Response of Mosses and Their Rhizobial Bacterial Communities to Heavy Metal Pollution in Manganese Mining Areas of South China

Moss-associated abundant microorganisms may play an important role in manganese ore remediation. In this paper, we investigated the structure and diversity of moss rhizobial communities in manganese slag piles at Xiaoqiao Manganese Mine, Songtao County, Tongren City, Guizhou Province, and explored the response of moss rhizobial communities under different levels of soil heavy metal contamination. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the heavy metal content in the soil. The structure and abundance of the moss rhizobia community were characterized by 16S rRNA high-throughput sequencing, and the relationship between the indicators was analyzed. The results showed that among the dominant bacteria in the moss rhizosphere of the manganese mine dumps, Actinomycetes, Proteus, Green algae and Cyanobacteria showed better tolerance to heavy metals. The results of the correlation analysis between bacterial abundance and heavy metal content showed that Mn was significantly positively correlated with Planctomycetes and positively correlated with Verrucomicrobia and Abditibacteriota. Cd was positively correlated with Planctomycetes and WPS-2. Pb was negatively correlated with Firmicutes and positively correlated with WS2. Analysis of the correlation between bacterial diversity and heavy metal content showed that Cu was significantly correlated with OTU, Ace, and Chao (p < 0.05). In summary, the diversity and community structure of moss rhizobia differed significantly under different levels of heavy metal contamination, and most moss rhizobia showed strong tolerance, and these bacteria may be a key factor in the remediation process of mine soils.