CD59 mutation and DNA oxidative damage in A(L) cells induced by crocidolite fibers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To determine the effects of buthionine sulfoximine (BSO) and free radical scavenger, dimethyl sulfoxide (DMSO), on mutation frequency and the formation of 8-hydroxydeoxyganosine (8-OHdG) induced by crocidolite fibers in human-hamster hybrid (A(L)) cells.</p><p><b>METHODS</b>The cytotoxicity and mutagenicity were determined by the formation of colonies. 8-OHdG was examined by immunoperoxidase staining. Non-protein sulfhydryl (NPSH) compound was assayed by modified Tietze's method.</p><p><b>RESULTS</b>The level of NPSH in A(L) cell pretreated with 25 micro mol/L of BSO was decreased to 2 nmol/10(7) cells, only 5% of the control after 24 h. The mutation frequency of CD59 gene of A(L) cell in crocidolite alone treated group was 208 +/- 18 while that in BSO pretreated group (397 +/- 55) was about twice the former (P < 0.05). The mutation frequency of CD59 gene in the group treated with crocidolite and in the presence of DMSO (57 +/- 8) was 72.6% less than that in crocidolite alone treated group. Crocidolite fibers induced a dose-effect relationship in the formation of 8-OHdG in A(L) cells (y = 150 + 20x, r = 0.9621). The level of 8-OHdG in cells was 289 +/- 6 at the dose of 6 micro g/cm(2) crocidolite, which was about twice the control group (137 +/- 9). In the presence of DMSO, 8-OHdG level decreased to 170 +/- 3 at the same dose of crocidolite.</p><p><b>CONCLUSION</b>Free radicals are the important inducer of mutagenesis and DNA damage in A(L) cells caused by crocidolite, which has dose-effect relationship.</p>

Antagonistic Properties of Lipopeptides and Volatiles Produced by Bacillus subtilis JA / 微生物学通报

Lipopeptides produced by Bacillus subtilis JA antagonized a broad spectrum of fungal pathogens. Crude lipopeptides were extracted with methanol from the precipitate which was obtained by adding 6 mol/L HCl to the cell-free culture broth.The crude extract was run on Diamonsil C_(18)column(5?m,250 mm?4.6 mm) in reverse phase HPLC system to purify the lipopeptides.Inhibitory ability and IC_(50)values of lipopeptides towards various microorganisms were determined by agar diffusion method.The results showed lipopeptides exhibited strong inhibitory activity against some important plant pathogenic fungi,including R.solani and F.oxysporum.The ability of B.subtilis JA to antagonize against the growth of the post-harvest pathogen -B,cinerea was tested in vitro.Spore germination of B.cinerea was strongly inhibited in the presence of JA cell suspension.Furthermore,B.subtilis JA can produce antifungal volatiles which strongly inhibited the spore germination and mycelial growth of B.cinerea.As a biocontrol agent,the synergic effect of lipopeptides and volatiles may play a major role in controlling the pathogens by B.subtilis JA.

Studyies on the Breeding and Cultivation of L-Lactic Acid Producing Strain / 微生物学通报

In order to obtain higher L-lactic acid yield industrial strain, the original strain Rhizopus oryzae PW352 was mutated by means of N+ ions implantation and a mutant strain Rhizopus oryzae RE3303 was obtained. Its lactic acid yield was increased by 75% than that of the original one. The acid producing condition was optimized by orthogonal design. The concentration of L-lactic acid reached to 131～136g/L and the conversion rate of glucose was as high as 86%～90% under the optimum condition.