Fig. 1

Morphological characteristics and antagonistic activities of B. paralicheniformis MDJK30. (a) Cellular morphology (magnification 10 × 100). (b) MDJK30 was inoculated on LB agar medium and incubated at 37 °C for 24 h. Strains were stained with 0.5% magenta dye. In vitro antagonistic activities of B. paralicheniformis MDJK30 against F. solani (c), B. subtilis (d), and E. coli (e). The antifungal activity of MDJK30 was determined against F. solani. A newly cultivated hyphal plug of F. solani was placed on the center of a new PDA plate and incubated for 1 day at 28 °C, and a single clone of MDJK30 was inoculated onto one side of the plug at a distance of 2 cm to incubate for another 3 days. The antibacterial assays for MDJK30 were performed against E. coli and B. subtilis. The precultured E. coli or B. subtilis were incubated in 5 mL LB liquid medium for 10 h at 37 °C. Then, 1 mL of the culture was mixed with 20 mL LB semisolid medium. A single colony of MDJK30 was placed on the center of cooled medium to incubate for 1 day at 37 °C. Qualitative analysis of siderophores (f) A single clone of B. paralicheniformis MDJK30 was inoculated on a CAS-agar plate for cultivation for 3 days at 37 °C. The presence of an orange ring around the colony suggested the capacity for producing siderophores to chelate iron in the medium. Analysis of casein degradation (g) A single clone of B. paralicheniformis MDJK30 was inoculated in the center of casein medium and cultivated for 2 days at 37 °C