In vitroantibacterial activity and antifungal mode of action of flocculosin, a membrane-active cellobiose lipid

Abstract

Aims: To investigate the in vitro antibacterial activity and antifungal mode of action of flocculosin, a cellobiose lipid produced by Pseudozyma flocculosa. Methods and Results: When tested against clinical bacterial isolates, the compound was particularly active against Gram‐positive bacteria and its effect was not mitigated against isolates known as resistant to other antibiotics. The antifungal activity of flocculosin was found to be rapid and concentration‐dependent. At lethal concentrations against Candida albicans, flocculosin caused a rapid leakage of intracellular potassium and inhibited acidification of the medium by plasma membrane ATPases suggesting a physical rather than a biochemical effect. TEM observations of cells exposed 6 h to flocculosin revealed disrupted membranes and disorganized mitochondria. Conclusions: Data obtained in this study confirm that flocculosin acts by disrupting the membrane surface of sensitive micro‐organisms. Significance and Impact of the Study: The elucidation of an antifungal mode of action of flocculosin can be exploited in furthering its antimicrobial potential against fungi and bacteria whose cell membranes are particularly sensitive to the action of the molecule.

The Transition from a Phytopathogenic Smut Ancestor to an Anamorphic Biocontrol Agent Deciphered by Comparative Whole-Genome Analysis

“…These proteins were recently determined to exhibit structural similarities to cytolytic toxins produced by marine organisms (actinoporins), which forms transmembrane pores (Ottmann et al, 2009). Interestingly, the rapid collapse of powdery mildew colonies by P. flocculosa has always been associated with an alteration of the plasma membrane and cytoplasmic leaking (Hajlaoui and Bélanger, 1991;Hajlaoui et al, 1994;Mimee et al, 2009). Thus, NPP1-containing proteins could be key elements explaining the antagonism of P. flocculosa toward powdery mildews.…”

Biosurfactants and Bioemulsifiers Biomedical and Related Applications – Present Status and Future Potentials

“…In nature, flocculosin is part of P. flocculosa biocontrol arsenal against other fungi. Recent reports however have suggested that flocculosin is also used by P. flocculosa as a nutrient source when experiencing food limitation and the molecule is rapidly deacylated under alkaline conditions losing its antimicrobial activity which may explain conflicting results concerning the antimicrobial activity of this class of glycolipids (Mimee et al, 2009). Other antifungal activity of biosurfactants against phytopathogenic fungi has also been described.…”

“…Another glycolipid, flocculosin, a cellobiose lipid produced by the yeast-like fungus Pseudozyma flocculosa, was particularly effective against Staphylococcus species, including MRSA. Its antibacterial activity was not influenced by the presence of common resistance mechanisms against methicillin and vancomycin and it was able to eliminate C. albicans cells in a very short period of time (Mimee et al, 2009). Trehalose lipids produced by Tsukamurella sp.…”

The Antibiotic and Membrane-damaging Activities of Cellobiose Lipids and Sophorose Lipids

“…humicola strain 9-6 kindly provided by Dr. W. Golubev was grown for 14 days in the medium described previously 8 . The glycolipid was purified from the culture liquid by precipitation at acidic pH values 17 . After the cultivation, the pH value of the medium was adjusted to 2.0 with 2N HCl, and the solution was incubated for 30 min for glycolipid absorption on the biomass.…”