Effect of Streptomyces sp. St1 on growth of and potential to stimulate anthracene removal by sunn hemp (Crotalaria juncea) grown in anthracene-contaminated soil

Abstract

This study was performed to investigate the ability of Streptomyces sp. St1 that has indole-3-acetic acid (IAA) production and phosphate solubilizing ability on the growth and remediation efficiency of sunn hemp cultivated in 202.9 mg/kg of anthracene-contaminated soils. Streptomyces sp. St1 immobilized in rice straw and coconut husk could increase sun hemp growth. On day 36 of the experiment, shoot length, shoot fresh weight, shoot dry weight, root fresh weight and total chlorophyll content in sunn hemp leaves were around 41.2-44.4 cm, 2.81-3.45 g, 0.44-0.53 g, 0.46-0.55 g and 47.4-79.2 mg/ml, respectively, in soil amended with Streptomyces sp. St1 immobilized in rice straw and coconut husk. Sunn hemp cultivated in anthracenespiked soil without Streptomyces sp. St1 inoculation died at 36 d after germination. Additional immobilized cells+spores of Streptomyces sp. St1 in rice straw and coconut husk in soil planted with sunn hemp maintained the cell density to a better extent than the free cells+spores. However, both free and immobilized cells+spores of Streptomyces sp. St1 did not improve anthracene removal from the soil with or without sunn hemp planting.

Keywords

• anthracene
• crotalaria juncea
• phytoremediation
• plant growth promoting bacteria