Characterization and Diversity of Native Azotobacter Spp. Isolated From Semi-Arid Agroecosystems of Eastern Kenya
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Date
2022
Authors
Wakarera, Priscillah Wanjira
Ojola, Patroba
Njeru, Ezekiel Mugendi
Journal Title
Journal ISSN
Volume Title
Publisher
The Royal Society
Abstract
Declining food production in African agroecosystems is attributable to
changes in weather patterns, soil infertility and limited farming inputs.
The exploitation of plant growth-promoting soil microbes could remedy
these problems. Such microbes include Azotobacter; free-living, nitrogenfixing bacteria, which confer stress tolerance, avail phytohormones and aid
in soil bioremediation. Here, we aimed to isolate, characterize and determine
the biodiversity of native Azotobacter isolates from soils in semi-arid Eastern
Kenya. Isolation was conducted on nitrogen-free Ashby’s agar and the morphological, biochemical and molecular attributes evaluated. The isolates
were sequenced using DNA amplicons of 27F and 1492R primers of the
16S rRNA gene loci. The Basic Local Alignment Search Tool (BLASTn)
analysis of their sequences revealed the presence of three main Azotobacter
species viz., Azotobacter vinelandii, Azotobacter salinestris and Azotobacter tropicalis. Kitui County recorded the highest number of recovered Azotobacter
isolates (45.4%) and lowest diversity index (0.8761). Tharaka Nithi County
showed the lowest occurrence (26.36%) with a diversity index of (1.057).
The diversity was influenced by the soil pH, texture and total organic
content. This study reports for the first time a wide diversity of Azotobacter
species from a semi-arid agroecosystem in Kenya with potential for
utilization as low-cost, free-living nitrogen-fixing bioinoculant.
Description
Article
Keywords
biodiversity, bioinoculant, Azotobacter, plant growth-promoting rhizobacteria, smallholder farmers
Citation
Wakarera, P. W., Ojola, P., & Njeru, E. M. (2022). Characterization and diversity of native Azotobacter spp. isolated from semi-arid agroecosystems of Eastern Kenya. Biology Letters, 18(3), 20210612.