CAROTENOIDS PRODUCTION IN DIFFERENT CULTURE CONDITIONS BY Sporidiobolus pararoseus

Carotenoids produced by Sporidiobolus pararoseus were studied. It was found that biomass was connected with carbon source, temperature, and pH, but carotenoids proportion was seriously influenced by dissolved oxygen and nitrogen source. Different carotenoids could be obtained by using selected optimum conditions. In the end we established the strategies to produce β-carotene or torulene. Fed-batch fermentation in fermentor was used to prove the authenticity of our conclusions. The cell biomass, β-carotene content, and β-carotene proportion could reach 56.32 g/L, 18.92 mg/L and 60.43%, respectively, by using corn steep liquor at 0–5% of dissolved oxygen saturation. β-Carotene content was 271% higher than before this addition. The cell biomass, torulene content, and torulene proportion could reach 62.47 g/L, 31.74 mg/L, and 70.41%, respectively, by using yeast extract at 30–35% of dissolved oxygen saturation. Torulene content was 152% higher than before this addition. The strategy for enhancing specific carotenoid production by selected fermentation conditions may provide an alternative approach to enhance carotenoid production with other strains.     

Production of carotenoids and lipids by <Emphasis Type="Italic">Rhodococcus opacus</Emphasis> PD630 in batch and fed-batch culture

Production of carotenoids by Rhodococcus opacus PD630 is reported. A modified mineral salt medium formulated with glycerol as an inexpensive carbon source was used for the fermentation. Ammonium acetate was the nitrogen source. A dry cell mass concentration of nearly 5.4 g/L could be produced in shake flasks with a carotenoid concentration of 0.54 mg/L. In batch culture in a 5 L bioreactor, without pH control, the maximum dry biomass concentration was ~30 % lower than in shake flasks and the carotenoids concentration was 0.09 mg/L. Both the biomass concentration and the carotenoids concentration could be raised using a fed-batch operation with a feed mixture of ammonium acetate and acetic acid. With this strategy, the final biomass concentration was 8.2 g/L and the carotenoids concentration was 0.20 mg/L in a 10-day fermentation. A control of pH proved to be unnecessary for maximizing the production of carotenoids in this fermentation.     

Carotenoids production in different culture conditions by Sporidiobolus pararoseus

Carotenoids produced by Sporidiobolus pararoseus were studied. It was found that biomass was connected with carbon source, temperature, and pH, but carotenoids proportion was seriously influenced by dissolved oxygen and nitrogen source. Different carotenoids could be obtained by using selected optimum conditions. In the end we established the strategies to produce β-carotene or torulene. Fed-batch fermentation in fermentor was used to prove the authenticity of our conclusions. The cell biomass, β-carotene content, and β-carotene proportion could reach 56.32?g/L, 18.92?mg/L and 60.43%, respectively, by using corn steep liquor at 0-5% of dissolved oxygen saturation. β-Carotene content was 271% higher than before this addition. The cell biomass, torulene content, and torulene proportion could reach 62.47?g/L, 31.74?mg/L, and 70.41%, respectively, by using yeast extract at 30-35% of dissolved oxygen saturation. Torulene content was 152% higher than before this addition. The strategy for enhancing specific carotenoid production by selected fermentation conditions may provide an alternative approach to enhance carotenoid production with other strains.     

Bioconversion of cheese whey permeate into fungal oil by <Emphasis Type="Italic">Mucor circinelloides</Emphasis>

Background

Oleaginous fungi are efficient tools to convert agricultural waste streams into valuable components. The filamentous fungus Mucor circinelloides was cultivated in whey permeate, a byproduct from cheese production, to produce an oil-rich fungal biomass. Response surface methodology was used to optimize the fermentation conditions such as pH and temperature for increased biomass yield and lipid accumulation. Quantification and characterization of the fungal biomass oil was conducted.

Results

Upstream lactose hydrolysis of the whey permeate increased the biomass yield from 2.4 to 7.8 (g dry biomass/L) compared to that of non-hydrolyzed whey permeate. The combination of low pH (4.5) and pasteurization minimized microbial competition, thus favoring fungal growth. A central composite rotatable design was used to evaluate the effects of temperature (22.4–33.6 °C) and a lower pH range (3.6–4.7) on biomass yield and composition. The highest biomass yield and oil content was observed at high temperature (33.6 °C), while the pH range evaluated had a less pronounced effect. The predictive model was validated at the optimal conditions of 33.6 °C and pH 4.5. The fungal biomass yield plateaued at 9 g dry cell weight per liter, while the oil content and lipid yield reached a maximum of 24% dry biomass and 2.20 g/L, respectively, at 168 h. Triacylglycerides were the major lipid class (92%), which contained predominantly oleic (41%), palmitic (23%), linoleic (11%), and γ-linolenic acid (9%).

Conclusions

This study provided an alternative way of valorization of cheese whey permeate by using it as a substrate for the production of value-added compounds by fungal fermentation. The fatty acid profile indicates the suitability of M. circinelloides oil as a potential feedstock for biofuel production and nutraceutical applications.

     

Investigation of factors influencing production of the monocyclic carotenoid torulene in metabolically engineered <Emphasis Type="Italic">Escherichia coli</Emphasis>

Factors influencing production of the monocyclic carotenoid torulene in recombinant Escherichia coli were investigated by modulating enzyme expression level, culture conditions, and engineering of the isoprenoid precursor pathway. The gene dosage of in vitro evolved lycopene cyclase crtY2 significantly changed the carotenoid profile. A culture temperature of 28°C showed better production of torulene than 37°C while initial culture pH had no significant effect on torulene production. Glucose-containing LB, 2×YT, TB and MR media significantly repressed the production of torulene, and the other carotenoids lycopene, tetradehydrolycopene, and -carotene, in E. coli. In contrast, glycerol-containing LB, 2×YT, TB, and MR media enhanced torulene production. Overexpression of dxs, dxr, idi and/or ispA, individually and combinatorially, enhanced torulene production up to 3.1–3.3 fold. High torulene production was observed in a high dissolved oxygen level bioreactor in TB and MR media containing glycerol. Lycopene was efficiently converted into torulene during aerobic cultures, indicating that the engineered torulene synthesis pathway is well coordinated, and maintains the functionality and integrity of the carotenogenic enzyme complex.     

Biomass, lipid content, and fatty acid composition of freshwater Chlamydomonas mexicana and Scenedesmus obliquus grown under salt stress

Two freshwater microalgae including Chlamydomonas mexicana and Scenedesmus obliquus were grown on Bold Basal Medium (BBM) with different levels of salinity up to 100 mM NaCl. The dry biomass and lipid content of microalgae were improved as the concentration of NaCl increased from 0 to 25 mM. Highest dry weight (0.8 and 0.65 g/L) and lipid content (37 and 34 %) of C. mexicana and S. obliquus, respectively, were obtained in BBM amended with 25 mM NaCl. The fatty acid composition of the investigated species was also improved by the increased NaCl concentration. At 50 mM, NaCl palmitic acid (35 %) and linoleic acid (41 %) were the dominant fatty acids in C. mexicana, while oleic acid (41 %) and α-linolenic acid (20 %) were the major fractions found in S. obliquus.     

Enhancement of carotenoids and lipids production by oleaginous red yeast Sporidiobolus pararoseus KM281507

Bioconversion of biodiesel-derived crude glycerol into carotenoids and lipids was investigated by a microbial conversion of an oleaginous red yeast Sporidiobolus pararoseus KM281507. The methanol content in crude glycerol (0.5%, w/v) did not show a significant effect on biomass production by strain KM281507. However, demethanolized crude glycerol significantly supported the production of biomass (8.64?±?0.13?g/L), lipids (2.92?±?0.03?g/L), β-carotene (15.76?±?0.85?mg/L), and total carotenoids (33.67?±?1.28?mg/L). The optimal conditions suggested by central composite design were crude glycerol concentration (55.04?g/L), initial pH of medium (pH 5.63) and cultivation temperature (24.01°C). Under these conditions, the production of biomass, lipids, β-carotene, and total carotenoids were elevated up to 8.83?±?0.05, 4.00?±?0.06?g/L, 27.41?±?0.20, and 53.70?±?0.48?mg/L, respectively. Moreover, an addition of olive oil (0.5???2.0%) dramatically increased the production of biomass (14.47?±?0.15?g/L), lipids (6.40?±?0.09?g/L), β-carotene (54.43?±?0.95?mg/L), and total carotenoids (70.92?±?0.51?mg/L). The oleic acid content in lipids was also increased to 75.1% (w/w) of total fatty acids, indicating a good potential to be an alternative biodiesel feedstock. Meanwhile, the β-carotene content in total carotenoids was increased to 76.7% (w/w). Hence, strain KM281507 could be a good potential source of renewable biodiesel feedstock and natural carotenoids.     

氮源种类及溶氧水平对锁掷酵母产类胡萝卜素组分的影响

在锁掷酵母（Sporidioboluspararoseus）发酵产类胡萝卜紊的过程中,发酵产物中类胡萝卜紊种类繁多,而且性质相似,加大了不同色素分离纯化的难度。为定向积累不同种类的类胡萝卜素,以本实验室保藏锁挪酵母JD-2为出发菌,研究了氮源种类和浓度及溶氧对锁掷酵母产类胡萝卜素的影响,并在7L发酵罐中进行了补料分批发酵试验。发现培养基中同时添加有机氮源和无机氮源且溶氧控制较低（5％）时有利于β-胡萝卜素的大量积累,最佳有机氮源和无机氮源分别为玉米浆（20g／L）、硫酸铵（5g／L）。补料分批发酵时β-胡萝卜素产量达到31．28mg／L,红酵母烯12．38mg／L。培养基中只添加有机氮源且相对溶氧控制相对较高（30％）时有利于红酵母烯的大量积累,最佳有机氮源为酵母膏（20g／L）。补料分批发酵时红酵母烯产量达到38．96mg／L,8．胡萝卜素12．36mg／L。     

Characterization of an evolved carotenoids hyper-producer of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> through bioreactor parameter optimization and Raman spectroscopy

An evolutionary engineering approach for enhancing heterologous carotenoids production in an engineered Saccharomyces cerevisiae strain was used previously to isolate several carotenoids hyper-producers from the evolved populations. β-Carotene production was characterized in the parental and one of the evolved carotenoids hyper-producers (SM14) using bench-top bioreactors to assess the impact of pH, aeration, and media composition on β-carotene production levels. The results show that with maintaining a low pH and increasing the carbon-to-nitrogen ratio (C:N) from 8.8 to 50 in standard YNB medium, a higher β-carotene production level at 25.52 ± 2.15 mg β-carotene g^?1 (dry cell weight) in the carotenoids hyper-producer was obtained. The increase in C:N ratio also significantly increased carotenoids production in the parental strain by 298 % [from 5.68 ± 1.24 to 22.58 ± 0.11 mg β-carotene g^?1 (dcw)]. In this study, it was shown that Raman spectroscopy is capable of monitoring β-carotene production in these cultures. Raman spectroscopy is adaptable to large-scale fermentations and can give results in near real-time. Furthermore, we found that Raman spectroscopy was also able to measure the relative lipid compositions and protein content of the parental and SM14 strains at two different C:N ratios in the bioreactor. The Raman analysis showed a higher total fatty acid content in the SM14 compared with the parental strain and that an increased C:N ratio resulted in significant increase in total fatty acid content of both strains. The data suggest a positive correlation between the yield of β-carotene per biomass and total fatty acid content of the cell.     

Carotenoid production by lactoso-negative yeasts co-cultivated with lactic acid bacteria in whey ultrafiltrate

Two strains were selected--the lactoso-negative yeast Rhodotorula rubra GED2 and the homofermentative Lactobacillus casei subsp. casei Ha1 for co-cultivation in cheese whey ultrafiltrate (WU) and active synthesis of carotenoids. Under conditions of intensive aeration (1.0 l/l min, 220 rpm), a temperature of 30 degrees C, WU with 55.0 g lactose/l, initial pH = 5.5, the carotenoid content in the cells reached a maximum, when the growth of the cultures had come to an end, i.e. in the stationary phase of the yeast. The maxima for dry cell accumulation (27.0 g/l) and carotenoid formation (12.1 mg/l culture medium) did not coincide on the 5th and 6th day, respectively. A peculiarity of the carotenoid-synthesizing Rh. rubra GED2 strain, co-cultivated with L. casei Ha1, was the production of carotenoids with high beta-carotene content (46.6% of total carotenoids) and 10.7% and 36.9% for torulene and torularhodin, respectively.     

Optimization of pineapple pulp residue hydrolysis for lipid production by Rhodotorula glutinis TISTR5159 using as biodiesel feedstock

The higher lipid productivity of Rhodotorula glutinis TISTR5159 was achieved by optimizing the pineapple pulp hydrolysis for releasing the high sugars content. The sequential simplex method operated by varied; solid-to-liquid ratio, sulfuric acid concentration, temperature, and hydrolysis time were successfully applied and the highest sugar content (83.2 g/L) evaluated at a solid-to-liquid ratio of 1:10.8, 3.2% sulfuric acid, 105 °C for 13.9 min. Moreover, the (NH₄)₂SO₄ supplement enhanced the lipid productivity and gave the maximum yields of biomass and lipid of 15.2 g/L and 9.15 g/L (60.2%), respectively. The C16 and C18 fatty acids were found as main components included oleic acid (55.8%), palmitic acid (16.6%), linoleic acid (11.9%), and stearic acid (7.8%). These results present the possibility to convert the sugars in pineapple pulp hydrolysate to lipids. The fatty acid profile was also similar to vegetable oils. Thus, it could be used as potential feedstock for biodiesel production.     

Fatty Acid Characterization and Biodiesel Production by the Marine Microalga <Emphasis Type="Italic">Asteromonas gracilis</Emphasis>: Statistical Optimization of Medium for Biomass and Lipid Enhancement

Lipid production is an important indicator for evaluating microalgal species for biodiesel production. In this study, a new green microalga was isolated from a salt lake in Egypt and identified as Asteromonas gracilis. The main parameters such as biomass productivity, lipid content, and lipid productivity were evaluated in A. gracilis, cultivated in nutrient-starved (nitrogen, phosphorous), and salinity stress as a one-factor-at-a-time method. These parameters in general did not vary significantly from the standard nutrient growth media when these factors were utilized separately. Hence, response surface methodology (RSM) was assessed to study the combinatorial effect of different concentrations of the abovementioned factor conditions and to maximize the biomass productivity, lipid content, and lipid productivity of A. gracilis by determining optimal concentrations. RSM optimized media, including 1.36 M NaCl, 1 g/L nitrogen, and 0.0 g/L phosphorus recorded maximum biomass productivity, lipid content, and lipid productivity (40.6 mg/L/day, 39.3%, and 15.9 mg/L/day, respectively) which agreed well with the predicted values (40.1 mg/L/day, 43.6%, and 14.6 mg/L/day, respectively). Fatty acid profile of A. gracilis was composed of C16:0, C16:1, C18:0, C18:3, C18:2, C18:1, and C20:5, and the properties of fuel were also in agreement with international standards. These results suggest that A. gracilis is a promising feedstock for biodiesel production.     

Efficient concomitant production of lipids and carotenoids by oleaginous red yeast <Emphasis Type="Italic">Rhodotorula glutinis</Emphasis> cultured in palm oil mill effluent and application of lipids for biodiesel production

Rhodotorula glutinis TISTR 5159 is oleaginous red yeast that accumulates both lipids and carotenoids. It was cultured in palm oil mill effluent (POME) with only the addition of ammonium sulfate and Tween 20 as a suitable nitrogen source and surfactant, respectively. Response surface methodology (RSM) was applied to optimize initial chemical oxygen demand (COD) in POME, C/N ratio, and Tween 20 concentration for concomitant production of lipids and carotenoids. Among three investigated factors, C/N ratio contributed a significant effect upon lipid and carotenoids production. Analysis of response surface plots revealed that the optimum C/N ratio for the biomass was 140, while that for lipid content and carotenoids were higher at 180 and 170, respectively. The high level of the nitrogen source (with a low C/N ratio) enhanced the biomass, making the accumulation of lipids and carotenoids less preferable. Hence, the two-stage process was attempted as an optimal way for cell growth in the first stage and product accumulation in the second stage. The lipid yield and carotenoid production obtained in the two-stage process were higher than those in the one-stage process. In the semi-continuous fermentation, R. glutinis TISTR 5159 accumulated high lipid content and produced a considerably high concentration of carotenoids during long-term cultivation. Additionally, efficient COD removal by R. glutinis TISTR 5159 was observed. The biodiesel produced from yeast lipids was composed mainly of oleic and palmitic acids, similar to those from plant oil.     

Torularhodin and torulene are the major contributors to the carotenoid pool of marine Rhodosporidium babjevae (Golubev)

A carotenoid-producing yeast strain, isolated from the sub-arctic, marine copepod Calanus finmarchicus, was identified as Rhodosporidium babjevae (Golubev) according to morphological and biochemical characteristics and phylogenetic inference from the small-subunit ribosomal RNA gene sequence. The total carotenoids content varied with cultivation conditions in the range 66–117 μg per g dry weight. The carotenoid pool, here determined for the first time, was dominated by torularhodin and torulene, which collectively constituted 75–91% of total carotenoids under various regimes of growth. β-Carotene varied in the range 5–23%. A high-peptone/low-yeast extract (weight ratio 38:1) marine growth medium favoured the production of torularhodin, the carotenoid at highest oxidation level, with an average of 63% of total carotenoids. In standard yeast medium (YM; ratio 1.7:1), torularhodin averaged 44%, with increased proportions of the carotenes, torulene and β-carotene. The anticipated metabolic precursor γ-carotene (β,ψ-carotene) constituted a minor fraction (≤8%) under all conditions of growth.     

Antioxidants characterization in selected cyanobacteria

Antioxidants—molecules that have the ability to inhibit the oxidation of other molecules and have many medicinal and industrial applications—are commonly found in algae. Due to the harmful effects of common synthetic antioxidants, their replacement with natural antioxidants would be advantageous. The goal of this study was to examine the efficacy of antioxidants (including antioxidant content, antioxidant activity and antioxidant enzymes) among 11 species of freshwater blue-green algae. Antioxidant activities were evaluated by assaying radical scavenging activity, reducing power and chelating activity. The results showed that Spirulina platensis has the highest radical scavenging activity and reducing power (524 and 244 % more than the control, respectively) and Nostoc linkia has the highest chelating activity (195 %). Examination of some antioxidant contents such as chlorophyll a, carotenoids and phenolic content revealed that S. platensis has the highest contents [10.6 mg/g dry weight (DW), 2.4 mg/g DW and 9.7 mg gallic acid equivalent /g DW, respectively]. The positive correlation (P <0.01) between algal content and antioxidant activity may be attributed to the potent antioxidant activity of these contents. Variation in the activity of three antioxidant enzymes (superoxide dismutase, catalase and peroxidase) was also reported. This study showed that the Cyanobacteria are promising sources of antioxidants.     

Lipid production and composition of fatty acids in Chlorella vulgaris cultured using different methods: photoautotrophic,heterotrophic, and pure and mixed conditions

This study investigated the biomass, lipid production, fatty acid content, and other nutrients present in microorganisms by using four culture methods: (1) photoautotrophic pure Chlorella vulgaris cultures (PP); (2) heterotrophic pure C. vulgaris cultures (PH); (3) mixed cultures of Rhodotorula glutinis and C. vulgaris under photoautotrophic conditions (MP); and (4) heterotrophic mixed cultures (MH). The microorganisms in MP culture showed the optimum growth condition and lipid production. Among the cultures, MP yielded the highest number of cells and biomass (5.9?×?10⁵ cells/mL and 0.523 g/L, respectively). Furthermore, lipid production in MP culture was 114.22 mg/L, which is 136 % higher than that in MH culture (48.22 mg/L). Considering the higher contents of palmitic acid (C16:0) at 24.65 %, oleic acid (C18:1) at 56.34 %, and protein at 42.39 g/100 g in the MP culture than in other cultures, we proposed that MP could be used effectively to support the growth of microorganisms. This method could also be used as a potential approach for biodiesel production.     

Effect of NaCl stress on rice physiological properties

Salinity is a major yield-reducing factor in coastal and arid irrigated rice production systems. Rice seedlings (Oryza sativa cv. Tarom Atri) were exposed to different NaCl concentrations for 8 days after germination. Plants height, fresh and dry weight, relative water content, pigment and carbohydrate content, photosynthetic efficiency and lipid peroxidase and antioxidant enzyme activity of rice seedlings grown under salt stress were investigated. Seedling grown under 25and 50 mM salt were shorter than the control. They could, however, develop their secondary leaves. Seedlings grown in the nutrient solution supplied with 100 and 200 mM extra salt could not develop their secondary leaves. Fresh weight ofseedlings grown under salt stress reduced up to 42.2% of the non-treated seedlings. Chlorophylls and carotenoids contents decreased significantly in the salt-treated seedlings. Carotenoid contents in NaCl-treated seedlings were decreased to 39.3%. No significant changes occurred in the photochemical efficiency of control and stressed plants. Increasing concentrations of NaCl resulted in increase and decrease of Na⁺ and K⁺ ions, respectively. NaCl salinity caused an increase in both peroxide content and lipid peroxidation. Seedlings which recovered for 24 h showed lower peroxide and malondialdehyde content.     

Enhancement of total phenolic and flavonoids extraction from <Emphasis Type="Italic">Rosmarinus officinalis</Emphasis> L using electromagnetic induction heating (EMIH) process

Electromagnetic induction heating (EMIH) assisted extraction of phenolic compounds from Rosmarinus officinalis L, and the antioxidant and antimicrobial activities of the plant extract were examined in this study. The extraction yield acquired with this process was found to be 25.1?±?2%, with maximum amounts of phenolic compounds: 127.87?±?2.1 mg Gallic acid equivalents per g dry weight and total flavonoids contents 14.48?±?1.5 mg quercetin equivalents per g dry weight, under optimum extraction conditions (extraction time 2 h, ratio of raw material to liquid 1:2 and 0% of NaCl). The antioxidant activity was assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH); 2, 2′-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) radical cation (ABTS⁺) and ferric reducing power (FRAP) methods. The results indicate the extract derived through EMIH showed a strong antioxidant ability (89.25%; EC₅₀ of 0.0148 µg/mL). Besides, the antimicrobial bioassay demonstrated that the extract possessed a good antimicrobial activity against all tested fungi and bacteria.     

Formation of carotenoids by rhodotorula glutinis in whey ultrafiltrate

The growth and carotenoid biosynthesis of the yeast Rhodotorula glutinis was studied by cocultivation with Lactobacillus helveticus in cheese ultrafiltrate containing 3.9% and 7.1% lactose. By growing this mixed culture in a 15-L fermentor MBR AG (Switzerland) at an air flow rate of 0.5 L/L min and agitation at 220 rpm for 6 days, a total yield of carotenoids of 268 mug/g dry cells wasobtained. Carotenoids were formed almost parallel with the cell growth, anda maximum production was reached at an early stationary phase. A high-performance liquid chromatographic system (HPLC) permitting simultaneous determination of major carotenoid pigments was used. The three main pigments (torularhodin, beta-carotene, and torulene) were formed in Rhodotorula glutinis, and reached a maximum concentration as follows: 182.0, 43.9, 23.0 mug,g dry cells. (c) 1994 John Wiley & Sons, Inc.     

24-Epibrassinolide ameliorates the effects of boron toxicity on <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> (L.) Heynh by activating an antioxidant system and decreasing boron accumulation

Brassinosteroids (BRs) play a significant role in alleviating the negative effects of various environmental stresses and in promoting the growth and development of plants. In this study, we investigated the effects of 24-epibrassinolide (EBL) on the growth, boron (B) accumulation and activation of the antioxidant system of Arabidopsis thaliana (L.) Heynh exposed to high concentrations of boric acid (BA). A. thaliana plants were grown in a hydroponic culture, and after 4 weeks, the plants were transferred to media containing either 0.80 or 1.60 mM BA. Following BA treatment, 0.01 and 1 µM EBL was sprayed on the entire foliar region of the seedlings. B toxicity induced oxidative stress and considerably inhibited the growth of the plants. The spraying of EBL on the B-treated plants resulted in increases in growth (both fresh and dry shoot mass, silique number, length and mass) and pigment content (total chlorophyll and carotenoids). Excessive B levels increased the activities of antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase, and increased the proline content in leaves of plants. However, treatment of the B-stressed plants with EBL further enhanced the activities of the antioxidant enzymes and increased the content of proline. The high level of lipid peroxidation in plants observed during exposure to a higher level of BA was decreased following EBL treatment. Thus, this study showed that the exogenous application of EBL ameliorates the toxic effects of B in a model plant by improving the plant’s antioxidant system and decreasing B accumulation. To our knowledge, this is the one of the first studies to examine the effect of BR in plants subjected to B toxicity.