Development Bioproduct from Bacillus subtilis BS-DOA 24 strain for Controlling Bacterial Wilt of Ginger (Ralstonia solanacearum)

Abstract

A collection of 135 isolates of Bacillus subtilis was obtained from soil, manure and roots of chili, tobacco, banana, Siam tulip, potato and tomato across 9 provinces of Thailand. All isolates were laboratory tested for inhibiting growth of Ralstonia solanacearum. Eight isolates of B. subtilis viz. BS-DOA 24, BS-DOA 69, BS-DOA 97, BS- DOA 108, BS-DOA 114, BS-DOA 125 and BS-DOA 132 were found as effective antagonist of R. solanacearum. Afterward, the effectiveness of these 8 isolates was verified in the greenhouse experiment. Ginger rhizomes were soaked into solutions with 8 different isolates of B. subtilis before being planted in soil mixed with R. solanacearum . The results showed that only isolates of BS-DOA 24 and BS-DOA 123 could control the bacterial wilt in ginger for 60%. The BS-DOA 24 and BS-DOA 123 isolates were selected for the field experiment. Isolate of BS-DOA 24 suppressed the said disease in ginger for 68%. Thus, the BS-DOA 24 isolate of B. subtilis was selected to develop for R. solanacearum antagonist powder. The appropriate ratio of BS-DOA 24 bacteria per talcum was 1 : 4 (v/w) which induced the highest population of BS-DOA 24 to 1.1 x 10 10 CFU/g. After storing at ambient air (ca.30 °C) for 12 months and at 4 °C for 15 months, this antagonist powder showed the efficiency to control the bacterial wilt of ginger in greenhouse and wilt infested field up to 60 and 65%, respectively. The experiment was further carried out at the farmer’s field at Phetchabun Province, where the BS-DOA B. subtilis could control the disease of bacterial wilt for 62% with yield of 2,260 kg/rai (ca. 361.6 kg/ ha). The results suggest that antagonist powder based on BS-DOA 24 B. subtilis could be a potential source to control the bacterial wilt disease and for further commercial development.