Heavy metal contamination of soils has received considerable attention in the contemporary science. Phytoremediation, the use of plants and their associated microorganism to remediate a site, is considered as a novel and highly promising technology for the remediation of metal-polluted soils. Therefor, plants and their associated microorganisms are characterized by varied and complex interactions and has been the subject of extensive research.

Colonizing the internal tissues of plants, endophytes are likely to interact more closely with their host. Recently, the benefits of combining endophytic bacteria with plants for increased remediation of pollutants have been successfully tried for toxic metal removal from contaminated soils. However, how the plants, heavy-metals and endophytic bacterial communities interact with each other has been not fully understood. And the knowledge on the diversity of endophytes under metal stress is an indispensable precondition for studying their interaction with the host plants more profitably.

In a paper in Environmental Science and Pollution Research, researchers in the Institute of Hunan University and Subtropical Agriculture, Chinese Academy of Sciences (ISA) employ molecular-based methods to investigate the diversity of endophytic bacterial communities of two hyperaccumulators (Solanum nigrum L. and Phytolacca acinosa Roxb.) growing in mine soils.

The researchers found that both heavy metal pollution and plant species contribute to the shaping of the dynamic endophytic bacterial communities of hyperaccumulators. “Heavy metal in contaminated soil determined, to a large extent, the composition of the different endophytic bacterial communities in S. nigrum growing soil with different level of metal contamination.” said lead researcher Dr. Chen Liang from ISA. “Detailed analysis of endophytic bacterial populations by cloning of 16S rRNA genes amplified from the stems of the two plants at the same site revealed a different composition.”

The researchers also found that a total of 51 taxa at the genus level that included α-, β- and γ-Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and unclassified bacteria in the clone libraries of two plants. The most abundant genus in S. nigrum was Sphingomonas (23.4%), while Pseudomonas prevailed in P. acinosa (21.4%).

The research was supported by the National Natural Science Foundation of China (51178173, 51202065, and 51078129), Program for Innovation Research Team in University (IRT1238), and Program for New Century Excellent Talents in University (11-0126).

The study entitled “A comparative analysis of endophytic bacterial communities associated with hyperaccumulators growing in mine soils” has been published in Volume 21, Issue 12, June 2014 of Environmental Science and Pollution Research, details could be found at http://link.springer.com/article/10.1007%2Fs11356-014-2670-9.