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Effects of Oxidative Challenge on Defensive Enzyme and Cofactors Level in Alkalibacterium sp.F26

Jingjing DUAN ; Liming LIU ; Zhaozhe HUA ; Jian CHEN

Microbiology.2008;35(9):1385-1392.

In this paper,a slight halophilic alkaliphile swain,Alkalibacterium sp.F26,which produced high level of intracellular CAT observed in previous research,was selected as a model microbial to explain the responses of this bacterium to oxidative stress.The results indicated that Alkalibacterium sp.F26 had obvious responses to higher concentration (＞1 mmol/L) of H2O2 than that to lower H2O2 (＜1 mmol/L) challenge from the aspects of defensive enzyme synthesis and cofactors level variation.As for catalase production,the activity increased up to 106.54 U/rag protein which was 1.76 fold of the control when cells were challenged by 3 mmol/L H2O2,but its activity only was 1.13 fold when H2P2 was 100 μmol/L.As far as energy state was concerned,ATP production and NAD+ generation were significantly inhibited from 20.55 μmol/L to 17.80 μmol/L and 69.89 μmol/L to 31.77 μmol/L,respectively,leading to the drop of energy charge from 0.77 to 0.68 and the increase of the portion of NADH/NAD+ from 0.08 to 0.41 in the former case.However,these effects were less distinct under lower concentration of H2O2.Except of the condition of 100 μmol/L H2O2,under which the activation of defensive mechanism resulted in an increase of ATE the level of ATP dropped from 22.69 μmol/L of the control to 22.38 μmol/L and 13.70 μmol/L when challenged by 50 μmol/L and 500 μmol/L H2O2.Besides,the concentration of NADH fluctuated and the NAD+ gradually reduced when H2O2 below 1 mmol/L.

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Isolation and Characterization of Antifungal Endophytic Bacteria from Soybean

Shumei ZHANG ; Changqing SHA ; Yuxia WANG ; Jing LI ; Xiaoyu ZHAO ; Xiancheng ZHANG

Microbiology.2008;35(10):1593-1599.

Endophytic bacteria reside in most healthy plants;it can not be easily influenced by outer environment.Some endophytic bacteria are beneficial to host plants,such as growth promotion,disease prevention and nitrogen fixation etc.Therefore,endophytic bacteria ale the potential microbial fungicides,it may be widely applied.In this study,endophytic bacteria were isolated from soybcan cultivar Hefeng 25 that was a main soybean cultivar in Heilongjiang province,China.The results indicated that the density of endophytic bacteria varied in different tissues of the plant.It was 3.4×103CFU/g in roots,2.8×103CFU/g in leaves,2.9×102 CFU/g in stems and 1.4×102 CFU/g in seeds.The activity of 121strains against Fusarium oxysporum f.sp.soybean,caused soybean root rot,were assayed.25.6% of them showed antagonistic activity against F. oxysporum f. sp.soybean.One of them,strain TF28 isolated from soybean roots could inhibit the growth of many fungal pathogens.The inhibitory rates against F. oxysporum from different plant species were 80.2%-96.7%.Based on the morphological,physiological and biochemical characteristics as well as the sequence of 16S rRNA,strain TF28 was identified as Bacillus amyloliquefaciens.

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Application of Microorganisms in the Degradation of Polluted Chemicals in Aquatic Environments

Yan PENG ; Junpeng CAI

Microbiology.2008;35(5):809-814.

Every year, waters on earth receive large quantities of wastewater from industry, agriculture, fish and poultry raising, and municipal sewage treatment plants. Consequently, the aquatic environment on the earth is under a serious challenge from a very large quantity of pollutants such as antibiotics, insecticides, herbicides, hydrocarbons, etc., contained in the domestic wastewater, industrial and agricultural waste water and illegal effluents. In particular, with the development of intensive aquiculture and poultry, the effluent pollution has recently become more and more serious with more attentions. Furthermore more and more chemical pollutants discharged into aquatic environment have been detected with the advancement of analytical techniques. These chemicals can cause toxic effects on water habitats after discharged into aquatic environment. However, microorganisms have many key functions in pollution control. In this review, applications of microorganism in the degradation of chemicals in aquatic environments are reviewed. It was concluded that most applications of microorganisms degrading chemicals focused on aquaculture waters, whereas other aquatic systems (such as river, lake, sea, coastal waters) have been scarcely studied.

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Molecular Cloning and Biochemical Characterization of Protocatechuate 3, 4-dioxygenase in Burkholderia sp.NCIMB 10467

Sha LUO ; Junjie ZHANG ; Ningyi ZHOU

Microbiology.2008;35(5):712-719.

Strain NCIMB 10467, a lignin degrader, was reclassified as genus Burkholderia according to its 16S rDNA sequence. It seems that the metabolism of protocatechuate by this strain is diverse under the induction of various substrates. A 9505-bp DNA fragment extending from α conserved region of the gene, which encodes β subunit of orthocleavage protocatechuate 3, 4-dioxygenase(P34D; EC 1.13.11.3),was obtained by genome walking. Sequence analysis revealed two deduced open reading frames, pcaG and pcaH, encoding the α and β subunits of P34D respectively in this fragment. The P34D activity could be detected when pcaGH were expressed in E. Coli and the disruption of pcaH in strain NCIMB 10467 has lead to loss of its ability to catabolize protocatechuate. It was proved that the cloned pcaGH were encoding a functional protocatechuate 3, 4-dioxygenase which was necessary for the protocatechuate metabolism in this strain.

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Characterization of AcrA gene from Vibrio alginolyticus Strain HY9901

Shuanghu CAI ; Zaohe WU ; Jichang JIAN ; Yishan LU

Microbiology.2008;35(1):67-72.

A 460 bp internal fragment of the AcrA gene from Vibrio alginolyticus strain HY9901 was amplified by PCR with designed primers and the unknown flanking sequence of 5 '- and 3 '- ends of the AcrA gene was finally characterized by inverse PCR and nested PCR. Sequence analysis showed the AcrA gene contained 1101 bp ORF encoding 366 amino acids and the deduced amino acid sequence of the precursor from Vibrio alginolyticus strain HY9901 showed significant homology with the putative protein of other Vibrio species. The AcrA shows 76%, 73%, 71% and 70% homology with V.vulnificus strain YJ016, V. parahaemolyticus strain RIMD 2210633, V. splendidus strain 12B01 and V. cholerae O1 biovar eltor str. N16961 respectively.

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THE BREEDING STUDY BY UV-INDUCING PROTOPLASTS OF LENTINUS EDODES

Zhirong LIANG ; Moping AN ; Zhanyuan TONG

Microbiology.2001;28(2):38-41.

The experiment was carried out to inquire about the possibility of strain selection and improvement in Lentinus edodes through protoplast formation and mutagenesis by UV. Mycelial growth rate, yield, and period of fructification of 105 selected regenerants from UV-treated protoplasts have been measured and compared with their parents. Several selected regenerants achieved some better qualities such as higher yield and earlier fruiting. Several repeated cultivations of these regenerants reconfirmed their new capacities. The results indicated that protoplast formation and mutagenesis are the potential methods for strain selection and improvement in edible fungi.

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0253-2654(2001)02-0012-04 THE PRELIMINARY RESEARCH ABOUT THE REASONS OF BUSTING BAGS OCCASIONALLY DURING SOY STORAGE

Zhiyuan SUN ; Huanshu LIU ; Xiaobin ZHANG

Microbiology.2001;28(2):12-15.

Shan Qi soy has busting bags, bacteria sum overproof, continue acidification and other problems occasionally during the storage. It's probably caused by the Lactobacillus continue growth in the soy. We tried expounding the relationship between growth and producing acid when Lactobacillus growing in the thin fermented material.

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CULTURE CONDITIONS FOR CREATININASE FORMATIONBY PSEUDOMONAS SP. K9510

Jianguo LIU ; Jiyuan KE ; Jinfang WANG ; Gaoxiang LI

Microbiology.2001;28(2):7-11.

From air bacteria capable of decomposing creatinine, three single independent strains K9510、K9511 and K9512 have been isolated. The highest creatinine amidohydrolase (EC 3.5.2.10; creatininase) producing strain K9510 was screened out. The strain K9510 was identified as Pseudomonas sp. The results of culture condition for creatininase formation by strain K9510 were obtained as follows: creatinine and creatine were found to be the effective inducers for enzyme formation; the solution of mixed metallic salts could stimulate cell growth and enzyme formation. The suitable medium for creatininase formation was consisted of 0.9% creatinine、 0. 15% yeast extract、 0. 09% malt extract、0.05% NH4C1 and some amount of the solution of mixed metallic salts at pH5. 5. When the bacterium was grown in 250mL conic flask containing 50mL of the medium mentioned above on the rotary shaker(250r/min) at 35℃ for 33 h, about 50 u creatininase was obtained.

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STUDIES ON HARMFUL MICROBES IN RECIRCULATING WATER SYSTEM OFHEATING PIPELINE IN TAIYUAN

Xinghua WANG

Microbiology.2001;28(2):4-7.

The microbial counts, type, as well as relationship between microbial counts and the temperature of water in reticulating water system of heating pipeline in Taiyuan were studied, which the main biofouling harmful microbes included slimeforming heterotrophic bacteria, sulfate reducing bacteria, iron bacteria and fungi, respectively. The results showed that the harmful microbes in water system were lower than that of control guideline during heating period, whereas the microbes were higher than that of control guideline, which would result in biofouling of water tube during non-heating period.

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THE STUDY OF RELATIONSHIP BETWEEN THE MOVEMENT OF SOILBACTERIAL NUMBER AND ECOLOGICAL FACTORS ON THELEYMUS CHINENSIS GRASSLAND

Chongbang ZHANG

Microbiology.2001;28(2):1-4.

This paper preliminary studied the movement of soil bacterial number, and the relationship with 8 kinds of ecological factors. The result indicated: soil bacterial number only appears a biggest value in one year (2.67×10-7个 individual g-1dry soil). Among 8 kinds of ecological factors, soil water content, temperature, hydrolyted nitrogen, quick acting postossium and active organic matter have straight relationship with siol bacteria, and have negative relationship with soil pH, electric conduct rate, effective phosphorus. The component analysis indicated that soil water content, temperature, electric conduct rate, active organic matter are principal effective factors.

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