Modified Growth Media of Bacillus amyloliquefaciens S20A1 and Biocontrol of Bacterial Leaf Blight of Rice

Abstract

The effective and high cost of general culture media under laboratory conditions is a major challenge for mass production of biological control agents. Generally, beans (Leguminosae) are wellknown crop with highly nutrient contents that could be supported the growth of bacteria. The study was conducted to develop the alternative low cost of media from locally available beans (black bean, mung bean and soybean) for enhance the capacity of the multiplication and biocontrol activities of Bacillus amyloliquefaciens S20A1, the effective antagonistic bacterial strain, to control bacterial leaf blight disease (BLB) of rice caused by Xanthomonas oryzae pv. oryzae. Maximum cell growth and percentage of BLB disease reduction was observed at two modified media formula, black bean + soybean mixture medium (BS) at the ratio of 1:1 and mung bean + soybean mixture medium (MS) (1:1 ratio) with 1.00 x 1010 CFU /mL and 63.10%, and 1.3 x 1010 CFU /mL and 63.82%, respectively when comparing with the general culture condition that showed 3.6 x 109 CFU/mL and 61.68% disease reduction. The composition of 30 grams mixed bean powder per liter of both modified media and then incubated on 150 rpm rotary shaker for 36 hours were the effective culture. The cost per liter of media was reduced 22 times and 19 times comparing with LB medium, readymade laboratory medium. Two bean powder extract media (BS and MS) also used for the cell multiplication and promotion of the biocontrol activities of fresh cell but also for formulated of strain S20A1 to control the bacterial leaf blight disease of rice. This study could provide reliable basis for small scale production and a scale-up to the industrial level.