Antibacterial activity and property of the fermentation product of marine Streptomyces sp. GB-2 / 生物工程学报

Marine Streptomyces GB-2, isolated from marine samples collected in the intel tidal zone of Lianyungang, was found to produce antibacterial substance which exhibited significant inhibitory effects on 11 Gram-positive bacteria and 4 Gram-negative bacteria. The antibacterial substance was proved to be neutral and water-soluble according to paper chromatogram analysis, and its production was significantly associated with aritificial seawater. The stability analysis of the fermentation broth of Streptomyces GB-2 showed that it was very stable at pH1 and pH12 under 121 degrees C and changed very little under ultraviolet treatment. The substance produced by strain GB-2 exhibited potential use in the areas of bio-control, food and medical application.

Inhibitory effect of new antimicrobial substance by Bacillus subtilis fmbJ on Newcastle disease virus and infectious Bursal disease virus in vitro / 生物工程学报

The resistance effect on Newcastle disease virus (NDV) and Infectious Bursal Disease Virus(IBDV) in vitro of a new antimicrobial substance (AS), which produced by a Bacillus subtilis strain named B. subtilis fmbJ. Results showed that the TD50 and TD0 value of this AS on Chicken Embryo Fibroblasts cell (CEF) were 128.95mg/L and 25.79mg/L, respectively. This AS could strongly inhibit the cytopathic effects of cell induced by NDV as well as IBDV, and increase the survival rate of cell remarkably. This AS could inhibit the function of NDV and IBDV, and it could defend against the infection and inhibit multiplication of NDV and IBDV, and the effect was the same as the antiviral medicine Ribavirin. It had lower toxicity to CEF cell, therefore we would study it further that it was as antiviral medicine.

Isolation and identification of lipopeptides produced by Bacillus subtilis fmbJ / 生物工程学报

Isolation and idenfication of lipopeptides from Bacillus subtilis fmbJ was carried out in this paper. With HPLC method, it was determined that the antimicrobial substance was composed of many components, and one of them had the similar retention time similar to surfactin. In addition, the antimicrobial substance was proved to include the closed cycle peptide bind by TLC, and one of them had the migrating rate similar to surfactin. Furthermore, ESI-MS analysis showed that the antimicrobial substance contained five homologues of fengycin, such as m/z1449.9, m/zl1463.8, m/zl1477.8, m/z1491.9 and m/z1505.9, and three homologues of surfactin, such as m/z1008.8, m/z1022.8 and m/z1036.8.

Study on the Characteristics of Nicotine Degradation by Strain DN2 and its Application / 中国生物工程杂志

The kinetics of nicotine degradation by O.intermedium DN2 and its application in tobacco waste were investigated. The results showed that the optimum temperature of nicotine degradation by O.intermedium was 30 ℃, the pH value was 6.5 and a mount of inoculum was 5 %. Under above conditions, the kinetics of nicotine degradation of initial concentration 500 mg/L was studied. The results indicated that the degradation process of nicotine with no-induced strain DN2 followed inverse S-shaped curve, and degradation process of nicotine with induced cells of DN2 followed Eckenfelder mode. The half life of nicotine degradation was 17.43 h and 4.10 h, respectively. And the results also showed that tolerance of O.intermedium DN2 to nicotine was up to 5000 mg/L when 0.1 % of glucose was added. Nicotine (2 220 mg/L) in extract of tobacco wastes degraded about 95.22 % by strain DN2 in 60 h incubation, indicating that strain DN2 was of application value in treatment nicotine pollution.

Production of functional lipids by lipase-catalyzed acidolysis of lard in solvent free system / 生物工程学报

China has richly and inexpensive fat and oils from animal and plants, but these resources could not get effectively utilization. In order to make the best of these resources, lipase-catalyzed acidolysis of lard with caprylic acid to produce functional lipid in solvent free system was investigated. Of the five lipases that were tested in the initial screening, immobilized lipase TL IM fromca T. languginosa resulted in the highest incorporation of capry lic acid into lard. This enzyme was further studied for the effect of enzyme load, substrate ratib, reaction time, reaction temperature and added water content on the incorporation of caprylic acid into lard. HPLC analyzed the products from the acidolysis reaction. The highest incorporation was attained at 20% enzyme load. Time course studied suggest that the incorporation of caprylic acid into lard was increased up to 38.77 mol% after 24h. Desirable mole ratio of substrates was 1:2 (lard: caprylic acid), caprylic acid incorporation up to 30.95 mol%. In the range of 45 - 60 degrees C , temperature had no significant effect on enzyme activity and caprylic acid incorporation changed little. When temperature was above 60 degrees C, incorporation of caprylic acid into lard was decreased. The highest incorporation of caprylic acid into lard 35.76 mol% was attained when added water content was 2.5%.

Media optimization for the novel antimicrobial peptide by Bacillus sp. fmbJ224 / 生物工程学报

The novel antimicrobial peptide in submerged fermentation by Bacillus sp. fmbJ224 is strongly influenced by many internal and external factors, namely medium constituents and fermentation conditions. In this study, Plackett-Burman design was undertaken to evaluate the effects of the seventeen factors. By the statistical regression analysis, the significant factors affecting the novel antimicrobial peptide in submerged fermentation by Bacillus sp. fmbJ224 were determined as follows: glucose, NH4NO3, glutamic acid, CaCl2, MnSO4. In the second phase of the optimization process, a response surface methodology (RSM) was used to optimize the above critical internal factors, and to find out the optimization concentraction levels and the relationships between these factors. By solving the quadratic regression model equation using appropriate statistic methods, the optimal concentration of the variables were determined as: 8.13 g/L glucose, 6.14 g/L NH4NO3, 4.2 g/L glutamic acid, 3.98 mg/L CaCl2, 4.87 mg/L MnSO4. The content of the novel antimicrobial peptide was increased from 1304.21 microg/mL to 1487.58 microg/mL. The experimental data under various conditions have validated the theoretical values.