• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.87-94
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• 2018

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at $22^{\circ}C$ and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1613-1620
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• 2012

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.