Efficacy of rice husk and halophilic bacterial biofilms in the treatment of saline water.

Abstract

Water salinity causes less production of agricultural productivity, low economic returns, soil destructions, less sustainability, and reduction in the germination rate. The current study was aimed to understand the combined potential of halophilic bacteria and rice husk in treating water salinity. In total, 10 halophilic bacterial isolates were isolated from Khewra Mines, Pakistan. Bacterial isolates were characterized by biochemical tests. 16S rRNA gene sequencing identified the isolate SO 1 as Bacillus safensis (accession number ON203008) being the promising halophilic bacteria tolerating upto 3 M NaCl concentration. Next, rice husk was used as carbon source for bacterial biofilm formation, growth and propagation. For saline water treatment, the experimental setting comprising glass wool, rice husk and artificial sea water (3 M) was set. B. safensis biofilm was developed in test samples to desaline the saline water containing 3 M NaCl concentration. Following NaCl decline, flame photometric analysis was used to check the desalination extent of treated saline water. Results showed decreased sodium level in sea water in the presence of rice husk and glass wool. The eluted water used for the germination of Zea mays seeds showed improved growth performance. Also, decreased photosynthetic pigments (chlorophyll "a" = 18.99, and chlorophyll "b" = 10.65), sugar contents (0.7593), and increased carotenoid (1526.91), protein contents (0.4521) were noted compared to control. This eco-friendly approach for bioremediation of salt-affected soils to optimize crop yields under stress through halophilic bacteria and rice husk may overcome the problem of the reduced yield of cash crops/agriculture and water shortage by salinity.