Effect of cypermethrin insecticide on the microbial community in cucumberphyllosphere
ZHANG Baoguo , ZHANG Hongxun , JIN Bo , TANG Ling , YANG Jianzhou , LI Baoju , ZHUANG Guoqiang , BAI Zhihui
DOI:
Received December 25, 2007,Revised March 12, 2008, Accepted , Available online
Volume 20,2008,Pages 1356-1362
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Cucumber (Cucumis sativus) is one of the most widely used vegetable in the world, and di erent pesticides have been extensively
used for controlling the insects and disease pathogens of this plant. However, little is known about how the pesticides a ect the
microbial community in cucumber phyllosphere. This study was the first attempt to assess the impact of pyrethroid insecticide
cyperemethrin on the microbial communities of cucumber phyllosphere using biochemical and genetic approaches. Phospholipid fatty
acid (PLFA) assay indicated that cyperemethrin insecticide treatment led to a significant increase in both total and bacterial biomass
and a decrease in fungal biomass and the ratio of Gram-positive (GP) bacteria to Gram-negative (GN) bacteria within the cucumber
phyllosphere. Principal-component analyses (PCA) suggested that the number of unsaturated and cyclopropane PLFAs (16:1!9t,
18:1!7, cy17:0, cy19:0) increased with the insecticide treatment, whereas the saturated PLFA i16:0, i17:0 decreased. The increase
of GN bacteria implied that the cypermethrin insecticide might be a nutrient for the growth of these phyllosphere microbes. Terminal
restriction fragment length polymorphism (T-RFLP) reinforced the PLFA results. A significant change of bacterial community structure
was observed in the separate dendrogram cluster between control and treated samples with the cucumber phyllosphere following
cypermethrin insecticide treatment. Moreover, the increased terminal restriction fragments (T-RFs) (58, 62, 89, 99, 119, 195, 239,
311, 340, and 473 bp) indicated that some bacteria might play a significant role in the insecticide degradation within the cucumber
phylosphere, whereas the disappeared T-RFs (44, 51, 96, 223, 306, and 338 bp) implied that some other bacteria might potentially serve
as microbial indicator of cyperemethrin insecticide exposure.
