Prospects of using marine actinobacteria as probiotics in aquaculture

In the present study, optimum culture conditions for the production of extracellular polysaccharides (EPS) in submerged culture of an edible mushroom, Laetiporus sulphureus var. miniatus and their stimulatory effects on insulinoma cell (RINm5F) proliferation and insulin secretion were investigated. The maximum mycelial growth (4.1 g l⁻¹) and EPS production (0.6 g l⁻¹) in submerged flask culture were achieved in a medium containing 30 g l⁻¹ maltose, 2 g l⁻¹ soy peptone, and 2 mM MnSO₄·5H₂O at an initial pH 2.0 and temperature 25°C. In the stirred-tank fermenter under optimized medium, the concentrations of mycelial biomass and EPS reached a maximum level of 8.1 and 3.9 g l⁻¹, respectively. Interestingly, supplementation of deep sea water (DSW) into the culture medium significantly increased both mycelial biomass and EPS production by 4- and 6.7-fold at 70% (v/v) DSW medium, respectively. The EPS were proved to be glucose-rich polysaccharides and were able to increase proliferation and insulin secretary function of rat insulinoma RINm5F cells, in a dose-dependent manner. In addition, EPS also strikingly reduced the streptozotocin-induced apoptosis in RINm5F cells indicating the mode of the cytoprotective role of EPS on RINm5F cells.     

Effect of mixed carbon substrate on exopolysaccharide production of cyanobacterium Nostoc flagelliforme in mixotrophic cultures

The effects of organic carbon sources on cell growth and exopolysaccharide (EPS) production of dissociated Nostoc flagelliforme cells under mixotrophic batch culture were investigated. After 7?days of cultivation, glycerol, acetate, sucrose, and glucose increased the final cell density and final EPS concentrations, and mixotrophic growth achieved higher biomass concentrations. The increase in cell growth was particularly high when glucose was added as the sole carbon source. On the other hand, EPS production per dry cell weight was significantly enhanced by adding acetate. For more effective EPS production, the effects of the mixture of glucose and acetate were investigated. Increasing the ratio of glucose to acetate resulted in higher growth rate with BG-11 medium and higher EPS productivity with BG-11₀ medium (without NaNO₃). When the medium was supplemented with a mixture of glucose (4.0?g?L^?1) and acetate (2.0?g?L^?1), 1.79?g?L^?1 biomass with BG-11 medium and 879.6?mg?L^?1 of EPS production with BG-11₀ medium were achieved. Adopting this optimal ratio of glucose to acetate established in flask culture, the culture was also conducted in a 20-L photobioreactor with BG-11 medium for 7?days. A maximum biomass of 2.32?g?L^?1 was achieved, and the EPS production was 634.6?mg?L^?1.     

Optimization of a chemically defined medium for mycelial growth and polysaccharide production by medicinal mushroom <Emphasis Type="Italic">Phellinus igniarius</Emphasis>

A chemically defined medium for mycelial growth and exopolysaccharide (EPS) production by submerged culture of Phellinus igniarius was investigated. The mainly defined medium compositions were optimized by using orthogonal matrix method. The optimal defined medium (per liter) was 40.0 g glucose, 4.0 g. glutamic acid, 4.0 g (NH₄)₂SO₄, and initial pH 6.0. Under the optimal medium, the maximal mycelial biomass and EPS production were 12.33 ± 0.89 and 1.21 ± 0.08 g l⁻¹ at 192 h in shake flask, while the maximal mycelial biomass and EPS production reached 13.86 ± 0.52 and 1.92 ± 0.07 g l⁻¹ at 168 h in 3 l fermenter, respectively. The molecular weights (g mol⁻¹) of four fractions isolated from EPS by gel permeation were about 6.4 × 10⁶, 3.3 × 10⁵, 2.7 × 10⁵ and 2.9 × 10³. This study should be widely applied to other secondary metabolites production from higher fungus in a chemically defined medium and quantitative regulation of the metabolic flux in polysaccharide biosynthesis.     

Optimization of exopolysaccharide production from Armillaria mellea in submerged cultures

Aims: To study the optimization of submerged culture conditions for exopolysaccharide (EPS) production by Armillaria mellea in shake‐flask cultures and also to evaluate the performance of an optimized culture medium in a 5‐l stirred tank fermenter. Methods and Results: Shake flask cultures for EPS optimal nutritional production contained having the following composition (in g l^?1): glucose 40, yeast extract 3, KH₂PO₄ 4 and MgSO₄ 2 at an optimal temperature of 22°C and an initial of pH 4·0. The optimal culture medium was then cultivated in a 5‐l stirred tank fermenter at 1 vvm (volume of aeration per volume of bioreactor per min) aeration rate, 150 rev min^?1 agitation speed, controlled pH 4·0 and 22°C. In the optimal culture medium, the maximum EPS production in a 5‐l stirred tank fermenter was 588 mg l^?1, c. twice as great as that in the basal medium. The maximum productivity for EPS (Q_p) and product yield (Y_P/S) were 42·02 mg l^?1 d^?1 and 26·89 mg g^?1, respectively. Conclusions: The optimal culture conditions we proposed in this study enhanced the EPS production of A. mellea from submerged cultures. Significance and Impact of the Study: The optimal culturing conditions we have found will be a suitable starting point for a scale‐up of the fermentation process, helping to develop the production of related medicines and health foods from A. mellea.     

The effect of nutrients and environmental conditions on biomass and oil production in Botryococcus braunii Race B strains

The green alga Botryococcus braunii is widely recognized as a source of non-fossil oil. However, limitations in Botryococcus biomass production hamper its commercial exploitation. This study examines the effects of nutrients (nitrogen and iron) and environmental conditions (temperature, light intensity and photoperiod) on biomass and oil production in two B. braunii Race B strains, Kossou-4 and Overjuyo-3. The highest biomass and oil production were obtained at a nitrogen concentration of 750 mg l^?1, iron concentration of 6 mg l^?1, at 25°C and at 135 µmol photons m^?2 s^?1 with a photoperiod of 16 h light:8 h darkness. Culturing the strains in Blue-green (BG11) medium containing optimized nutrients under optimal conditions resulted in an up to ~10.6-fold increase in biomass. In Kossou-4 and Overjuyo-3 strains, biomass increased from 1.647 g 10 l^?1 and 3.137 g 10 l^?1 respectively in normal BG11 medium to 17.390 g 10 l^?1 and 21.721 g 10 l^?1 in optimized BG11 media and growth conditions. This was accompanied by ~8–10.5-fold increase in oil production compared with that in normal BG11 medium. Oil (0.324 g 10 l^?1 and 0.211 g 10 l^?1) was produced in normal BG11 medium in Kossou-4 and Overjuyo-3 strains respectively, compared with 2.642 g 10 l^?1 (Kossou-4) and 2.206 g 10 l^?1 (Overjuyo-3) in modified BG11 media under optimized conditions. Therefore, optimization of nutrients and environmental conditions can increase biomass and oil production in the two strains of B. braunii.     

Production of polysaccharide–peptide complexes by submerged mycelial culture of an entomopathogenic fungus Cordyceps sphecocephala

The effects of medium components and environmental factors on the production of mycelial biomass and polysaccharide–peptide complexes (exobiopolymers) by Cordyceps sphecocephala J-201 were investigated in submerged cultures. The optimal temperature and initial pH for the production of both mycelial biomass and exobiopolymers in flask cultures were found to be 25 °C and pH 4–5, respectively. The optimal combination of the media constituents was as follows (g l⁻¹): sucrose 40, yeast extract 6, polypepton 2, KH₂PO₄ 0.46, K₂HPO₄ 1, and MgSO₄·7H₂O 0.5. The results of bioreactor culture revealed that the maximum concentration of mycelial biomass (28.2 g l⁻¹) was obtained at an agitation speed of 300 rpm and at an aeration rate of 2 vvm, whereas maximum exobiopolymer production (2.5 g l⁻¹) was achieved at a milder agitation speed (150 rpm). There was a significant variance in mycelial morphology between different aeration conditions. Looser mycelial pellets were developed, and their size and hairiness increased as the aeration rate increased from 0.5 to 2.0 vvm, resulting in enhanced exobiopolymer production. The apparent viscosities of fermentation broth increased rapidly towards the end of fermentations at the conditions of high aeration rate and agitation speed, which were mainly due to high amount of mycelial biomass rather than exobiopolymers at the later stages of fermentation. The three different exobiopolymers (FR-I, -II, and -III) were fractionated by a gel filtration chromatography on Sepharose CL-6B. The carbohydrate and protein contents in each fraction were significantly different and the molecular weights of FR-I, FR-II, and FR-III were determined to be 1831, 27, and 2.2 kDa, respectively. The compositional analysis revealed that the three fractions of crude exobiopolymers consisted of acidic and nonpolar amino acids, such as aspartic acid, glutamic acid, glycine, and valine in protein moiety, and of mainly mannose and galactose in sugar moiety.     

Statistical optimization of simple culture conditions to produce biomass of an ochratoxigenic mould biocontrol yeast strain

Aim: To maximize biomass production of an ochratoxigenic mould–controlling strain of Lachancea thermotolerans employing response surface methodology (RSM). Methods and Results: Using Plackett–Burman screening designs (PBSD) and central composite designs (CCD), an optimized culture medium containing (g l^?1): fermentable sugars (FS), 139·2, provided by sugar cane molasses (CMz), (NH₄)₂HPO₄ (DAP), 9·0, and yeast extract (YE), 2·5, was formulated. Maximal cell concentration obtained after 24 h at 28°C was 24·2 g l^?1cell dry weight (CDW). The mathematical model obtained was validated in experiments performed in shaken‐flask cultures and also in aerated bioreactors. Maximum yield and productivity values achieved were, respectively, of 0·23 g CDW/g FS in a medium containing (g l^?1): FS, 87·0; DAP, 7·0; YE, 1·0; and of 0·96 g CDW l^?1 h^?1 in a medium containing (g l^?1): FS, 150·8 plus DAP, 6·9. Conclusions: Optimized culture conditions for maximizing yeast biomass production determined in flask cultures were applicable at a larger scale. The highest yield values were attained in media containing relatively low‐CMz concentrations supplemented with DAP and YE. Yeast extract would not be necessary if higher productivity is the aim. Significance and Impact of the Study: Cells of L. thermotolerans produced aerobically could be sustainably produced in a medium just containing cheap carbon, nitrogen and phosphorus sources. Response surface methodology allowed the fine‐tuning of cultural conditions.     

Influence of the nutritional conditions on haloalcohol dehalogenase HheC production by recombinant Escherichia coli P84A/MC1061

In this research, we first determined the three most significant nutrient factors affecting haloalcohol dehalogenase HheC production by Escherichia coli P84A/MC1061. These were glycerol, yeast extract, and ammonium sulfate. The steepest ascent method was then applied to obtain the optimal design intervals of the three factors. An application of center composite design was used, and the ingredients of the optimized medium were 1.8 g l^?1 glycerol, 48 g l^?1 yeast extract, 2.2 g l^?1 ammonium sulfate, 5 g l^?1 compound phosphate, 1 g l^?1 magnesium sulfate, and 1.19?×?10^?5?g l^?1 ferric sulfate. The enzyme activity reached 109,365 U ml^?1 under the most favorable conditions, which is a 277.7 % increase compared with the control group. Our study of cellular respiration parameters (oxygen uptake rate and carbon dioxide emission rate) revealed that the metabolic activity of the strain was strongly promoted under these optimal nutrient conditions and that yeast extract had a positive effect on respiratory intensity and the expression levels of HheC.     

Production of exopolysaccharides by submerged mycelial culture of <Emphasis Type="Italic">Grifola frondosa</Emphasis> TFRI1073 and their antioxidant and antiproliferative activities

The exopolysaccharide (EPS) extract of a newly screened Grifola frondosa TFRI1073 was evaluated antioxidant activity, including superoxide anion scavenging activity and reducing power, and the antiproliferative activities by using lung (A549 cells) and breast (MDA-MD-231 cells) cancer cell line. The exopolysaccharide of G. frondosa plays the important role on antioxidant and antiproliferative activities. Nutritional requirements for mycelial biomass and EPS production by G. frondosa were studied. Flushing the culture medium with carbon sources has a stimulating effect on both mycelial biomass and EPS production. In addition, nitrogen sources appeared to be an important and significant component for mycelial biomass. Vitamins were probably not essential for mycelial biomass and EPS production. Inorganic salts appeared to have a significant effect on both mycelial biomass and EPS productions. The effect of phosphate ion on mycelial biomass was better than on EPS production. The information generated in this study will facilitate physiological research of a newly screened G. frondosa TFRI1073, helping to develop the exopolysaccharide of a new dietary supplement and functional food from G. frondosa.     

Optimization of submerged culture conditions for exopolysaccharide production in <Emphasis Type="Italic">Sarcodon aspratus</Emphasis> (Berk) S.lto TG-3

The effect of medium components (carbon, nitrogen, and mineral sources) and environmental factors (initial pH and temperature) for mycelial growth and exopolysaccharide (EPS) production in Sarcodon aspratus(Berk) S.lto TG-3 was investigated. The optimal temperature (25°C) and initial pH (5.0) for the EPS production in shake flask cultures of S. aspratus were determined using the two-dimensional contour plot. The most suitable carbon, nitrogen, and mineral sources for EPS production were glucose, yeast extract, CaCl₂ and KH₂PO₄, respectively. Notably, the EPS production was significantly enhanced by supplementation of calcium ion. Subsequently, the optimum concentration of glucose (30gl^–1), yeast extract (15gl^–1), CaCl₂ (1.1gl^–1), and KH₂PO₄ (1.2gl^–1) were determined using the orthogonal matrix method. The effects of nutritional requirement on the mycelial growth of S.aspratuswere in regular sequence of glucose>KH₂PO₄>yeast extract>CaCl₂, and those on EPS production were in the order of glucose>yeast extract>CaCl₂>KH₂PO₄. Under the optimal culture conditions, the maximum EPS concentration in a 5-l stirred-tank reactor was 2.68gl^–1 after 4days of fermentation, which was 6-fold higher than that at a basal medium. The two-dimensional contour plot and orthogonal matrix method allowed us to find the relationship between environmental factors and nutritional requirement by determining optimal operating conditions for maximum EPS production in S.asparatus. The statistical experiments used in this work can be useful strategies for optimization of submerged culture processes for other mushrooms.     

Medium optimization, molecular characterization, and bioactivity of exopolysaccharides from Pleurotus eryngii

An optimal medium for exopolysaccharides (EPS) production was obtained through one-factor-at-a-time method and response surface methodology. Under optimal culture medium, the maximum EPS concentration in shake flask was 5.16 g/l. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography/multiangle laser light scattering, and the weight average molar masses (M _w) of Fr-I and Fr-II were determined to be 4.098 × 10⁴ and 1.114 × 10⁴ g/mol, respectively. The molecular confirmation of Fr-I was revealed to be a rigid rod form in aqueous solution. Moreover, monosaccharide composition and characteristic groups were investigated by GC and Fourier transform infrared, respectively. Finally, pharmacology experiment in vitro indicated EPS Fr-II of Pleurotus eryngii exhibited higher antioxidant and antitumor abilities than Fr-I, which might be attributed to the different molecular weights and chemical compositions in the EPS fraction.     

Optimization of culture conditions and medium components for the production of mycelial biomass and exo-polysaccharides with Cordyceps militaris in liquid culture

Both crude exo-biopolymers and mycelial biomass, produced by liquid culture of Cordyceps species, are believed to possess several potential health benefits. As a result of its known biological activities, Cordyceps militaris has been extensively characterized in regards to potential medicinal applications. However, optimized liquid culture conditions for enhanced polysaccharide productivity have yet to be developed, which is a necessary step for industrial applications. Therefore, in this study, the liquid culture conditions were optimized for maximal production of mycelial biomass and exo-polysaccharide (EPS) by C. militaris. The effects of medium composition, environmental factors, and C/N ratio were investigated. Among these variables 80 g, glucose; 10 g, yeast extract; 0.5 g, MgSO₄·7H₂O; and 0.5 g, KH₂PO₄ in 1 L distilled water were found to be the most suitable carbon, nitrogen, and mineral sources, respectively. The optimal temperature, initial pH, agitation, and aeration were determined to be 24°C, uncontrolled pH, 200 rpm, and 1.5 vvm, respectively. Under these optimal conditions, mycelial growth in shake flask cultures and 5 L jar bioreactors was 29.43 and 40.60 g/L, respectively, and polysaccharide production in shake flask cultures and 5 L jar bioreactors was 2.53 and 6.74 g/L, respectively.     

Pilot-scale culture of somatic embryos of Eleutherococcus senticosus in airlift bioreactors for the production of eleutherosides

Purpose of work

To establish pilot scale bioreactor cultures of somatic embryos of Siberian ginseng for the production of biomass and eleutherosides. Somatic embryos of Eleutherococcus senticosus were cultured in airlift bioreactors using Murashige and Skoog medium with 30 g sucrose l^?1 for the production of biomass and eleutherosides. Various parameters including the type of bioreactor, aeration volume, and inoculum density were optimized for 3 l capacity bioreactors. Balloon-type airlift bioreactors, utilizing a variable aeration volume of 0.1–0.3 vvm and an inoculum of 5 g l^?1, were suitable for biomass and eleutheroside production. In 500 l balloon-type airlift bioreactors, 11.3 g dry biomass l^?1, 220 µg eleutheroside B l^?1, 413 µg eleutheroside E l^?1, and 262 µg eleutheroside E1 l^?1 were produced.     

Enhancement of polysaccharides production in <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> by the addition of ethyl acetate extracts from <Emphasis Type="Italic">Eupolyphaga sinensis</Emphasis> and <Emphasis Type="Italic">Catharsius molossus</Emphasis>

To screen stimulators from Chinese medicinal insects for mycelial growth and polysaccharides production of Ganoderma lucidum, G. lucidum was inoculated into the media with and without supplementation of medicinal insect extracts. The ethyl acetate extract of Eupolyphaga sinensis at 55 mg l⁻¹ lead to significant increase in both biomass and intracellular polysaccharides (IPS) concentration from 8.53 ± 0.41 to 14.16 ± 0.43 and 1.28 ± 0.09 to 2.13 ± 0.11 g l⁻¹, respectively. In addition, the ethyl acetate extract of Catharsius molossus at 55 mg l⁻¹ significantly enhanced extracellular polysaccharides (EPS) production; the EPS yield increased from 350.9 ± 14.1 to 475.1 ± 15.3 mg l⁻¹. There were no new components in the two types of polysaccharides obtained by the addition of the insect extracts.     

Hydrogen sulphide production by Zymomonas and its elimination in a mutant strain

Strains of Zymomonas mobilis grown in media containing either glucose or sucrose were assessed for the production of hydrogen sulphide (H₂S). In a liquid medium with low glucose concentration (20 g l^?1) only a proportion of the strains tested formed H₂S, but in medium containing a higher glucose concentration (100 g l^?1) all the strains tested produced H₂S. Four Z. mobilis strains were assayed quantitatively for H₂S production and strain ZM4 was found to produce the most H₂S in glucose medium. The amount of yeast extract and glucose, and the type of sugar used in the medium affected the amount of H₂S formed by strain ZM4. A mutant, designated ZM4701, of strain ZM4 was isolated which did not produce any detectable H₂S in liquid medium containing yeast extract plus either glucose or sucrose. The nutritional requirements of ZM4701 were investigated.     

Optimization of submerged culture condition for the production of mycelial biomass and exopolysaccharides by Agrocybe cylindracea

The optimization of submerged culture conditions and nutritional requirements was studied for the production of exopolysaccharide (EPS) from Agrocybe cylindracea ASI-9002 using the statistically based experimental design in a shake flask culture. Both maximum mycelial biomass and EPS were observed at 25 degrees C. The optimal initial pH for the production of mycelial biomass and EPS were found to be pH 4.0 and pH 6.0, respectively. Subsequently, optimum concentration of each medium component was determined using the orthogonal matrix method. The optimal combination of the media constituents for mycelial growth was as follows: maltose 80 g/l, Martone A-1 6 g/l, MgSO4 x 7H2O 1.4 g/l, and CaCl2 1.1 g/l; for EPS production: maltose 60 g/l, Martone A-1 6 g/l, MgSO4 x 7H2O 0.9 g/l, and CaCl2 1.1 g/l. Under the optimal culture condition, the maximum EPS concentration achieved in a 5-l stirred-tank bioreactor indicated 3.0 g/l, which is about three times higher than that at the basal medium.     

A Review of: “Progress in Separation and Purification Vol. 3, E. S. Perry and C. J,van Oss,eds., Willy/Intersciencc,New York, 1970; xi + 316 pares; hard cover; 515.95”

The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Pleurotus geesteranus 5 ^# were determined using an orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g maltose, 5.0 g tryptone, 1 mM NaCl, 5 mM KH₂PO₄, and initial pH 6.0 at 28 °C. In the optimal culture medium, the maximum EPS production was 16.97 g/L in a shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The approximate weight-average molar masses of the Fr-I and Fr-II of EPS were determined to be 3.263 × 10⁴ and 5.738 × 10³ g/mol, respectively. The low values of polydispersity ratio (1.176 and 1.124 for Fr-I and Fr-II, respectively) of EPSs mean that these EPS molecules exist much less dispersed in aqueous solution without forming large aggregates. Furthermore, the experiments in vitro indicated that P. geesteranus 5^# EPS exhibit high antitumor and antioxidative effects.     

α-Ketoglutaric acid production from rapeseed oil by Yarrowia lipolytica yeast

The possibility of using rapeseed oil as a carbon source for microbiological production of α-ketoglutaric acid (KGA) has been studied. Acid formation on the selective media has been tested in 26 strains of Yarrowia lipolytica yeast, and the strain Y. lipolytica VKM Y-2412 was selected as a prospective producer of KGA from rapeseed oil. KGA production by the selected strain was studied in dependence on thiamine concentration, medium pH, temperature, aeration, and concentration of oil. Under optimal conditions (thiamine concentration of 0.063 μg?g cells^?1, pH?3.5, 30 °C, high dissolved oxygen concentration (pO₂) of 50 % (of air saturation), and oil concentration in a range from 20 to 60 g?l^?1), Y. lipolytica VKM Y-2412 produced up to 102.5 g?l^?1 of KGA with the mass yield coefficient of 0.95 g?g^?1 and the volumetric KGA productivity (Q _KGA) of 0.8 g?l^?1?h^?1.     

Improved simultaneous production of mycelial biomass and polysaccharides by submerged culture of <Emphasis Type="Italic">Hericium erinaceum</Emphasis>: optimization using a central composite rotatable design (CCRD)

The aim of this study was to optimize the culture medium used for the mycelial growth and production of intracellular polysaccharides (IPS) and exopolysaccharides (EPS) in a submerged culture of Hericium erinaceum. Of the various factors examined, including carbon and nitrogen sources, vitamins, mineral elements, and initial pH, those that proved to have a significant effect were then tested using a 2⁴ central composite rotatable design (CCRD). Under the optimal culture conditions, the maximal yield of biomass reached 14.24 ± 0.45 g l⁻¹ and was 1.85-fold higher than in the basal medium. The kinetics of EPS biosynthesis in a bioreactor showed that although the highest yield of EPS (2.75 ± 0.27 g l⁻¹) could be obtained on day 8, the process of biosynthesizing high molecular weight polysaccharides proceeded until the depletion of the carbon source in the medium (after 14 days of cultivation). Our results could be very helpful in the large-scale production of bioactive polysaccharides from H. erinaceum.     

Effect of soybean oil on the production of mycelial biomass and pleuromutilin in the shake-flask culture of <Emphasis Type="Italic">Pleurotus mutilis</Emphasis>

Effect of soybean oil on mycelial biomass and pleuromutilin biosynthesis by Pleurotus mutilis-04 was investigated in shake flask culture. The maximum pleuromutilin production and mycelial biomass were 8.32 ± 0.02 g l⁻¹ and 49.10 ± 1.00 g l⁻¹ when 20 g l⁻¹ soybean oil was fed at 24 and 96 h respectively. A repeated fed-batch fermentation strategy with feeding 3 g l⁻¹ soybean oil from 96 to 144 h at 24 h intervals was developed successfully to maintain mycelial growth and provide abundant fatty acids for pleuromutilin biosynthesis. Compared with glucose as the sole carbon source, soybean oil was obviously beneficial for the production of pleuromutilin. The results suggested that manipulation of metabolic regulation by soybean oil was an effective way to enhance the production pleuromutilin.