Ochratoxin production by Aspergillus ochraceus as affected by methionine and structurally related compounds

1983 ◽  
Vol 29 (5) ◽  
pp. 536-540 ◽  
Author(s):  
N. Lisker ◽  
N. Paster ◽  
I. Chet
Keyword(s):  
Radial Growth ◽  
Sole Carbon Source ◽  
Synthetic Medium ◽  
Methionine Sulfoxide ◽  
Dry Weight ◽  
Aspergillus Ochraceus ◽  
Inhibitory Effects ◽  
Methionine Sulfone ◽  
Initial Ph ◽  
Related Compounds

When 10−2 M of L- or D-methionine was added to a synthetic medium containing xylose as the sole carbon source, ochratoxin production by Aspergillus ochraceus was strongly inhibited. At that concentration methionine derivatives, e.g., α-methyl-DL-methionine, DL-methionine sulfoxide, and L-methionine sulfone, did not inhibit ochratoxin production, whereas DL-methionine S-methyl sulfonium chloride (MMSC) inhibited ochratoxin production to a large extent. L-Methionine, as well as MMSC, also completely inhibited sclerotia formation, while D-methionine and DL-methionine sulfoxide caused only a partial inhibition. At lower concentrations (10−3 and 10−4 M), none of the compounds exhibited inhibitory effects. In cases where strong ochratoxin inhibition was detected, fungal radial growth or mycelial dry weight was inhibited by only 10–25%, while the initial pH of the medium dropped from ~6.5 to ~4.4–5.0. Adjustment of the initial pH of media supplemented with 10−2 ML-methionine, D-methionine, or MMSC to a pH of ~7.8 did not change the inhibitory effects on ochratoxin production in media containing L-methionine. On the other hand, sclerotia formation was restored in all three treatments.

Effects of cysteine and structurally related compounds on ochratoxin production by Aspergillus ochraceus

1985 ◽  
Vol 31 (11) ◽  
pp. 973-976 ◽  
Author(s):  
N. Lisker ◽  
N. Paster ◽  
I. Chet
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Synthetic Medium ◽  
Fungal Growth ◽  
Toxin Production ◽  
Aspergillus Ochraceus ◽  
Homocysteine Thiolactone ◽  
The Media ◽  
Related Compounds

Addition of 10−2 ML-cysteine, L-cystine, or S-ethyl-L-cysteine to a synthetic medium containing xylose as the sole carbon source did not decrease ochratoxin production by Aspergillus ochraceus. At that concentration, DL-homocysteine thiolactone HCl, DL-cysteine HCl, L-ethionine, S-methyl-L-cysteine, and glutathione (reduced) strongly inhibited ochratoxin production. DL-Homocysteine thiolactone HCl, DL-cysteine HCl, and L-ethionine also strongly inhibited fungal growth. At lower concentrations (10−3and 10−4 M) only L-ethionine decreased the toxin production. Ochratoxin inhibition caused by DL-homocysteine thiolactone HCl, DL-cysteine HCl, and glutathione was observed only in cases where the pH of the media was below 5.0. The inhibition caused by 10−3 M ethionine was partially prevented by the addition of 10−3 M methionine but this was not the case after the addition of S-methyl-L-cysteine to the medium.

scholarly journals Effect of Lactose on Soluble-glucan Production and on the Ultrastructure of Sclerotium rolfsii Sacc. Grown in Submerged Culture

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Y. Okon ◽  
I. Chet ◽  
Naomi Kislev ◽  
Y. Henis
Keyword(s):  
Carbon Source ◽  
Submerged Culture ◽  
Sole Carbon Source ◽  
Synthetic Medium ◽  
Sclerotium Rolfsii ◽  
Dry Weight ◽  
Solid Media

SUMMARY A significant increase in mycelial dry weight and a decrease in production of extracellular glucan were observed when lactose was added to a submerged culture of Sclerotium rolfsii grown in a liquid glucose-synthetic medium. When added as a sole carbon source, lactose at 2·5% (w/v) induced the formation of dark, spherical, compact bodies. The ultrastructure of these bodies is compared with that of sclerotia formed on solid media.

Optimization of Technical Parameters on the Medium Formulation and Culture Conditions in Production of Pleurotus eryngii Liquid Spawn

2021 ◽  
pp. 1019-1036
Author(s):  
Chol Jong ◽  
MyongIl Jin ◽  
YongChol Ju ◽  
DeTian Li ◽  
HaiFeng Zhu ◽  
...  
Keyword(s):  
Response Surface ◽  
Surface Analysis ◽  
Yeast Extract ◽  
Dry Weight ◽  
Pleurotus Eryngii ◽  
Response Surface Analysis ◽  
Liquid Volume ◽  
Rotating Speed ◽  
Initial Ph ◽  
Liquid Spawn

Liquid spawn, an important technical support for industrial production of edible fungi, has some advantages, such as fast growth, strong activity, uniform quality and easy inoculation. However，the study of the fermentation parameters of Pleurotus eryngii liquid spawn is less, which cannot effectively guide the production practice. Therefore, in order to provide a theoretical basis for the production of liquid spawn and industrial production of Pleurotus eryngii, response surface analysis was used to optimize the liquid spawn formula and conditions. The best carbon and nitrogen source of liquid medium was glucose and yeast extract, respectively. The optimum formula of medium was obtained by response surface analysis. Combined with the practical operation, the formula was modified to 29.00 g/L glucose, 2.90g/L yeast extract, 0.90g/L KH2PO4 and 1.00g/L MgSO4. The effects of various factors on the dry weight of mycelia were analyzed, the results indicated that the influence follow the sequence: glucose, KH2PO4, yeast extract and MgSO4, among them, the first two factors had significant effect. The interaction between glucose and KH2PO4 had obviously effects on the dry weight of mycelia. The interaction between glucose and yeast extract had a certain effect. The optimum culture conditions of liquid spawn were obtained by response surface analysis. Combined with the actual situation, the conditions were modified to liquid volume 106.00mL/250mL, rotating speed 165.00r/min, temperature 23.60℃, initial pH 6.70. The effects of various factors on the dry weight of mycelia was analyzed, the results indicated that the influence follow the sequence: initial pH, liquid volume, temperature and rotating speed, among them, the first three factors had extremely significant effect. The interaction of liquid volume and rotating speed, temperature and initial pH had obviously effects on mycelial dry weight.

scholarly journals Isolation and Characterization of a Mutant of the Marine Bacterium Alcanivorax borkumensis SK2 Defective in Lipid Biosynthesis

2010 ◽  
Vol 76 (9) ◽  
pp. 2884-2894 ◽  
Author(s):  
Efraín Manilla-Pérez ◽  
Alvin Brian Lange ◽  
Stephan Hetzler ◽  
Marc Wältermann ◽  
Rainer Kalscheuer ◽  
...  
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Marine Bacterium ◽  
Neutral Lipids ◽  
Nile Red ◽  
Dry Weight ◽  
Wax Ester ◽  
Gene Encoding ◽  
Isolation And Characterization ◽  
Key Enzyme

ABSTRACT In many microorganisms, the key enzyme responsible for catalyzing the last step in triacylglycerol (TAG) and wax ester (WE) biosynthesis is an unspecific acyltransferase which is also referred to as wax ester synthase/acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT; AtfA). The importance and function of two AtfA homologues (AtfA1 and AtfA2) in the biosynthesis of TAGs and WEs in the hydrocarbon-degrading marine bacterium Alcanivorax borkumensis SK2 have been described recently. However, after the disruption of both the AtfA1 and AtfA2 genes, reduced but substantial accumulation of TAGs was still observed, indicating the existence of an alternative TAG biosynthesis pathway. In this study, transposon-induced mutagenesis was applied to an atfA1 atfA2 double mutant to screen for A. borkumensis mutants totally defective in biosynthesis of neutral lipids in order to identify additional enzymes involved in the biosynthesis of these lipids. At the same time, we have searched for a totally TAG-negative mutant in order to study the function of TAGs in A. borkumensis. Thirteen fluorescence-negative mutants were identified on Nile red ONR7a agar plates and analyzed for their abilities to synthesize lipids. Among these, mutant 2 M131 was no longer able to synthesize and accumulate TAGs if pyruvate was used as the sole carbon source. The transposon insertion was localized in a gene encoding a putative cytochrome c family protein (ABO_1185). Growth and TAG accumulation experiments showed that the disruption of this gene resulted in the absence of TAGs in 2 M131 but that growth was not affected. In cells of A. borkumensis SK2 grown on pyruvate as the sole carbon source, TAGs represented about 11% of the dry weight of the cells, while in the mutant 2 M131, TAGs were not detected by thin-layer and gas chromatography analyses. Starvation and lipid mobilization experiments revealed that the lipids play an important role in the survival of the cells. The function of neutral lipids in A. borkumensis SK2 is discussed.

Aflatoxin Production in Black Currant, Blueberry and Strawberry Jams

1978 ◽  
Vol 41 (5) ◽  
pp. 344-347 ◽  
Author(s):  
O. PENSALA ◽  
A. NISKANEN ◽  
S. LINDROTH
Keyword(s):  
Yeast Extract ◽  
Raw Materials ◽  
Fungal Growth ◽  
Dry Weight ◽  
Aflatoxin Production ◽  
Fungal Mycelium ◽  
Black Currant ◽  
Initial Ph ◽  
Different Temperatures ◽  
Yeast Extract Sucrose

Unsweetened and sweetened (20 and 44% sucrose) black currant, blueberry and strawberry jams with spores of Aspergillus parasiticus NRRL 2999 were incubated at different temperatures and atmospheres for 0.5, 1, 2, and 6 months. Hyphal dry weight, pH of medium and aflatoxin production were examined. Also, the aflatoxin distribution between mold and jam layers was examined in jam with uncontrolled and controlled pH (initial pH 3.1–3.6 and 5.6 respectively) and in 20% yeast extract sucrose broth (initial pH 5.6) after 2 weeks of incubation. Aflatoxin was observed in black currant and strawberry jams stored at 22 and 30 C, but not in blueberry jam. Addition of sugar prevented production of aflatoxin in detectable amounts, although it enhanced fungal growth. Storage at 4 C resulted in a marked reduction in fungal growth. The high CO2 atmosphere prevented production of aflatoxin in detectable amounts in black currant and blueberry jams but not in strawberry jam. Raising the initial pH of the stored jam caused an increase in aflatoxin synthesis, although the amount of fungal mycelium, in contrast was reduced. Aflatoxin synthesis as a function of fungal growth was significantly weaker in the jams than in the yeast extract sucrose broth. The results imply that the jam raw materials, particularly blueberry, contain substances inhibiting production of atlatoxins. Alternatively, it is also possible that the jam materials contain only small amounts of nutrients necessary for synthesis of aflatoxin.

scholarly journals Cd and Zn interactions and toxicity in ectomycorrhizal basidiomycetes in axenic culture

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4478 ◽  
Author(s):  
Vinicius H. De Oliveira ◽  
Mark Tibbett
Keyword(s):  
Radial Growth ◽  
Solid Medium ◽  
Axenic Culture ◽  
Dry Weight ◽  
Zinc Toxicity ◽  
Solid Media ◽  
Wide Range ◽  
Ecm Fungi ◽  
Ectomycorrhizal Basidiomycetes ◽  
Tolerance Indices

BackgroundMetal contamination in soils affects both above- and belowground communities, including soil microorganisms. Ectomycorrhizal (ECM) fungi are an important component in belowground community and tolerant strains have great potential in enhancing plant-based remediation techniques. We assessed cadmium and zinc toxicity in five ECM species in liquid media (Hebeloma subsaponaceum;H. cylindrosporum;H. crustuliniforme;Sclerodermasp.;Austroboletus occidentalis) and investigated the potential of Zn to alleviate Cd toxicity. Due to highly divergent results reported in the literature, liquid and solid media were compared experimentally for the first time in terms of differential toxicity thresholds in Cd and Zn interactions.MethodsA wide range of Cd and Zn concentrations were applied to ectomycorrhizal fungi in axenic cultures (in mg L−1): 0; 1; 3; 9; 27; 81; 243 for the Cd treatments, and 0; 1; 30; 90; 270; 810; 2,430 for Zn. Combined Zn and Cd treatments were also applied toH. subsaponaceumandSclerodermasp. Dry weight was recorded after 30 days, and in case of solid medium treatments, radial growth was also measured.Results and DiscussionAll species were adversely affected by high levels of Cd and Zn, andA. occidentaliswas the most sensitive, with considerable biomass decrease at 1 mg L−1Cd, whileSclerodermasp. andH. subsaponaceumwere the most tolerant, which are species commonly found in highly contaminated sites. Cd was generally 10 times more toxic than Zn, which may explain why Zn had little impact in alleviating Cd effects. In some cases, Cd and Zn interactions led to a synergistic toxicity, depending on the concentrations applied and type of media used. Increased tolerance patterns were detected in fungi grown in solid medium and may be the cause of divergent toxicity thresholds found in the literature. Furthermore, solid medium allows measuring radial growth/mycelial density as endpoints which are informative and in this case appeared be related to the high tolerance indices found inH. subsaponaceum.

scholarly journals Anti-fungal activities of constituents from Uvaria scheffleri and Artabotrys brachypetalus

2006 ◽  
Vol 51 (1) ◽  
pp. 79-86 ◽  
Author(s):  
A.C. Odebode ◽  
S.A. Jonker ◽  
C.C. Joseph ◽  
S.W. Wachira
Keyword(s):  
Fusarium Solani ◽  
Radial Growth ◽  
Fungal Pathogens ◽  
Dry Weight ◽  
Stem Bark ◽  
Inhibitory Effect ◽  
In Vitro Bioassay ◽  
Botryodiplodia Theobromae ◽  
Anti Fungal

The anti-fungal activity of schefflone, a mixture of dimmer, 3,5 dimethoxy carvacrol and annonaceous acetogenin, extracted from stem-bark and root of Uvaria scheffleri and Artabotrys bruchypetalus against Fusarium solani, Botryodiplodia theobromae, Asperillus niger and Aspergillus flavus was determined. An in-vitro bioassay showed that the minimum inhibitory effect of the compounds to the fungal pathogens occurred at 200 ppm in both radial growth and mycelia dry weight measurements. Acetogenin from A brachypetalus had a very strong anti-fungal effect on all the test fungi. The effects of the compounds were more pronounced on F solani than on the other. The bioassay methods also play a significant role in the sensitivity of the samples on the pathogens. .

scholarly journals Effect of photosensitisers on growth and morphology of Phytophthora citrophthora coupled with leaf bioassays in pear seedlings

2020 ◽  
Vol 56 (No. 2) ◽  
pp. 74-82 ◽  
Author(s):  
Antonios Zambounis ◽  
Oksana Sytar ◽  
Dimitris Valasiadis ◽  
Zoe Hilioti
Keyword(s):  
Mycelial Growth ◽  
Biological Effects ◽  
Dry Weight ◽  
Colony Growth ◽  
Inhibitory Effect ◽  
Economic Losses ◽  
Inhibitory Effects ◽  
Phytophthora Citrophthora ◽  
Irregular Shapes ◽  
Zoospore Production

The phytopathogenic oomycetes of the genus Phytophthora cause devastating economic losses worldwide.<br />Naphthodianthrone compounds, present in plant extracts of buckwheat and Saint John’s wort act as photosensitiser<br />agents and exhibit antimicrobial activity against a number of pathogens. In this study, we investigated the potential<br />inhibitory effects of fagopyrin and hypericin on Phytophthora citrophthora (R.E. Sm. &amp; E.H. Sm.) Leonian 1906, the<br />main causal agent of rot diseases in deciduous trees. Fagopyrin had the highest inhibitory effect in the colony growth<br />at a concentration of 2% of a stock solution (3 mg/mL), inducing clubbed hyphae with round tips. Notably, hypericin<br />also inhibited the radial colony growth and increased the hyphal branching at the subapical region, while also promoting<br />the formation of enlarged cells with irregular shapes growing collectively as biofilm-like structures. In terms of the<br />mycelial dry weight, although both photosensitisers had considerable inhibitory effects, the fagopyrin treatment was<br />most effective. Leaf bioassays showed that under dark conditions the photosensitiser pre-treated zoospores formed a<br />dense, but aberrant, mycelial growth with penetration defects. In contrast, when the zoospore production was performed<br />under light conditions, the zoospores failed to cause necrotic lesions and penetration events implying that their<br />virulence was impaired. These findings shed light on the biological effects of fagopyrin and hypericin in the regulation<br />of the mycelial growth, morphology and pathogenicity of P. citrophthora.

scholarly journals Growth inhibitory effects of gossypol and related compounds on fungal cotton root pathogens

2014 ◽  
Vol 59 (2) ◽  
pp. 161-168 ◽  
Author(s):  
J.E. Mellon ◽  
M.K. Dowd ◽  
S.B. Beltz ◽  
G.G. Moore
Keyword(s):  
Inhibitory Effects ◽  
Root Pathogens ◽  
Cotton Root ◽  
Growth Inhibitory ◽  
Related Compounds
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