Effect of the products of the vital activity of yeast-like fungi on levorin synthesis

The effect on levorin synthesis of the cells and fermentation broth filtrates of Candida tropicalis after their cultivation in the fermentation medium was studied. It was found that the yeast-like fungi belonging to Candida excreted during their development some products capable of stimulating the synthesis of levorin by 40--60 per cent. When the actinomycete producing levorin was grown on the medium containing 80 per cent of the filtrate the level of levorin synthesis was the same as that observed with mixed cultivation of the actinomycete and C. tropicalis. The study on the conditions providing accumulation of the stimulating substances showed the following: production of the stimulating substances started during the first hours of the yeast growth and reached its maximum by the 48th hour, these substances being consumed by the actinomycete during the fermentation process. Aeration is required for production of the stimulating substances but its high levels are not necessary.     

Drug sensitivity of Candida in patients with kidney diseases receiving immunosuppressive therapy

It was shown that prednisolone and its combination with azathioprine++ increased contamination of the patients with yeast-like fungi and promoted development of candidiasis in them to a greater extent than cyclophosphamide. In the patients treated with the immunodepressants there was observed a carrier state in regard to various yeast-like fungi: 12 species belonging to 6 genera were isolated from the pathological materials. Determination of sensitivity to antifungal drugs in 200 Candida strains revealed that amphotericin B was the most active agent. Then followed mycoheptin, nystatin and nitroxolin. Levorin was the least active drug. The MICs of the drugs for the majority of the cultures were 0.5, 4-8, 8-16 and 32-64 micrograms/ml respectively. Candida resistant strains (mainly to levorin and mycoheptin) were isolated only from recipients of kidney transplants during the early postoperative period when the patients were subjected to intensive immunodepressive and prophylactic antifungal therapy. Among the fungi of the Candida genus C. guillermondii and C. parapsilosis proved to be the most resistant. Under the hospital conditions and in vitro studies it was found that cyclophosphamide and combinations of prednisolone with cytostatics increased resistance of Candida to the antifungal drugs. Rapid increasing of the fungi resistance to levorin and mycoheptin was observed. The increase in the resistance to amphotericin B was somewhat lower and that to nitroxolin and nystatin was extremely low. The study of the combined effect of the immunodepressants and antifungal drugs demonstrated that the immunodepressants increased the antifungal activity of amphotericin B, levorin and nitroxolin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Action of the products of the vital activity of yeastlike fungi on the biosynthesis of levorin, levoristatin and fatty acids by a Streptomyces levoris culture

The data on the effect of the products of vital activity of Candida tropicalis, a yeast-like fungus, on the biosynthesis of levorin, levoristatin and fatty acids by Streptomyces levoris are presented. It was shown that the effect of the biostimulators was not specific with respect to production of levorin, since in the presence of the products of vital activity of C. tropicalis an increase in the synthesis of levoristatin and fatty acids was also observed. The qualitative and quantitative composition of the fatty acids of the mycelium of S. levoris was studied. Interrelation between the biosynthesis of levorin and synthesis of unsaturated fatty acids and branched chain fatty acids was noted.     

Effect of various microorganisms on the activity of levorin

Levorin added to nutrient media with growing cultures of aerobic gram-positive bacilli, Escherichia, enterococci and filamentous fungi was partially inactivated. The antibiotic activity decrease depended on the strain characteristics, incubation period and temperature. Fermentation broth filtrates of the experimental strains also inactivated levorin while to a lesser extent than the growing organisms. In contaminated levorin pastes, the antibiotic activity was lower. The fermentative nature of inactivation was not proved.     

Cation conductance and efflux induced by polyene antibiotics in the membrane of skeletal muscle fiber.

Cation conductance and efflux induced by polyene antibiotics amphotericin B (AMB), amphotericin B methyl ester (AME), nystatin, mycoheptin, and levorin on frog isolated skeletal muscle fibers and whole sartorius muscles were investigated. Conductance was measured under current-clamp conditions using a double sucrose-gap technique. Cation efflux was studied using flame emission photometry. Some new data were obtained concerning the effects of levorin and mycoheptin on biological membranes. The power dependence of polyene-induced cation transport on antibiotic concentration in muscle membrane was lower than that in bilayers. The decline in the equilibrium conductance caused by polyene removal (except for levorin) was very fast. There was reverse temperature dependence of AMB- and nystatin-induced conductances. Both induced conductance and efflux values demonstrated a correlation with the order of antifungal activities: levorin > AMB, mycoheptin > AME > nystatin, except for AME, which was more potent on yeastlike cells. These effects were interpreted in terms of possible differences in the kinetics of channel formation in biological and model membranes and in light of the role of nonconducting antibiotic forms in biological membranes.     

Effect of a biostimulant formed by yeastlike fungi on the dynamics of the accumulation of CoA, biotin and levorin in the process of growth of S. levoris

Regularities of the effect of a biostimulator produced by years-like fungi on accumulation of CoA, biotin and levorin in a developing culture of S. levoris were studied. It was shown that addition of the biostimulator to the fermentation medium resulted in increased accumulation of CoA and biotin in the mycelium of the levorin-producing culture within the first 48 hours of the growth and in their more intensive consumption at the final stages of the fermentation process. The rate of the levorin synthesis in the medium with the biostimulator markedly exceeded that in the control.     

Mechanism of polyene antibiotic inactivation. Possible ways for levorin stabilization

Various means for levorin isolation were studied with the EPR method and approaches to stabilization of the antibiotic on storage under natural conditions were discussed. It was shown that formation of the radicals begins already at the first stage of the antibiotic isolation, i.e. during extraction from the mycelium. Treatment of the solvents with an inert gas or addition of antioxidants decreased the number of free radicals in a freshly isolated product. The antibiotic inactivation rate depended on the initial concentration of the free radicals and conditions of natural storage. The levorin stability increased when oxygen was thoroughly removed from the solvents at all isolation stages and the antibiotic was subsequently stored under conditions preventing any access of the air. The stabilizing effect was also observed when the oxidative effect of the amino sugar moiety on destruction of the polyenic chromophore during the antibiotic complex formation with respect to the amino group was decreased.     

Delayed hypersensitivity to Candida albicans

Conditions and factors influencing the formation of delayed hypersensitivity (DH) to yeast-like fungi of the species C. albicans under experimental conditions have been studied. The intensity of this reaction has been found to depend on the dose and method used for infecting mice, the time of the test and the qualitative state of fungal cells. As the result of this study, the infectious model of DH to C. albicans has been proposed. This model may be used for the study of the influence of different exogenous and endogenous factors of cell-mediated immune response to candidiasis.     

Multiple Stress Factors affecting Growth of Rock-inhabiting Black Fungi

Black fungi, belonging to the Dematiaceae, with yeast-like growth patterns, were isolated from rock surfaces in the Mediterranean. They tolerate high temperatures and sodium chloride stress although they are neither thermophilic nor halophilic organisms. Environmental stress factors not only affect growth velocity of the fungi but also the colony shape. A shift of the smooth and flat colonies developed under optimal culture conditions to more clump-like growth similar to the colony shape on the natural rock substratum is caused by both high temperature and osmotic stress. The “principle of uniformity” is proposed as a new term to interpret specific morphotypes of pleomorphic fungi of different taxonomic assignment.     

Bacterial-fungal associations in the intestine under the conditions of colonization by yeast-like fungi of the genus Candida

The composition of the fecal microflora in somatic patients and patients with enteric infections under the conditions of surpluscolonization by yeast-like fungi of the genus Candida was analyzed. The study revealed that the high level of fungal contamination was linked with decreased colonization resistance of the intestine (deficiency in bifidoflora) and with the presence of opportunistic microorganisms: Staphylococcus aureus, hemolytic and lactose-negative Escherichia coli, as well as nonfermenting Gram negative bacteria. The antilysozyme activity of enterobacteria was found to increase in the course of their joint cultivation with fungi of the genus Candida, that may be regarded as one of the mechanisms of the formation and maintenance of pathobiocenosis.     

Formation of peroxide compounds and their role in the inactivation of polyene antibiotics levorin and mycoheptin

The kinetics of peroxide formation in the process of levorin and mycoheptin oxidation at a temperature of 57 degrees C was studied. It was shown that the peroxide compounds actively participated in the processes of levorin and mycoheptin inactivation as intermediate products of their transformation. Addition of the peroxides increased the rate of the antibiotic degradation even if there was no oxygen and subsequently decreased the periods of their storage. Conditions for the use of the iodometric method for determination of the peroxides in the poyenic compounds are discussed.     

Characteristics of diffusion of polyene antibiotic levorin

Studies were performed which provided estimation of the impact of some physico-chemical properties of levorin, a polyene antibiotic, and in particular its multicomponent nature and capacity for isomerization on formation of inhibition zones in assay of the antibiotic activity by the agar diffusion method. It was shown that the levorin complex components markedly differed in the biological activity and diffusion capacity. The diffusive properties of the highly active components A2 and A3 were better. The diffusion rate of isomerized levorin was much lower than that of the initial levorin. To provide better diffusion of the levorin components with low diffusion capacity it was recommended to use a new solution composed of ethanol, glycerol and water at a ratio of 15:25:60.     

临床标本中酵母样真菌的分离鉴定和药敏结果分析

目的调查目前临床标本中酵母样真菌感染现状及耐药性情况。方法常规分离临床标本中的酵母样真菌,用科玛嘉显色培养基及法国生物-梅里埃API20CAUX鉴定系统鉴定菌种,并用K—B法进行药敏试验。结果研究期间共分离到193例有临床意义的酵母样真菌,检出率较高的依次为白假丝酵母菌（62．7％）,热带假丝酵母菌（20．2％）,光滑球拟酵母菌（9．3％）。在6种抗真菌药中,对伊曲康唑、氟康唑的耐药率增高。结论近年来由酵母样真菌感染引起的疾病及其对常用抗真菌药物的耐药率有明显增加,应加强真菌的检测和耐药性监测工作,以指导临床合理使用药物。     

Comparison of morphogenetic networks of filamentous fungi and yeast.

Fungi generally display either of two growth modes, yeast-like or filamentous, whereas dimorphic fungi, upon environmental stimuli, are able to switch between the yeast-like and the filamentous growth mode. Signal transduction pathways have been elucidated in the budding yeast Saccharomyces cerevisiae, establishing a morphogenetic network that links cell-cycle events with cellular morphogenesis. Recent molecular genetic studies in several filamentous fungal model systems revealed key components required for distinct steps from fungal spore germination to the maintenance of polar hyphal growth, mycelium formation, and nuclear division. This allows a mechanistic comparison of yeast-like and hyphal growth and the establishment of a core model morphogenetic network for filamentous growth including signaling via the cAMP pathway, Rho modules, and cell cycle kinases. Appreciating similarities between morphogenetic networks of the unicellular yeasts and the multicellular filamentous fungi will open new research directions, help in isolating the central network components, and ultimately pave the way to elucidate the central differences (of many) that distinguish, e.g., the growth mode of filamentous fungi from that of their yeast-like relatives, the role of cAMP signaling, and nuclear division.     

Antistaphylococcal activity of the complex of natural cytokines

The in vitro study of the action of the complex of natural cytokines (CNC), or preparation Superlymph, on different microbial test strains (Staphylococcus aureus, Escherichia coli, yeast-like fungi of the genus Candida) was carried out. CNC suppressed the growth of S. aureus test culture, depending on the concentration of the preparation. The inhibiting effect was observed in the presence of Ca and Mg bivalent cations in the medium. Under the chosen conditions of the experiment CNC did not inhibit the growth of E. coli test cultures, as well as test cultures of yeast-like fungi of the genus Candida. In addition to its antibacterial effect, Superlymph also produced some effect on the release of cathepsin G, the lysosomal enzyme of human leukocyte granules.     

Influence of incubation conditions on cell surface hydrophobicity of Candida species fungi

Cell surface hydrophobicity (CSH) is considered to be one of several virulence factors of Candida yeast-like fungi. The aim of the study was a measurment of hydrophobic properties of Candida sp. depending on growth conditions. A total of 139 strains of Candida (80 - C. albicans and 59 - C. non-albicans) were examined. The method of salt aggregation test (SAT) was used. The strains were cultured on three different media, in two variants of incubation temperature and time. The incubation temperature and microbiological medium affected CSH of just C. albicans strains. The influence of incubation time on CSH of examined species of Candida was not occurred. There was a strong correlation between CSH and species of Candida demonstrated in the study Hydrophobic properties were more frequent and stronger among strains of C. non-albicans than C. albicans species. The results of the study indicates that CSH of Candida spp. is a dynamic feature. The ability to change surface properties may play a role in pathogenesis of candidosis.     

Sensitivity of Candida strains to polyenic antibiotics in the treatment of oral candidiasis

Sensitivity of 146 clinical strains of Candida albicans to nystatin, levorin and amphoglucamine was studied on solid media with the replica method. The strains were isolated from 79 patients with candidiasis of the oral mucosa. It was found that sensitivity of the fungi to the polyenic antibiotics was different which should be considered in treatment of candidiasis. On the basis of the mean MICs for the clinical strains and their distribution by the MICs it was shown that the activity level of levorin and amphoglucamine was higher than that of nystatin. During the treatment resistance of the Candida strains to the polyenic antibiotics increased and cross resistance developed which required application of other treatment means.     

Monitoring and control of pullulan production using vision sensor

The production of the polysaccharide pullulan by the yeast-like fungi, Aureobasidium pullulans, is accompained by cellular morphogenetic changes. High productivity and yield of the process have been found to correlate with high concentration of yeast-like cells in the culture. The morphogenetic changes of A. pullulans cells depend on the culture conditions, e.g., dissolved oxygen, shear rate and medium composition. In order to improve the productivity of the process, a novel control law was formulated. A feeding strategy dependent on the culture cellular composition was designed and aimed to keep the yeast-like cell concentration high. The culture morphogenetic composition during the process was monitored by a recently developed vision sensor. Feeding was actuated when the yeast-like cell concentration decreased below a threshold. The proposed control strategy improved pullulan production by increasing both productivity and yield of the cells by 67% and 80%, correspondingly. The results point to the advantage and the potential of using the monitoring and control system and algorithm to increase productivity and yield in cellular bioprocesses.     

Impact of morphogenetic effectors on the growth pattern and the lipid composition of the mycelium and the yeastlike cells of the fungus Mucor hiemalis

We investigated the growth and the cell lipid composition of the mycelium and of the yeast-like form of Mucor hiemalis VKMF-1431 obtained under aerobic conditions by treatment with the morphogenetic agents itraconazole, exogenous triacylglycerols (TAGs), and trehalose. The sporangiospores of a 20-day culture were inoculated on the medium with glucose. Under these conditions, the fungus produced both mycelium and yeast-like cells. It was established that, upon the germination of old (20-day) sporangiospores, the fungus predominantly used the mycelium development strategy in the presence of trehalose and TAGs. It was characterized by a low ratio between the two bulk membrane lipids (PEA/PC) and increased levels of PC and polyunsaturated fatty acids (FA). Compared to the mycelium, the yeast cell morphotype obtained on the medium with glucose was distinguished by an elevated PEA/PC ratio, lowered TAG, free sterol (FS) and esterified sterol (ES) levels, a decreased ES/FS ratio that correlated with the reserve sterol pool size, and a lowered content of unsaturated fatty acids (the linoleic and the ??-linolenic acid). These peculiarities of the lipid composition of yeastlike cells correlated with the intensity of yeastlike growth. Light and electron microscopy revealed differences between the above cell morphotypes. With itraconazole, yeast-like cells were characterized by the destruction of the endoplasmic reticulum membranes and formation of a large number of vacuoles. The suggestion was confirmed that the state/age of inoculum sporangiospores exerts an influence on the capacity for dimorphism in mucorous fungi such as M. hiemalis. The data obtained testify to an involvement of lipids in the process of adaptation to environmental factors and to their regulatory role in morphogenetic processes associated with the formation of alternative morphotypes of the mucorous fungus.     

Ein beitrag zur ökologie der hefen aus Nordost-Mecklenburg

253 strains of yeast and yeast-like organisms were collected from 14 areas predominately on sea coasts in North-East Mecklenburg in German Democratic Republic between April and August 1970. 241 of these isolates are from various parts of plants and represent 13 genera. The most widespread fungi wereAureobasidium pullulans, Metschnikowia pulcherrima, M. reukaufii and carotenes containing yeast-like fungi. The qualitative composition of isolates varied with meteorological conditions directly or indirectly. Up to 5° CAureobasidium, Rhodotorula, Rhodosporidium, Kloeckera andCandida were found, all other genera not untill the atmosphaeric temperature in average 5–10° C reached,Saccharomyces andHansenula at higher temperature than 10° C.The most isolated yeasts did not ferment sugars or only glucose, but minority of them fermented sucrose and maltose.Metschnikowia species appeared in summer months and were isolated in smaller quantity then in warmer countries. In comparison with the number of carotenes containing isolates,Metschnikowia pecies were isolated in ten time smaller minority than in South Slovakia in 1959.The predominance of carotenes containing yeasts impressed to the whole set of isolated populations some specific features in connection with tolerancy to salts, activity of urease, growth temperature, splitting of fat substances, assimilation of hydrocarbones, etc.