Optimization of the medium and cultivation conditions of Penicillium roquefortii f39 producing the diketopiperazine alkaloid roquefortine

We optimized the medium for cultivation of Penicillium roquefortii f39, a producer of roquefortine. In this medium, the roquefortine yield increased 1.5-2-fold. The increase in roquefortine content was associated with high biomass yield, but not with an increase in biosynthetic activity of the mycelium. Direct correlation was found between extracellular roquefortine concentration and amount of the inoculum. The introduction of sucrose into the growth medium allowed us to increase the concentration of roquefortine during fermentation to 90 mg/l.     

Optimization of the Medium and Cultivation Conditions of Penicillium roquefortii f39 Producing the Diketopiperazine Alkaloid Roquefortine

We optimized the medium for cultivation of Penicillium roquefortii f39, a producer of roquefortine. In this medium, the roquefortine yield increased 1.5–2-fold. An increase in roquefortine content was associated with high biomass yield, but not with an increase in biosynthetic activity of the mycelium. Direct correlation was found between extracellular roquefortine concentration and the amount of the inoculum. The use of sucrose in the inoculum medium allowed us to increase the concentration of roquefortine during fermentation to 90 mg/l.     

Optimization of alkaline protease production by batch culture of Bacillus sp. RKY3 through Plackett-Burman and response surface methodological approaches

The proteolytic enzymes are the most important group of commercially produced enzymes. The production of alkaline protease was optimized using a newly isolated Bacillus sp. RKY3. The fermentation variables were selected in accordance with the Plackett-Burman design and were further optimized via response surface methodological approach. Four significant variables (corn starch, yeast extract, corn steep liquor, and inoculum size) were selected for the optimization studies. The statistical model was constructed via central composite design (CCD) using three screened variables (corn starch, corn steep liquor, and inoculum size). An overall 2.3-fold increase in protease production was achieved in the optimized medium as compared with the unoptimized basal medium. Enzyme activity increased significantly with optimized medium (939 u ml(-1)) when compared with unoptimized medium (417 u ml(-1)).     

New Approaches to Increasing the Yield of Laccase from <Emphasis Type="Italic">Panus tigrinus</Emphasis>

We optimized the conditions for laccase production by the lignolytic fungus Panus tigrinus 8/18. 2,4-Dimethylphenol was used as an aromatic inducer. Introduction of 2,4-dimethylphenol and 2 mM CuSO₄ into a rich medium was followed by a tenfold increase in the yield of this enzyme. Additional treatment of the medium with perftoran (an oxygen-transporting agent) and immobilization of the fungus on polycaproamide fibers significantly increased the activity of laccase in the medium. Thus, optimum conditions for cultivation of P. tigrinus were found, which allowed an increase in laccase activity in the medium 25-fold as compared to that achieved using any other method described previously.     

Application of factorial designs for optimization of cyclodextrin glycosyltransferase production from Klebsiella pneumoniae pneumoniae AS-22.

Production of cyclodextrin glycosyltransferase (CGTase) from Klebsiella pneumoniae pneumoniae AS-22 was optimized in shake flasks using a statistical experimental design approach. Effect of various components in the basal medium, like carbon, nitrogen, phosphorus, and mineral sources as well as initial pH and temperature, were tested on enzyme production. The optimum concentrations of the selected media components were determined using statistical experimental designs. Two level fractional factorial designs in five variables, namely, dextrin, peptone, yeast extract, ammonium dihydrogen orthophosphate, and magnesium sulphate concentrations were constructed. The optimum medium composition thus found consisted of 49.3 g/L dextrin, 20.6 g/L peptone, 18.3 g/L yeast extract, 6.7 g/L ammonium dihydrogen orthophosphate, and 0.5 g/L magnesium sulphate. The maximum CGTase activity obtained was 21.4 U/mL in 28 h of incubation. The cell growth and CGTase production profiles were studied with the optimized medium in shake flasks and in 1-L fermenters. It was observed that the enzyme production was growth associated both in shake flask and in fermenter, although it was slower in shake flask. The maximum CGTase activity obtained in the fermenter was 32.5 U/mL in 16 h. The optimized medium resulted in about 9-fold increase in the enzyme activity as compared to that obtained in the basal medium in shake flask as well as in fermenter.     

Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5

To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.     

Studies on a new marine streptomycete BT-408 producing polyketide antibiotic SBR-22 effective against methicillin resistant Staphylococcus aureus

A new actinomycete strain designated as BT-408 producing polyketide antibiotic SBR-22 and showing antibacterial activity against methicillin resistant Staphylococcus aureus has been characterized and found to be a novel strain of Streptomyces psammoticus. Nutritional and cultural conditions for the production of antibiotic by this organism under shake-flask conditions have been optimized. Glucose and ammonium nitrate were found to be best carbon and nitrogen sources respectively for growth and antibiotic production. Similarly initial medium pH of 7.2, incubation temperature of 30 degrees C and incubation time of 96 h were found to be optimal. Optimization of medium and cultural conditions resulted in 1.82-fold increase in antibiotic yield.     

New ways to increasing the yield of laccase from Panus tigrinus fungi

We optimized the conditions for production of laccase by lignolytic fungi Panus tigrinus 8/18. 2,4-Dimethylphenol was used as an aromatic inductor. The addition of 2,4-dimethylphenol and 2 mM CuSO4 to a rich medium was followed by a tenfold increase in the yield of this enzyme. Additional treatment of the medium with perftoran (oxygen-carrying agent) and immobilization of the fungus on polycaproamide fibers increased significantly laccase activity in the medium. The conditions for cultivation of P. tigrinus fungi were optimized. It allowed us to increase laccase activity in the medium by 25 times (compared to activity of the enzyme obtained with previously described methods).     

Seeds as natural matrices for immobilization of Aspergillus niger mycelium producing pectinases

J. FIEDUREK, J. SZCZODRAK AND J. ROGALSKI. 1995. A simple method for the immobilization of Aspergillus niger mycelium producing polygalacturonase (PG) and pectinesterase (PE) is described. Fungal conidia were immobilized on wheat, rye, barley, peas, buckwheat and mustards seeds. Spongy mycelia overgrowing the seed surfaces on mineral medium with pectin produced extracellular PG and PE; the highest production was reached on the wheat carrier. Some of the variables influencing the enzymatic activity have been optimized. After every 24 h, a culture liquid with 6˙8–7˙8 U of PG ml⁻¹ and 7˙0–10˙1 U of PE ml⁻¹ was obtained. This procedure also made possible repeated batch enzyme production and, as many as eight subsequent 24-h batches could be fermented by using the same carrier without any loss of PG activity. The addition of sodium orthovanadate (1 mmol) into the medium with pectin caused a significant increase in PG and PE activity produced by free cells of A. niger (by 1˙59-fold and 1˙67-fold respectively), and only 0˙47-fold of PG activity in case of the immobilized mycelium.     

Effective enhancement of polylactic acid-degrading enzyme production by Amycolatopsis sp. strain SCM_MK2-4 using statistical and one-factor-at-a-time approaches

This study aims to find the optimal medium and conditions for polylactic acid (PLA)-degrading enzyme production by Amycolatopsis sp. SCM_MK2-4. Screening of the most effective components in the enzyme production medium by Plackett–Burman design revealed that the silk cocoon and PLA film were the most significant variables enhancing the PLA-degrading enzyme production. After an response surface methodology, a maximum amount of PLA-degrading enzyme activity at 0.74?U?mL^?1 was predicted and successfully validated at 95% after 0.39% (w/v) silk cocoon and 1.62% (w/v) PLA film were applied to the basal medium. The optimal initial pH value, temperature, and inoculum size were evaluated by a method considering one-factor-at-a-time. The values were recorded at an initial pH in the range of 7.5–9.0, a temperature of 30–32°C, and an inoculum size of 4–10%. The highest activity of approximately 0.95?U?mL^?1 was achieved after 4 days of cultivation using the optimized medium and under optimized conditions in a shake flask. Upscaling to the use of a 3-L stirred tank fermenter was found to be successful with a PLA-degrading activity of 5.53?U?mL^?1; which represents a 51-fold increase in the activity compared with that obtained from the nonoptimized medium and conditions in the shake flask.     

Differential synthesis of an alkaline endonuclease in Physarum polycephalum

During the sclerotization of microplasmodia of Physarum polycephalum in non-nutrient salt medium or in salt medium supplemented by glucose, RNA or nucleotides a 6-fold increase in the specific activity of an alkaline endonuclease was found within 6 h after the induction. The increase was based on de novo synthesis of the enzyme and it was strongly correlated to the sharp drop in the level of cellular RNA in the first hours of the process of scerotization. The induction in exhausted growth medium or in salt medium supplemented by protein or mannitol showed a gradual 2-3-fold increase of the endonuclease in 30 h, parallel to the gradual decrease of the RNA. No changes in the specific activity of the endonuclease were found during logarithmic growth or under conditions of starvation without the induction to sclerotization.The alkaline, polyA-specific endonuclease could possibly regulate the turnover of RNA.     

The amino acid sequences of two putative copper-site peptides from the "blue" copper protein, stellacyanin.

Mouse neuroblastoma cells grown in medium containing 10 percent fetal bovine serum have negligible amounts of glutathione peroxidase activity. Introduction of selenite to the medium to produce a concentration of 600 nM resulted in a 30-fold increase in the enzyme activity. This increase is directly proportional to the concentration below 60 nM and levels off at concentrations above this value. Selenate produces no increase in enzyme activity when present alone nor does it inhibit induction when present with selenite. Tellurite produces no increase in enzyme activity when present alone but does inhibit induction when present with selenite.     

The effect of the carbon sources and calcium ions on the activity of thermostable alpha-amylase in Bacillus sp. 86

Amylolytic activity of Bacillus sp. 86 thermophilic strain was studied as affected by carbon sources. Glucose and saccharose being added to the nutrition medium with baker's yeast as the basic source of carbon the activity of alpha-amylase decreased. Introduction of native or soluble starch to the medium promoted a sharp increase in the enzymic activity. Bacillus sp. 86 being periodically cultivated in the optimized medium containing 4% of soluble starch and 0.5% of CaCl2, an eight-fold increase of amylolytic activity of cultural liquid was achieved as compared to the enzyme activity in the primary medium.     

Production of Laccase and Optimization of Its Production by Bacillus sp. Using Distillery Spent Wash as Inducer

A bacillus sp. isolated from the sediments of a distillery mill was used for laccase production under optimized culture conditions. The distillery effluent was used as an inducer for overproduction of laccase by employing the Taguchi approach. Screening of different medium components and their effect on laccase production was studied using an M-16 orthogonal array. The formation of laccase was considerably increased by addition of 1 mM copper sulfate (51.95 U/ml), which was further enhanced by the use of different inducers. The usefulness of the Taguchi method for optimization of culture conditions was investigated with five selected factors at four levels, and it was observed that the optimized medium resulted in a 9-fold increase in extracellular laccase production compared with the control. The optimized medium composition for laccase production was dextrose (1%), tryptone (0.1%), CuSO₄ (1 mM), and an inducer (distillery effluent 10% [v/v]) at pH 7, which altogether resulted in 107.32 U/ml extracellular laccase activity. Hence, the Taguchi approach proved to be a reliable tool in optimizing culture conditions and achieving the best possible combination for enhanced laccase production.     

Production of catalytic cells for formaldehyde production and alcohol oxidase by a catabolite repression-insensitive mutant of a methanol yeast Candida boidinii A5

A catabolite repression-insensitive mutant of Candida boidinii A5, strain ADU-15, was investigated as to alcohol oxidase production and the production of cells exhibiting the maximum catalytic activity for formaldehyde production. The mutant strain ADU-15 showed higher cell productivity and higher alcohol oxidase activity when grown on mixed substrates (glucose-methanol), especially with a high concentration of glucose in the medium. Thus, even under substrate (glucose-methanol)-limited chemostat conditions, where the glucose concentration was low, partial derepression of alcohol oxidase by glucose in mutant strain ADU-15 was detected. The chemostat culture conditions with the glucose-methanol medium were optimized for alcohol oxidase production and the production of cells exhibiting the maximum catalytic activity for formaldehyde production, respectively. By means of chemostat culturing on mixed substrates, we improved the alcohol oxidase productivity 5.0-fold and the productivity of cells exhibiting the maximum catalytic activity for formaldehyde production 3.8-fold, in comparison with the parent strain chemostat cultured with methanol as the single substrate.     

Expression of alkaline proteinase gene in two recombinant <Emphasis Type="Italic">Bacillus cereus</Emphasis> feather-degrading strains

Two Bacillus cereus feather-degrading strains (23/1 and 6/2) were transformed using a recombinant plasmid p5.2 carrying the alkaline proteinase gene (aprE). A high level of the aprE gene expression was observed when the recombinant strains were grown on sporulation medium. The expression of the aprE gene proceeded during the early stationary phase and the p5.2 plasmid was segregationally and structurally stable in both strains. The two recombinant strains grown on a mineral medium with 1 % chicken feather as source of energy, carbon and nitrogen exhibited higher proteolytic activity (≈6-fold and 2.4-fold higher for strains 23/1 (p5.2) and 6/2 (p5.2), respectively. Keratinolytic activity increased ≈3.5-fold and 4.15-fold, respectively. The keratinolytic activity further increased when an optimized medium with yeast extract and corn oil was used. Considerable amounts of free amino acids were obtained after the biodegradation of feather which makes the new strains promising for application in feather-waste treatment to, e.g., transformation to animal feedstuff.     

A combined approach for improving alkaline acetyl xylan esterase production in Pichia pastoris, and effects of glycosylation on enzyme secretion, activity and stability

High level expression of axe1, a gene previously cloned from Volvariella volvacea that encodes an acetyl xylan esterase with two potential N-linked glycosylation sites, has been achieved in Pichia pastoris using a codon-optimized axe1 synthesized by the primer extension PCR procedure. The GC content of the codon-optimized axe1 was 48.62% compared with 55.49% in the native gene. Using the codon-optimized construct, AXE1 expression in P. pastoris was increased from an undetectable level to 136.45U/ml six days after induction of yeast cultures grown in BMMY medium. A further increase (to 463U/ml) was achieved when conditions for yeast culture were optimized as follows: 2.8% methanol, 0.63% casamino acids, and pH 8.0. This latter value represented a 3.4-fold and 246-fold increase in the enzyme levels recorded in non-optimized P. pastoris cultures and in rice straw-grown cultures of V. volvacea, respectively. N-linked glycosylation played an essential role in AXE1 secretion but had only a slight effect on the catalytic activity and stability of the recombinant enzyme.     

Hybrid on-line optimal control strategy for producing α-amylase by Bacillus subtilis

The combined effect of macronutrients in the extraction medium on α-amylase produced by Bacillus subtilis were studied by using response surface methodology in shaken flask cultures. The production of amylase was significantly affected by the interaction between wheat bran and the cotton seed extract in the extraction medium and by the interaction between the cotton seed extract and starch. The optimal combination in the extraction medium for maximum α-amylase production was determined as 10.80 g·L?1 of wheat bran, 9.90 g·L?1 of cotton seed extract, 0.5 g·L?1 of starch, 2.0 g·L?1 of yeast extract, 5.00 g·L?1 of NaCl and 2.00 g·L?1 of CaCl?. A 12.55-fold increase of enzyme activity was recorded in the optimized medium compared to the result acquired in a minimum essential medium. The optimized medium was used to compare different cultivation strategies in fermenters. The pH-stat strategy for reducing cellular stress response and the substrate concentration-stat strategy for reducing substrate inhibition were independently investigated. The temperature-limited strategy has been proposed to solve the proteolytic digestion problem, although the high-pressure strategy resulted in high productivity. A hybrid strategy simultaneously controlling pH, temperature, substrate concentration and pO? was finally investigated to enhance the efficiency of the process. This hybrid strategy resulted in high activity of α-amylase, increasing the productivity almost three-fold as compared to an ordinary fed-batch culture.     

Elicitor-mediated induction of enzymes of lignin biosynthesis and formation of lignin-like material in a cell suspension culture of spruce (Picea abies)

Incubations of photomixotrophic suspension culture cells of spruce (Picea abies) (L.) (Karst) with an autoclaved cell wall preparation of Rhizosphaera kalkhoffii as elicitor led to a rapid increase of the activity of a number of enzymes involved in lignin biosynthesis. l-phenylalanine ammonia-lyase (EC 4.3.1.5) was induced about 10-fold, feruloyl-Coenzyme A reductase (ED 1.2.1.44) 4-fold, cinnamyl alcohol dehydrogenase (NADP⁺) (EC 1.1.1.195) 2-fold and peroxidase (EC 1.11.1.7) about 1.5-fold. The induction of the enzymes, with the exception of the peroxidase, was transient, showing maximal activity within 3 days after elicitation. Extracellular peroxidase activity, determined in the culture medium, rapidly decreased on initiation of elicitation.Concomitant with the increase of activity of the enzymes of lignin synthesis was a rapid clouding of the culture medium. Phloroglucinol-HCl staining revealed the presence of lignin-like material in the medium and also in the cells. The IR-spectrum of this material was identical with the IR-spectrum of authentic spruce lignin.Abbreviations PAL l-phenylalanine ammonia-lyase - FCR feruloyl-Coenzyme A reductase - CAD cinnamyl alcohol dehydrogenase - POD peroxidase