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Commercialization of lignocellulosic ethanol fermentation requires its high titer, but the reactive oxygen species (ROS) accumulation during the bioprocess damaged the cells and compromised this goal. To improve the cellular anti-oxidative activity during non-detoxified corncob residue hydrolysate fermentation, seed cells were prepared to possess a higher level of intracellular biotin pool (IBP), which facilitated the biosyntheses of catalase and porphyrin. As a result, the catalase activity increased by 1.3-folds compared to control while the ROS level reduced by 50%. Cell viability in high-IBP cells was 1.7-folds of control and the final ethanol titer increased from 31.2 to 41.8 g L(-1) in batch fermentation. The high-IBP cells were further used for repeated-batch fermentation in the non-detoxified lignocellulosic hydrolysate, and the highest titer and average productivity of ethanol reached 63.7 g L(-1) and 1.2 g L(-1)h(-1). The results were favorable to future industrial application of this lignocellulosic bioethanol process., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Polysaccharides and ganoderic acids (GAs) are the major bioactive constituents of Ganoderma species. However, the commercialization of their production was limited by low yield in the submerged culture of Ganoderma despite improvement made in recent years. In this work, twelve Ganoderma strains were screened to efficiently produce polysaccharides and GAs, and Ganoderma lucidum 5.26 (GL 5.26) that had been never reported in fermentation process was found to be most efficient among the tested stains. Then, the fermentation medium was optimized for GL 5.26 by statistical method. Firstly, glucose and yeast extract were found to be the optimum carbon source and nitrogen source according to the single-factor tests. Ferric sulfate was found to have significant effect on GL 5.26 biomass production according to the results of Plackett-Burman design. The concentrations of glucose, yeast extract and ferric sulfate were further optimized by response surface methodology. The optimum medium composition was 55 g/L of glucose, 14 g/L of yeast extract, 0.3 g/L of ferric acid, with other medium components unchanged. The optimized medium was testified in the 10-L bioreactor, and the production of biomass, IPS, total GAs and GA-T enhanced by 85, 27, 49 and 93 %, respectively, compared to the initial medium. The fermentation process was scaled up to 300-L bioreactor; it showed good IPS (3.6 g/L) and GAs (670 mg/L) production. The biomass was 23.9 g/L in 300-L bioreactor, which was the highest biomass production in pilot scale. According to this study, the strain GL 5.26 showed good fermentation property by optimizing the medium. It might be a candidate industrial strain by further process optimization and scale-up study.

For economically feasible lignocellulosic ethanol production, it is crucial to obtain a robust strain and develop an efficient fermentation process. An earlier-screened yeast strain Pichia guilliermondii was adapted to corncob residues (CCR) hydrolysate and used for high titer ethanol production without any detoxification or external nutrient supplementation. With an optimized fed-batch strategy, the maximum ethanol titer and productivity reached 56.3 g/l and 0.47 g l(-1) h(-1), respectively. To further increase the ethanol productivity, the fed-batch process was repeated three times with cell reuse, and the maximum ethanol titer and productivity reached 51.2 g/l and 1.11 g l(-1) h(-1), respectively. The results demonstrated that the combination of fed-batch with repeated fermentation was effective in improving the fermentation efficiency and achieving high ethanol productivity from CCR. The reported system is considered promising for commercial production of bioethanol from biomass hydrolysate in the future., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Recently signal transduction engineering of secondary metabolism is receiving great interest as a powerful tool towards efficient production of valuable secondary metabolites. This work found that the calcineurin-signal transduction was significant to triterpene biosynthesis by higher fungus (mushroom). Addition of calcium ion (at 10mM) to static liquid cultures of Ganoderma lucidum, a famous traditional medicinal mushroom, was proved as a useful strategy to enhance the production of antitumor ganoderic acids (GAs), which resulted in 3.7-, 2.6-, 4.5-, 3.2- and 3.8-fold improvement of total GAs, individual GA-Mk, -T, -S, and -Me, respectively. Experiments using Ca2+ sensor inhibitors indicated the involvement of calcineurin signal in regulating GAs biosynthesis. Quantitative gene transcription analysis revealed that the expression levels of genes of GAs biosynthesis and Ca2+ sensor were up-regulated with calcium addition while down-regulated under the inhibitors addition, suggesting that higher GAs production may be resulted from higher expressions of those genes. Based on the results obtained, a possible model on the effect of external calcium ion on the GAs biosynthesis via calcineurin signal transduction pathway was proposed., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Validamycin A (VAL-A) is an important and widely used agricultural antibiotic. In this study, statistical screening designs were applied to identify significant medium variables for VAL-A production and to find their optimal levels. The optimized medium caused 70% enhancement of VAL-A production. The difference between optimized medium and original medium suggested that low nitrogen source level might attribute to the enhancement of VAL-A production. The addition of different nitrogen sources to the optimized medium inhibited VAL-A production, which confirmed the importance of nitrogen concentration for VAL-A production. Furthermore, differences in structural gene transcription and enzyme activity between the two media were assayed. The results showed that lower nitrogen level in the optimized medium could regulate VAL-A production in gene transcriptional level. Our previous study indicated that the transcription of VAL-A structural genes could be enhanced at elevated temperature. In this work, the increased fermentation temperature from 37 to 42 °C with the optimized medium enhanced VAL-A production by 39%, which testified to the importance of structural gene transcription in VAL-A production. The information is useful for further VAL-A production enhancement.

The effect of divalent metal ions (i.e., Mn(2+), Mg(2+), Zn(2+), Cu(2+), and Co(2+)) on the production of anticancer ansamitocin P-3 (AP-3) by submerged cultures of Actinosynnema pretiosum in medium containing agro-industrial residues was investigated, and Mg(2+) was found to be the most effective. Under the optimal condition of Mg(2+) addition, the maximal AP-3 production titer reached 85 mg/L, which was 3.0-fold that of the control. The activities of methylmalonyl-CoA carboxyltransferase (MCT) and methylmalonyl-CoA mutase (MCM) were enhanced. The content of two precursors, malonyl-CoA and methylmalonyl-CoA, was lower than that of control. This work demonstrates that Mg(2+) addition is a simple and effective strategy for increasing AP-3 production through the regulation of enzyme activity and pools of precursors. The information obtained can be helpful to its efficient production on large scale., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A novel fermentation strategy to enhance antibiotics production was demonstrated by inducing reactive oxygen species (ROS), and validamycin A (VAL-A) production by Streptomyces hygroscopicus 5008 in agro-industrial residues containing medium was taken as an example. By optimizing H2O2 amount and addition time, the intracellular ROS level was increased, and VAL-A production titer was enhanced by 40% on day 4 when 25 μM H2O2 was added at 8th h of fermentation. Addition of diphenyleneiodonium chloride (ROS inhibitor) reduced the H2O2 induction effect. The transcription level of eight VAL-A structure genes was enhanced by ROS, and activities of glucose-6-phosphate dehydrogenase and ValG enzyme were increased while glyceraldehyde 3-phosphate dehydrogenase activity was inhibited. This work demonstrated that ROS induction was a useful strategy for VAL-A fermentation, and the information on gene transcription and enzyme activities may be helpful to further understanding the mechanism of ROS effect on the antibiotic biosynthesis., (Copyright © 2010. Published by Elsevier Ltd.)

Supply of isobutanol to enhance the production of anti-tumor agent ansamitocin P-3 (AP-3) in medium containing agro-industrial residues was investigated with analysis of gene transcription, enzyme activity, and intermediate accumulation. Under the optimal addition of isobutanol, about 4-fold improvement of AP-3 production was obtained, and the consumption of isobutanol and accumulation of isobutyrate, malonyl-CoA, and acetyl-CoA were observed. Compared to the control without isobutanol addition, activities of both isobutanol dehydrogenase and valine dehydrogenase were enhanced in isobutanol supplemented culture. Transcription level of genes in AP-3 biosynthetic and isobutyryl-CoA catabolic pathways responded to isobutanol addition in a similar way as AP-3 biosynthesis. It is concluded that isobutanol addition was an effective strategy for increasing AP-3 production via regulation of gene transcription and pools of precursors, and the information obtained might be helpful to the fermentation productivity improvement on large scale., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Ganoderic acids (GAs) were bioactive secondary metabolites produced by a traditional mushroom Ganoderma lucidum. We describe a simple and efficient method for the separation and quantitative determination of four GAs, namely Ganoderic acid T (GA-T), Ganoderic acid Mk (GA-Mk), Ganoderic acid Me (GA-Me) and Ganoderic acid S (GA-S) from dried triterpene-enriched extracts of G. lucidum mycelia powder by capillary zone electrophoresis (CZE). Under the optimum conditions, the four GAs reached the baseline separation in 9 min with Glycyrrhetinic acid (GTA) as internal standard. The four GAs and internal standard (GTA) were detected at a wavelength 245 nm. All calibration curves showed good linearity (r(2)>0.9958) within test ranges. Limit of detection (LOD) and limit of quantification (LOQ) were less than 0.6 and 1.8 microg/mL, respectively. The relative standard deviation (R.S.D.) values of precision and recoveries were less than 5% and recoveries ranged from 91.4% to 103.6%. This was the first report on simultaneous determination of the four GAs and the results provided a firm basis for the trace analysis of GAs in dried fermentation mycelia powder of G. lucidum with high accuracy., (Copyright 2010 Elsevier B.V. All rights reserved.)

Bacillus cereus ZH14 was previously found to produce a new type of antiviral ribonuclease, which was secreted into medium and active against tobacco mosaic virus. In order to enhance the ribonuclease production, in this study the optimization of culture conditions using response surface methodology was done. The fermentation variables including culture temperature, initial pH, inoculum size, sucrose, yeast extract, MgSO(4).7H(2)O, and KNO(3) were considered for selection of significant ones by using the Plackett-Burman design, and four significant variables (sucrose, yeast extract, MgSO(4).7H(2)O, and KNO(3)) were further optimized by a 2(4) factorial central composite design. The optimal combination of the medium constituents for maximum ribonuclease production was determined as 8.50 g/l sucrose, 9.30 g/l yeast extract, 2.00 g/l MgSO(4).7H(2)O, and 0.62 g/l KNO(3). The enzyme activity was increased by 60%. This study will be helpful to the future commercial development of the new bacteria-based antiviral ribonuclease fermentation process.

Liquid static cultivation of Ganoderma lucidum was previously found to be very efficient for improving the production of its valuable antitumor compound ganoderic acid (GA) (Fang and Zhong in Biotechnol Prog 18:51-54, 2002). In this work, effects of oxygen concentration within the range of 21-100% (v/v) in the gaseous phase on the mycelia growth, GA production, and gene transcription of key enzymes for GA biosynthesis in liquid static cultures of G. lucidum were investigated. A high cell density of 29.8 +/- 1.7 g/l DW and total GA production of 1427.2 +/- 74.2 mg/l were obtained under an optimal gaseous O(2) level of 80%. The expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase, squalene synthase and lanosterol synthase genes of GA biosynthetic pathway as detected by quantitative real-time PCR was also affected by the gaseous oxygen concentration in the liquid static culture. H(2)O(2) was generated as reactive oxygen species in response to high oxygen concentrations in the gas phase, and it seemed to be involved in the regulation of GA biosynthesis. The information obtained in this study provided an insight into the role of gaseous O(2) in the GA production and it will be helpful for further enhancing its productivity.

The influences of fermentation conditions and truffle species (i.e., Tuber melanosporum, Tuber sinense, Tuber indicum, and Tuber aestivum) on the volatile organic compounds (VOCs) originated from truffle fermentation mycelia were studied by using chromatographic fingerprint system for the first time. Gas chromatography combined with statistical methods including similarity analysis and hierarchical cluster analysis was applied to develop chromatographic fingerprint system for truffle VOCs evaluation. Fermentation conditions affected the VOCs from truffle fermentation mycelia much more significantly than truffle species. This indicated that it is possible to adjust the aroma of truffle fermentation mycelia similar with the natural fruiting-body through the control of fermentation process.

For the first time, a fed-batch fermentation process of Tuber melanosporum was developed for the efficient production of bioactive mycelia and Tuber polysaccharides. Each 1.67 g/L of peptone and 8.33 g/L of yeast extract were added on day 3, 6, and 9, respectively, and sucrose was fed to maintain its concentration around 35-5 g/L when its residual level decreased to 10-5 g/L. Then, the maximal biomass, the production of extracellular polysaccharides (EPS) and intracellular polysaccharides (IPS) reached 53.72+/-2.57 g DW/L, 7.09+/-0.62 and 4.43+/-0.21 g/L, respectively. Compared with the batch culture conducted in the enriched medium, the biomass, the production of EPS and IPS were enhanced by 55.8%, 222.3% and 103.2%, respectively. Not only the cell density but also the production of EPS and IPS were the highest ever reported in truffle fermentation, and the biomass was also the highest as ever reported in mushroom fermentation.

Bacterial cellulose (BC) has been widely used in many fields because of its nano-structure and excellent biomaterial performance. This work studied fermentation production of bacterial cellulose by Gluconacetobacter xylinus ATCC53524 using mixed carbon sources of glucose and glycerol. The results indicated that with 20 g/L of total carbon source, in medium at the ratio of glucose to glycerol being 1: 3 (w/w), the highest BC titer of 8.42 g/L was reached, which was 1.92 times higher than in conventional medium (20 g/L glucose). Metabolic analysis indicated that 57.1 % of the carbon source was converted into BC in the medium of glucose: glycerol at 1: 3, while it was only 29.6 % in the glucose medium. More ATP was also produced at 1: 3 of glucose: glycerol. The activity of two key enzymes - phosphoglucomutase and UDP-glucose pyrophosphorylase was 1.98-fold and 2.27-fold higher at 1: 3 of glucose: glycerol than those in the glucose medium, respectively. Furthermore, the BC produced in the former case showed higher Young's modulus, better crystallinity, thicker fibers and lower porosity. The work demonstrated the use of glucose and glycerol at 1: 3 (w/w) was an effective strategy in improving the BC-producing strain's fermentation performance and BC properties. [Display omitted] • The ratio of medium glucose to glycerol greatly affected bacterial cellulose (BC) synthesis. • The BC production was highest in the medium at 1:3 of glucose:glycerol, where more ATP was produced. • The medium glucose/glycerol affected metabolites accumulation and enzyme activities. • The BC from the optimal medium had a higher Young's modulus and crystallinity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen supply positively affected the biosynthesis of a novel ganoderic acid. • Insightful information on the effect of oxygen on S. cerevisiae metabolism was revealed. • The work is helpful to further improve ganoderic acid production by the yeast cell. A novel bioactive ganoderic acid, 3 , 28-dihydroxy-lanosta-8, 24-dien-26-oic-acid (DHLDOA), was recently biosynthesized using a heterologous host Saccharomyces cerevisiae by our group, but its low fermentation titer was an obstacle to large-scale application. In this study, the positive effect of oxygen supply on DHLDOA production by the yeast fermentation in shake-flask was revealed. The highest cell mass with an OD 600 value of 27.92 was obtained at initial K L a of 15.6 h−1, and the highest DHLDOA titer of 8.79 mg/L was obtained at initial K L a of 12.6 h−1, which was 1.64- and 1.77-fold that at 4.2 and 15.6 h−1, respectively. Slightly higher pyruvate accumulation, lower citrate level, and adequate precursor pools of DHLDOA anabolism were found to be associated with higher DHLDOA production at initial K L a of 12.6 h−1, in which relatively higher CYP5150L8 and CYP5139G1 activities were also observed. Taken together, the results indicated that oxygen supply caused the global changes of the yeast metabolism, including the DHLDOA biosynthesis. This work will be helpful to further improvement of DHLDOA production by the yeast fermentation. [ABSTRACT FROM AUTHOR]

• Positive effect of furfural on validamycin-A (VAL-A) fermentation was found. • Xylose mother liquor medium with 1 g/L furfural enhanced the VAL-A titer by 40 % compared to control. • The work is helpful to VAL-A fermentation using hemicellulose hydrolysates. Furfural is one of main inhibitors in hemicellulose hydrolysates such as xylose mother liquor, but its positive effect on the production of validamycin-A (VAL-A), a widely used agricultural antibiotic, was interestingly found in fermentation of Streptomyces hygroscopicus 5008. The furfural level in medium up to 1 g/L was effectively converted to furfuryl alcohol and furoic acid by the microorganism. Both intracellular H 2 O 2 level and ValG enzyme activity of the cells were enhanced by furfural addition. Xylose mother liquor medium with supplementation of about 1 g/L furfural could enhance the VAL-A titer by 39 %. This work is helpful to VAL-A fermentation using the hemicellulose hydrolysate. [ABSTRACT FROM AUTHOR]

Validamycin A (VAL-A) is an important agricultural antibiotic produced by Streptomyces hygroscopicus 5008, which uses starch as carbon source occupying about 20% of total production cost. To reduce the medium cost, corncob hydrolysate – a hemicellulose hydrolysate was applied as a low-cost substrate to VAL-A fermentation. It was found that three major sugars in corncob hydrolysate including d -glucose, d -xylose and l -arabinose could all be utilized by S. hygroscopicus 5008 to produce VAL-A while d -xylose was the main contributor. A higher VAL-A production titer from d -xylose was achieved by using a genetically engineered strain TC03 derived from S. hygroscopicus 5008, which resulted in 1.27-fold improvement of VAL-A production from the medium containing 13% (v/v) corncob hydrolysate compared to that by its original strain. A medium cost analysis was done and compared with previous reports. This work indicates a great potential of the hemicellulose hydrolysate as substrate for antibiotic fermentation. [ABSTRACT FROM AUTHOR]

Two-stage cultivation of Ganoderma lucidum was performed for the enhanced production of ganoderic acid (GA). Cellulase was identified to be an effective elicitor for the improvement of GA production, and GA titer reached 1334.5 mg/l compared to the control (779.6 mg/l) using lactose as the substrate without cellulase addition. Loading of 5 mg/l cellulase on day 3 resulted in the maximal GA titer of 1608 mg/l. To our knowledge, this is the first time that cellulase was used as the elicitor to enhance GA production. Submerged fermentation in a 2.0-l bioreactor was also conducted with cellulase as the elicitor, and as a result the maximal GA titer of 1252.7 mg/l was obtained on day 12. This is so far the best GA production obtained in submerged fermentation of G . lucidum . [ABSTRACT FROM AUTHOR]

ABSTRACT γ-Butyrolactones (GBLs), such as A-factor, are one type of signaling molecules produced by Streptomyces species and have been reported to regulate secondary metabolism. However, they are usually produced in very small amount, which has hindered their structural elucidation and application for antibiotic overproduction. In this work, 1,4-butyrolactone (1,4-BL), as an easily accessible and cheap analogue of GBLs, was applied to the fermentation of validamycin A (VAL-A), an important antifungal antibiotic produced by Streptomyces hygroscopicus 5008. The addition of 1,4-BL enhanced VAL-A production by 30% in both shaking flasks and bioreactors. The transcriptional levels of the adpA homologue ( adpA-H) and VAL-A biosynthetic genes were significantly increased. Among the three A-factor receptor homologous genes identified in the genome of S. hygroscopicus 5008, shbR3 was proved to be responsible for the inducing activity of 1,4-BL by gene disruption and circular dichroism analysis, and ShbR3 could bind to the promoter region of adpA-H as indicated by EMSA analysis. Furthermore, the mutation of adpA-H abolished the transcription of VAL-A biosynthetic genes and VAL-A productivity. In EMSA analysis, AdpA-H could directly bind to the promoter regions of VAL-A gene cluster. Moreover, addition of the 1,4-BL also improved the VAL-A production in a high-yielding strain TL01. The results showed that 1,4-BL could stimulate A-factor-like cascade and subsequently enhance VAL-A production in S. hygroscopicus 5008. Biotechnol. Bioeng. 2013;110: 2984-2993. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The effect of divalent metal ions (i.e., Mn2+, Mg2+, Zn2+, Cu2+, and Co2+) on the production of anticancer ansamitocin P-3 (AP-3) by submerged cultures of Actinosynnema pretiosum in medium containing agro-industrial residues was investigated, and Mg2+ was found to be the most effective. Under the optimal condition of Mg2+ addition, the maximal AP-3 production titer reached 85mg/L, which was 3.0-fold that of the control. The activities of methylmalonyl-CoA carboxyltransferase (MCT) and methylmalonyl-CoA mutase (MCM) were enhanced. The content of two precursors, malonyl-CoA and methylmalonyl-CoA, was lower than that of control. This work demonstrates that Mg2+ addition is a simple and effective strategy for increasing AP-3 production through the regulation of enzyme activity and pools of precursors. The information obtained can be helpful to its efficient production on large scale. [Copyright &y& Elsevier]

Abstract: Effects of oxygen concentration within 21–100% in gaseous phase on the morphology and ganoderic acids (GAs) production by Ganoderma lucidum in liquid static culture were studied. A higher oxygen concentration increased individual GAs production, and more spores and higher total GA content were obtained at an oxygen level of 80%. [Copyright &y& Elsevier]

Abstract: The main components of polysaccharide, protein and lipid (i.e., whole elicitor) and the sole polysaccharide component (i.e., polysaccharide elicitor) isolated from the cultured mycelia of Tuber aestivum vittad significantly stimulated the accumulation of extracellular polysaccharides (EPS), and the highest EPS production of 0.92±0.07g/L was obtained by the elicitation of its whole elicitor. The highest content (i.e., 12.91±1.05mg/100mg) and production (i.e., 1.94±0.18g/L) of intracellular polysaccharides (IPS) was obtained by adding the combination components of polysaccharide and protein (i.e., elicitor of polysaccharide and protein) from Tuber sinense. Specific ganoderic acid (GA) biosynthesis (i.e., GA content) was stimulated by adding the elicitor of polysaccharide and protein, while inhibited by the polysaccharide elicitor prepared from Tuber melanosporum. While, the maximal GA production of 315.5±12.4mg/L was obtained under the elicitation of polysaccharide elicitor from Penicillium citrinum because of a relatively high cell density. [Copyright &y& Elsevier]

The effects of oxygen supply on the submerged fermentation of Ganoderma lucidum, a famous traditional Chinese medicinal mushroom, for simultaneous production of bioactive compounds—Ganoderma polysaccharide and ganoderic acid (GA) were studied. An initial volumetric oxygen transfer coefficient (KLa) value within the range of 16.4–96.0 h−1 had a significant effect on the cell growth, cellular morphology and metabolites biosynthesis. At an initial KLa of 78.2 h−1, a maximal cell concentration of 15.62 g l−1 by dry weight was obtained, as well as a maximal intracellular polysaccharide (IPS) production of 2.19 g l−1 and its maximal productivity of 217 mg l−1 per day. An increase of initial KLa led to a bigger size of mycelia aggregates and a higher production and productivity of GA. The GA production and productivity at an initial KLa of 96.0 h−1 was 1.8-fold those at an initial KLa of 16.4 h−1. Dissolved oxygen tension (DOT) also affected the fermentation process. The cell growth of G. lucidum was significantly inhibited when DOT was controlled ∼10% of air saturation, which was due to the oxygen limitation in mycelia aggregates. The production of extracellular polysaccharide (EPS) and contents of IPS and GA ∼10% of DOT were higher than those ∼25% of DOT. However, the total production and productivity of IPS and GA at a low DOT were lower than those at a high DOT. The fundamental information obtained in this study will be useful for submerged fermentation of G. lucidum on a large scale. [Copyright &y& Elsevier]

A process for simultaneous efficient production of bioactive ganoderic acid (GA) and Ganoderma polysaccharide by fed-batch fermentation of Ganoderma lucidum was developed. Effects of carbon source and initial sugar concentration on the production of GA and polysaccharide were studied at first. Sucrose as a carbon source was suitable for the extracellular polysaccharide (EPS) production although the cells could not grow well. Lactose was beneficial for the cell growth and production of GA and intracellular polysaccharide (IPS). When the initial lactose concentration exceeded 35 g/l, the GA accumulation was decreased. The GA production was remarkably improved by pulse feeding of lactose, when its residual concentration was between 10 and 5 g/l. The fed-batch fermentation process in shake flasks could be successfully reproduced in stirred bioreactors (STR) with dissolved oxygen (DO) controlled between 20 and 35% of air saturation during fermentation. The maximum cell density reached 21.89±0.35 and 20.95±0.01 g DW/l in STR and flasks, respectively. The production of EPS reached 0.87±0.05 (STR) and 0.75±0.05 g/l (flask), and the total production of IPS reached 2.49±0.07 (STR) and 2.40±0.05 g/l (flask). The total production of GA reached 367.1±17.4 and 297.9±13.7 mg/l for STR and flask, respectively, and their corresponding productivity was 29.6±0.5 and 14.3±0.1 mg/l per day. Not only the cell density but also the content, production and productivity of GA and IPS obtained in this work are the highest reported in agitated fermentation of G. lucidum. [Copyright &y& Elsevier]

The effects of nitrogen source and initial glucose concentration were studied in submerged fermentation of higher fungus Ganoderma lucidum for simultaneous production of bioactive ganoderic acid and polysaccharide. The cells could not grow well when either yeast extract or peptone was used as the sole nitrogen source. However, a combined addition of 5 g/l of yeast extract and 5 g/l of peptone was optimal for the cell growth and metabolite production. Initial glucose concentration within 20–65 g/l also greatly affected the cell growth and product biosynthesis. The extracellular polysaccharide production was remarkably improved at a high initial glucose concentration. The highest levels of cell density (16.7 g DW/l), intracellular polysaccharide (1.19 g/l) and ganoderic acid (212.3 mg/l) were obtained at an initial glucose concentration of 50 g/l. [Copyright &y& Elsevier]

Abstract: The effect of nitrogen limitation on the production of the antitumor compounds, ganoderic acids (GAs), by Ganoderma lucidum and on transcription levels of triterpene biosynthesis genes in this mushroom was investigated. At 3mM glutamine, a maximal content of GA-Mk, GA-T, GA-S, and GA-Me was 2.16, 11.76, 31.09, and 7.04μg/mg cell dry weight, respectively, which was 2.8-, 5.8-, 8.3-, and 5.1-fold that obtained at 60mM glutamine. The transcription levels of biosynthetic genes encoding 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl pyrophosphate synthase, squalene synthase, lanosterol synthase, and a putative nitrogen regulator, AreA, were up-regulated by 37-, 18-, 4.5-, 3.2-, and 13-fold, respectively, in nitrogen limitation conditions, suggesting that increased GAs biosynthesis may result from higher expression of those genes. This study demonstrated a useful strategy for enhancing GAs production and provided useful information for further investigation on its biosynthesis regulation. [Copyright &y& Elsevier]

Abstract: Investigations on Ganoderma lucidum fermentation suggested that the responses of the cell growth and metabolites biosynthesis to pH and dissolved oxygen tension (DOT) were different. The ganoderic acid (GA) production of 321.6mg/L was obtained in the pH-shift culture by combining a 4-day culture at pH 3.0 with the following 6-day culture at pH 4.5, which was higher by 45% and 300% compared with the culture at pH 3.0 and 4.5, respectively. The GA production of 487.1mg/L was achieved in the DOT-shift culture by combining a 6-day culture at 25% of DOT with a following 6-day culture at 10% of DOT, which was higher by 43% and 230% compared with the culture at 25% and 10% of DOT, respectively. A fed-batch fermentation process by combining the above-mentioned pH-shift and DOT-shift strategies resulted in a significant synergistic enhancement of GA accumulation up to 754.6mg/L, which is the highest reported in the submerged fermentation of G. lucidum in stirred-tank bioreactor. [Copyright &y& Elsevier]

Highlights: [•] Oxygen supply was found to play a key role in fermentation of Cordyceps taii. [•] Oxygen supply significantly affected the production of biomass and helvolic acid. [•] Related gene transcriptional levels corresponded with helvolic acid biosynthesis. [•] The work would be useful to large-scale production of C. taii. [Copyright &y& Elsevier]

Abstract: A total of 59 volatile organic compounds (VOCs) were identified from Tuber melanosporum fermentation: 53 from its fermented mycelia and 32 from the fermentation broth. Alcohol-derived compounds were predominant in both the fermentation mycelia and the broth, although long chain fatty acids and isoprenoids were, for the first time, also found in the mycelia. The intense wine bouquet properties of the broth arose from several specific flavor substances, including sulfur compounds, pyrazines, furans and jasmones. Comparing the VOCs identified in this work with those previously reported, our results are more similar to the composition of the Tuber fruiting-body than previous Tuber fermentations. The composition and accumulation of flavor volatiles (e.g., pyrazines, sulfur compounds, and esters) and major constituents (e.g., 3-methyl-1-butanol and 2-phenylethanol) in this fermentation were significantly influenced by the sucrose concentration in the medium. The obtained information could therefore be useful in applications to convert the flavors of truffle mycelia similar to those of the fruiting-body by optimising the fermentation process. [Copyright &y& Elsevier]

Abstract: The effect of ethanol on the production of the important agro-antibiotic validamycin A (Val-A) in medium containing agricultural by-products was investigated. Under the optimal condition of ethanol addition, the maximal Val-A production titer reached 18g/L, which increased by 60% compared to the control. To provide an insight into cell response to ethanol, the intracellular reactive oxygen species (ROS), gene transcription and enzyme activity were determined. Intracellular ROS as the molecular signal was increased in the ethanol condition. Global regulators afsR and glnR were involved in regulation of Val-A biosynthesis, and the transcription of eight Val-A structural genes was enhanced. The activity of glucose-6-phosphate dehydrogenase (G6PD) was enhanced while glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was inhibited. A signal transduction cascade from cell signal response to activated transcription of Val-A biosynthetic genes and enhanced antibiotic production is proposed. The information can be helpful for the improvement of large-scale fermentation. [Copyright &y& Elsevier]

Abstract: A novel fermentation strategy to enhance antibiotics production was demonstrated by inducing reactive oxygen species (ROS), and validamycin A (VAL-A) production by Streptomyces hygroscopicus 5008 in agro-industrial residues containing medium was taken as an example. By optimizing H2O2 amount and addition time, the intracellular ROS level was increased, and VAL-A production titer was enhanced by 40% on day 4 when 25μM H2O2 was added at 8thh of fermentation. Addition of diphenyleneiodonium chloride (ROS inhibitor) reduced the H2O2 induction effect. The transcription level of eight VAL-A structure genes was enhanced by ROS, and activities of glucose-6-phosphate dehydrogenase and ValG enzyme were increased while glyceraldehyde 3-phosphate dehydrogenase activity was inhibited. This work demonstrated that ROS induction was a useful strategy for VAL-A fermentation, and the information on gene transcription and enzyme activities may be helpful to further understanding the mechanism of ROS effect on the antibiotic biosynthesis. [ABSTRACT FROM AUTHOR]

Abstract: Besides the identified key factors of pH-shift from 3.0 to 4.5 on day 4 and dissolved oxygen tension (DOT) shift from 25 to 10% on day 6, lower shear stress was also demonstrated to be a key factor in scaling-up the fed-batch fermentation of the medicinal mushroom Ganoderma lucidum from a shake flask to a stirred-tank bioreactor. The maximal biomass (22.62g/L), intercellular polysaccharide production (4.74g/L), and ganoderic acid production (798.0mg/L) were attained at a low impeller tip speed of 1.234m/s. Based on the identified key factors of pH-shift, DOT-shift and lower shear stress, the fed-batch fermentation of G. lucidum was successfully step-wise scaled-up from 7.5- to 200-L stirred-tank bioreactor. Through the qualitative and quantitative side-by-side comparison of G. lucidum growth and metabolites accumulation, it was concluded that the comparability of the fed-batch fermentation process were well controlled and the products were maintained during the process scale-up. [ABSTRACT FROM AUTHOR]

Abstract: Exopolysaccharides (EPSs) from Cordyceps taii have potent pharmacological effects and present an unparalleled resource for drug discovery, and optimization of EPS yield through systematic analysis and refinement of fermentation parameters was therefore sought. A one-variable-at-a-time method identified xylose (NH4)2SO4, and vitamins A and D as the optimum source of carbon, nitrogen, and growth-stimulating factor, respectively. Ammonium salts led to acidification of the culture medium, and the combination of (NH4)2SO4 with soybean steep liquor, the best organic nitrogen source, was therefore selected for subsequent optimization. Further experiments identified only xylose, soybean steep liquor and (NH4)2SO4 as having statistically significant effects on EPS production by a Plackett–Burman design. Re-optimization of these factors employed a path of steepest ascent approach followed by a central composite design modeling the response surface as a function of the experimental conditions. This predicted that optimum production of EPS would be achieved using a combination of xylose 31.27g/l, soybean steep liquor 4.85g/l, and (NH4)2SO4 0.15g/l. Experimental validation revealed that the actual yield of EPS (43.87±0.28g/l) was accurately predicted by the model. This level of production represented an increase of over 8-fold vs. the highest yield (5.21±0.14g/l) obtained in preliminary experiments. [Copyright &y& Elsevier]

Abstract: Validamycin A (VAL-A), produced by Streptomyces hygroscopicus, is an important anti-fungal agro-antibiotic. In this work, the effect of fermentation temperature on VAL-A biosynthesis by S. hygroscopicus 5008 was investigated between 28°C and 42°C, and an interesting threshold of temperature for VAL-A biosynthesis was found between 35°C and 37°C. At a relatively higher temperature, a much higher VAL-A productivity was obtained together with faster protein synthesis and sugar consumption. Transcriptional analysis of samples from early, middle and late stages of fermentation at various temperatures demonstrated that three operons, valABC, valKLMN and valG, for all eight necessary structure genes, were dramatically promoted when temperature reached the threshold. Activities of both glucose-6-phosphate dehydrogenase (G6PDH) of pentose-phosphate pathway and ValG of VAL-A biosynthesis were also enhanced at a higher cultivation temperature. The interesting temperature effect with a 2°C threshold shift from 35°C to 37°C on the antibiotic biosynthesis was understood to be related to the gene transcriptional levels and key enzyme activities. [Copyright &y& Elsevier]

Abstract: Polyoxin B, an antifungal agro-antibiotic, is used for treating serious plant diseases. Until now there have been no reports on the antibiotic quantification in liquid in spite of its need for fermentation studies. This work reported a microbiological assay, the cylinder-plate method, for the determination of polyoxin B. The results of assay were treated statistically by analysis of variance (ANOVA) and were found linear in the range of 10–500μg/ml (r 2 =0.998), precise (intra-assay: relative standard deviation (R.S.D.)=0.64; inter-assay: R.S.D.=1.70) and accurate. This newly established method was applied to determine the antibiotic titer in Streptomyces cacaoi fermentation with comparison to HPLC analysis. The microbiological assay was satisfactory for polyoxin B quantification, and a simple, sensitive, cost-effective and specific agar diffusion bioassay for polyoxin B was thus developed. This work also demonstrated the usefulness of the microbiological assay for quantitative analysis of antibiotics in fermentation. [Copyright &y& Elsevier]