalent by real-time PCR.Plasmid 03/2010; 64(1):36-40. · 1.52 Impact Factor -
Article: Functional analysis of the plasmid pM4 replicon from Lactobacillus plantarum M4: determination of the minimal replicon and functionality identification of the putative sso.
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ABSTRACT: In order to determine the minimal replicon and the single strand origin (sso) of the plasmid pM4, different fragments of pM4 were amplified by polymerase chain reaction (PCR) and cloned into pBEm, a replication probe vector for Lactobacillus. The deletion analysis results showed that the minimal replicon of pM4 could be determined within a 1280bp fragment consisting of double strand origin (dso) and rep gene encoding replication protein. Based on plasmid segregation stability assay and its ability to convert single-stranded DNA (ssDNA) to double-stranded DNA (dsDNA) by Southern hybridization, an sso of replication was located at nucleotides -118-92 in the plasmid pM4, about 300bp upstream of dso. In addition, the host range assay indicated that plasmid pM4 could replicate in L. casei 05-21, L. rhamnosus AS 1.2466(T) and L. plantarum 05-19 of all the tested Lactobacillus strains. Analysis of the pM4 replicon will allow its use in constructing a food-grade vector for application in food industry.Plasmid 08/2009; 62(3):166-71. · 1.52 Impact Factor -
Article: Characterization of a novel rolling-circle replication plasmid pYSI8 from Lactobacillus sakei YSI8.
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ABSTRACT: A plasmid from Lactobacillus sakei YSI8, designated as pYSI8, was sequenced and characterized. It consisted of a 4973bp circular molecule with a G+C content of 35.6%. The plasmid pYSI8 was predicted to contain five putative ORFs, in which ORF1 shared 79% and 76% identity with Rep proteins of pLH2 and pLC2, members of rolling-circle replication (RCR) pMV158 family. Detection of single-stranded DNA (ssDNA) intermediates by Southern hybridization and mung bean nuclease treatment confirmed that pYSI8 replicated via the RCR mechanism. Accumulation of ssDNA in rifampicin-treated strains implied that the host-encoded RNA polymerase was involved in the conversion of ssDNA to double-stranded DNA (dsDNA). Furthermore, the copy number of pYSI8 was estimated to be 41.9+/-0.5 in each cell by real-time polymerase chain reaction.Plasmid 04/2009; 62(1):30-4. · 1.52 Impact Factor -
Article: Characterization of a rolling-circle replication plasmid pLR1 from Lactobacillus plantarum LR1.
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ABSTRACT: A cryptic plasmid from Lactobacillus plantarum LR1, designated pLR1, was sequenced and characterized. It consisted of a 2066-bp circular molecule with a G + C content of 52.7%. The plasmid pLR1 was predicted to contain five putative ORFs, in which ORF1 shared 93% and 92% identity with Rep proteins of pLP1 and pC30il, members of rolling-circle replication (RCR) pC194 family. Detection of single-stranded DNA (ssDNA) intermediates by Southern hybridization and mung bean nuclease treatment confirmed that pLR1 replicated via the RCR mechanism. Accumulation of ssDNA in rifampicin-treated strains implied that the host-coded RNA polymerase was involved in the conversion of ssDNA to double-stranded DNA (dsDNA). Furthermore, the copy number of pLR1 was estimated to be 36 in each cell by real-time polymerase chain reaction.Current Microbiology 11/2008; 58(2):106-10. · 1.82 Impact Factor -
Article: Expression, purification and characterization of pectin methylesterase inhibitor from kiwi fruit in Escherichia coli.
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ABSTRACT: A significant problem in production of fruit juices for human consumption is auto-clarification, where enzyme catalyzes pectin demethylation resulting in loss of the ''natural" cloudy appearance of juices. To overcome this problem, a plant inhibitor protein which blocks the action of pectin methylesterase has been used. In this paper, expression of recombinant kiwi pectin methylesterase inhibitor (PMEI) was carried out in Escherichia coli, and the target protein was expressed in the form of inclusion bodies. The expression level reached 46% of total cell protein. Then the fusion protein was purified by nickel ion metal affinity chromatography, and the purity was finally up to 98%. After refolding in GSH/GSSG redox system, recombinant PMEI not only could efficiently inhibit PMEs from eight different plants, but could remain effective inhibitor activity in the pH 3.0-10.0 and 20-40 degrees C. Thus, recombinant PMEI has potential application in the production of fruit juices product industry.Protein Expression and Purification 09/2008; 60(2):221-4. · 1.59 Impact Factor -
Article: Characterization of a cryptic plasmid pM4 from Lactobacillus plantarum M4.
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ABSTRACT: A cryptic plasmid from Lactobacillus plantarum M4 isolated from fresh milk, designated as pM4, was sequenced and characterized. It was 3320 bp in length with a G+C content of 38.73 mol%. The plasmid pM4 was predicted to encode three putative ORFs, in which ORF1 shared 99% and 98% homology, respectively, with the Rep proteins of reported plasmids pWCFS101 and pF8801, members of the rolling circle replication (RCR) pC194 family. Sequence analysis revealed a typical pC194 family double strand origin (dso) and a putative single strand origin (sso) located upstream of the rep gene. Mung bean nuclease analysis and Southern hybridization confirmed the presence of single-stranded DNA (ssDNA) intermediates, suggesting that pM4 belongs to the RCR pC194 family. Accumulation of ssDNA in rifampicin-treated strains implied that the host-encoded RNA polymerase was involved in the conversion of ssDNA to double-stranded DNA. Furthermore, the relative copy number of pM4 was estimated to be about 25 in each cell by real-time PCR. The new RCR plasmid would be valuable in constructing cloning vectors for application in the food industry.FEMS Microbiology Letters 07/2008; 285(2):183-7. · 2.04 Impact Factor -
Article: Ultraviolet Raman study of thymine on the Au electrode.
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ABSTRACT: We record the potential-dependent Raman spectra of thymine adsorbed on the roughened Au electrode by ultraviolet (UV) excitation at 325 nm, and we find that the surface-enhanced Raman spectra of thymine changed intensely with the negative shift of the applied potential. When the vibrational mode changes, the resonance potential (potential of maximum intensity) varies accordingly, indicating that the thymine molecules were chemisorbed on the roughened Au surface. The charge transfer (CT) mechanism could probably explain the experiment results in the present work.Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 12/2007; 68(3):778-82. · 2.10 Impact Factor -
Article: Piperidine adsorption on two different silver electrodes: A combined surface enhanced Raman spectroscopy and density functional theory study
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ABSTRACT: The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver electrode the piperidine molecular lies flat on the silver surface. In the meantime, the potential dependent SERS of piperidine on the modified electrode were studied.Journal of Nanoparticle Research 09/2007; 9(5):817-824. · 3.29 Impact Factor -
Article: Characterization and application of an anti-Listeria bacteriocin produced by Pediococcus pentosaceus 05-10 isolated from Sichuan Pickle, a traditionally fermented vegetable product from China
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ABSTRACT: Pediococcus pentosaceus 05-10, isolated from a traditionally fermented Sichuan Pickle, produced a bacteriocin (Pediocin 05-10) active against Listeria, Lactobacillus, Streptococcus, Enterococcus, Pediococcus and Leuconostoc. Pediocin 05-10 was sensitive to proteolytic enzymes, but stable between pH 2–10 and heat resistant (15 min at 121 °C). It did not adhere to the surface of the producer cells. However, adsorption to both resistant and sensitive cells was observed. Production of the bacteriocin started at the early exponential phase and reached its maximum at the early stationary phase. This result suggested that Pediocin 05-10 was produced in a growth-associated manner. Its mode of action was bactericidal, as determined against Listeria monocytogenes 54002. Pediocin 05-10 was estimated below 6.5 kDa by tricine–SDS–PAGE. The application experiment showed that Pediocin 05-10 could significantly reduce the counts of L. monocytogenes 54002 in pork ham during storage at 4 °C for 10 days. Thus, Pediocin 05-10 has potential for application in food preservation, especially in the meat products industry.Food Control.
Top co-authors
Top Journals
Institutions
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2011
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Beijing Genomics Institute
Shenzhen, Guangdong Sheng, China -
Beijing University of Agriculture
Beijing, Beijing Shi, China -
Government of the People's Republic of China
Beijing, Beijing Shi, China
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2008–2011
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China Agricultural University
- College of Food Science and Nutritional Engineering
Beijing, Beijing Shi, China
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2007
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Capital Normal University
- Beijing Key Laboratory for Nano-Photonics and Nano-Structure
Beijing, Beijing Shi, China
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