Production of a thermostable extracellular lipase by Kluyveromyces marxianus

Kluyveromyces marxianus was grown in submerged culture in a complex medium with several potential inducers of lipolytic activity (triacylglycerols, fatty acids). The highest extracellular lipolytic enzyme production (about 80 U ml^–1 in 3 d) was obtained when the medium was supplemented with 2 g urea l^–1 plus 5 g tributyrin l^–1. Addition of surfactants (1 g l^–1) did not improve production. The lipase had a high thermal stability in aqueous solution (73% residual activity after 9 d at 50 °C, 16 min half-life time at 100 °C). It was also stable at acidic pH and showed good tolerance to organic solvents (70% residual activity after 2 d in n-hexane of cyclohexane).     

Culture conditions of tannase production by Lactobacillus plantarum

Lactobacillus plantarum produced an extracellular tannase after 24 h growth on minimal medium of amino acids containing 2 g tannic acid l^–1. Enzyme production (6 U ml^–1) was optimal at 37 °C and pH 6 with 2 g glucose l^–1 and 7 g tannic acid l^–1 in absence of O₂.     

Production potential of eicosapentaenoic acid by the diatom Nitzschia laevis

To investigate the production potential of eicosapentaenoic acid (EPA) by the diatom Nitzschia laevis, the growth characteristics and fatty acid composition of the cells were studied under photoautotrophic, mixotrophic and heterotrophic conditions of growth. The specific growth rate and maximum biomass concentration were respectively 0.466 d^–1 and 2.27 g l^–1 for mixotrophic culture, 0.344 d^–1 and 2.04 g l^–1 for heterotrophic culture, and 0.167 d^–1 and 0.5 g l^–1 for photoautotrophic culture, respectively. As for EPA production, the yield and productivity were respectively 52.32 mg l^–1 and 10.46 mg l^–1 d for mixotrophic culture, 35.08 mg l^–1 and 6.37 mg l^–1 d for heterotrophic culture, and 6.78 mg l^–1 and 3.39 mg l^–1 d for photoautotrophic culture, respectively. Results suggest that mixotrophic culture is the most suitable growth mode for the production of EPA by the diatom Nitzschia laevis. The results are useful for the development of a cost-effective fermentation process for EPA production by Nitzschia laevis.     

Impact of carbon and nitrogen nutrition on the quality, yield and composition of blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

The impact of growing cultures of Paecilomyces fumosoroseus in liquid media containing four combinations of glucose and casamino acids (8 g l^–1 or 80 g l^–1 glucose, 1.32 g l^–1 or 13.2 g l^–1 casamino acids) was evaluated, based on blastospore production, germination rate, viability after freeze-drying and short-term storage stability. When blastospores were produced using a high casamino acid concentration, blastospore yields and germination rates were significantly higher (13.2–18.5×10⁷ blastospores ml^–1, 50–60% germination after 4 h), compared to cultures grown in media containing lower casamino acid concentrations (0.4–2.3×10⁷ blastospores ml^–1, 10–20% germination after 4 h). Chemical analyses of blastospore composition showed that accelerated blastospore germination may be related to increased proteinaceous reserves rather than to glycogen or lipid accumulation. Tolerance to freeze-drying by blastospores suspended in spent medium was enhanced by a high initial casamino acid concentration in the culture medium (75% survival) and by the residual glucose concentrations in the spent medium. Under the conditions of this study, the storage stability of blastospores of P. fumosoroseus was unaffected by the nutritional condition in which they were produced.     

Enhanced shear protection and increased production of an anti-tumor polysaccharide by Agaricus blazei in xanthan-supplemented cultures

Xanthan supplementation provided shear protection and stimulated polysaccharide production by Agaricus blazei. In xanthan-free cultures, the optimal cell yield, 0.63 g biomass g^–1 glucose, and product yield, 0.19 g polysaccharide g^–1 glucose, were, respectively, when the critical impeller tip speed was 50.3 cm s^–1 and 100.5 cm s^–1. Furthermore, the critical impeller tip speed of cell yield shifted from 50.3 cm s^–1 to 100.5 cm s^–1 with the supplementation of 1 g xanthan l^–1. Maximum specific product yield, namely 0.74 g polysaccharide g^–1 biomass, was achieved with inlet air supply of 3% O₂ and impeller tip speed of 100.5 cm s^–1.     

Bioconversion of linoleic acid into conjugated linoleic acid during fermentation and by washed cells of Lactobacillus reuteri

Conjugated linoleic acid (CLA) was produced at 300 mg l^–1 after 24 h culture of Lactobacillus reuteri in de Man–Rogosa–Sharpe medium containing 0.9 g linoleic acid (LA) l^–1 and 1.67% (v/v) Tween 80. CLA was mainly located in the extracellular space of the cells. Washed cells previously grown on LA were less active than unadapted washed cells in converting LA into CLA. Most of the CLA transformed by washed L. reuteri cells was located in cells or associated with cells. CLA production by washed L. reuteri cells was most efficient in conversion with 0.45 g LA l^–1 at pH 9.5 and 37°C for 1 h.     

Oxalic acid production from lipids by a mutant of Aspergillus niger at different pH

Crude rapeseed oil and post-refining fatty acids were used as substrates for oxalic acid production by a mutant of Aspergillus niger. Both the final concentration and the yield of the product were highest at pH 4 to 5. With a medium containing 50 g lipids l^–1, production reached a maximum of 68 g oxalic acid l^–1 after 7 d. A high yield of the product (up to 1.4 g oxalic acid g^–1 lipids consumed) was achieved with oil and fatty acids combined.     

Production of mannitol by a novel strain of Candida magnoliae

A novel microorganism was isolated which is able to produce mannitol when grown in the presence of fructose and glucose as carbon sources. In flask culture in a medium containing 150 g fructose l^–1, it yielded 67 g mannitol l^–1 after 168 h. In fed-batch culture with 3–12% (w/v) fructose, production reached a maximum of 209 g mannitol l^–1 after 200 h, corresponding to an 83% yield and a 1.03 g l^–1 h^–1 productivity. The isolated strain was identified as Candida magnoliae based on identical sequences in the D1/D2 domain of its 26S rDNA and a similar carbon source utilization pattern with C. magnoliae reference strains.     

Enzyme production in continuous cultivation by the thermophilic fungus, Thermomyces lanuginosus

The production of extracellular enzymes by the thermophilic fungus Thermomyces lanuginosus was studied in chemostat cultures at a dilution rate of 0.08 h^–1 in relation to variation in the ammonium concentration in the feed medium. Under steady state conditions, three growth regimes were recognised and the production of several extracellular enzymes from T. lanuginosus was recorded under different nutrient limitations ranging from nitrogen limitation to carbon/energy limitation. The range and the production of carbohydrate hydrolysing enzymes and lipase increased from Regime I (NH₄Cl 600 mg l^–1) to Regime III (NH₄CI 1200 mg l^–1), whereas production of protease was highest in Regime II (600 mg l^–1 < NH₄Cl <1200 mg l^–1).     

Evaluation of the potential of Aspergillus niger species for the bioconversion of L-phenylalanine into 2-phenylethanol

Aspergillus niger was explored, for the first time, for the production of 2-phenylethanol (a rose-like aroma) using L-phenylalanine as precursor. Among the strains screened, A. niger CMICC 298302 was shown to produce, in a culture medium containing 6 g L-phenylalanine l^–1 and 60 g glucose l^–1, 1375 mg 2-phenylethanol l^–1 with a productivity of 153 mg l^–1 day^–1 and a molar yield of 74%. 2-Phenylethanol concentrations of 1 to 2 g l^–1 led to a two-fold and ten-fold decrease, respectively, in the mycelial radial growth rate. However, 2-phenylethanol was synthesized as the sole aromatic product and accumulated in the culture broth.     

High density cell culture of Panax notoginseng for production of ginseng saponin and polysaccharide in an airlift bioreactor

High cell density of Panax notoginseng in a 17 l airlift bioreactor was achieved in batch cultivation using a modified MS medium. The dry cell weight, ginseng saponin and polysaccharide reached 24, 1.7 and 2.8 g l^–1, respectively, after 15 d. A strategy of sucrose feeding based on changes in the specific O₂ uptake rate was applied to the cell cultures, which increased these respective yields to 30, 2.3 and 3.2 g l^–1.     

Preparation and testing of Sardinella protein hydrolysates as nitrogen source for extracellular lipase production by Rhizopus oryzae

Various fish protein hydrolysates (FPH) from sardinella (Sardinella aurita) were used as nitrogen sources for the production of extracellular lipase by the filamentous fungus Rhizopus oryzae. The best results were obtained with defatted meat–fish protein hydrolysates (DMFPH), indicating the presence in the lipid fraction of some constituents which may repress lipase synthesis. Furthermore, it was found that the extensive hydrolysis of fish proteins resulted in a higher lipase production. The use of 40 g DMFPH l^–1 for the growth of Rhizopus oryzae in medium R1 resulted in a lipase production of 394 U ml^–1, higher than the yield obtained with standard soy peptone as nitrogen source (373 U ml^–1). The most appropriate medium for the growth and the production of lipase is composed only of 24 g DMFPH l^–1 and 10 g glucose l^–1, indicating that the strain can obtain its nitrogen and salts requirements directly from fish substrate.     

Degradation of tributyltin by the filamentous fungus Cunninghamella elegans, with involvement of cytochrome P-450

Cunninghamella elegans degraded tributyltin (TBT) at 20 mg l^–1 when grown in Sabouraud medium. Above this concentration, growth was inhibited. After 7 d 70% TBT (added at 10 mg l^–1) was converted to less toxic derivatives: dibutyltin and monobutyltin. TBT metabolism was totally blocked by cytochrome P-450 inhibitors, metyrapone and proadifen. Only in medium with 1-aminobenzotriazole, was dibutyltin (0.42 mg l^–1) found after 7 d of culturing. It is postulated that the significant resistance of C. elegans to TBT is associated with the capacity of the fungus to metabolise TBT.     

Extracellular production of a glycolipid biosurfactant, mannosylerythritol lipid, from Candida antarctica

Candida antarctica (sp. SY16) required avegetable oil as the carbon source to produce a biosurfactant, mannosylerythritol lipid (MEL-SY16). Biosurfactant production was 31 g l^–1 after 7 days in a batch culture and was not growth associated. In a two-stage culture, glycerol and oleic acid were used as an initial and a feeding carbon source, respectively, and 41 g l^–1 biosurfactant was produced after 8 days.     

Selective production of bikaverin in a fluidized bioreactor with immobilized Gibberella fujikuroi

The best culture medium composition for the production of bikaverin by Gibberella fujikuroi in shake-flasks, i.e. 100 g glucose l^–1; 1 g NH₄Cl l^–1; 2 g rice flour l^–1; 5 g KH₂PO₄ l^–1 and 2.5 g MgSO₄ l^–1, was obtained through a fractional factorial design and then scaled-up to a fluidized bioreactor. The effects of carbon and nitrogen concentrations, inoculum size, aeration, flow rate and bead sizes on batch bikaverin production using immobilized G. fujikuroi in a fluidized bioreactor were determined by an orthogonal experimental design. Concentrations of up to 6.83 g bikaverin l^–1 were obtained when the medium contained 100 g glucose l^–1 and 1 g NH₄Cl l^–1 with an inoculum ratio of 10% v/v, an aeration rate of 3 volumes of air per volume of medium min^–1, and a bead size of 3 mm. Based on dry weight, the bikaverin production was 30–100 times larger than found in submerged culture and approximately three times larger than reported for solid substrate fermentation.     

Glycerol production by Candida krusei employing NaCl as an osmoregulator in batch and continuous fermentations

Addition of 40 g NaCl l^–1 to a chemically defined medium containing 140 g glucose l^–1 in shake-flask culture improved glycerol production by Candida krusei from 16.5 g l^–1 to 47.7 g l^–1. With 40 g NaCl l^–1 at a dilution rate of 0.065 h^–1, glycerol concentration, glycerol yield (based on glucose consumed), and productivity in a four-stage cascade bioreactor were higher by 240%, 27% and 28%, respectively, than in a single-stage continuous culture system.     

Optimization of glycerol feeding for clavulanic acid production by Streptomyces clavuligerus with glycerol feeding

Glycerol at 10–20 g l^–1 increased clavulanic acid production by Streptomyces clavuligerus in shake-flask culture. The biosynthesis of clavulanic acid continued for longer by feeding glycerol and production increased to 250 mg l^–1 compared with 115 mg l^–1 without feeding. In fermenter batch culture, degradation of clavulanic acid began after 72 h. With glycerol feeding in fed-batch culture, clavulanic acid production was not only increased further to about 280 mg l^–1 but also remained stable up to 130 h.     

Production of fructosylxyloside by the new fructosyltransferase from Bacillus macerans EG-6

The new fructosyltransferase (FTase) from Bacillus maceransEG-6 showed a broad acceptor specificity, and resulted in the formation of fructosylxyloside (FX) with d-xylose being the most effective acceptor. The optimal FTase concentration for FX production was 0.6 unit per g sucrose, which gave the highest transfer ratio, 83%, of fructosyl moiety from sucrose to d-xylose. Maximum yield of FX was 114 g l^–1with 200 g sucrose l^–1and 300 g d-xylose l^–1.     

Production of poly(3-hydroxybutyrate) from whey by fed-batch culture of recombinant Escherichia coli in a pilot-scale fermenter

Production of poly(3-hydroxybutyrate) [P(3HB)] from wheyby fed-batch culture of recombinant Escherichia coli CGSC 4401 harboring a plasmid containing the Alcaligenes latus polyhydroxyalkanoate (PHA) biosynthesis genes was examined in a 30 l fermenter supplying air only. With lactose below 2 g l^–1, cells grew to 12 g dry cell l^–1 with 9% (w/w) P(3HB) content. Accumulation of P(3HB) could be triggered by increasing lactose to 20 g l^–1. By employing this strategy, 51 g dry cell l^–1 was obtained with a 70% (w/w) P(3HB) content after 26 h. The productivity was 1.35 g P(3HB) l^–1 h^–1. The same fermentation strategy was used in a 300 l fermenter, and 30 g dry cell l^–1 with 67% (w/w) P(3HB) content was obtained in 20 h.     

Tannase production by Bacillus licheniformis

Bacillus licheniformis KBR 6 produced maximum extracellular tannase activity at 0.21 U ml^–1 with 1.5% (w/v) tannic acid either in the absence or presence of glucose (1 g l^–1) after 18–21 h growth though the organism did not attain maximum growth until 36 h.