Anthony J. De Lucca

Hongos patógenos communes en la Agricultura y la Medicina

Resumen La mayoria de los hongos son saprobios y no patogenos de plantas, animals y humanos. Sin embargo, un numero relativamente pequeno de especies fungicas son fitopatogenas, causan efermedad humana (por ejemplo, infecciones, alergias), y producen toxinas que afectan a plantas, animales y humanos. Entre los hongos patogenos estan los miembros de los generos Aspergillus y Fusarium junto con otros generos (por ejemplo, Alternaria, Mucor) que son denominados “patogenos fungicos emergentes”. Estos hongos representan una amenaza comun tanto para la produccion agricola como para la salud de las personas sanas o inmunodeficientes. En conjunto, estos hongos pueden causar enormes perdidas economicas en la agricultura, perdidas alimenticias por deterioro, y enfermedades humanas y animales graves, a menudo fatales. Las plantas pueden ser origen de estos compuestos antifungicos porque estos necesitan desarrollarlos para resistir las infecciones por hongos presentes en su ambiente.

Antifungal peptides: potential candidates for the treatment of fungal infections.

Many diversely produced natural peptides, as well as those produced semisynthetically and synthetically, have been found to inhibit the growth or even be lethal to a wide range of fungi. Some of these have the potential to aid mankind in combating mycoses caused by emerging pathogens or as a result of the increasing number of antibiotic-resistant fungi. Antifungal peptides may also assist in non-medical fields such as agriculture. For example, introduction by transgenic research of antifungal peptides could improve crop production yields by increasing host resistance to fungal invasion. The aim of this review is to provide information on research on these important peptides.Many diversely produced natural peptides, as well as those produced semisynthetically and synthetically, have been found to inhibit the growth or even be lethal to a wide range of fungi. Some of these have the potential to aid mankind in combating mycoses caused by emerging pathogens or as a result of the increasing number of antibiotic-resistant fungi. Antifungal peptides may also assist in non-medical fields such as agriculture. For example, introduction by transgenic research of antifungal peptides could improve crop production yields by increasing host resistance to fungal invasion. The aim of this review is to provide information on research on these important peptides.

Binding between lipopolysaccharide and cecropin A

Cecropin A (CA), a bioactive peptide, produced significant lethality toPantoea agglomerans (PA) at low concentrations. Significant mortality occurred immediately after addition of CA. Separate preincubations of lipopolysaccharides (LPS) from the following bacteria: PA,Serratia marcescens, Escherichia coli (EC), andSalmonella typhimurium with CA were performed prior to the bioassay. CA was also preincubated with diphosphoryl lipid A (DPL-A) from EC andS. minnesota (SM), trilinolein, palmitic, lauric and myristic acids (fatty acids contained in the lipid A of PA-LPS) and bovine brain gangliosides. Spectral analyses to determine the interaction between glycosphingolipids (sphingomyelin, bovine brain gangliosides, and galactocerebrosides) and CA were performed. Results showed that all types of LPS and DPL-A as well as the gangliosides studied blocked CA lethality to PA. The level of inhibition of CA antibacterial properties was dependent on LPS and DPL-A concentration. The individual fatty acids and trilinolein did not affect CA lethality to PA. Spectral studies showed complexation between CA and PA-LPS, both types of DPL-A, and the glycosphingolipids. Biological and chemical analyses confirm that CA binds to the diphosphoryl lipid A moiety of LPS.

Fungicidal and Bactericidal Properties of Bisabolol and Dragosantol

Abstract α-Bisabolol, a natural plant sesquiterpene alcohol, and dragosantol, a racemic mixture of synthetic bisabolol, were studied for their fungicidal properties separately against the nongerminated and germinating conidia of several species of Aspergillus and Fusarium which represent problems in agriculture and medicine. Bactericidal assays against Pseudomonas aeruginosa and Staphylococcus aureus were also performed. Compared to the controls, both compounds displayed statistically significant (p < 0.001) lethality for the tested microorganisms. α-Bisabolol and dragosantol produced nearly 98% viability loss against the germinating conidia of A. flavus, A. fumigatus, A. niger, A. terreus, F. oxysporum, F. solani, and F. verticillioides (formerly F. moniliforme) at, or below, 10 μM. The viability of nongerminated F. oxysporum conidia was significantly reduced. Both compounds showed very rapid and significant reduction of P. aeruginosa viability at 7.5 μM. Staphylococcus aureus was more resistant to these compounds though significant viability loss occurred after 2 h incubation at 12.5 μM. Minimum inhibition concentration studies (NCCLS Method-38A) showed that bisabolol inhibited the growth of clinical isolates of the dermatophytic pathogens Trichophyton tonsurans (2–8 μg/mL), T. mentogrophytes (2–4 μg/mL), T. rubrum (0–1 μg/mL) and Microsporum canis (0.5–2.0 μg/mL). Results showed α-bisabolol and dragosantol have potent fungicidal and bactericidal properties against the tested strains. Because both compounds are safe for use in cosmetics, the data presented here suggest potential utility as antimicrobials in cosmetics, food and as a topical antifungal treatment

Antifungal Properties of Wheat Histones (H1-H4) and Purified Wheat Histone H1

Wheat ( Triticum spp.) histones H1, H2, H3, and H4 were extracted, and H1 was further purified. The effect of these histones on specific fungi that may or may not be pathogenic to wheat was determined. These fungi included Aspergillus flavus , Aspergillus fumigatus , Aspergillus niger , Fusarium oxysporum , Fusarium verticillioides , Fusarium solani , Fusarium graminearum , Penicillium digitatum , Penicillium italicum , and Greeneria uvicola . Non-germinated and germinating conidia of these fungi were bioassayed separately. The non-germinated and germinating conidia of all Fusarium species were highly susceptible to the mixture (H1-H4) as well as pure H1, with viability losses of 99-100% found to be significant (p < 0.001) at ≤10 μM or less for the histone mixture and pure H1. F. graminearum was the most sensitive to histone activity. The histones were inactive against all of the non-germinated Penicillium spp. conidia. However, they significantly reduced the viability of the germinating conidia of the Penicillium spp. conidia, with 95% loss at 2.5 μM. Non-germinated and germinating conidia viability of the Aspergillus spp. and G. uvicola were unaffected when exposed to histones up to 10 μM. Results indicate that Fusarium spp. pathogenic to wheat are susceptible to wheat histones, indicating that these proteins may be a resistance mechanism in wheat against fungal infection.

Efficacy of bait supplements for improving the rate of discovery of bait stations in the field by Formosan subterranean termites (Isoptera: Rhinotermitidae).

ABSTRACT Field tests of four different bait supplements were conducted in City Park, New Orleans, LA. The four bait supplements tested included two different formulations of decayed material, a sports drink, and the combination of an application of an aqueous solution of Summon Preferred Food Source disks with the disk itself. Although all the bait supplements in this study resulted in a slightly greater number of treated stations discovered compared with control stations, only the application of the aqueous solution combined with the disk caused a significant increase in the number of stations discovered by termites. This treatment resulted in a significantly greater rate of discovery of treated stations versus control stations after only 14 d in the field. Termites were able to discover six times as many treated as control stations after 14 d, 9 times as many after 28 d, and 12 times as many after 42 d. These findings provide evidence that the diffusion of an aqueous solution into the soil underneath monitoring stations significantly decreased the length of time required for termites to infest stations.

Silver enhances the in vitro antifungal activity of the saponin, CAY-1

The fungicidal properties of purified CAY‐1, dissolved silver ion and ethylenediamine tetraacetic acid (EDTA) separately were studied in vitro as were the abilities of silver and EDTA to enhance CAY‐1 fungicidal properties. Non‐germinated and germinating conidia of Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium verticillioides (Fusarium moniliforme), Fusarium oxysporum and Fusarium solani were incubated separately with CAY‐1 (0–24.8 μg ml−1), silver (0–111.1 μg ml−1), and EDTA (0–2400 μg ml−1). Controls consisted of non‐germinated or germinated conidia in test medium. To assess combined activity, compounds, based on the sub‐lethal doses of each as defined in the initial experiments, were combined and tested in bioassays. Controls for the mixed sets consisted of non‐germinated or germinated conidia only or with the sub‐lethal CAY‐1 test concentrations. The minimum inhibitory concentrations (MICs) for CAY‐1 and silver, both separate and combined, were determined. Viability assays showed CAY‐1 activity only against the germinating conidia of A. flavus, A. niger and F. solani. Silver was active against the germinating conidia of all fungi and the non‐germinated conidia of F. oxysporum and F. solani. Combined silver and CAY‐1 produced significant viability loss at concentrations not effective separately. EDTA was not fungicidal separately and did not enhance CAY‐1 fungicidal properties. MIC data showed that CAY‐1 plus silver had an additive effect. Results indicate that dissolved silver was fungicidal in vitro and enhanced the fungicidal properties of CAY‐1 at concentrations ineffective when tested separately.