Isolation, identification, and environmental adaptability of heavy-metal-resistant bacteria from ramie rhizosphere soil around mine refinery

Six bacteria strains from heavy-metal-polluted ramie rhizosphere soil were isolated through Cd(2+) stress, which were numbered as JJ1, JJ2, JJ10, JJ11, JJ15, and JJ18. Sequence alignment and phylogenic analysis showed that strain JJ1 belonged to Pseudomonas, strain JJ2 belonged to Cupriavidus, strains JJ11 and JJ15 belonged to Bacillus, and strains JJ10 and JJ18 belonged to Acinetobacter. The tolerance capability of all the strains was the trend of Pb(2+) > Zn(2+) > Cu(2+) > Cd(2+), the maximum tolerance concentration to Cd(2+) was 200 mg/L, to Pb(2+) was 1600 mg/L, to Zn(2+) was 600 mg/L, and to Cu(2+) was 265 mg/L. Strains JJ1, JJ11, JJ15, and JJ18 could grow well under pH 9.0, and strains JJ2, JJ11, and JJ18 could grow well under 7% of NaCl. The results showed that as a whole these strains had high environmental adaptability. This is the first report that heavy-metal-tolerant bacteria were found from ramie rhizosphere soil, which could be as a foundation to discover the relationship between ramie, rhizosphere bacteria and heavy metals.