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Objective: We studied the effect of methyl bromide fumigation on soil edaphic denitrification., Methods: We adopted nosZ-PCR-RFLP (restriction fragment length polymorphism) method, nosZ-MPN-PCR (Most-Probable-Number- PCR) counting method and soil nitrate elimination rate method, to explore the effect of methyl bromide fumigation on community structure, quantity and activity of denitrifying bacteria in soil., Result: After methyl bromide fumigating soil for 100 d, soil denitrification did not change obviously (P > 0. 05). Margalef index, Shannon-wiener index and Evenness index had no significant difference (P > 0.05) in nosZ denitrifying bacterial communities between fumigated soil and the control. There were Rhodopsendomonas, Pseudomonas fluorescens, Herbacspirillum, uncultured bacterium partial in both of them. However, Azospirillum, Rhizobium melibei, Nitrosospira multiformis were exclusively found in the control, and Uncultured Azospirillum sp, Mesorhizobium sp were in fumigated one. Moreover, the number of denitrifying bacteria in the control resolved by nosZ-MPN-PCR (Most-Probable-Number-PCR) was 1.4 times higher than that of the fumigated one., Conclusion: After 100 d fumigating soil, the composition of nosZ denitrifying microbial community and the population of denitrifying bacteria changed. Furthermore, there was no difference in denitrification between the fumigated soil and the control.

Objective: To study the diversity of lactic acid bacteria (LAB) and dominant LAB in fermented cabbage., Methods: Culture-dependent and -independent (16S rRNA gene clone libraries were constructed) methods were used to determine the composition of LAB in fermented cabbage., Results: Ninety LAB isolated from fermented cabbage were identified as species of Lactobacillus and Leuconostoc, whereas 115 clones of the 16S rRNA gene sequence from fermented cabbage DNA were identified as Lactobacillus, Weissella, Pediococcus and Leuconostoc., Conclusion: The significant difference of the LAB compositions by the two methods implies that some specialized nutrients may lead to a distinctive selection of the dominant organisms. Lactobacillus plantarum appeared as the dominant species in fermented cabbage by both methods.