Search

As the world moves toward a green economy and sustainable agriculture, bacterial viruses or bacteriophages (phages) become attractive biocontrol agents for controlling crop diseases. Effective utilization of phages in farms requires integrated knowledge of crops, pathogens, phages, and surroundings. Phages must encounter environmental fluctuations, including temperature, and must remain infectious for successful bacteria lysis. This work studied a soilborne RSJ2 phage discovered in Thailand, which can eliminate Ralstonia solanacearum, causing bacterial wilt disease in chili. We investigated how phage infectivity and nanomechanics responded to thermal changes. The plaque-based assay showed that the infectivity of the RSJ2 phage was stable within 24-40 °C, an average temperature fluctuation in tropical regions. The structural examination also showed that the phage remained intact. The nanomechanical property of the phage was inspected by the atomic force microscopy-based nanoindentation. The result revealed that the phage stiffness within 24-40 °C was statistically similar (0.05-0.06 N/m). Upon heating at 40 °C for 1, 5, and 10 h and resting at 25 °C, the stiffness of the phage particles increased to 0.09-0.11 N/m (54-83% increase). The stiffness results suggest structural adaptation of the protein subunits as a response to thermal alteration. The study exhibits that the phage structure is highly dynamic and can nanomechanically respond to varying temperatures. The phage stiffness may reveal insight into phage adaptation to environmental factors. Equipped with the knowledge of phage infectivity, structure, and nanomechanics, we can design practical guidelines for effective phage usage in farming and propelling green and safe agriculture., (© 2024. The Author(s).)

The urgent necessity of reducing pesticides in the agricultural sector compels us to explore alternative, environmentally friendly approaches for controlling pathogenic bacteria and crop diseases. The usage of bacterial viruses or bacteriophages (phages) to control pathogenic bacteria is still limited due to the lack of understanding of the factors influencing shelf life. We examined the effects of pH and NaCl on the storage buffers on the infectivity of the RSJ2 phage. The RSJ2 phage infects Ralstonia solanacearum, causing bacterial wilt disease in tomatoes. The buffer that retained the highest phage titer (63 % after two months) was at pH 8.3 and 0.5 M NaCl. pH and NaCl concentrations directly affected the phage particles. The phage stiffness was measured with the nanoindentation technique, and a correlation between the phage remaining titers and the stiffness was revealed. The average stiffness associated with the highest remaining titer was 0.07 N/m, which falls into the intermediate stiffness range. The results agree with the previous study on the C22 phage stiffness, revealing an association between intermediate stiffness and phage infectivity. Phage stiffness can become an attribute of phage metastability and can be used to predict the phage shelf life. [ABSTRACT FROM AUTHOR]