Search

In order to identify qualitative markers of a potential mycoherbicide against Canada thistle based on the mycelium of the fungus Stagonospora cirsii VIZR 1.41, changes in its pathogenicity and lipid profiles during submerged cultivation on liquid sucrose-soybean medium were analyzed. The fatty-acid composition of major lipids and the identification of molecular species of structural lipids were determined. The lipid composition during fungal growth changed together with its pathogenicity. The highly pathogenic mycelium of the fungus (at the log phase of growth) was characterized with the relatively highest content of structural lipids: phosphatidylcholine (PC), phosphatidylethanolamine (PE), and ergosterol (ES). Their relative concentration decreased with culture age and a decrease in pathogenicity. The highest lipid yield was found at the beginning of stationary growth phase (at the maximal biomass yield) of S. cirsii; triacylglycerides (TAGs) were the most abundant. The double-bond index of fatty acids in glycerolipids decreased with culture age, and the substitution of molecular PC species (34:2 versus 36:4) and PE (36:4 versus 34:2) was observed as well. High levels of ES, TAG, PC (in particular, 34:2 forms) and PE (36:4 forms) were presumed to be qualitative markers of S. cirsii mycelium. [ABSTRACT FROM AUTHOR]

Secondary metabolites were isolated from cultures of four geographically distant isolates of the cosmopolitan fungus, Bipolarissorokiniana for intense biological characterization. Analysis of extracts from their liquid and solid cultures with TLC and HPLC-MS showed high similarity of their composition despite on fungal origin. From the extracts of B. sorokiniana 14 metabolites (terpenes, quinones, xanthones etc.) were isolated using column chromatography and preparative HPLC; among them, 12 known substances were identified. Chloromonilinic acid B (CAB) showed the highest level phytotoxic activity on wheat leaves. The most of isolated compounds inhibited growth of Bacillussubtilis, of which methyl-8,3-hydroxy-3-methyl-4-chloroxanthon-1-carboxilate (MMC) demonstrated the strongest activity. Some metabolites of B. sorokiniana (CAB and MMC) were shown to have insecticidal activity against common cereal aphid. All the compounds were cytotoxic (especially, cochlioqionones and fusaroproliferin) when tested on Sf9 cell line. However, no one was acute toxic for infusoria. Evidently, the production of multiple bioactive compounds makes B. sorokiniana a strong competitor in different ecological niches and a dangerous contaminant of grain. [ABSTRACT FROM AUTHOR]

More than 300 metabolites of fungi of the genera Alternaria have been reported in the last few decades; some of them display phytotoxic, antibiotic, antifungal, and antiprotozoal activity. This review synthesizes the current information on the structure, biological activity, and possible application of Alternaria metabolites in plant protection, pharmacology, and chemotaxonomy. Some Alternaria fungi are suggested as mycoherbicides. The toxicology of application of the Alternaria fungi as mycoherbicides is discussed. [ABSTRACT FROM AUTHOR]

In order to determine the possible toxic properties of a potential mycoherbicide based on the fungus Stagonospora cirsii S-47, the effects of solid and liquid media composition on the yield of extractive matter (YEM), the spectrum of biological activity, and the chromatography profiles of extracts obtained from cultures of this fungus were studied. The maximal YEM (~250 mg/L) was obtained from filtrates taken from a 2-week culture of S. cirsii S-47 grown on a sucrose–soy meal medium. The same time was optimal for the production of maximal YEM (~1.5 g/kg) when the fungus was grown on pearl-barley substrate. The fungal extracts showed phytotoxic, antimicrobial, cytotoxic, and antiesterase activity. Extracts from culture filtrates generally demonstrated a higher level and wider spectrum of biological activity than extracts from solid S. cirsii S-47 culture. The maximal phytotoxic and antimicrobial activity was found in dichloromethane extracts from the filtrate of 3-week fungal culture on Czapek medium, while extracts from two-week-old culture strongly inhibited carboxyl esterase. The maximal cytotoxic activity against the U251 cell line was found in ethyl acetate extract from a 3-week culture of S. cirsii S-47 produced on YMG liquid medium. The extract compositions varied considerably depending on the culture substrate. [ABSTRACT FROM AUTHOR]

A simple HPLC technique for the quantitative determination of phytotoxins (stagonolide A and herbarumin I) in liquid culture of the fungus Stagonospora cirsii S-47 has been developed. Some examples of its application are given. The technique was tested in a study of effects of the concentration of refined sunflower oil and the cultivation duration on the production level of these toxins. At an oil concentration of 0.5% or higher in modified Czapek medium with vitamins, the accumulation of S. cirsii biomass and the concentration of stagonolide A increased, while the concentration of herbarumin I decreased. Maximal amounts of both phytotoxins were obtained on the tenth day of submerged S. cirsii cultivation in flasks. When S. cirsii was grown in the same medium supplied with 1% of oil in a laboratory bioreactor, the maximal concentration of stagonolide A (116 mg/L) in the liquid culture was achieved after 5 days of fermentation followed by its considerable reduction after 6 days, while after 7 days of the submerged growth the maximal content of herbarumin I (116 mg/L) increased sharply. The technique of the phytotoxins analysis was used to monitor them during their isolation, as well as for preparative HPLC. [ABSTRACT FROM AUTHOR]

The effect of the nitrogen source (sodium nitrate and soybean meal) on the growth, pathogenicity, and lipid composition of mycelium of Stagonospora cirsii Davis VIZR 1.41, a potential mycoherbicide against Canada thistle (Cirsium arvens (L.) Scop.), was studied. The fungus grew significantly (two times) faster on sucrose-soybean meal medium (SSM) than on modified Czapek medium (CM). The fungal mycelium during the exponential growth phase demonstrated the maximal pathogenicity level on the third day on SSM and on the sixth day on CM. Canada thistle leaf tissues were more susceptible (25% higher development of necrotic lesion) to mycelium obtained on SSM than to mycelium obtained on CM. The nitrogen source strongly affected the lipid composition of S. cirsii mycelium. In S. cirsii mycelium obtained on SSM, the total lipid content was 1.7 times lower; the ratio of nonpolar lipids to polar lipids was three times lower than that for fungal mycelium grown on CM. Considerable differences were found in the composition of nonpolar (sterols and fatty acid) and polar (sphingolipids) lipids with respect to the nitrogen source in the culture medium. The higher contents of sterols, free fatty acids, and some glycoceramides in the mycelium of S. cirsii obtained on SSM may be related to its higher pathogenicity level and can serve as a marker of mycoherbicide quality. [ABSTRACT FROM AUTHOR]

Five compounds, 4-chloropinselin, chloromonilinic acids B and C, alternariol, and emodin, are the first to be identified in the metabolite composition of Alternaria sonchi, a pathogen of field sowthistle (Sonchus arvensis L.). The metabolite profiles of extracts have been significantly influenced by fermentation and extraction techniques. Solid-state fermentation of A. sonchi S-102 on millet was preferable for the production of alternethanoxin A, chloromonilicin, and 4-chloropinselin with a yield of about 460, 70, and 2760 mg/kg respectively, while the use of pearl barley was optimal for the production of alternethanoxin B (215 mg/kg) and alternethanoxin D (29 mg/kg). Extracts from the culture broth and mycelium of A. sonchi obtained after surface cultivation of the fungus contained 4-chloropinselin, alternariol, emodin, and a number of unidentified biologically active compounds. The extracts display relatively low phytotoxic and antimicrobial activity and only trace levels of alternariol. Thus, there is low toxicological risk for the application of this fungus as a bioherbicide producer. [ABSTRACT FROM AUTHOR]