Members of Candida species cause significant problems in medicine and in many industrial branches also. In order to prevent from Candida sp. development, essential oils are more and more frequently applied as natural, non-toxic, non-pollutive and biodegradable agents with a broad spectrum of antimicrobial activity. The aim of the research was to determine changes in morphology and metabolic properties of Candida albicans in the presence of thyme and tea tree oils. Changes of enzymatic activity of isolates were observed in the presence of both tested essential oils, and they were primarily associated with loss or decrease of activity of all enzymes detected for control. Furthermore, only for 3 out of 11 isolates additional activity of N-acetyl-β-glucosaminidase, α-mannosidase, α-fucosidase and trypsin was detected. Vivid changes in biochemical profiles were found after treatment with tea tree oil and they were related to loss of ability to assimilate D-xylose, D-sorbitol and D-trehalose. The main differences in morphology of isolates compared to the control strain concerned formation of pseudohyphae structures. Both examined essential oils caused changes in cell and colony morphology, as well as in the metabolism of Candida albicans. However, the extent of differences depends on the type and concentration of an essential oil. The most important finding is the broad spectrum of changes in yeast enzymatic profiles induced by thyme and tea tree oils. It can be supposed that these changes, together with loss of ability to assimilate saccharides could significantly impact Candida albicans pathogenicity.

Candida spp. cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. As a result of the increasing antibiotic resistance among pathogenic yeasts, the interest in alternative agents of antifungal activity is growing. This study evaluated the antimicrobial activity of selected essential oils (EOs) against Candida clinical and food-borne strains, including antibiotic-resistant isolates, in relation to yeast cell surface hydrophobicity (CSH). Candida strains showed different range of susceptibility to tea tree, thyme, peppermint, and clove oils, and peppermint oil demonstrated the lowest anticandidal activity with minimal inhibitory concentrations (MICs) of 0.03-8.0% v/v. MIC values for thyme and clove oils ranged from 0.03% to 0.25% v/v, and for tea tree oil-from 0.12% to 2.0% v/v. The exception was Candida tropicalis food-borne strain, the growth of which was inhibited after application of EOs at concentration of 8% v/v. Due to diverse yeast susceptibility to EOs, isolates were divided into five clusters in a principal component analysis model, each containing both clinical and food-borne strains. Hydrophobic properties of yeast were also diversified, and 37% of clinical and 50% of food-borne strains exhibited high hydrophobicity. The study indicates high homology of clinical and food-borne Candida isolates in relation to their susceptibility to anticandidal agents and hydrophobic properties. The susceptibility of yeasts to EOs could be partially related to their CSH. High antifungal activity of examined EOs, also against antibiotic-resistant isolates, indicates their usefulness as agents preventing the development of Candida strains of different origin.

Candida is a yeast species recognized as the most frequent etiological agent of systemic and invasive thrush in humans. Invasions can affect all tissues, organs and systems of human in various stages of development. In the last 10 years Candida infections have increased 15 times. The purpose of our study was to determine the sensitivity of four antibiotics belonging to three different groups of antifungal agents against clinical and food-borne Candida strains. Our studies showed that of all tested strains, 7% was resistant to nystatin, 32% to fluconazole, 23% to voriconazole, and no strains grew in the presence of caspofungin. Despite the differences in biochemical profiles of clinical and food-borne isolates of Candida, a group of strains showing resistance to antibiotics include both types of isolates. At the same time circulating of antibiotic-resistant strains outside the hospital environment and the yeast infection via food is possible.

Abstract:The aim of this work was to develop the composition of a medium for the cultivation of six microbial strains forming a deodorizing consortium: Pseudomonas fluorescens, Enterococcus faecium, Bacillus subtilis, Bacillus megaterium, Leuconostoc mesenteroides and Lactobacillus plantarum. The study focused on the optimization of a highly efficient culture medium composed of readily available components of plant origin to maximize microbial biomass yields, and to create a less expensive alternative to the commercial Tryptic Soy Broth medium (TSB). After preliminary efficiency screening of all tested media components, we selected four substrates for further optimization-soy protein concentrate (SPC), glucose or sucrose, and phosphate salts. The final concentrations of all components were fine-tuned using the Taguchi design for experiments according to an L 9 array. Taguchi optimization led to formulation of a culture medium, which was approximately 5 times cheaper than TSB (depending on the components used). Consequently, microbial biomass yields were improved by up to 15-fold (1564%), depending on the strain. The results obtained in the laboratory experiments were then confirmed in pilot-(42 L) and industrial-(300 L) scale fermentation. Our results show that this method of using a parallel culture microbioreactor with the Taguchi approach can be recommended for optimization of culture media based on substrates of plant origin.