New insights in Trichoderma harzianum antagonism of fungal plant pathogens by secreted protein analysis.

Trichoderma harzianum ALL42 were capable of overgrowing and degrading Rhizoctonia solani and Macrophomina phaseolina mycelia, coiling around the hyphae with formation of apressoria and hook-like structures. Hyphae of T. harzianum ALL42 did not show any coiling around Fusarium sp. hyphae suggesting that mycoparasitism may be different among the plant pathogens. In this study, a secretome analysis was used to identify some extracellular proteins secreted by T. harzianum ALL42 after growth on cell wall of M. phaseolina, Fusarium sp., and R. solani. The secreted proteins were analyzed by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. A total of 60 T. harzianum ALL42 secreted proteins excised from the gel were analyzed from the three growth conditions. While seven cell wall-induced proteins were identified, more than 53 proteins spots remain unidentified, indicating that these proteins are either novel proteins or proteins that have not yet been sequenced. Endochitinase, ß-glucosidase, α-mannosidase, acid phosphatase, α-1,3-glucanase, and proteases were identified in the gel and also detected in the supernatant of culture.

Susceptibility of human pathogenic bacteria to antimicrobial peptides from sesame kernels.

Hospital infection caused by Gram-negative bacteria is a serious and common problem, especially in developing countries. Aiming to reduce these infections, this report focuses on the identification and characterization of novel antimicrobial peptides from sesame (Sesamum indicum) kernel meals. Thus, sesame flour was extracted and precipitated with ammonium sulfate (100%). After dialysis, a rich fraction was applied to affinity red-Sepharose CL-6B chromatography, followed by reversed-phase high-performance liquid chromatography. Mass spectrometry analysis indicated the presence of a major peptide with molecular mass of approximately 5.8 kDa in both cultivars. The bactericidal activities of antimicrobial peptides were evaluated against several human pathogens that had been effective only against Klebsiella sp., a Gram-negative bacterium responsible for human urinary infection. These data indicate the biotechnological potential of sesame peptides as an alternative method for hospital infection control and also the decrease of bacterial resistance to synthetic antibiotics.