Impact of Cationic and Neutral Gemini Surfactants on Conidia and Hyphal Forms of Aspergillus brasiliensis

Abstract

This study investigates the biological activity of two cationic gemini surfactants, hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide) C6 and pentamethylene-1,5-bis-(N,N-dimethyl-N-dodecylammonium bromide) C5, and their two neutral analogs, hexamethylene-1,6-bis-(N-methyl-N-dodecylamine) (A6) and pentamethylene-1,5-bis-(N-methyl-N-dodecylamine) (A5). Experiments were performed with Aspergillus brasiliensis, which is used in the standard tests for biocides. The minimal inhibitory concentration (MIC) values for conidia and mycelium were determined using the dilution method. The viability of the conidia was evaluated using the plate count method. The dry mass of the mycelium was determined using the thermogravimetric method. Ergosterol was extracted from the mycelium and evaluated by gas chromatography. The effect of gemini surfactants on fungal morphology was observed using scanning electron microscopy. Cationic gemini surfactants were found to be active at lower concentrations compared to their non-ionic analogues, rapidly reducing the total number of conidia that were able to grow. They also decreased both the ergosterol content in the mycelium and its dry weight. These results suggest that cationic gemini surfactants C6 and C5 could have a wide range of practical applications as active compounds. However, it should be remembered that usage at too low concentrations, below the MIC, will only lead to short-term disturbances in the development of conidia and mycelium.

Remediation of Artificially Hydrocarbon Polluted Vadose Zone Soil in Glass Column through Percolation with Solution of Nutrient, Nutrient-Surfactant or Surfactant

“…Selected surfactants have been shown by Chen et al, (2006) to restrain the degradation of polycyclic aromatic hydrocarbons by white-rot fungi. In other related studies, surfactants have been shown to inhibit spore germination and ergosterol production by fungi (Kozirog et al, 2018;Mwamburi et al, 2015;Tanuja et al, 2010). It can thus be generalized that surfactants puts a pressure on the hydrocarbon degrading ability of fungi, and this pressure can be relaxed in the presence of nutrients as observed in this study.…”

Hydroxytyrosol (HT) Analogs Act as Potent Antifungals by Direct Disruption of the Fungal Cell Membrane

“…); therefore, their activity is due partly to the ability of these molecules to function as nonionic surfactants (surface-active compounds), disrupting the fungi membrane. The mechanism by which surfactants exert their activity is not entirely understood, it is, however, hypothesized that, due to their amphiphilic character, they are inserted into the fungi lipid bilayer (possibly in other microbial membranes also), where they elicit an immediate destruction effect ( Kubo et al, 2001a ; Koziróg et al, 2018 ). In that aspect, the amphiphilic character of the HT analogs presented in this work and the experimental evidence for rapid destruction of the fungus membrane allow us to reasonably assume that they act primarily as nonionic surfactants, though other additional molecular interaction could account for the final effect.…”

Current and future chemical treatments to fight biodeterioration of outdoor building materials and associated biofilms: Moving away from ecotoxic and towards efficient, sustainable solutions

“…For these reasons, such compounds are very attractive as biocides in materials science, especially when they expose ammoniums as polar groups (Brycki et al, 2017;Tyagi and Tyagi, 2009). For instance, the antifungal activity of cationic gemini surfactants has been recently demonstrated against 22 Aspergillus brasiliensis by measuring the content of ergosterol, a method used to estimate the level of mold infestation in buildings (Koziróg et al, 2018). Additionally, it has been shown that the antimicrobial efficiency of these compounds depends on the length and type of spacer as well as their hydrophobic counterpart.…”