[Response of Photosynthetic Bacterial Community to Cadmium Contamination in Paddy Soil].

Heavy metal pollution in rice fields leads to huge losses in rice yield every year and is thus of increasing concern. Therefore, it is important to understand the changes in the microecology and physicochemical properties of paddy soil under different levels of cadmium pollution. The purpose of this study was to investigate the response of the photosynthetic bacterial community in paddy soil to different cadmium pollution levels using 16S sequencing technology. The results showed that pH, total cadmium, and available cadmium content decreased gradually with the increase in cadmium pollution. The soil α diversity was slightly different in the high cadmium (Cd), medium Cd, and low Cd groups; however, the enriched photosynthetic populations and photosynthetic bacterial communities were significantly different among these groups. The effective connections between photosynthetic bacterial species in the high Cd group were significantly greater than those in the medium and low Cd groups, the connections were closer, and the density was higher. Alkaline nitrogen, pH, available (P/K), total (N/P), organic matter, total cadmium, and available cadmium were important factors affecting the photosynthetic bacterial community and were significantly correlated with the photosynthetic bacterial community, explaining 59.90% of the variation in the photosynthetic bacterial community. Effective Cd content was significantly positively correlated with Methylorubrum populi, Methylorubrum extorquens, Methylobacterium sp. Leaf125, and Rhodopseudomonas sp. AAP120 (R>0.05, P<0.05). This study will provide a theoretical basis for the microbial remediation of cadmium contamination in paddy fields. This study is important for understanding the effects of cadmium pollution on specific functional microbial populations in paddy soils.

[Effects of Rhodopseudomonas palustris PSB06 on Pepper Rhizosphere Microbial Community Structure].

The use of biological pesticide can greatly reduce the soil pollution in the environment. Exploring the effect of biological pesticide on community diversity and distribution of pathogenic bacteria will provide theoretic basis for subsequent researches on biological pesticide micro-ecological control. In order to explore the microbial ecological mechanism of pepper phytophthora blight, this research compared the difference of microbial diversity between rhizosphere soil of infected and healthy plants, and the effects of Rhodopseudomonas palustris PSB06 on microbial diversities of plant rhizosphere soil were investigated using Illumina MiSeq sequencing technology. The results showed that there was less difference in the microbial diversity from the same soil between the seventh day and the fourteenth day. The microbial diversity of rhizosphere soil of healthy plants was higher than that of rhizosphere soil of infected plants. The soil sprayed with Rhodopseudomonas palustris PSB06 exhibited the highest diversity. Moreover, the abundance of Actinomycetes in the rhizosphere soil of healthy plants was higher than that of infected plants, and the highest abundance of Actinomycetes was observed in the soil sprayed with Rhodopseudomonas palustris PSB06. The microbial diversity between rhizosphere soil of infected and healthy plants was significantly different. Spraying Rhodopseudomonas palustris PSB06 could significantly alter the microbial community structure of the soil. It could also increase the diversity of microorganism and the abundance of Actinomycetes in the soil.