Biofertilizer production using phosphate solubilizing bacteria isolated from rhizosphere soil of cowpea (vigna unguiculata)

Abstract

^{Phosphate-solubilizing bacteria (PSB) do enhance the availability of phosphorus in soil thereby promoting sustainable agriculture. This study aimed to isolate and characterize PSB from the rhizosphere soil of cowpea (Vigna unguiculata) and access its potential for biofertilizer production. Rhizosphere soils samples were collected from some farms within Sokoto metropolis. Physicochemical properties were determined using standard procedures. PSB were screened from the soil samples using Pikovskaya’s agar and nutrient agar. The screened PSB were isolated and characterised biochemically using standard procedures. The potential of the screened phosphate solubilizing bacterial isolates as biofertilizer using charcoal as a base material were assessed on the growth of cowpea (Vigna unguiculata).Results shows slightly acidic pH ranging from 6.72 to 6.57. Temperature was recorded from 36.7 to 37.1. The cation exchange capacity (CEC) was recorded highest (4.23±0.021) in Arkilla Layout (ALO) and lowest (3.01±0.410) in Arkilla Gandu (AGND). Seven bacterial species were identified as Paenibacillus dendritiformis. Pseudomonas putida, Pseudomonas aeruginosa, Bacillus megaterium, Bacillus cereus, Bacillus subtilis, andBacillus licheniformis. Paenibacillus dendritiformisexhibited the highest solubilization efficiency of (3.77±0.106) and was molecularly characterized using 16S rRNA sequencing, compared to Bacillus cereus with solubilizing efficieciency of (1.13± 0.014). The biofertilizer formulation developed and tested on cowpea plants revealed that selected PSB isolates significantly increased phosphorus availability and improved cowpea growth compared to control treatments. The tested biofertilizer on cowpea plant revealed that suspension with Paenibacillus dendritiformis had the highest growth of shoot (6.6) and number of leaves (21.50). The Isolate with highest PSI (Paenibacillus dendritiformis) was molecularly characterized as Paenibacillus dendritiformis was found to have 92.12% similarity index after running the sequence on a BLAST. Thesefindings highlight the potential of PSB to be a good source of biofertilizers suspension with charcoal base as an eco-friendly alternative to synthetic fertilizers and organic manure.}