Caracciolo Anna Barra, Grenni Paola, Ciccoli Roberto, Di Landa Giuseppe, Cremisini Carlo
Water Research Institute, National Research Council, Rome, Italy.
Pest Manag Sci. 2005 Sep;61(9):863-9. doi: 10.1002/ps.1096.
Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. Simazine, 6-chloro-N2,N4-diethyl-1,3,5-triazine-2,4-diamine, is a triazine herbicide used in agriculture for selective weed control with several types of crops and it is frequently applied to soils receiving N-fertilizers. Degradation experiments were performed in the laboratory to assess whether the biodegradation of simazine in soil may be influenced by the presence of urea. Simazine degradation rates under different experimental conditions (presence/absence of urea, microbiologically active/sterilized soil) were assessed together with the formation, degradation and transformation of its main metabolites in soil. Simazine degradation was affected by the presence of urea, in terms both of a smaller half-life (t(1/2)) and of a higher amount of desethyl-simazine formed. The soil bacterial community was also studied. Microbial abundances were determined by epifluorescence direct counting. Moreover in situ hybridization with rRNA-targeted fluorescent oligonucleotide probes was used to analyze the bacterial community structure. Fluorescent in situ hybridization (FISH) was used to detect specific groups of bacteria such as the alpha,beta,gamma-subdivisions of Proteobacteria, Gram-positive bacteria with a high G + C DNA content, Planctomycetes, Betaproteobacterial ammonia-oxidizing bacteria and nitrifying bacteria. The presence of the herbicide and/or urea affected the bacterial community structure, showing that FISH is a valuable tool for determining the response of bacterial populations to different environmental conditions.
农业中土壤和地下水受到农药和硝酸盐污染是一个全球范围内的环境和公共卫生问题。西玛津，即6-氯-N2,N4-二乙基-1,3,5-三嗪-2,4-二胺，是一种用于农业中对多种作物进行选择性除草的三嗪类除草剂，常用于施氮肥的土壤。在实验室中进行了降解实验，以评估土壤中尿素的存在是否会影响西玛津的生物降解。评估了不同实验条件下（有无尿素、微生物活性土壤/灭菌土壤）西玛津的降解速率，以及其在土壤中主要代谢产物的形成、降解和转化情况。尿素的存在影响了西玛津的降解，表现为半衰期（t(1/2)）更短，且形成的去乙基西玛津量更多。还对土壤细菌群落进行了研究。通过落射荧光直接计数法测定微生物丰度。此外，使用rRNA靶向荧光寡核苷酸探针进行原位杂交，以分析细菌群落结构。荧光原位杂交（FISH）用于检测特定的细菌群体，如变形菌门的α、β、γ亚群、高G + C DNA含量革兰氏阳性菌、浮霉菌门、β-变形菌纲氨氧化细菌和硝化细菌。除草剂和/或尿素的存在影响了细菌群落结构，表示FISH是确定细菌群体对不同环境条件响应的有价值工具。
