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Research Advances on Taxol Producion by Microbe Fermentation

Microbiology.1992;0(03):-.

The biodiversity of the taxol-producing endophytic fungi,advantage of taxol production by microbe fermentation,isolation of endophytic fungi,and the separation,purification and determination of taxol in fermentation liquid were reviewed.The pathways to improve the production of taxol by endophytic fungi were also comprehensively discussed.

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A Primary Study on Population Biodiversity of Marine Microorganisms from East China Sea

Zhigang SONG

Microbiology.1992;0(01):-.

Marine bacteria from the samples of sea sediments and seawater were directly plated on isolation media and the biodiversity of isolates was examined with DNA fingerprinting.542 single colonies were obtained from the media.ARDRA with enzyme Hinf I revealed 16 operational taxonomic units(OTU) which were dominated by OTU5 group which accounts for 19 isolates,and OTU7 group which accounts for 11 isolates.The biodiversity of isolates from these two dominant OTU groups was further investigated by a genomic fingerprinting technique, ERIC-PCR.The results indicated that there were 12 different ERIC-PCR types present among the OTU5 group while only 4 among the OTU7.The data indicated rich diversity profiles of marine microorganisms were presented in the East China Sea.

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Detection of Spoilage Bacteria in Beer by Polymerase Chain

Xiaoqun TIAN

Microbiology.1992;0(01):-.

A new method for rapid detecting beer-spoilage by PCR was developed.This method is based on the sequence of a hop-resistance gene horA,which a pair of specific primers were designed based on the partial sequence of it.Using the primers,beer-spoilage Lactobacillus species were detected by PCR.The sensitivity was reached to 3CFU.The pre-enrichment of samples was needed only 12~16 h.The duration for beer-spoilage determination by PCR(24h)was markly shorter than by conventional method(5~7d).

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Ca~(2+) Signaling Pathway Involved in Bipolaris maydis Conidium Germination and Appressorium Formation

Junxia ZHAO

Microbiology.1992;0(04):-.

Bipolaris maydis, the causal agent of northern leaf blight of maize, forms a dome-shaped infection structure, an appressorium, to infect its host. To elucidate if calcium signaling pathway is correlated with conidium germination and appressorium formation of Bipolaris maydis induced by hydrophobic surface. Conidia were treated by three kinds of inhibitors. Microscopic examination and statistical data showed: (ⅰ)EGTA, a chelating agent selective for Ca~(2+), Verapamil which could block Ca~(2+) channels, KN93, a selective inhibitor of CaMK could inhibit germination and appressorium formation. (ⅱ)Under the same concentrations of inhibitors, appressorium formation was inhibited more strongly than conidium germination. These inhibitors caused the formation of small and abnormal appressorium. These results strongly suggested that Ca~(2+ )signaling pathway was involved in conidium germination and appressorium formation induced by hydrophobic surface.

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INTERACTION OF ASSOCIATIVE NITROGEN-FIXATION BACTERIA WITH EVCAIYPTUS

Lihua KANG

Microbiology.1992;0(04):-.

The interaction of Klebsiella mytoca NG13/pMC73A with Eucalyptus were studied. The results showed that the root surface and even the inner cortex of Eucalyptus were colonized by K. oxytoca. The K. oxytoca was reisolated from rhizosphere, root surface and inner root of inoculated Eucalyptus. The inoculation with K. oxytoca stimulated the excretion of Eucalyptus root and affected the contents of amino acids, carbohydrates, phytohormones of root exudates. The seedlings of Eucalyptusto to inoculation with K. oxytoca increased growth, total dry matter and N content by 29.81% - 100.40% after 3 months in comparinson to the uninoculated seedlings.

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Study on Fermentation Kinetics of Nisin by Lactococcus lactis

Xuliang ZHUANG

Microbiology.1992;0(03):-.

The kinetics of growth, lactic acid and nisin production and substrate consumption by Lactococcus lactis subsp. lactis SM526 were studied in different pH. Growth, lactic acid and nisin production were modelled using a simple logistic equation while substrate consumption was foud to be a function of growth and lactic acid production rate. The optimal pH for growth and lactic acid production was 7.0 while it was 6.5 for nisin production according to the models developed.

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Affinity Selection of Human ScFv Against Botulinum Neurotoxin Serotype A

Hui WANG

Microbiology.1992;0(01):-.

In this work, rare specific binders to botulinum neurotoxin antigen were selected from human phage immunized library through three rounds of panning in vitro. Of them, clone ScFvB17 is of high affinity and specificity to target antigen. B17 is of 750bp encoding 250 amino acid. Analysis results of gene structure showed V-genes of B17 belonging respectively to VH4 or? chainⅡ family are new antibody Fv genes. More important result showed that recombinant ScFvB17 expressed in E.coli could bind specific for neurotoxin competing with antiserum. Successful selection of human phage antibody library and obtaining specific ScFv against botulinum neurotoxin serotype A provide useful materials for further study on detection of neurotoxin and human engineering therapeutic antitoxin.

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CLONING OF GENES ESSENTIAL FOR XANTHAN POLYSACCHARIDE BIOSYNTHESIS FROM XANTHOMONAS CAMPESTRIS NK-01

Shiyan LI

Microbiology.1992;0(05):-.

Xanthomonas campestris NK-01 produces amounts of xanthan polysaccharide. Nonmucoid mutants, defective in synthesis of xanthan polysaccharide, were isolate after treatment with ethylmethanesulfonate. To isolate genes essential for xanthan polysaccharide synthesis complete libraries of DNA fragments from wild-type Xanthomonas campestris NK-01 were constructed in E. coli HB101. The pooled clone bank was conjugated en masse from E. coli into a nonmucoid mutant. Kanamycin-resistant exconjugants were then screened for the ability to form mucoid colonies. Analysis plasmids form muciod exconjugants indicated that overlapping segments of DNA had been cloned. These plasmids were tested for complementation of nine additional nonmucoid mutants. A 13. 4 kb region of DNA was determined to contain at least some genes essential for xanthan polysacchdride synthesis.

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Cloning and Squence Analysis of Gene Coding for Dextransucrase from Leuconostoc mesenteroides

Yanchun SHAO

Microbiology.1992;0(03):-.

The desired DNA product of dsr1 and dsr2 was amplified from the total DNA of the L0309 screened in this lab by PCR with two pairs of gene specific primers.The segment of dsr1 and dsr2 was inserted into pUC19 vector and integrated into the entire gene of dsrx.The result of restriction endonuclease mapping and sequencing shows that 4566 bp of dsrx covers the entire open reading frame,encoding 1522 amino acid residues.There is an identity of 99% between the gene of U81374 and dsrx about their nuclear acid sequences.The homology of the deduced amino acid level amount to 98.49% with that of U81374.

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USING SNAIL ENZYMES TO EXTRACT AND PURIFY THE DNA OF CRYPTOCOCCUS

Zhiqiang ZHAO

Microbiology.1992;0(01):-.

This article introduced a method to extrct and purify the DNA of Cryptococcus. Protoplasts were obtained after digested by snail enzyme. We washed them with SE liquid again and again to get rid of the capsular polysaccharides and split them with thermal treatment of 55 degrees centigrade. Then, satisfactory results of the extrction and the purification were achieved. From one wet gram of the yeast, more than 600 ?g DNA can be acquired. The DNA gained is especially suited for the determination of G+C mol% content by use of the T_m method.

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