Fig 1.
Extracts from T. asperelloides exhibit antibacterial activity.
Bacterial growth curve of S. aureus ATCC 29213 (a, b and c), ATCC 6538 (d, e and f) and clinical isolate 184 (g, h and i), all treated in a period from 2, 4, 6, 8, 24 and 48 hours, with TE, HWF and LWF in 0.5 μg mL-1, 1.1 μg mL-1, 2.3 μg mL-1and 4.6 μg mL-1concentrations. n = 3, in triplicate. TE: total extract; HWF: high weight fraction; LWF: low weight fraction. For the clinical isolate, higher concentration (1.1 μg mL-1 or above) of TE was required to control bacteria growth comparably to gentamicin (Fig 1G). However, HWF was effective on controlling the clinical isolate growth even in low concentration (Fig 1G). Interestingly, the LWF of the ethanolic extract had a poor performance in controlling S. aureus (Fig 1C, 1F, and 1I).
Fig 2.
High weight fraction of T. asperelloides efficiently eradicates S. aureus biofilm.
Staphylococcus biofilm growth was evaluated by absorbance in ATCC 29213 (a, d and g), ATCC 6538 (b, e and h) and clinical isolate 184 (c, f and i), after 24 hours in different concentrations. Control represents non-treated biofilm. The gentamicin-treated biofilm was at concentration of 4.6 μg mL-1. n = 3, in triplicate; numbers inside columns represent the mean and error bars represent standard deviation. TE: total extract; HWF: high weight fraction; LWF: low weight fraction.
Fig 3.
Qualitative evaluation of T. asperelloides antibiotic activity.
Biofilm of S. aureus strain ATCC 29213 was treated for 24 hours T. asperelloides extracts. Dilutions 1:10 of this biofilm were ressuspended in 0.9% NaCl and were cultured in Petri dish containing trypticsoy agar medium for 24 hours. The control represents untreated biofilm. The biofilm treated with gentamicin was at 4.6 μg mL-1. TE: total extract; HWF: high weight fraction; LWF: low fraction of weight.
Fig 4.
Trichoderma extracts reduce S. aureus biomass.
Biomass was evaluated by crystal violet method. Microtiter plates were photographed under an optical microscope and quantified by a microplate reader at 570 nm. Biofilms formed after 24 hours were treated with TE and HWF at 2.3 μg mL-1. The control represents untreated biofilm. The biofilm treated with gentamicin was at 4.6 μg mL-1. n = 3, in triplicate; numbers within the columns represent the mean and error bars represent standard deviation. TE: total extract; HWF: high weight fraction.
Fig 5.
Extract from Trichoderma damages S. aureus cell wall.
Effect of 24-hour treatment with high weight fraction of T. asperelloides on biofilms formed by S. aureus ATCC 29213, clinical isolate 184 and non-biofilm-forming S. epidermidis ATCC 12228. Scanning electron microscope images (top part of each image) and transmission electron microscope (bottom part). The images a, b and c were obtained from untreated biofilm (control); the images d, e and f were obtained from biofilm treated with gentamicin; and the images g, h and i were obtained from biofilm treated with T. asperelloides high weight fraction (HWF). The arrows indicate damaged cells.