Biogenic silver nanoparticles (AgNPs) were obtained throughout the fungal biosynthesis using extracellular filtrate of the epiphytic fungus B. ochroleuca and were incorporated in cotton and polyester fabrics by common impregnation procedure that was repeated once, twice or four times. Both fabrics were analyzed by scanning electron microscopy (SEM), and the effectiveness of impregnation was determined using inductively coupled plasma optical emission spectrometry (ICP OES). The AgNPs loaded fabrics showed potent antimicrobial activity on Staphylococcus aureus and Escherichia coli as well as on clinically relevant Candida albicans, Candida glabrata, and Candida parapsilosis, indicating that the AgNPs impregnation of cotton and polyester fabrics was efficient. AgNPs effectively inhibited the biofilm formation by Pseudomonas aeruginosa and was not toxic to Galleria mellonella larvae indicating a promising probability of biotechnological application.

Silver nanoparticles (AgNPs) are widely incorporated into different hygiene, personal care, and healthcare products. However, few studies have been undertaken to determine the effects of biogenic AgNPs on human health. The effect of biosynthesized AgNPs using the fungus Aspergillus tubingensis culture was evaluated on human umbilical vein endothelial cells (HUVECs), normal human fibroblasts (FN1), human hepatoma cells (HEPG2) and a Galleria mellonella model. HUVECs were more susceptible to biogenic AgNPs than normal fibroblasts FN1 and intense cytotoxicity was observed only for very high concentrations at and above 2.5 μM for both cells. Normal human fibroblasts FN1 exposed to AgNPs for 24 h showed viability of 98.83 ± 8.40% and 94.86 ± 5.50% for 1.25 and 2.5 μM, respectively. At 5 and 10 μM, related to the control, an increase in cell viability was observed being 112.66 ± 9.94% and 117.86 ± 8.86%, respectively. Similar results were obtained for treatment for 48 and 72 h. At 1.25, 2.5, 5 and 10 μM of AgNPs, at 24 h, HUVECs showed 51.34 ± 7.47%, 27.01 ± 5.77%, 26.00 ± 3.03% and 27.64 ± 5.85% of viability, respectively. No alteration in cell distribution among different cycle phases was observed after HUVEC and normal fibroblast FN1 exposure to AgNPs from 0.01 to 1 μM for 24, 48 and 72 h. Based on the clonogenic assay, nanoparticles successfully inhibited HEPG2 cell proliferation when exposed to concentrations up to 1 μM. In addition to that, AgNPs did not induce senescence and no morphological alteration was observed by scanning electron microscopy on the endothelial cells. In the larvae of the wax moth, Galleria mellonella, a model for toxicity, AgNPs showed no significant effects, which corroborates to the safety of their use in mammalian cells. These results demonstrate that the use of A. tubingensis AgNPs is a promising biotechnological approach and these AgNPs can be applied in several biomedical situations.

Burkholderia seminalis strain TC3.4.2R3 is an endophytic bacterium isolated from sugarcane roots that produces antimicrobial compounds, facilitating its ability to act as a biocontrol agent against phytopathogenic bacteria. In this study, we investigated the thermoregulation of B. seminalis TC3.4.2R3 at 28 °C (environmental stimulus) and 37 °C (host-associated stimulus) at the transcriptional and phenotypic levels. The production of biofilms and exopolysaccharides such as capsular polysaccharides and the biocontrol of phytopathogenic fungi were enhanced at 28 °C. At 37 °C, several metabolic pathways were activated, particularly those implicated in energy production, stress responses and the biosynthesis of transporters. Motility, growth and virulence in the Galleria mellonella larvae infection model were more significant at 37 °C. Our data suggest that the regulation of capsule expression could be important in virulence against G. mellonella larvae at 37 °C. In contrast, B. seminalis TC3.4.2R3 failed to cause death in infected BALB/c mice, even at an infective dose of 10 7 CFU.mL −1 . We conclude that temperature drives the regulation of gene expression in B. seminalis during its interactions with the environment.

No abstract