BB-007

Fungal entomopathogens, especially Beauveria bassiana, are often studied within the context of their use in biological pest control; however, there is limited knowledge of their distributions in host plants and soil ecosystem. We examined the distribution of B. bassiana and its influence on rice plants and paddy soils. B. bassiana could only be detected on the foliar surfaces of rice plants within 15 days under Bb-4 (7.5 × 10(4) conidia/mL) and Bb-7 (7.5 × 10(7) conidia/mL) treatments. The endophytic colonization of B. bassiana could not be found in stems, roots, or seeds of rice plants under Bb-4 and Bb-7 treatments. The fungus was found only in the leaves of rice plants under Bb-4 and Bb-7 treatments at 15 days after inoculation. Moreover, B. bassiana was absent from paddy soils under Bb-4 and Bb-7 treatments at all times. Enzyme activity (urease and phosphatase) in the paddy soils of Bb-4 and Bb-7 treatments showed no significant difference from the control. It is possible that B. bassiana was not able to colonize paddy soil. Detailed understanding of distribution and ecological interactions of B. bassiana is helpful for understanding and predicting the effects of fungal entomopathogens on host populations, and the interactions among fungal entomopathogens and other organisms in the community.

Eleven dominant mesophilic and thermophilic bacteria were identified from the phase-1 compost and casing of button mushroom (Agaricus bisporus). During phase 1 (at 45-48 °C), Bacillus subtilis (BSB1, BSB3, BSB5, and BSB13), Paenibacillus polymyxa (PPB6), Bacillus sp. (BB7), B. cereus (BCB8 and BCB12), and Acinetobacter johnsonii (AJB15/B) were identified as useful bacterial species by 16S rRNA sequencing. Whereas, in casing soil (at 22-25 °C) Alcaligenes faecalis (AFB11) and Pseudomonas aeruginosa (PAB16/P) were identified as useful mesophiles. PAB16/P showed the strongest antagonistic activities against M. perniciosa (wet bubble disease) with the highest mycelial growth inhibition (91.89%), followed by BB-7 (76.39%). The other isolates, BSB1, BSB3, BSB5, PPB6, BCB8, and BSB13, also inhibited the growth of M. perniciosa by 61.11 to 72.55%. The degradation of wheat straw via six microbe complexes (MC-1 to MC-6) was monitored based on CO₂ release. The highest CO₂ release (174666.70 ppm) was recorded in MC-3 (a combination of PAB16/P, AJB15/B, AFB11, and BSB5) compared with the lowest in control (43166.60 ppm). Compost inoculated with MC-3 produced the highest crop yield (16.20 kg/100 kg substrate) whereas lowest in control (12.84 kg/100 kg substrate). MC-3 may be recommended for button mushroom compost, to manage wet bubble disease and increase crop yield.