A Study on the Survival Dynamics of Bacillus Subtilis in Water Using Green Fluorescent Protein Labeling

Abstract A cocktail formulation ( Bacillus subtilis -dimethomorph, DMBS) was developed with good control of Phytophthora blight of pepper and other crops based on the integration of biological and chemical control, which was composed of Bacillus subtilis strain BS and dimethomorph. On the basis of the general principles of the hydrolysis research of agro-chemicals, the survival dynamics of BS in the cocktail formulation of DMBS in de-ionized water, ground water, tap water, river water and raining water were studied using green fluorescent protein (GFP) labeling and bacteriological methods. The results showed that GFP labeling is an efficient method for detecting the survival of B. subtilis in all the five types of water. At the temperature of (25 ± 1) °C, the quantity of the bacteria in its single formulation (SF) and in DMBS rapidly decreased within 12 days of storage. After 12 days of incubation, the numbers of bacteria showed a fluctuating ascending or descending behavior with the extension of the storage. At the temperature of (50 ± 1) °C, the quantity of bacteria in both formulations quickly declined within 12 days of incubation in both autoclaved and un-autoclaved treatments. After that, the amount of bacteria tended to show a stabilizing or mildly descending behavior. The amount of bacteria slowly decreased in all the five types of water, the quantity was above 10 4 cfu ml −1 after incubation for 86 days under the conditions of (25 ± 1) °C and (50 ± 1) °C. The incubation temperature and autoclaved status had certain effects on the survival dynamics of B. subtilis in SF and in DMBS, whereas the amount of dimethomorph in DMBS had no remarkable effect on the changing behavior of the bacteria.