Endophytic growth-promoting bacteria in Bothriochloa pertusa in San Jorge ecosystems in Colombia

Bacterias endófitas promotoras de crecimiento en Bothriochloa pertusa en ecosistemas del San Jorge en Colombia

The aim of the study was to evaluate the in vitro plant growth-promoting activity of endophytic bacteria isolated from different tissues of the Colossian grass (Bothriochloa pertusa) in cattle farms in San Jorge, department of Sucre, Colombia. The methodology consisted of isolating endophytic bacteria and determining the population density in CFU/g of tissue, followed by quantitative and qualitative tests of biological nitrogen fixation, phosphate solubilization, siderophore production and Indole Acetic Acid (AIA) production, to finally identify, by sequencing, bacteria with positive growth promotion activity. The results identified endophytic bacteria species belonging to the phylum Firmicutes such as Bacillus subtilis, Bacillus megaterium, Bacillus cereus, Bacillus paramycoides and Exiguobacterium acetylicum, Within the gammaproteobacterial phylum, Enterobacter cloacae was identified. Higher populations were found in roots tissues 1.8 X 108 and 3.5 X 109 CFU/g. With respect to municipality, a higher population density was found in San Marcos (2.2 x 109) with respect to stem and leaf. San Benito resulted in lower values (8.93 x 108 CFU/g of tissue). Out of 65 endophytic bacteria isolated, 15 showed N2-to-ammonium reducing capacity; 18 morphotypes showed phosphate solubilizing capacity; 4 AIA production and 15 siderophore-producing morphotypes. In conclusion, endophytic in vitro isolated bacteria showed activity to promote phosphorus growth, ammonium, AIA production, and siderophore, a protein involved in iron chelation and a competitive mechanism for phytopathogen control.