镉污染对滨海滩涂围垦区西兰花根际土壤细菌群落结构的影响

The Effects of Cadmium Contamination on Soil Bacterial Structure and Diversity in Rhizosphere Soils of Broccoli in Coastal Reclamation Area

研究镉(Cd)污染对滩涂湿地围垦区西兰花根际土壤细菌群落结构的影响,探求有益于Cd污染农田土壤修复的耐Cd细菌菌群。采用Illumina Miseq高通量测序技术,分析Cd浓度分别为0,3.5,60 mg·kg^(-1)时对台州湾滩涂湿地围垦区西兰花根际土壤细菌群落结构和多样性指数的影响。结果表明:所有样品中检测到的细菌菌群分属于35门、97纲、205目、315科、506属。低浓度Cd污染时,西兰花根际土壤细菌Chao 1指数和Shannon指数与对照相比大幅度升高,而高浓度Cd污染时,土壤细菌Chao 1指数和Shannon均大幅度下降。随着Cd污染程度的增加,西兰花根际土壤放线菌门和浮霉菌门相对丰度呈一直下降的趋势,拟杆菌门和芽单胞菌门相对丰度呈一直升高的趋势。土壤变形菌门和髌骨菌门相对丰度呈先下降后上升的趋势,而土壤酸杆菌门、棒状杆菌门、疣微菌门、硝化螺旋菌门和厚壁菌门相对丰度呈先上升后下降的趋势。变形菌门、拟杆菌门、髌骨菌门和芽单胞菌门在高浓度Cd污染下为农田土壤细菌群落的主体。土壤罗思河小杆菌属相对丰度在低浓度Cd污染时呈下降趋势,而在高浓度Cd污染时呈升高趋势,土壤鞘氨醇单胞菌属的相对丰度在低浓度Cd污染时呈上升趋势,在高浓度Cd污染时呈下降趋势。土壤罗思河小杆菌属、马赛菌属、黄杆菌属和杜擀氏菌属可以被认为是西兰花根际土壤高抗Cd污染的细菌菌属。研究结果可为滨海滩涂地西兰花重金属污染土壤微生物修复提供依据。

In order to study the effects of cadmium contamination on soil bacterial structure and diversity in rhizosphere soils of broccoli in coastal reclamation area,and to find out the cadmium-resistant bacterial which were beneficial to the remediation of cadmium contamination,high throughput sequencing method was used to analyze the effects of cadmium stress on bacterial community and diversity in rhizosphere soils of broccoli in coastal reclamation areas of Taizhou estuary,Zhejiang Province.The concentrations of cadmium were set at 0,3.5,or 60 mg·kg^(-1),respectively,and were marked as CdO,Cd3.5,Cd60,correspondingly.The results showed that cadmium stress could cause changes in both bacterial diversity and community structure.There were 35 phyla,97 classes,205 orders,315 families,and 506 genera in the rhizosphere soil of broccoli in this studied areas under different gradients of cadmium contamination.Low cadmium stress might raise the Chaol index and Shannon index of soil bacterial community and high cadmium stress might reduce the Chaol index and Shannon index of soil bacterial community.With the increase of Cd stress,the relative abundance of Actinobacteri and Planctornyces in the soils of broccoli showed a downward trend all the time,while the relative abundance of Bacteroidetes and Gemmatimonadetes are on the increase all the time.The relative abundance of soil Proteobacteria and Patescibacteria decreased first and then increased.The relative abundances of Acidobacteria,Rokubacteria,Errucomicrobia,Nitrospirae and Firmicutes in soil are increased first and then decreased.Proteobacteria,Bacteroidetes,Patescibacteria and Gemmatimonadetes are the dominant groups in high Cd contamination.With the increase of Cd stress,the relative abundance of Pseudarthrobacter,Muciaginibacter and Rhodopseudomonas in the rhizosphere soil of broccoli showed a downward trend all the time,while the relative abundance of Flavobacterium is on the increase all the time.The relative abundance of soil Rhodanobacter decreased first and then increased.The relative abundances of Sphingomonas in soil were increased first and then decreased.This indicated that low cadmium stress might stimulate the growth and production of cadmium-sensitive bacteria,which made the community structure more complex and diverse.High concentration of cadmium significantly inhibited bacteria,resulting in the extinction of some species and the decrease of diversity.High cadmium contamination could induce cadmium-resistant bacteria such as Rhodanobacter to become dominant groups,and the community structure tended to be stable and single.The bacterial community structure had obvious response characteristics to different cadmium pollution stresses and could be used as a sensitive index for soil quality evaluation of cadmium contaminated fields.There were a large number of Rhodanobacter,Gemmatimonadaceae-unclassified,Massilia,Candidate-Adlerbacteria-unclassified,Chitinophagaceae-unclassified,Alphaproteobacteria-unclassified,Flavobacterium and Duganella in the Cd60 group,which could be used as a reference for microbial remediation of cadmium contaminated broccoli planting fields in coastal reclamation areas.