Effect of temperature and glucose supply on the production of polyunsaturated fatty acids by the fungus Mortierella alpina CBS 343.66 in fermentor cultures

The fungus Mortierella alpina CBS 343.66 was grown in a fermentor at different pH, temperatures and supplies of carbon source (glucose) in order to optimize the culture conditions for rapid biomass and lipid production with a high proportion of polyunsaturated fatty acids, especially arachidonic acid (AA). Good growth and lipid production with 31% AA was obtained at pH 6.5 and 25°C. A temperature decrease to 18°C gave a significantly higher degree of polyunsaturated fatty acids. Eicosapentaenoic acid was not detected at 25°C, but was formed at 18°C at about 10%. The AA concentration but was similar for 18°C about 10%. The AA concentration was similar for 18°C and 25°C (around 30%): 18°C allowed relatively good growth and had a beneficial effect on the fungus morphology, i.e. pellets were formed. Best lipid production and a AA content of up to 33% was achieved at an excess of glucose (carbon source) and a deficit of ammonium chloride (nitrogen source). The percentage of AA of the total fatty acid composition was constant as ong as glucose was present. At glucose exhaustion, the proportion of AA increased to 57%. The increase in AA corresponded to a decrease in palmitic acid, stearic acid and oleic acid. Correspondence to: G. Molin     

Stimulation of the biosynthesis of carotenes by oxidative stress in Blakeslea trispora induced by elevated dissolved oxygen levels in the culture medium

The adaptive response of the fungus Blakeslea trispora to the oxidative stress induced by elevated dissolved oxygen concentrations during carotene production was investigated by measuring the specific activities of catalase (CAT) and superoxide dismutase (SOD) and the micromorphology of the fungus using a computerized image analysis system. Changes in the ratio of the volume of air (V_a) over the medium and the volume of medium (V_m) in the flask caused changes of the morphology of microorganism from clumps to pellets and increases in the specific activities of CAT and SOD. The oxidative stress in B. trispora resulted in a significant increase in carotene production, and a maximum proportion of β-carotene (60%), γ-carotene (50%), and lycopene (10%) (as percentages of total carotenes) was observed at a ratio V_a/V_m of 15.7, 4.0 and 1.5, respectively. The highest concentration of carotenes (115.0 mg/g dry biomass) was obtained in V_a/V_m ratio of 9.0.     

Biomass production and nitrogen contents of the CAM plants Kalanchoe daigremontiana and K. tubiflora in cultures with different nitrogen and water supply

Summary Two CAM plant species (Kalanchoe daigremontiana and K. tubiflora) were cultivated in pure cultures with two different levels of nitrogen and water supply. A comparison of the plant dry weight showed that the productivity was severely reduced under low nitrogen or/and water conditions. Additionally the proportion of the different organs contributing to the total biomass, and thus the ratio of root/shoot dry weight shifted substantially. At the same time the production of leaf buds in ratio to leaf biomass was increased. Concentrations of organic nitrogen and nitrate in the shoots were drastically reduced under low nitrogen or/and water conditions, but organic nitrogen concentration in the roots remained relatively high. The leaf conductance over a day was investigated only for K. daigremontiana, and decreased with reduced water and nitrogen supply. The results indicate that CAM plants do not have the predicted high nitrogen use efficiency. Under environmental stress they change from biomass production towards provisions for life preservation.     

Carotene production from waste cooking oil by Blakeslea trispora in a bubble column reactor: The role of oxidative stress

The oxidative stress induced by hydroperoxides and reactive oxygen species (ROS) during carotene production from waste cooking oil (WCO) and corn steep liquor (CSL) by the fungus Blakeslea trispora in a bubble column reactor was investigated. The specific activities of the intracellular enzymes superoxide dismutase (SOD) and catalase (CAT) as well as the micromorphology of the fungus were measured in order to study the response of the fungus to oxidative stress. The changes of the morphology of microorganism leaded to pellets formation and documented using a computerized image analysis system. As a consequence of the mild oxidative stress induced by hydroperoxides of WCO and ROS a significant increase in carotene production was obtained. The highest carotene concentration (980.0 mg/l or 51.5 mg/g dry biomass) was achieved in a medium consisted of CSL (80.0 g/L) and WCO (50.0 g/L) at an aeration rate of 5 vvm after 6 days of fermentation. In this case the carotenes produced consisted of β‐carotene (71%), γ‐carotene (26%), and lycopene (3%). The strong oxidative stress in the fungus caused a significant increase of γ‐carotene concentration. Bubble column reactor is a useful fermentation system for carotene production in industrial scale.     

Comparison of growth and performance in upland and lowland switchgrass types to water and nitrogen stress

The objective of the study was to examine lowland (Alamo and Kanlow) and upland (Blackwell and Caddo) cultivars of switchgrass (Panicum virgatum L.) for differences in response to water deficit and nitrogen fertilizer. Cultivars were grown in pots with fritted clay at two water levels: well watered and deficit conditions (-0.1 and -1.0 MPa) and two nitrogen levels (10 and 100 kg ha(-1)). Nitrogen determined growth potential of the cultivars more than water availability. The lowland cultivars produced greater biomass yields than upland cultivars. However, upland cultivars showed a smaller response to drought stress. Under water stress conditions all cultivars exhibited a higher leaf percentage of total dry matter (DM), with the upland cultivars having the highest leaf percentage of total DM. Nitrogen proved to have more of an effect on single-leaf photosynthesis rates than water. Alamo demonstrated the greatest biomass production among all cultivars. The differences found between the two lowland cultivars suggest that Alamo would be better suited for forage and biomass production in central Texas, being a higher producer under drought and non-drought conditions than Kanlow as well as upland cultivars.     

Influence of arbuscular mycorrhiza on the growth and antioxidative activity in cyclamen under heat stress

The influence of the arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum, on the growth, heat stress responses and the antioxidative activity in cyclamen (Cyclamen persicum Mill.) plants was studied. Cyclamen plants (inoculated or not with the AM fungus) were placed in a commercial potting media at 17–20 °C for 12 weeks in a greenhouse and subsequently subjected to two temperature conditions in a growth chamber. Initially, plants were grown at 20 °C for 4 weeks as a no heat stress (HS?) condition, followed by 30 °C for another 4 weeks as a heat stress (HS+) condition. Different morphological and physiological growth parameters were compared between G. fasciculatum-inoculated and noninoculated plants. The mycorrhizal symbiosis markedly enhanced biomass production and HS + responses in plants compared to that in the controls. A severe rate of leaf browning (80–100 %) was observed in control plants, whereas the mycorrhizal plants showed a minimum rate of leaf browning under HS + conditions. The mycorrhizal plants showed an increase activity of antioxidative enzymes such as superoxide dismutase and ascorbate peroxidase, as well as an increase in ascorbic acid and polyphenol contents. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity also showed a greater response in mycorrhizal plants than in the control plants under each temperature condition. The results indicate that in cyclamen plants, AM fungal colonisation alleviated heat stress damage through an increased antioxidative activity and that the mycorrhizal symbiosis strongly enhanced temperature stress tolerance which promoted plant growth and increased the host biomass under heat stress.     

Sclerotial biomass and carotenoid yield of Penicillium sp. PT95 under oxidative growth conditions and in the presence of antioxidant ascorbic acid

AIMS: To determine the effect of oxidative stress and exogenous ascorbic acid on sclerotial biomass and carotenoid yield of Penicillium sp. PT95. METHODS: In this experiment, high oxidative stress was applied by the inclusion of FeSO(4) in the growth medium and exposure to light. Low oxidative stress was applied by omitting iron from the growth medium and by incubation in the dark. Supplementation of exogenous ascorbic acid (as antioxidant) to the basal medium caused a concentration-dependent delay of sclerotial differentiation (up to 48 h), decrease of sclerotial biomass (up to 40%) and reduction of carotenoid yield (up to 91%). On the contrary, the exogenous ascorbic acid also caused a concentration-dependent decrease of lipid peroxidation in colonies of this fungus. CONCLUSIONS: Under high oxidative stress growth condition, the sclerotial biomass and carotenoid yield of PT95 strain in each plate culture reached 305 mg and 32.94 microg, which were 1.23 and 3.71 times higher, respectively, than those at low oxidative stress growth condition. These data prompted us to consider that in order to attain higher sclerotial biomass and pigment yield, the strain PT95 should be grown under high oxidative stress and in the absence of antioxidants. SIGNIFICANCE AND IMPACT OF THE STUDY: These results suggest that strain PT95 may be used for solid-state fermentation of carotenoid production under high oxidative stress growth conditions.     

Role of hydrolytic enzymes and oxidative stress in autolysis and morphology of <Emphasis Type="Italic">Blakeslea trispora</Emphasis> during β-carotene production in submerged fermentation

The role of hydrolytic enzymes (proteases and chitinase) and oxidative stress in the autolysis and morphology of Blakeslea trispora during β-carotene production from a chemically defined medium in shake flask culture was investigated. The process of cellular autolysis was studied by measuring the changes in biomass dry weight, pH, concentration of β-carotene, specific activity of the hydrolytic enzymes and micromorphology of the fungus using a computerized image analysis system. In addition, the phenomenon of autolysis was associated with high concentrations of reactive oxygen species (ROS). The accumulation of ROS produced during fermentation causes oxidative stress in B. trispora. Oxidative stress was examined in terms of the activities of two key defensive enzymes: catalase (CAT) and superoxide dismutase (SOD). The profile of the specific activities of the above enzymes appeared to correlate with the oxidative stress of the fungus. The high activities of CAT and SOD showed that B. trispora is found under oxidative stress during β-carotene production. The culture began to show signs of autolysis nearly in the growth phase and autolysis increased significantly during the production phase. The morphological differentiation of the fungus was a result of the degradation of the cell membrane by hydrolytic enzymes and oxidative stress. Increased β-carotene production is correlated with intense autolysis of clumps, which has as a consequence the increase of the freely dispersed mycelia.     

The glutathione response to salt stress in the thermophilic fungus, Thermomyces lanuginosus

In order to investigate the role of glutathione in response to salt stress in the thermophilic fungus, Thermomyces lanuginosus, the biomass and the intracellular pool of protein and the glutathione + glutathione disulphid (GSH + GSSG) was measured for four days in a medium with NaCl or KCl added and in the basal medium. Due to the osmotic and ionic stress imposed by the salts, the growth of T. lanuginosus was delayed and the inhibitory effect of KCl exceeded that of NaCl. Glutathione seemed to be involved in the response of T. lanuginosus towards high concentrations of salt, as the level of stress was negatively correlated with the amount of total glutathione. Salt stress did not result in an increased intracellular protein production. GSH accumulated while nutrients were abundant and were subsequently degraded later, suggesting that nutrients stored in GSH are used when the medium is depleted.     

Exploration of fungal spores as a possible storehouse of proteolytic biocatalysts

Studies were carried out to define the relation between enzyme production and fungal sporulation, in solid-state cultivation conditions of the filamentous fungus Aspergillus oryzae NRRL 2217 to get information on possible links between metabolite synthesis and differentiation phenomena. The efforts taken to explore the possibility for the presence of a neutral protease inside the spores of this fungus was to increase the overall enzyme yield. Results showed that the production of enzyme (neutral protease) and biomass (total protein) were synchronised, both reaching their respective maximum levels at 48 h of fermentation, and decreasing thereafter. Neutral protease synthesis was not related to sporulation. The spores produced were subjected to various permeabilisation procedures, and the increase in the levels of neutral protease was monitored. Mechanical shear was the sole technique that was able to disrupt spores but even this failed to increase enzyme titres, confirming the absence of intra-spore proteases.     

Effects of prometryn and acetochlor on arbuscular mycorrhizal fungi and symbiotic system

Prometryn and acetochlor are common herbicides widely used to control weeds in agricultural systems. The impacts of the two herbicides on spore germination, hyphal elongation, the biomass and malondialdehyde content of carrot hairy roots were investigated using a strict in vitro cultivation system associating the Ri T‐DNA‐transferred carrot hairy roots with Glomus etunicatum. Alternatively, root colonization, daughter spore production and the proportion of hyphae with succinate dehydrogenase (SDH) and alkaline phosphatase (ALP) activities were also investigated. No significant impact on spore germination was noted in the presence of acetochlor at all three concentrations tested, while a significant decrease was observed with prometryn only at the highest concentration. Moreover, an inverse correlation was identified between herbicides concentrations and G. etunicatum root colonization and spore production as well as hyphal SDH and ALP activity, with a positive correlation identified among these four factors. Both herbicides exerted negative effects on the arbuscular mycorrhizal (AM) fungus and symbiosis at increasing concentrations, with prometryn apparently more toxic than acetochlor. Furthermore, the AM symbiotic system was shown to improve biomass, reduce malondialdehyde accumulation and ease lipid peroxidation in carrot hairy roots and decrease damage in host plants, thus enhancing plant tolerance to adverse conditions.

Significance and Impact of the Study

In this study, the effect of prometryn and acetochlor on the physiology and metabolic activities of the AM fungus Glomus etunicatum were investigated. Our findings demonstrate for the first time, the impact of the two herbicides at three concentrations (0·1, 1 and 10 mg l^?1) on transformed carrot hairy roots/AM fungus association under strict in vitro culture conditions, which may guide the application of the two herbicides in modern agriculture.     

Carbon concentration and oxygen availability affect lipid and carotenoid production by carob pulp syrup‐grown Rhodosporidium toruloides NCYC 921

The simultaneous effect of oxygen availability and carbon source concentration on yeast lipid and carotenoid production has never been studied before. In this work, a Doehlert distribution design was used to study the simultaneous effect of carbon concentration and oxygen availability on Rhodosporidium toruloides NCYC 921 carotenoid and lipid production. A cheap industrial byproduct was used as carbon source (carob pulp syrup). A total sugar concentration of 106.3 g/L and a medium volume of 0.120 L induced the highest total carotenoid and total fatty acid productivities (4.60 μg/Lh and 0.029 g/Lh, respectively). Flow cytometry was used to assess yeast stress response under different cultivation conditions. The highest proportion of cells with permeabilised membrane (>20%) was induced when the cultivations were carried out at the highest sugar concentration studied (130.0 g/L) or when the culture reached the minimum final medium pH (4.60). The results showed that the total sugar concentration had a positive influence on the yeast biomass and carotenoid content, while the oxygen availability had little influence on the biomass concentration, but had a slight positive influence on the carotenoid content. Regarding the fatty acids, the two factors had a negative impact on the synthesis of these compounds.     

Ethanol and value‐added byproducts from rice straw by dimorphic fungus Mucor hiemalis

Different morphologies of Mucor hiemalis were induced and used for the production of ethanol and biomass from rice straw through a separate hydrolysis and fermentation process. The yield of enzymatic hydrolysis was improved from 40.4% for the untreated straw to 80–93% by employing sodium hydroxide and concentrated phosphoric acid pretreatments with or without ultrasonication. The best hydrolysis performance was achieved after pretreatment by sodium hydroxide assisted with ultrasonication. The ethanol yields from the hydrolysates were 0.39–0.44 g/g depending on the pretreatment method and the fungus morphology. The yeast‐like form of the fungus showed faster glucose assimilation and slightly higher ethanol yield compared to the other morphologies. The biomass yield of mostly yeast‐like cells was more than the other morphologies (0.202–0.282 g/g glucose). Moreover, the biomass of the yeast‐like cells had more protein content (46.7–52.4 %) compared to filamentous cells (37.7–46.3 %). The cell wall, alkali‐insoluble material (AIM) of the biomass, represented 16.3–20.1% of the biomass. On average, total chitin‐chitosan content of AIM of the biomass of purely filamentous, mostly filamentous, mostly yeast‐like, and purely yeast‐like forms of the fungus was 0.460, 0.373, 0.330, and 0.336 g/g AIM of the biomass, respectively.     

Growth and biomass turnover ofHydrocharis dubia L. cultured under different nutrient conditions

Growth of a floating-leaved plant,Hydrocharis dubia L., was examined under varying nutrient conditions between 0.3 and 30 mgN l⁻¹ total inorganic nitrogen.H. dubia plants cultured under the most nutrient-rich condition showed the highest maximum ramet density (736 m⁻²), the highest maximum biomass (80.4 g dry weight m⁻²), and the highest total net production (185 g dry weight m⁻² in 82 days). Plants under nutrient-poor conditions had a relatively large proportion of root biomass and a small proportion of leaves with a long life span. Compared with other floating-leaved and terrestrial plants, the maximum biomass ofH. dubia was relatively small. This, and the rapid biomass turnover, was related to the short life span of leaves (13.2–18.7 days) and large biomass distribution to leaves.     

Growth responses of <Emphasis Type="Italic">Salix gracilistyla</Emphasis> cuttings to a range of substrate moisture and oxygen availability

The objective of this study is to determine the effects of substrate moisture and oxygen availability on growth traits of Salix gracilistyla Miquel, which colonizes gravel bars along rivers, the shoot growth schedule, biomass production, and resource allocation were examined under greenhouse conditions. We used four treatments representing a range of substrate moisture and oxygen availability: drought (D), flooding with standing water (FS), flooding with running water (FR), and control without drought or flooding (C). Cuttings in D stopped flushing and had low biomass production, reduced total leaf mass, and small leaves. Under anaerobic conditions, cuttings in FS stopped flushing and had low biomass production, small root biomass, low biomass allocation to roots, shallow roots, high biomass allocation to hypertrophied lenticels, and a few small, thick leaves. Under aerobic conditions, cuttings in FR showed continuous branch elongation and flushing, large biomass production, and large leaf biomass, similar to cuttings in C, in addition to low allocation to hypertrophied lenticels and many large leaves. The growth of cuttings was not inhibited by flooding of the roots throughout the experiment unless the conditions were anaerobic. Thus, cuttings respond to water stress under low moisture conditions by reducing the transpiration area and respond to flooding under low oxygen conditions by high allocation to hypertrophied lenticels and reduced transpiration area. Plasticity in the shoot growth schedule, biomass production, and resource allocation according to moisture conditions and the ability to develop hypertrophied lenticels upon flooding allow S. gracilistyla to colonize sites in which both desiccation and flooding occur.     

Synergistic interactions of arbuscular mycorrhizal fungi and rhizobia promoted the growth of <Emphasis Type="Italic">Lathyrus sativus</Emphasis> under sulphate salt stress

In order to examine the influence of microsymbionts on plants, arbuscular mycorrhizal (AM) fungi and rhizobia were used to examine the growth of Lathyrus sativus under sulphate salt stress. Seedlings of L. sativus were inoculated with a combination of selected microsymbionts. Plants were grown under greenhouse conditions with five Na₂SO₄ concentrations (0, 1%, 2%, 3% and 4% (weight : weight)). The inoculations combinations used were the AM fungus, Glomus mosseae and/or the rhizobium, Mesorhizobium mediterraneum. The results showed that sulphate salinity inhibited plant growth and biomass production. However, compared with the control treatments, dual-inoculation of G. mosseae and M. mediterraneum reduced the harmful influence of sulphate salinity. Parmeters including plant height, the extent of AM colonization, total biomass, nodules biomass, P concentration, N concentration and proline concentration confirmed that dual inoculation plays a vital role in promoting the growth of L. sativus under sulphate salt stress. The results suggested that the use of this dual inoculation could be exploited in grassland plantation establishment and in pastoral ecosystem reclamation programmes in arid and semi-arid areas subject to moderate salt contamination.     

Variations in water status, gas exchange, and growth in Rosmarinus officinalis plants infected with Glomus deserticola under drought conditions

The influence of the arbuscular mycorrhizal fungus Glomus deserticola on the water relations, gas exchange parameters, and vegetative growth of Rosmarinus officinalis plants under water stress was studied. Plants were grown with and without the mycorrhizal fungus under glasshouse conditions and subjected to water stress by withholding irrigation water for 14 days. Along the experimental period, a significant effect of the fungus on the plant growth was observed, and under water stress, mycorrhizal plants showed an increase in aerial and root biomass compared to non-mycorrhizal plants. The decrease in the soil water potential generated a decrease in leaf water potential (psi(l)) and stem water potential (psi(x)) of mycorrhizal and non-mycorrhizal plants, with this decrease being lower in mycorrhizal water-stressed plants. Mycorrhization also had positive effects on the root hydraulic conductivity (Lp) of water stressed plants. Furthermore, mycorrhizal-stressed plants showed a more important decrease in osmotic potential at full turgor (psi(os)) than did non-mycorrhizal-stressed plants, indicating the capacity of osmotic adjustment. Mycorrhizal infection also improved photosynthetic activity (Pn) and stomatal conductance (g(s)) in plants under water stress compared to the non-mycorrhizal-stressed plants. A similar behaviour was observed in the photochemical efficiency of PSII (Fv/Fm) with this parameter being lower in non-mycorrhizal plants than in mycorrhizal plants under water stress conditions. In the same way, under water restriction, mycorrhizal plants showed higher values of chlorophyll content than did non-mycorrhizal plants. Thus, the results obtained indicated that the mycorrhizal symbiosis had a beneficial effect on the water status and growth of Rosmarinus officinalis plants under water-stress conditions.     

Lipid production in batch and fed-batch cultures of Rhodosporidium toruloides from 5 and 6 carbon carbohydrates

ABSTRACT: BACKGROUND: Microbial lipids are a potential source of bio- or renewable diesel and the red yeast Rhodosporidium toruloides is interesting not only because it can accumulate over 50% of its dry biomass as lipid, but also because it utilises both five and six carbon carbohydrates, which are present in plant biomass hydrolysates. METHODS: R. toruloides was grown in batch and fed-batch cultures in 0.5 l bioreactors at pH 4 in chemically defined, nitrogen restricted (C/N 40 to 100) media containing glucose, xylose, arabinose, or all three carbohydrates as carbon source. Lipid was extracted from the biomass using chloroform-methanol, measured gravimetrically and analysed by GC. RESULTS: R. toruloides was grown on glucose, xylose, arabinose or mixtures of these carbohydrates in batch and fed-batch, nitrogen restricted conditions. Lipid production was most efficient with glucose (up to 25 g lipid L1, 48 to 75% lipid in the biomass, at up to 0.21 g lipid L1h1) as the sole carbon source, but high lipid concentrations were also produced from xylose (36 to 45% lipid in biomass). Lipid production was low (15-19% lipid in biomass) with arabinose as sole carbon source and was lower than expected (30% lipid in biomass) when glucose, xylose and arabinose were provided simultaneously. The presence of arabinose and/or xylose in the medium increased the proportion of palmitic and linoleic acid and reduced the proportion of oleic acid in the fatty acids, compared to glucose-grown cells. High cell densities were obtained in both batch (37 g L1, with 49% lipid in the biomass) and fed-batch (35 to 47 g L1, with 50 to 75% lipid in the biomass) cultures. The highest proportion of lipid in the biomass was observed in cultures given nitrogen during the batch phase but none with the feed. However, carbohydrate consumption was incomplete when the feed did not contain nitrogen and the highest total lipid and best substrate consumption were observed in cultures which received a constant low nitrogen supply. CONCLUSIONS: Lipid production in R. toruloides was lower from arabinose and mixed carbohydrates than from glucose or xylose. Although high biomass and lipid production were achieved in both batch and fed-batch cultures with glucose as carbon source, for lipid production from mixtures of carbohydrates fed-batch cultivation was preferable. Constant feeding was better than intermittent feeding. The feeding strategy did not affect the relative proportion of different fatty acids in the lipid, but the presence of C5 sugars did.     

Effect of culture conditions on antifouling compound production of a sponge-associated fungus

Microorganisms associated with invertebrate hosts have long been suggested to be a source for bioactive metabolites. In this study, we reported that a sponge-associated fungus, Letendraea helminthicola, produced two antifouling compounds: 3-methyl-N-(2-phenylethyl) butanamide and cyclo(D-Pro-D-Phe). To optimize the production of these antifouling compounds, we then examined the production of compounds under different culture conditions (temperature, salinity, pH, and carbon and nitrogen sources). This fungus grew well and produced more compounds at temperatures between 18 and 30°C; the fungus grew well at 75 parts per thousand (ppt) salinity but produced the highest amount of antifouling compounds at 30 and 45 ppt. The optimal initial pH value for mycelial growth was 5.5 to 6.5, whereas the production of the antifouling compounds was maximized at pH 3.5 and 4.5. Glucose and xylose (as carbon sources) increased the production of antifouling compounds. Yeast extract and peptone (as nitrogen sources) maximized the production of mycelial biomass and antifouling compounds. Our results indicate that culture conditions greatly affect the production of bioactive compounds from mycelial fungal cultures as exemplified by strain L. helminthicola and that the conditions favorable for fungal growth may not be the best conditions for bioactive compound production.     

Effect of copper-induced oxidative stress on sclerotial differentiation and antioxidant properties of Penicillium thomii PT95 strain

Penicillium thomii PT95 strain was able to form abundant orange, sand-shaped sclerotia in which carotenoids were accumulated. The aim of this work was to determine the effects of copper-induced oxidative stress on the sclerotial differentiation and antioxidant properties of PT95 strain. The results showed that the time of exudates initiation, sclerotial initiation and sclerotial maturation of PT95 strain were advanced in 1–2 days under the copper-induced oxidative stress growth conditions. The analytical results of sclerotial biomass, carotenoids content in sclerotia showed that copper-induced oxidative stress favored the sclerotial differentiation and biosynthesis of carotenoids. Under the copper-induced oxidative stress growth conditions, the total phenolics content and DPPH free radical scavenging activity of sclerotia of this fungus were decreased as compared with the control. However, the oxidative stress induced by a lower amount of CuSO₄ in media could enhance significantly the reducing power of sclerotia.