No abstract

Endophytes are microorganisms that live asymptomatically inside plant tissues. They are beneficial to their host in many aspects, especially as a defense against foreign phytopathogens through the production of a variety of metabolites. These substances can serve as sources of new natural products for medicinal, agricultural, and industrial purposes. This article is focused on endophytic fungi from Vitis vinifera. The purpose of the research was their isolation and identification during the Vitis vinifera growing season. Subsequently, the isolates were tested for the production of biotechnologically interesting metabolites (siderophores, antioxidants, and antifungal compounds). In total, 24 endophytic fungi were isolated, the most represented genus was Cladosporium sp. The results of the test for antioxidant and antifungal properties, as well as siderophore production, have shown that the population of Vitis vinifera endophytic microscopic fungi could serve as a promising source of metabolites with a wide range of applications.

Vitis vinifera canes are waste material of grapevine pruning and thus represent cheap source of high-value polyphenols. In view of the fact that resistance of many pathogenic microorganisms to antibiotics is a growing problem, the antimicrobial activity of plant polyphenols is studied as one of the possible approaches. We have investigated the total phenolic content, composition, antioxidant activity, and antifungal activity against Candida biofilm of an extract from winter canes and a commercially available extract from blue grapes. Light microscopy and confocal microscopy imaging as well as crystal violet staining were used to quantify and visualize the biofilm. We found a decrease in cell adhesion to the surface depending on the concentration of resveratrol in the cane extract. The biofilm formation was observed as metabolic activity of Candida albicans, Candida parapsilosis and Candida krusei biofilm cells and the minimum biofilm inhibitory concentrations were determined. The highest inhibition of metabolic activity was observed in Candida albicans biofilm after treatment with the cane extract (30 mg/L) and blue grape extract (50 mg/L). The composition of cane extract was analyzed and found to be comparatively different from blue grape extract. In addition, the content of total phenolic groups in cane extract was three-times higher (12.75 gGA/L). The results showed that cane extract was more effective in preventing biofilm formation than blue grape extract and winter canes have proven to be a potential source of polyphenols for antimicrobial and antibiofilm treatment.

Glycosphingolipids in filamentous fungi are significant components of the plasma membrane and are vital for different cellular processes, such as growth, morphological transition or signal transduction. Fungal growth inhibitors targeting glycosylinositolphosphoceramide (GIPCs) biosynthesis or antifungal compounds binding to GIPCs present in membranes could present a safe way of preventing fungal growth on crops since GIPCs are not present in mammalian cells. Mass spectrometry-based shotgun lipidomics was used to analyze sphingolipids of 11 fungal strains isolated from plant material. Molecular species with inositol ceramides containing zero to five carbohydrates were identified. Differences in the amount of individual molecular species were influenced by the taxonomic affiliation. All tested strains exhibited a relatively high content (more than 40 mol.%) of GIPCs with three and more saccharides attached to the polar head. It could be assumed that the sphingolipid profiles of the tested plant pathogens would be an adaptation mechanism to antifungal plant defensins.

Microbial biofilms formed by pathogenic and antibiotic-resistant microorganisms represent a serious threat for public health in medicine and many industrial branches. Biofilms are involved in many persistent and chronic infections, the biofouling of water and food contamination. Therefore, current research is involved in the development of new treatment strategies. Biofilm is a complex system, and thus all aspects of the measurement and monitoring of its growth and eradication in various conditions, including static and dynamic flow, are issues of great importance. The antibiofilm character of rhamnolipid mixtures produced by four Pseudomonas aeruginosa strains was studied under different conditions. For this purpose, the biofilm of opportunistic pathogen Trichosporon cutaneum was used and treated under static conditions (microscope glass coverslip in a Petri dish) and under dynamic conditions (a single-channel flow cell). The results show that the biological activity of rhamnolipids depends both on their properties and on the conditions of the biofilm formation. Therefore, this aspect must be taken into account when planning the experimental or application design.