Effects of ectomycorrhizal fungus Boletus edulis and mycorrhiza helper Bacillus cereus on the growth and nutrient uptake by Pinus thunbergii

The present greenhouse study was undertaken to evaluate the effects of co-inoculating the ectomycorrhizal (ECM) fungus Boletus edulis with the mycorrhiza helper bacterium Bacillus cereus HB12 or HB59 on the growth and nutrient uptake of Pinus thunbergii. The inoculation with mycorrhiza helper bacterium significantly (P a parts per thousand currency signaEuro parts per thousand 0.05) increased the ectomycorrhizal colonization. Treatments with dual inoculum (the mycorrhiza helper bacterium plus mycorrhiza) significantly (P a parts per thousand currency signaEuro parts per thousand 0.05) increased the P. thunbergii growth. Bacteria-mycorrhizae interactions resulted in a great utilization of phosphate and potassium. The single inoculation resulted in a higher root activity than the control while the co-inoculation led to the highest root activity. The 6-CFDA staining assay showed that B. cereus enhanced fungal activity in ectomycorrhizal symbiosis. The results conclusively suggest that B. cereus isolated from the rhizosphere of P. thunbergii can potentially be used as individual inoculant or co-inoculated with ECM fungi to increase the production in sustainable ecological systems. These results support the potential use of B. cereus (HB12 or HB59) and B. edulis as mixed inoculants stimulating growth of P. thunbergii.