Nanomechanical resilience and thermal stability of RSJ2 phage.

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.

Curcuma longa ethanol extract and Curcumin inhibit the growth of Acanthamoeba triangularis trophozoites and cysts isolated from water reservoirs at Walailak University, Thailand.

CURCUMA LONGA: (C. longa) rhizome extract has been traditionally used to treat many infections. Curcumin, a pure compound isolated from the plant, has been documented to possess a wide spectrum of pharmacological effects. The present study aimed to investigate the effects of Thai medicinal plant extracts including C. longa extract and Curcumin on Acanthamoeba triangularis, a causative agent of human Acanthamoeba keratitis. The parasite was isolated from the recreational reservoir at Walailak University, Thailand. The organism was identified as A. triangularis using morphology and 18S rDNA nucleotide sequences. The pathogen was tested for their susceptibility to ethanol extracts of Thai medicinal plants based on eye infection treatment. The ethanol C. longa extract showed the strongest anti-Acanthamoeba activity against both the trophozoites and cysts, followed by Coscinium fenestratum, Coccinia grandis, and Acmella oleracea extracts, respectively. After 24 h, 95% reduction of trophozoite viability was significantly decreased following the treatment with C. longa extract at 125 µg/mL, compared with the control (P < 0.05). The extract at 1,000 µg/mL inhibited 90% viability of Acanthamoeba cyst within 24 h, compared with the control. It was found that the cysts treated with C. longa extract at 500 µg/mL demonstrated abnormal shape after 24 h. The MIC values of C. longa extract and Curcumin against the trophozoites were 125 and 62.5 µg/mL, respectively. While the MICs of the extract and curcumin against the cysts were 500 and 1,000 µg/mL, respectively. The results suggested the potential medicinal benefits of C. longa extract and Curcumin as the alternative treatment of Acanthamoeba infections.

Acanthamoeba in Southeast Asia - Overview and Challenges.

Acanthamoeba, one of free-living amoebae (FLA), remains a high risk of direct contact with this protozoan parasite which is ubiquitous in nature and man-made environment. This pathogenic FLA can cause sight-threatening amoebic keratitis (AK) and fatal granulomatous amoebic encephalitis (GAE) though these cases may not commonly be reported in our clinical settings. Acanthamoeba has been detected from different environmental sources namely; soil, water, hot-spring, swimming pool, air-conditioner, or contact lens storage cases. The identification of Acanthamoeba is based on morphological appearance and molecular techniques using PCR and DNA sequencing for clinico-epidemiological purposes. Recent treatments have long been ineffective against Acanthamoeba cyst, novel anti-Acanthamoeba agents have therefore been extensively investigated. There are efforts to utilize synthetic chemicals, lead compounds from medicinal plant extracts, and animal products to combat Acanthamoeba infection. Applied nanotechnology, an advanced technology, has shown to enhance the anti-Acanthamoeba activity in the encapsulated nanoparticles leading to new therapeutic options. This review attempts to provide an overview of the available data and studies on the occurrence of pathogenic Acanthamoeba among the Association of Southeast Asian Nations (ASEAN) members with the aim of identifying some potential contributing factors such as distribution, demographic profile of the patients, possible source of the parasite, mode of transmission and treatment. Further, this review attempts to provide future direction for prevention and control of the Acanthamoeba infection.