Bioremediation of organophosphorus pesticides in contaminated foodstuffs using probiotics has been increasingly under the spotlight in recent years,though the biodegradation mechanism and derived intermediate products...Bioremediation of organophosphorus pesticides in contaminated foodstuffs using probiotics has been increasingly under the spotlight in recent years,though the biodegradation mechanism and derived intermediate products remain unclear.This study aimed to help fill this knowledge gap and examined the degradation mechanism of organophosphorus pesticide,chlorpyrifos,in milk by Lactobacillus delbrueckii ssp.bulgaricus using gas chromatography-tandem mass spectrometry(GC-MS/MS)combined with transcriptome analysis.After the strain was cultured for 20 h in the presence of chlorpyrifos,differential expressions of 383 genes were detected,including genes probably implicated during chlorpyrifos degradation such as those related to hydrolase,phosphoesterase,diphosphatase,oxidoreductase,dehydratase,as well as membrane transporters.GC-MS/MS analysis revealed the changes of secondary metabolites in L.bulgaricus during milk fermentation due to chlorpyrifos stress.6-Methylhexahydro-2H-azepin-2-one,2,6-dihydroxypyridine and methyl 2-aminooxy-4-methylpentanoate as intermediates,along with the proposed pathways,might be involved in chlorpyrifos biodegradation by L.bulgaricus.展开更多
从生态系统响应和游客主观认知的双重视角，对六盘山旅游区旅游步道对人类旅游践踏干扰的响应进行了研究。结果表明：①自然状态下旅游践踏干扰主要集中在旅游步道边缘1—3m范围内，但不同生态系统差异较大。在调查的3个景区中，小南川...从生态系统响应和游客主观认知的双重视角，对六盘山旅游区旅游步道对人类旅游践踏干扰的响应进行了研究。结果表明：①自然状态下旅游践踏干扰主要集中在旅游步道边缘1—3m范围内，但不同生态系统差异较大。在调查的3个景区中，小南川景区乔灌草生态统主要集中在旅游步道1m左右；凉殿峡景区高山草甸生态系统集中在1—2m之间；野荷谷景区华北落叶松林下生态系统则达到3m左右；②采用地表覆盖物响应指数（Index of Land Cover Impact，IL-CI）和游客可接受改变限度（Limits of Acceptable Change，LAC）来衡量受干扰旅游步道响应程度，在1m范围内各调查样区ILCI均达到4级或5级严重冲击程度；1—2m间以凉殿峡景区ILCI值较高（39％），介于1—2级之间，而小南川与野荷谷景区儿口值属1级轻微影响；3m及以外三者影响基本较小。游客对游道沿线土壤裸露度可接受改变限度为55．7％，3个调查样区1m范围内植被覆盖减少率（CR）均超过此水平；③调查样区旅游步道响应强弱与游道坡度、边坡坡度以及游道宽度具有一定相关性；④地表覆盖物响应指数因与其它各响应变量间显著相关，可作为评估旅游干扰系统响应的一项简易而有效的指标。研究结果也表明，目前旅游践踏干扰已对游道沿线环境以及游客游憩体验产生了一定的负面影响。因此，改变目前景区开发无序状态，加强旅游步道规划设计和游客行为规范，建立长期环境监测系统，将对制定防治游憩冲击策略，促进六盘山生态旅游区可持续发展具有重要指导价值。展开更多
基金supported by Natural Science Foundation of China(41907357)Natural Science Foundation of Shandong(ZR2019PC048)the Key R&D project of Shandong Province(2021TZXD007).
文摘Bioremediation of organophosphorus pesticides in contaminated foodstuffs using probiotics has been increasingly under the spotlight in recent years,though the biodegradation mechanism and derived intermediate products remain unclear.This study aimed to help fill this knowledge gap and examined the degradation mechanism of organophosphorus pesticide,chlorpyrifos,in milk by Lactobacillus delbrueckii ssp.bulgaricus using gas chromatography-tandem mass spectrometry(GC-MS/MS)combined with transcriptome analysis.After the strain was cultured for 20 h in the presence of chlorpyrifos,differential expressions of 383 genes were detected,including genes probably implicated during chlorpyrifos degradation such as those related to hydrolase,phosphoesterase,diphosphatase,oxidoreductase,dehydratase,as well as membrane transporters.GC-MS/MS analysis revealed the changes of secondary metabolites in L.bulgaricus during milk fermentation due to chlorpyrifos stress.6-Methylhexahydro-2H-azepin-2-one,2,6-dihydroxypyridine and methyl 2-aminooxy-4-methylpentanoate as intermediates,along with the proposed pathways,might be involved in chlorpyrifos biodegradation by L.bulgaricus.
文摘从生态系统响应和游客主观认知的双重视角，对六盘山旅游区旅游步道对人类旅游践踏干扰的响应进行了研究。结果表明：①自然状态下旅游践踏干扰主要集中在旅游步道边缘1—3m范围内，但不同生态系统差异较大。在调查的3个景区中，小南川景区乔灌草生态统主要集中在旅游步道1m左右；凉殿峡景区高山草甸生态系统集中在1—2m之间；野荷谷景区华北落叶松林下生态系统则达到3m左右；②采用地表覆盖物响应指数（Index of Land Cover Impact，IL-CI）和游客可接受改变限度（Limits of Acceptable Change，LAC）来衡量受干扰旅游步道响应程度，在1m范围内各调查样区ILCI均达到4级或5级严重冲击程度；1—2m间以凉殿峡景区ILCI值较高（39％），介于1—2级之间，而小南川与野荷谷景区儿口值属1级轻微影响；3m及以外三者影响基本较小。游客对游道沿线土壤裸露度可接受改变限度为55．7％，3个调查样区1m范围内植被覆盖减少率（CR）均超过此水平；③调查样区旅游步道响应强弱与游道坡度、边坡坡度以及游道宽度具有一定相关性；④地表覆盖物响应指数因与其它各响应变量间显著相关，可作为评估旅游干扰系统响应的一项简易而有效的指标。研究结果也表明，目前旅游践踏干扰已对游道沿线环境以及游客游憩体验产生了一定的负面影响。因此，改变目前景区开发无序状态，加强旅游步道规划设计和游客行为规范，建立长期环境监测系统，将对制定防治游憩冲击策略，促进六盘山生态旅游区可持续发展具有重要指导价值。
