Enhancement of chromate phytoremediation and soil reclamation potential of Brassica campestris L. by Aspergillus niger

In the past decades, chromium contamination of agricultural land has become an emerging concern. For land reclamation, several strategies including bioremediation have been used. Owing the potential of hyperaccumulators, the current project aims to enhance the phytoremediation potential of Brassica campestris L. with the application of chromate tolerant endophytic fungus Aspergillus niger CSR3. when B. campestris was watered with chromate concentration (300, 500, and 1000 ppm) in the form of potassium chromate (K2CrO4), seed germination, hypocotyl length, root shoot length, and leaf area were severely reduced (p < 0.05). However, reproductive parts of the plants remained viable once initiated. Inoculation of the selected endophyte stimulated host growth, reducing the severity of the chromate stress. Interestingly, CSR3-inoculated plants accumulated 1.82-, 1.51-, and 2.16-fold greater quantities of chromate than the un-inoculated plants. To cope better with the stress, endophyte-associated host had stronger antioxidant system supported by enhanced production of nonenzymatic antioxidants (flavonoids, phenolics, and proline) and enzymatic antioxidants (SOD, CAT, APX, and POD) than the non-endophytes host plants. It may be concluded that hyperaccumulator B. campestris accumulates even higher quantities of chromate in the presence of endophytic A. niger CSR3 and tolerates elevated levels of chromate with boosted antioxidant system. Thus, hyperaccumulator host associated with heavy metal tolerant endophytic fungi can be the possible efficient way to reclaim the contaminated site from the heavy metals effectively in a short time period.

Automated summary

In recent years, chromium contamination in agricultural land has become a growing concern, and various strategies have been used to remediate the damage caused. This study aimed to enhance the phytoremediation potential of Brassica campestris L. by applying a chromate tolerant endophytic fungus, Aspergillus niger CSR3. The results showed that the presence of the endophytic fungus stimulated the growth of B. campestris and increased its ability to accumulate chromate. Additionally, the plants associated with the endophyte had a stronger antioxidant system to cope with the chromate stress. These findings suggest that using hyperaccumulator plants and heavy metal tolerant endophytic fungi can be an efficient way to reclaim contaminated sites.