Microbial community structure analysis and isolation of vanadium-resistant strains in vanadium mining–impacted soil

Abstract

Vanadium (V) is an essential trace metal for living organisms with broad application, and extensive mining activities have caused heavy metal pollution in the mining area. Currently, there is little information available on the microbial ecology of V mining-impacted soil. Here we report the analysis of microbial community and diversity of V-resistant bacteria in the V-titanium (Ti) magnetite (Fe₃O₄) mining area in Panzhihua, southwestern China, which is one of the biggest V-Ti Fe₃O₄ production bases in the world. We found that V made the key contribution to the distribution pattern and microbial community of sampling sites. The sequencing analysis showed high diversity in both surface and subsurface soil samples; in total 129 V-resistant strains (84 strains with V⁵⁺-resistance and 45 strains V⁴⁺-resistance) were isolated from the metal contaminated soil samples. Actinobacteria, Proteobacteria, and Firmicutes were found to be the dominant phyla under both of the cultivation-dependent and cultivation-independent approaches. Arthrobacter, Streptomyces, Rhodococcus, Nocardioides, Paenibacillus, Bacillus, and Burkholderia were the dominant V-resistant genera, and their tolerance to V varied among different strains. Arthrobacter was found to be the most dominant genera among the isolated strains. Eight isolates with better resistance to V also showed resistance to more than nine heavy metals as well as several antibiotics. The phylogenetically diverse metal-resistant strains could be potential resources for bioremediation of metal-contaminated soils.