Isolation and Identification of Phosphate Solubilizing and Nitrogen-Fixing Bacteria from Lake Ol’Bolossat Sediments, Kenya

Phosphate solubilizing and nitrogen-fixing bacteria have a vital role in improving soil fertility and reverting adversely affected soil properties. These bacteria could contribute towards sustainable agriculture with a focus on reducing excessive use of commercial fertilizers. This study aimed at investigating autochthonous populations of phosphate solubilizing and nitrogen-fixing bacteria from Lake Ol’Bolossat sediments. The total microbial counts ranged between 4.8 x 103 to 8.5 x 105 cfu/ml. A total of 50 bacteria were isolated, 34 were obtained from Pikovskaya’s agar medium while 16 were obtained from Norris Glucose Nitrogen free medium. Based on morphological and 16S rRNA gene analyses, the isolates were clustered under the genera Bacillus, Arthrobacter, Pseudomonas, Paenibacillus, Fictibacillus and Acinetobacter. Among potentially novel strains, four strains NFDA2, PKGBC1 (MT799539), PKGB5 and SCEC2 (MT799543) belonged to genus Bacillus, three strains NFGA1 (MT799529), NFGA4 and SCDB3 belonged to the genus Pseudomonas, two strains NFEB6 (MT799528) and NFDC5 belonged to the genus Paenibacillus, one strain PKHC3 (MT7995441) belonged to the genus Arthrobacter while one strain NFDC4, belonged to the genus Acinetobacter. Generally, the phosphate solubilizing bacteria were the most diverse and genera Bacillus, Fictibacillus and Pseudomonas were the most dominant, however, nitrogen-fixing bacteria were dominated by genera Arthrobacter and Pseudomonas.