Diversity and prevalence of indigenous soil bacillus spp. in the major cabbage growing agroecological zones of Uganda

Abstract

Different species of genus Bacillushave been reported from different environments of the world. They are reported to play a role of soil fertility improvement, plant growth promotion and disease and pest management. Most of these reports on Bacillus species are from studies conducted outside Uganda and therefore information on the prevalence and diversity of bacillus species in Ugandan soils is scanty.This study aimed at determining the prevalenceand diversity of Bacillusspp. isolated from the cabbage rhizosphere in the four major cabbage-growingagroecological zones of Uganda. The experimentwas conducted in a laboratory at the Collegeof VeterinaryMedicine, Animal Resourcesand Biosafety Makerere University for morphological and biochemical identification of the Bacillusbacteria.DNA extraction and PCR were conducted at the College of Natural Resources Makerere University while sequencing was done at Macrogen laboratories in Korea and Inqaba Biotec in South Africa. Morphological, biochemical and genomic analyses revealed five Bacillusspp. (22 Bacillus strains) grouped as B. cereus, B. mycoides, B. thuringiensis, B. megaterium and B. bingmayongensis. B. cereus andB. megaterium were the most dominant and widely spreadBacillus spp. A phylogenetic tree indicated three major clads, showingthatB. thuringiensis was closely related toB. cereus whileB.bingmayongesis was closely relatedto B.megaterium. TheB. mycoides were closely related to someB. cereus strains and B. bingmayongensis. The phylogenetic tree further showed that some Bacillus strains of the same species were distantly related.It was therefore concluded thatmost abundant and prevalent Bacillusspp. in Ugandan soils were B. cereus andB. megaterium. The presence and abundanceof these bacillus species in the Ugandan soil presents an opportunity for soil scientists to innovatively manipulate them for use as biofertilizers and biopesticides for crop production and management. Such innovations would reduce the reliance of farmers on synthetic fertilizers that are pollutants to the environment and unhealthy to the users and consumers.