Antifungal activity of Lysinibacillus macroides against toxigenic Aspergillus flavus and Fusarium proliferatum and analysis of its mycotoxin minimization potential.

BACKGROUND: Toxigenic fungi (Aspergillus and Fusarium) and their metabolites represent the major cause of corn and corn-based products contamination and consequently lead to severe economic and health issues. AIM: Our current study aimed to investigate the efficacy of using L. macroides Bac6 as a biological control agent against the toxigenic fungi; A. flavus f10 and F. proliferatum f30 and their mycotoxins. RESULTS: The results illustrated that A. flavus f10 produced the aflatoxins AFB1 and AFG2 with concentrations of 21.239 and 13.593 ppb, respectively. While F. proliferatum f30 produced fumonisin B1 (9600 ppb). Furthermore, L. macroides showed a high potential for inhibition of toxigenic fungal growth using a dual culture method. F. proliferatum f30 and A. flavus f10 were found to be inhibited by a percentage of 80 and 62.5%, respectively. The results were confirmed using the scanning electron microscope. The antagonistic bacteria, L. macroides, showed chitinase productivity and activity of 26.45 U/L and 0.12 U/mL/min, respectively, which illustrates its potential application as a biocontrol agent. The GC-MS analysis revealed an abundance of Pyrrolo[1,2-a] pyrazine-1,4-dione, Hexahydro in the bacterial supernatant that exhibited antifungal characteristics. L. macroides had a significant reduction of AFB1 and AFG2 produced by A. flavus f10, recording 99.25% and 99% inhibition, respectively. It also showed strong inhibition of fumonisin B1 (90% inhibition) produced by F. proliferatum f30. CONCLUSION: Thus, the current study is a prospective study evaluating for the first time the potential impact of L. macroides Bac6 against the toxigenic fungi and their toxins.

Fungicidal activities and molecular docking of the marine alga Ulva lactuca and Punica granatum peel extracts on Alternaria tomato spot disease.

In this study, we utilized pomegranate peel and marine algae Ulva lactuca (U. lactuca) as rich and sustained sources of bioactive compounds to combat tomato-black spot disease. n-Hexane extracts from the peel of pomegranate (Punica granatum) (PPE) and the marine algal biomass U. lactuca (ULE) were used alone and in combinations to verify their impact against Alternaria alternata (A. alternata). The applied extracts exhibited severe destructive effects on both fungal growth and structure such as mycelia malformation, underdeveloped conidia, cell wall deformation, and shrinkage. Moreover, increased deformations and protrusions, and notch-like structures, were noticed in A. alternata mycelia treated with mixed extracts (PPE and ULE) compared to all other treatments. The protein and reduced sugar contents in tomato fruits were significantly increased in the infected fruits with A. alternata. The highest enzyme activities of pectinase, cellulase, catalase (CAT), and ascorbate peroxidase (APX) were recorded in infected tomatoes in comparison with the healthy ones. Molecular docking studies showed that each extract is rich with bioactive compounds that have a promising inhibition effect on A. alternata cellulases. Pomegranate and Ulva extract showed promising antifungal activity against A. alternata which revealed their feasibility and applicability as biocontrol agents in postharvest disease management and food preservation against fungal pathogens.

Exposure to pyrogallol impacts the hemato-biochemical endpoints in catfish (Clarias gariepinus).

Pyrogallol is widely used in several industrial applications and can subsequently contaminate aquatic ecosystems. Here, we report for the first time the presence of pyrogallol in wastewater in Egypt. Currently, there is a complete lack of toxicity and carcinogenicity data for pyrogallol exposure in fish. To address this gap, both acute and sub-acute toxicity experiments were conducted to determine the toxicity of pyrogallol in catfish (Clarias gariepinus). Behavioral and morphological endpoints were evaluated, in addition to blood hematological endpoints, biochemical indices, electrolyte balance, and the erythron profile (poikilocytosis and nuclear abnormalities). In the acute toxicity assay, it was determined that the 96 h median-lethal concentration (96 h-LC50) of pyrogallol for catfish was 40 mg/L. In sub-acute toxicity experiment, fish divided into four groups; Group 1 was the control group. Group 2 was exposed to 1 mg/L of pyrogallol, Group 3 was exposed to 5 mg/L of pyrogallol, and Group 4 was exposed to 10 mg/L of pyrogallol. Fish showed morphological changes such as erosion of the dorsal and caudal fins, skin ulcers, and discoloration following exposure to pyrogallol for 96 h. Exposure to 1, 5, or 10 mg/L pyrogallol caused a significant decrease in hematological indices, including red blood cells (RBCs), hemoglobin, hematocrit, white blood cells (WBC), thrombocytes, and large and small lymphocytes in a dose-dependent manner. Several biochemical parameters (creatinine, uric acid, liver enzymes, lactate dehydrogenase, and glucose) were altered in a concentration dependent manner with short term exposures to pyrogallol. Pyrogallol exposure also caused a significant concentration-dependent rise in the percentage of poikilocytosis and nuclear abnormalities of RBCs in catfish. In conclusion, our data suggest that pyrogallol should be considered further in environmental risk assessments of aquatic species.

Biosafe Management of Botrytis Grey Mold of Strawberry Fruit by Novel Bioagents.

Recently, there have been urgent economic and scientific demands to decrease the use of chemical fungicides during the treatment of phytopathogens, due to their human health and environmental impacts. This study explored the biocontrol efficacy of novel and eco-friendly preen (uropygial) oil and endophytic Bacillus safensis in managing postharvest Botrytis grey mold in strawberry fruit. The preen oil (25 µL/mL) showed high antifungal activity against B. cinerea Str5 in terms of the reduction in the fungal radial growth (41.3%) and the fungal colony-forming units (28.6%) compared to the control. A new strain of Bacillus safensis B3 had a good potential to produce chitinase enzymes (3.69 ± 0.31 U/mL), hydrolytic lipase (10.65 ± 0.51 U/mL), and protease enzymes (13.28 ± 0.65 U/mL), which are responsible for the hydrolysis of the B. cinerea Str5 cell wall and, consequently, restrict fungal growth. The in vivo experiment on strawberry fruit showed that preen (uropygial) oil reduced the disease severity by 87.25%, while the endophytic bacteria B. safensis B3 reduced it by 86.52%. This study reports the efficiency of individually applied bioagents in the control of phytopathogenic fungi for the first time and, consequently, encourages their application as a new and innovative strategy for prospective agricultural technology and food safety.