Assessment the microbiological and molecular aspects of soil isolated bacteria that suppress Pythium ultimum in Abha/KSA

Abstract

Background Pythium ultimum is largely threatening many economically important plants by causing seedling damping-off disease. Microbial control approach is considered a new, effective, and safe trend in the eradication of phytopathogens. Aims The current work focused on the isolation and molecular identification of soil isolated bacteria that suppress the damping-off-causing pathogen (P. ultimum). Moreover, optimization of environmental factors and detection of the mode of action of P. ultimum suppression was taken into consideration. Materials and methods Soil bacteria were isolated and screened for their antagonistic potential toward P. ultimum. The most vigorous isolate was characterized and identified. Some environmental factors were optimized using a well-plate assay. The inhibitory effect of bacteria, whether fungistatic or fungicidal, was detected. Mode of action of fungal inhibition was studied as well. Statistical analysis Statistical analysis was carried out using one-way analysis of variance in Excel. Results The bacterial isolate was identified as Enterococcus faecalis. The extracellular filtrate presented higher fungal inhibition (68%) compared with the bacterial cells (53%). The environmental factors for fungal inhibition were optimized to be pH 8, 28°C, 100% inoculum size, and third day of incubation reaching maximal values of 75, 76, 81, and 83%, respectively. Conclusion E. faecalis is a promising fungicidal agent against P ultimum through the production of diffusible metabolites.