Effects of Heavy Metal Stress on the Growth Curves of Two Sepcies of Bacteria

[Objective] The aim was to study on the effects of heavy metal stress on the growth curves of Escherichia coli and Bacillus subtili. [Method] Using traditional culture method,Escherichia coli and Bacillus subtili were cultured under heavy metal stress including Cu2＋,Hg2＋,Pb2＋,Cd2＋ and Cr6＋ in different concentrations. Then the growth curves of the bacteria were determined to investigate the effects of exogenous heavy metals on the growth of the two kinds of bacteria. [Result] The proliferation of the two bacteria was inhibited at high concentrations of Hg2＋ and Cd2＋ respectively,and G＋ is more sensitive to them than G-; when the heavy metal concentration was 50 mg/L,the toxicity of the five kinds of heavy metals on the two bacteria was Hg2＋Cd2＋Cu2＋Cr6＋≈Pb2＋. [Conclusion] The research will provide a basis to explore the effects of heavy metal on environment and ecological system.

婴儿泌尿系感染1例

婴幼儿泌尿系感染临床表现不典型,易漏诊或误诊,我院遇到1例报道于下。患儿女,1岁。发烧,爱哭,大便较稀,每日4～5次,无粘液血便,伴呕吐。体检:体温38℃.神志清.无脱水征。心肺(一)。腹部略胀,叩诊鼓音,肠鸣音较活跃。血、尿、粪常规均正常。拟诊小儿肠炎。

Production of Human Epidermal Growth Factor in Fed-batch Culture of Acetate-tolerant Escherichia coli

An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor （hEGF） whose expression was under the control of phoA promoter. The recombinant cells were cultured in a chemically defined medium, and glucose was added at different specific provision rates during the growth and expression phases. It was found that pH had a significant effect on the extracellular hEGF production. The extracellular hEGF concentration was 75.5mg·L^-1, 5.2-fold of the level reached at pH 7.0, even though more acetate was produced. Nitrogen source was limited in the later growth phase. Supplementation of ammonium promoted the consumption of phosphate and reduced the time to exhaust phosphate, but the extracellular hEGF production was similar to that without supplementation of ammonium.

The Effect of Mixture of Alpinia Galanga, Eurycoma Longifolia Jack and Syzygium Aromaticum Crude Extract on the Growth of Saccharomyces Cerevisiae and Escherichia Coli

Alpinia galanga, Eurycoma longifolia Jack and Syzygium aromaticum have been widely used in traditional medicine for decades. Antimicrobial activities for individual crude extract were well established. Crude methanolic extracts of Alpinia galanga, Eurycoma longifolia Jack and Syzygium aromaticum and the combination for all extracts were tested using well diffusion techniques against Saccharomyces cerevisiae （ATCC 9763） and Escherichia coli （ATCC 25922）. The mixed extracts were prepared based on the concentration ratio of 50 μg/μL which are 1：1, 1：1：1 and 1：2：2. Single Syzygium aromaticum extract showed higher inhibition zone on Saccharomyces cerevisiae compared to Escherichia coli. There is reduction in diameter of inhibition zone for single extract and mixture extracts either in combination of two or three extracts tested on Saccharomyces cerevisiae and Escherichia coli growth but they are not significant. In conclusion, Syzygium aromaticum showed highest activity against Saccharomyces cerevisiae and Escherichia coli. Reduction in diameter of inhibition zone indicated that Alpinia galanga and Eurycoma longifolia Jack extracts had antagonistic effect with Syzygium aromaticum.

Comparative Study of the Static Magnetic Field Effects on Growth Rate with Relative Antibiotic Susceptibility in Escherichia coli

We studied the biological effects of different magnetic fields. Identified bacterial strain Escherichia coli （type I） has been exposed to the dipolar magnetic field force （400, 800, 1200 and 1600 Gausses） which prepared locally with incubation for different period times （24, 48 and 72 hrs） at 37℃. The effects were evaluated by optical density （OD） at 600 nm determining their growth density incorporation with negative control and depending of McFarland turbidity standard （0.5）, in addition to its susceptibility to various antibiotics. Results illustrate different forces of magnetic field decreased the growth rate of E. coli in particular at 24 hrs incubation comparing with unexposed or control samples. The magnetic field increased the logarithmic phase within 4-6 hrs of treatment but decreased after 16 to 18 hrs. Furthermore, changes in the antibiotic sensitivity were observed after exposure period of 6 hrs since E. coli cells became more sensitive to certain antibiotics. While after a 16 hrs exposure period, it became more resistant to the same antibiotics comparing with control groups.

Expression and purification of bioactive high-purity human midkine in Escherichia coli

Midkine is a heparin-binding growth factor, which plays important roles in the regulation of cell growth and differentiation. The non-tagged recombinant human midkine （rhMK） is therefore required to facilitate its functional studies of this important growth factor. In the present work, rhMK was expressed in Escherichia coli （E. coli） BL21 （DE3）. The expression of midkine was efficiently induced by isopropyl-13-D-thiogalactopyranoside （IPTG）. After sonication, midkine was recovered in an insoluble form, and was dissolved in guanidine hydrochloride buffer. Renaturation of the denatured protein was carried out in the defined protein refolding buffer, and the refolded protein was purified using S-Sepharose ion-exchange chromatography. The final preparation of the rhMK was greater than 98% pure as measured by sodium dodecylsulfate-polyacrylamid gel electrophoresis （SDS-PAGE） and reverse phase high performance liquid chromatography （RP-HPLC）. The purified rhMK enhanced the proliferation of NIH3T3 cells.

Study on Drug Property Differences of Shexiang (Moschus) and Bingpian (Borneolum Synthcticum) Based on Analysis of Biothermodynamics

Objective: To study the drug property differences of Shexiang (Moschus) and Bingpian (Borneolum Synthcticum) with biothermodynamics, and to verify the objectivity and authenticity of the drug property. Methods: The growth-thermogram curves of Escherichia coli (E. coli) affected by Shexiang (Moschus) and Bingpian (Borneolum Synthcticum) at different concentrations were determined with microcalorimetry, and the power-time curves (thermogram curves) of E. coli metabolism and characteristic parameters, such as growth rate constant (k), maximum output power (Pm), peak time (tp), total heat-output (Qt), etc. were analyzed with the principal component analysis (PCA) to find the close correlative parameters, so as to objectively reflect the drug property differences of Shexiang (Moschus) and Bingpian (Borneolum Synthcticum). Results: The values of P2 in the second exponential growth phase increased with the increase of the concentrations of Shexiang (Moschus) and Bingpian (Borneolum Synthcticum), and the P2 of Shexiang (Moschus) was larger than that of Bingpian (Borneolum Synthcticum); Q2 increased with the increase of the concentrations of Shexiang (Moschus), but for Bingpian (Borneolum Synthcticum) it was opposite. It is indicated that they have different effects on P2 and Q2 of E. coli in the second exponential growth phase, and have differences in warm and cold natures. Conclusion: The microcalorimetry can accurately and objectively appraise differences of the drug property of Shexiang (Moschus) and Bingpian (Borneolum Synthcticum) and verify the objectivity and authenticity of the drug property, so as to provide a new and useful method for studies of the drug property of Chinese drugs.