Evaluating the potential of electrolysed water for the disinfection of citrus fruit in packinghouses.

BACKGROUND: The largest and most profitable market for citrus is the production of fresh fruit. Xanthomonas citri subsp. citri is a Gram-negative plant pathogen and the etiological agent of citrus canker, one of the major threats to citrus production worldwide. In the early stages of infection, X. citri can attach to plant surfaces by means of biofilms. Biofilm is considered an essential virulence factor, which helps tissue colonization in plants. Thus, sanitization of citrus fruit is mandatory in packinghouses before any logistic operation as packing and shipment to the market. The aim of this study was to evaluate electrolysed water (EW) as a sanitizer for the disinfection of citrus fruit in packinghouses. RESULTS: Using a protocol to monitor cell respiration we show that EW, obtained after 8 and 9 min of electrolysis, sufficed to kill X. citri when applied at a concentration of 500 µL mL-1 . Furthermore, microscopy analysis, combined with time-response growth curves, confirmed that EW affects the bacterial cytoplasmatic membrane and it leads to cell death in the first few minutes of contact. Pathogenicity tests using limes to simulate packinghouse treatment showed that EW, produced with 9 min of electrolysis, was a very effective sanitizer capable of eliminating X. citri from contaminated fruit. CONCLUSION: It was possible to conclude that EW is significantly effective as sodium hypochlorite (NaClO) at 200 ppm. Therefore, EW could be an alternative for citrus sanitization in packinghouses. © 2020 Society of Chemical Industry.

Toxicological evaluation of vegetable oils and biodiesel in soil during the biodegradation process

Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida. are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa and lettuce (Lactuca sativa. to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

Toxicological evaluation of vegetable oils and biodiesel in soil during the biodegradation process.

Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida) are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa) and lettuce (Lactuca sativa) to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.