Enhanced Growth of Barley (Hordeum vulgare L.) by Biofertilizer Produced from Biodegraded Nile perch (Late niloticus) Wastewater

Abstract

Nile perch (Late niloticus) is the most substantial and highly caught fish for export, improving economy in Tanzania. Currently in Tanzania, most of fish processing plants generate a considerable amount of waste that is directly discarded into the river or landfills. Hence, fish waste pollutes the aquatic environment and its habitat. Despite high production of fish waste, little effort has been made for biological treatment and reutilization. For this reason, the reutilization of (NPWW) as biofertilizer was investigated in this study. To examine this feasibility, the NPWW biodegradation was conducted in a 600 mL-flask scale for 72 h with the mixed culture of three Bacillus species (B. agri, B. anthracis and B. circulans). During the biodegradation, CODCr and TN removal of the culture supernatant were 52.7% and 44.3%, respectively. The test of germination index test for NPWW supernatant argue that the biodegraded NPWW was phytotoxic-free beyond 50-fold dilution. The quality of the biodegraded NPWW as a biofertilizer was verified through the hydroponic culture of barley (Hordeum vulgare L) for 14 days which showed that the leaf grew to 16.6 cm as the roots and stems elongated to 5.06 cm. The biodegraded NPWW enhanced the barley growth by 20.5% in leaf length and 22.4% stems compared with those of control. In addition, the 72-h culture supernatant exhibited highest antioxidant activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging of (85.5%), 2,2’-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization (99.7%) and hydroxyl radical scavenging ability (96.7%). All the results indicate that the NPWW and used Bacillus species are potential sources of biofertilizer, and the application of the biofertilizer to agricultural industry is promising.