Abstract:

Abstract:A fungus CQ31 isolated from soil samples was identified as Chaetomium sp.. This strain produced effectively xylanases utilizing several liguocellulosic materials in the solid-state fermentation (SSF), and corn straw was the best carbon source. The results of single-factor-experiment showed that the corn straw as the carbon source, tryptone as the nitrogen source, initial moisture content of 80% and initial pH 9.0 were the optimal conditions for xylanase production. Under the optimized conditions, it produced xylanase which was 4897 U/g dry substrate while mannanase was 803 U/g dry substrate after 7 days of cultivation. Therefore, xylanase and mannanase production by Chaetomium sp. CQ31 in SSF possess potential for commercial applications.

Abstract:Two current main chromogenic media products of abroad and the newly developed PEN-TCF from Guangdong Huankai Microbial Sci. & Tech. Corporation were compared in this study. Their recovery of different Staphylococcus aureus strains, minimum detection limits and the recovery, specificity and anti-distubance of detecting artificial contaminated samples were studied. The results showed that 3 media had similar minimum detection limits, Chromogenic Media A and PEN-TCF had better sensitivity but worse anti-distubance, while Chromogenic Media B had better anti-distubance yet lower sensitivity, and Media B and PEN-TCF were more specific than Media A.

Abstract:A biosurfactant producing bacterial strain C-3 was isolated from the sludge of a petroleum refinery and identified as Pseudomonas aeruginosa. The optimal conditions for the growth and biosurfacant production of strain C-3 were investigated. The results showed that strain C-3 could grow well and produce the largest amount of biosurfacant under the following conditions: seed-oil as sole carbon source, 30°C, initial pH 8, Ca2+ concentration of 20 mg/L, 75 mL medium in 250 mL Erlenmeyer flask. The biosurfactants produced by strain C-3 was identified as lipopeptides, showing high surface activity and emulsifying efficiency with critical micelle concentration (CMC) being 50 mg/L.

Abstract:The lipopeptide samples were purified by normal reverse-phase column chromatography after isolated from the cell free broth of Brevibacillus brevis HOB1. A lipopeptide was separated from these samples by preparative HPLC, and determined to have a molecular weight of 1035.7 D by ESI-MS. The fatty acid part was identified to be C15 β-hydroxyl fatty acid by GC/MS. A quantitative analysis of the PITC-derivated amino acids of the lipopeptide by HPLC gave the following molar ratios: Asp 1, Glu 1, Val 1, Leu 4. All the results indicated that the lipopeptide has a structure similar to C15 surfactin. This study revealed that surfactin series lipopeptides can be produced by Brevibacillus genus in addition to Bacillus genus.

Abstract:According to the comparative research of conventional sterile fermentation and uncooked material fermentation, the conditions of tannase production from Aspergillus Niger B0201 under solid-state fermentation using gallnut was studied. The results showed that the liquid?solid ratio of 1.6: 1, temperature of 30°C, initial pH of 6.0 were the optimal conditions for tannase production under uncooked material fermentation with gallnut content of 20% and (NH4)2SO4 for nitrogen sources. Under this condition, tannase activity reached to 51.2 U/gds after 96 h of cultivation, which was 3.6 times as the conventional sterile fermentation. The results above revealed that under uncooked material fermentation for tannase production was a feasible method with high efficiency.

Abstract:An enrichment culture showing specific algae-lysing activity was isolated from the mixtures of different samples and Microcystis aeruginosa. The process of algal lysis was monitored by chlorophyll measurement, PCR, and denaturing gradient gel electrophoresis (DGGE). The result showed that the enrichment culture had still high algicidal activity against M. aeruginosa after 1/100000 dilution. Rubritepida sp. C1, Pseudomonas sp. C2 and Sphingomonas sp. C3, as accompanying bacteria, existed in M.aeruginosa. The bacterial community in M. aeruginosa showed significant change after adding the enrichment culture, where uncultured Flavorbacterium sp. A2, Sphingomonas sp. C3 and Hydrogenophaga sp. A3 were observed, and A2 became a dominant species. The obvious correlation can be seen between change of bacterial population and extinction of M. aeruginosa. Compared identification of pure bacterium with sequencing of DGGE band, it was inferred that uncultured bacteria were probably play an important role in controlling the growth and abundance of M. aeruginosa.

Abstract:The growth and fermentation of Saccharomyces cerevisiae are both complexed physiology process. Here, we used laser tweezers Raman spectroscopy (LTRS) as tool and reported physiological metabolism such as nucleic acid, proteins, lipid, ethanol and glucose in active dry wine yeast cells. Our results indicated significantly changes of intracellular components at 6 h during log growth phase and 9 h that point between aerobic respiration to anaerobic fermentation. RNA synthesis was rapidly trigged in cultivated media and reached the maximum at 6 h. However, mitochondria respiration and syntheses of protein and lipid were slower than metabolism of nucleic acid in initial 3 h and then reached the maximum at crucial 9 h. The ethanol was also yielded at this time accompanying increase of glucose metabolism and reached the maximum of 0.98%. However, later, the metabolism of macromolecular, expected mitochondria respirations, were deeply declining after 9 h. All results show that LTRS can be utilized to monitor the metabolism of yeast growth and fermentation in quantitative or semi-quantitative analyses. In addition, improved kinetic model of ethanol fermentation processes also can be benefited from these metabolism parameters.

Abstract:A strain designated as GS-1, capable of degrading triazophos efficiently, was isolated from the sludge in an organophosphate-pesticides wastewater treatment plant. Strain GS-1 was identified preliminarily as Diaphorobacter sp. based on its physiological and biochemical characters and the result of the 16S rDNA homologue sequence analysis. Strain GS-1 could grow with triazophos as its sole carbon source, and degrade 100 mg/L triazophos to non-detectable level within 12 h. The metabolite, 1-phenyl-3-hydroxy-1, 2,4-triazole, produced during triazophos biodegradation was finally transformed within 36 h. The optimal initial pH value and temperature for triazophos degradation by GS-1 was 7.0 and 30°C, respectively. Strain GS-1 could also degrade some other organophosphorus-pesticides such as fenitrothion, phoxim, chlorpyrifos and methyl-parathion. Strain GS-1 also showed chemoatxis to triazophos, fenitrothion and phoxim, indicating the close relationship between degrading and chemotaxis characteristics. This study demonstrated that strain GS-1 had great potential in the bioremediation of organophosphorus-pesticides contaminated sites.

Abstract:Secreted proteins (the secretome) of the Brucella may mediate important pathogen-host interactions, but such proteins are technically difficult to analyze. In the present study, we describe an approach to identify Brucella melitensis secreted proteins by using proteome analysis. TCA-acetone was used to recovery extracellular proteins from the culture of Brucella melitensis, and two-dimensional gel electrophoresis followed by mass spectrometry for protein resolution and identification. At last, 40 proteins were identified. These proteins included substrate-binding proteins of ABC transporters, outermembrane proteins and heat shock proteins. The identification of these secreted proteins provides important clues for the understanding of the molecular mechanism of Brucella and interesting candidates for the vaccine to treat or prevent Brucella infections.

Abstract:Fatty acids of Ralstonia solanacearum cultured under different temperatures, times, pH values and cultural media were detected by using gas chromatography (GC) method. Rs-J.1.4-010704-01v, a virulent strain of R. solanacearum isolated from ginger was chosen for the experiment. The results showed that the kind of fatty acid of Rs-J.1.4-010704-01v fluctuated from 14 to 33. The contents of its three plentiful fatty acids, C16:1ω7c/C15:0 ISO 2OH, C16:0 and C18:1ω7c (with retain times of 10.644, 10.950 and 14.177 min, respectively), also varied in a range of 55.66% to 75.69%. The diversification of the bacterium’s fatty acids at various cultural conditions was clustered into four groups by cluster analysis, according to the kinds and percentage contents of the fatty acids detected. The pathogenicities of Rs-J.1.4-010704-01v under 20°C and 25°C were deduced to be mid-virulent, with C16:0 less than C16:1ω7c/C15:0 ISO 2OH. The bacterium showed as a virulent strain under the other cultural conditions including 30°C~40°C, 24 h~96 h, pH 5~9 and four cultural media (LB、NA、TTC and TSB), with C16:0 more than C16:1ω7c/C15:0 ISO 2OH. However, the difference between C16:0 and C16:1ω7c/C15:0 ISO 2OH raised significantly from 2.35 to 13.23 under 40°C and 48 h~96 h. Meanwhile, the kind of fatty acid increased more than 30 as the cultural time increased. It was concluded that temperature and cultural time had more significant effects on the fatty acid composition of R. solanacearum than pH value and cultural medium.

Abstract:Strong inhibition of Bacillus subtilis strain NJ-18 on mycelia growth of Alternaria solani was observed in the antagonistic tests by cylinder plate methods, and the inhibition width was 21.5 mm. Observation under microscope found that the supernatant of fermentation from NJ-18 could make the pathogen hyphae cells malformed and swelled, and consequently the growth of the pathogen was inhibited. Determining of the colonization in potato plants by the signed rifampicin-resistance in NJ-18 showed that it could colonize well in the plants, the colonization quantity of NJ-18 in the root and stem of the potato detected 30 days after fermentation irrigation was 103 CFU/g plant’s fresh weight. In pot experiment, we inoculated the tomato plants with the spore suspensions of Alternaria solani after spraying the fermentation of NJ-18, the results were investigated in 14 days and the efficacy in controlling the disease was 72.9%, which was significantly higher than 45.7%, the efficacy resulted from spray treatment of 2000 fold dilution of 50% iprodione wetable powder.

Abstract:Two strains of infectious bacteria and a GCRV-like virus were isolated from grass carp which seemed to be infected by both virus and bacteria in Guangdong and Fujian provinces. CIK cells were inoculated with tissue fluid filtrated from the diseased fish. GCRV-like virus particles and virus inclusion body were observed in the cytoplasm of the infected cells under electron microscope. Artificial infection experiments showed that healthy grass carp died after infected with both the bacteria strains and virus-infected cell culture supernatant. Bacteria morphology, characteristics, physiology and biochemistry assays were used to identify the isolated bacteria. The characteristics of the two strains isolated were in accordance with those of Aeromonas hydrophila. PCR was performed to identify the bacteria. Both 16S rRNA gene and gryB gene of the two strains possessed high similarity with those of A. hydrophila registered in GenBank. AerA and ahpA genes could be amplified in both strains which indicated that both of them possessed strong pathogenicity. The two strains were therefore identified to be virulent strains of A. hydrophila. The diseased grass carp analyzed was supposed to be mixed infected by both A. hydrophila and virus.

Abstract:One Butachlor-degrading bacterium named LYC-1 was isolated from a soil sample by enrichment culture. Combining morphologic characteristics and physiobiochemical characteristics with 16S rRNA sequence analysis, strain LYC-1 was identified as Acinetobacter sp.. The optimal temperature and pH value for growth of strain LYC-1 was 30°C and pH 7.5 , respectively. The strain could degrade butachlor more than 80% when it was cultured in 100 mg/L butachlor medium for 7 days.

Abstract:The genetic indentification of 16S rDNA or ITS, capability of phosphate-solubilization and pH of medium, and optimization of medium of some microorganism isolated from mangrove were investigated in this study. The result showed that the fungi normally had much higher capacity to dissolve the inorganic phosphate than the bacteria, the capacity of the fungi was closely correlated to the pH of medium, but the relationship was weak for the bacteria. It was illustrated by single factor experiments that the optimal carbon and nitrogen sources were maltose and urea respectively. The orthogonal design was employed in testing the optimum composition of medium composed of 5 g/L maltose, 0.05 g/L urea, 5 g/L NaCl, pH 5. In this optimal medium, the effectively enrichment of bacteria could reach up to 6.06×109 CFU/mL under 30°C for 48 hours cultivation.

Abstract:Using of clearing zones on pachyman agar medium, there are 217 plant endophytic actinomycetes, producing β-1,3-glucanase were screened. 45.6% of the strains produced β-1,3-glucanase, in which the strains from cucumber are up to 38. The percentages of endophytic actinomycetes from different hosts produceing β-1,3-glucanases were different. The percentage of the strains in Rhizoma Polygonatum produced β-1,3-glucanases is the highest, up to 88.9%. The Inhibited effects of plant endophytic actinomycetes which produced extracellular β-1,3-glucanases on mycelium growth of Sclerotinia sclerotiorum were detected in vitro. Cucumber endophytic actinomycete gCLA4 strain was screened out from 99 isolates, which can strongly inhibit the growth of S. sclerotiorum. The optimal β-1,3-glucanases fermentation conditions of strain gCLA4 were investigated, they were pachyman 0.2%, peptone as nitrogen, pH 7~8 for 5 days. The β-1,3-glucanases of strain gCLA4 had some inhibiting efficiency on 13 plant pathogens, in which inhibiting efficiency to Botryosphaeria dothidea was the strongest.

Abstract:A strain, Escherichia coli AC-521, which could efficiently covert glycerol to lactic acid, was isolated from soil samples. A series of morphological and biochemical characteristics and sequence analysis of 16S rDNA reveal that it belongs to Escherichia coli. Through orthogonal experiment of L16(45), the optimum medium compositions were determined as initial glycerol 70 g/L, yeast extract 4 g/L, peptone 7 g/L, (NH4)2SO4 10 g/L, and K2HPO4 2.5 g/L. The 5L fermenter fed-batch fermentation was performed under optimal conditions, giving 74.5 g/L lactic acid with a yield of 0.87 mol/mol glycerol after 80 hours.

Abstract:Based on the standard strain-Vibrio parahaemolyticus BJ1.1997, temperature (7°C~43°C) and salinity (0.5%~9.5% NaCl) which affected its growth status was studied with uniform design. The results showed that Logistic equation is optimal in primary models, the second is Gompertz equation, the last is Linear equation, so growth parameters can calculated from Logistic equation. The secondary model was developed by square root models, its r value was 0.9863, the lowest growth temperature was 9.0506°C and the highest growth salinity was 5.93% [the corresponding lowest growth water activity (Aw min) was 0.9227]. Through F test, residual analysis and evaluation by bias factor and accuracy factor, the model can exactly describe the relationship between the growth rate and combined effect of temperature and salinity (water activity).

Abstract:A Staphylococcus aureus strain, designated zfb, was isolated from a clinical bovine mastitis case of a dairy cow. Staphylococcus aureus zfb can have resistance to methicillin and no lipase contrast by ATCC 25923. The production of the capsule was assessed by the diffuse colonial morphology in serumsoft agar. A mouse infection model was used to determine the LD50 and the invasiveness of SA zfb. The LD50 of SA 25923 to experimental mice was 10-2.5/mL, and the LD50 of SA zfb to experimental mice was 10-4.33/mL. The purpose to detect characteristics of SA zfb makes it an interesting candidate for the preparation and assay of an avirulent mutants against staphylococcal infections and further investigate on pathogenic mechanism.

Abstract:In this research, the zuelacmycin-producing strain Streptomyces venezuelaevar. qinlingensis RL-2 was used as original strain, the spore suspension of which was induced by UV, LiCl and the compound treatmeat (UV+LiCl) respectively. The zuelacmycin-high-yield strain UVL-108 was obtained by the treatment that the exposure time under UV irradition was 45 s and the concentration of LiCl was 0.4%. The heredity characters of mutant UVL-108 were stable in succesive six generations. The antibacterial activity and the fermentation titer of mutant UVL-108 were determinded by bidirectioned culture and mycelial linear growth respectively. The results demonstrated the antibaterial activity of mutant UVL-108 was improved by 77%, and the relative toxicity of fermentation to Phyricularia grisea was improved by two times compared with the original strain.

Abstract:Seventy-two endophytic fungi isolated from Cephalotaxus hainanensis Li were screened for antitumor and antimicrobial activities. The results showed that 9 strains presented cytotoxic activities to at least one of the tested tumor cells, five strains exhibited strong antimicrobial activity against Staphylococcus aureus, one strain had inhibitory effect on Phytophthora parasitica. It was evidently that the endophytic fungi of C. hainanensis are potential resources to find valuable bioactive components.

Abstract:Effect of rosmarinic acid on the kinetics of L-asparaginase catalyzed reaction was studied. The result showed that rosmarinic acid could reduce the apparent kinetic parameters (apparent Michaelis-Menten constant, Kmapp) of the enzyme, which indicated that rosmarinic acid was an activator of L-asparaginase. Ferrous ions could increase the antibacterial activity of rosmarinic acid. Absorption spectra analysis indicated that there existed a direct interaction between rosmarinic acid and ferrous ions, with a mole ratio of 1:1.

Abstract:The interaction between Gliotoxin and bovine serum albumin (BSA) was studied by the fluorescence, Circular Dichroism (CD) and ultraviolet visible (UV-Vis) techniques. The fluorescent experiment showed that the intrinsic fluorescence of BSA was quenched by the binding of gliotoxin in a static quenching procedure, with an association constant of 7.2′103 L/mol and in hydropobic forces. And the CD spectrum revealed that gliotoxin effected the conformation of BSA by increased the mass of α-helix.

Abstract:MLFE (Micrococcus luteus fibrinolytic enzyme) is a fibrinolytic enzyme produced by Micrococcus luteus ML909 strain. The promoter and signal peptide-coding sequence of α-amylase gene from Bacillus amyloliquefaciens DC-4 was cloned and fused to the sequence coding for mature peptide of MLFE (Gen-Bank: EU232121), forming the fusion gene called amymlfe. This hybrid gene was inserted into the Es-cherichia coli-Bacillus subtilis shuttle plasmid vector pSUGV4 and expression plasmid pSU-AmyMLFE was constructed. After transformation with B. subtilis WB600, transformant WB600/pSU-AmyMLFE was obtained and produced clear hydrolyzed zones on fibrin plates. The fibrinolytic activity in supernatants of WB600/pSU-AmyMLFE fermented for 24 hours was tested and found to be 238 UKU/mL. The results of SDS-PAGE analysis showed that there was indeed recombinant protein in supernatants. The Western blotting showed that the molecular weight of the expressed protein was the same as expected. These results indicate that the gene, amymlfe, is successfully expressed in B. subtilis WB600.

Abstract:The full length cDNA clones for hMPV NL/1/00 and NL/1/99 strains from both subtypes, and the four helper vectors pCITE-N, pCITE-L, pCITE-P and pCITE-M2.1 for expressing major viral proteins were co-transfected into BSR-T7 cell to rescue live virons by reverse genetics technique. BSR-T7 cells were transfected using Lipofectamine 2000 with 3 μg of the full-length cDNA plasmid, 0.3 μg of pCITE-N, 0.15 μg of pCITE-L, 0.3 μg of pCITE-P, and 0.24 μg of pCITE-M2.1. Three days after transfection, cells were subjected to one -80°C freeze-thaw cycle to prepare lysates. The lysate was used to inoculate Vero E6 cells. The obvious CPE in Vero E6 cells was observed 6 days after inoculation. The 450 bp RT-PCR products was accordant with the expectant. The specific immunofluorescence was observed for inoculated positive cells. The results demonstrated that infectious hMPV was successfully rescued. The NL/1/00 recombinant virus grew to peak titer of 106.4 TCID50/mL in Vero-E6 cells at 6 days after inoculation and 105. 33 TCID50/mL for recombinant NL/1/99 virus.

Abstract:Microorganisms play a key role in bio-hydrogen producing. Progress in microorganisms producing hydrogen by anaerobic metabolism is reviewed in recent years in the present paper. The species of microorganisms producing hydrogen by anaerobic metabolism, and current status of breeding and application of efficient hydrogen-producing microorganisms were summarized. The hydrogen-production capability, substrates utilization, and metabolic characteristics of anaerobic and thermophilic hydrogen-producing microorganisms were summarized especially, the species and metabolic characteristics of thermophilic carboxydotrophic hydrogenogenic bacterium were introduced briefly.

Abstract:Arsenic is known as a toxic metalloid, which mainly exists in inorganic forms such as arsenite and arsenate in the natural environment. A number of microorganisms have evolved different resistant mechanisms for arsenic detoxification to cope with the widespread distribution of the poisonous arsenic. Four distinct microbial arsenic-resistant mechanisms have been described including As(III) oxidation, cytoplasmic As(V) reduction, respiratory As(V) reduction, and As(III) methylation. These mechanisms confer arsenic resistance in microorganisms that play important roles in the transformation and geological cycle of arsenic. This review mainly focuses on the researches on these molecular mechanisms and potential application for environmental arsenic bioremediation using microorganisms.

Abstract:Teaching principles and class content were stated for a experimental course of common pathogenic bacteria detection methods for the undergraduate student in food quality and safety major. They include course material preview, advanced teaching methods, combination of teaching and research, graduate teaching assistant, experimental reports writing and experimental skills evaluation. All these means lead to a good teaching outcome.

Abstract:We have obtain a steady and reliable dyeing methods for the uniuncleate and dicaryotic hyphae of Pleurotus tuber-regium by using different foster hyphae way, comparing two kinds of fastness liquid and three dye stuff on the hyphae nuclear stain effect, and then optimization grouping.