Efficient conversion of lactic acid to butanol with pH-stat continuous lactic acid and glucose feeding method by Clostridium saccharoperbutylacetonicum

In order to achieve high butanol production by Clostridium saccharoperbutylacetonicum N1-4, the effect of lactic acid on acetone–butanol–ethanol fermentation and several fed-batch cultures in which lactic acid is fed have been investigated. When a medium containing 20 g/l glucose was supplemented with 5 g/l of closely racemic lactic acid, both the concentration and yield of butanol increased; however, supplementation with more than 10 g/l lactic acid did not increase the butanol concentration. It was found that when fed a mixture of lactic acid and glucose, the final concentration of butanol produced by a fed-batch culture was greater than that produced by a batch culture. In addition, a pH-controlled fed-batch culture resulted in not only acceleration of lactic acid consumption but also a further increase in butanol production. Finally, we obtained 15.5 g/l butanol at a production rate of 1.76 g/l/h using a fed-batch culture with a pH-stat continuous lactic acid and glucose feeding method. To confirm whether lactic acid was converted to butanol by the N1-4 strain, we performed gas chromatography–mass spectroscopy (GC-MS) analysis of butanol produced by a batch culture during fermentation in a medium containing [1,2,3-¹³C₃] lactic acid as the initial substrate. The results of the GC-MS analysis confirmed the bioconversion of lactic acid to butanol.     

Enhanced <Emphasis Type="SmallCaps">l</Emphasis>-phenylalanine production by recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis> BR-42 (pAP-B03) resistant to bacteriophage BP-1 via a two-stage feeding approach

The l-phenylalanine (l-Phe) production by Escherichia coli WSH-Z06 (pAP-B03) was frequently prevented by bacteriophage BP-1 infestation. To cope with the bacteriophage BP-1 problem for an improved l-Phe production, one bacteriophage BP-1-resistant mutant, E. coli BR-42, was obtained from 416 mutant colonies of E. coli WSH-Z06 after N-methyl-N’-nitro-N-nitrosoguanidine (NTG) mutagenesis by selection for resistance to bacteriophage BP-1. The recombinant E. coli BR-42-carrying plasmid pAP-B03 had a high capacity in l-Phe production and a remarkable tolerance to 1 × 10¹⁰ pfu (plaque-forming unit)/ml bacteriophage stock. For an enhanced l-Phe production by E. coli BR-42 (pAP-B03), the effects of different feeding strategies including pH–stat, constant rate feeding, linear decreasing rate feeding, and exponential feeding on l-Phe production were investigated; and a two-stage feeding strategy, namely exponential feeding at μ _set = 0.18 h⁻¹ in the first 20 h and a following linear varying rate feeding with F = (−0.55 × t + 18.6) ml/h, was developed to improve l-Phe production. With this two-stage feeding approach, a maximum l-Phe titer of 57.63 g/l with a high l-Phe productivity (1.15 g/l/h) was achieved, which was 15% higher than the highest level (50 g/l) reported so far according to our knowledge. The recombinant E. coli BR-42 (pAP-B03) is a potential l-Phe over-producer in substantial prevention of bacteriophage BP-1 infestation compared to its parent strain WSH-Z06 (pAP-B03).     

Enhanced 2,3-butanediol production by <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> SDM

Enhanced 2,3-butanediol (BD) production was carried out by Klebsiella pneumoniae SDM. The nutritional requirements for BD production by K. pneumoniae SDM were optimized statistically in shake flask fermentations. Corn steep liquor powder and (NH₄)₂HPO₄ were identified as the most significant factors by the two-level Plackett–Burman design. Steepest ascent experiments were applied to approach the optimal region of the two factors and a central composite design was employed to determine their optimal levels. The optimal medium was used to perform fed-batch fermentations with K. pneumoniae SDM. BD production was then studied in a 5-l bioreactor applying different fed-batch strategies, including pulse fed batch, constant feed rate fed batch, constant residual glucose concentration fed batch, and exponential fed batch. The maximum BD concentration of 150 g/l at 38 h with a diol productivity of 4.21 g/l h was obtained by the constant residual glucose concentration feeding strategy. To the best of our knowledge, these results were new records on BD fermentation. Cuiqing Ma and Ailong Wang contributed equally to this work.     

Intra- and extra-cellular organophosphorus hydrolase production with recombinant <Emphasis Type="Italic">E. coli</Emphasis> using fed-batch fermentation

A fed-batch fermentation process for the production of organophosphorus hydrolase (OPH) (EC 3.1.8.1) by E. coli pET812 was developed in this research. With batch fermentation, the maximum OPH concentrations attained by batch fermentation were as low as 4 × 10⁵ U/l because cell growth and OPH production were inhibited by a high initial concentration of glucose. To develop a fed-batch fermentation process for obtaining higher concentrations of OPH, highly concentrated glucose solution (500 g/l) was added intermittently or continuously to increase the carbon source concentration. Eventually, 3.2 × 10⁶ U/l of OPH was produced with fed-batch fermentation in 24 h. This was eight times higher than the yield with conventional batch fermentation. A total concentration of 399–441 mg of OPH was produced/l, which was four times higher than that reported when using E. coli. Nearly half (44%) of the produced OPH was secreted into the culture solution.     

Production of β-carotene by recombinant Escherichia coli with engineered whole mevalonate pathway in batch and fed-batch cultures

Recombinant Escherichia coli engineered to contain the whole mevalonate pathway and foreign genes for β-carotene biosynthesis, was utilized for production of β-carotene in bioreactor cultures. Optimum culture conditions were established in batch and pH-stat fed-batch cultures to determine the optimal feeding strategy thereby improving production yield. The specific growth rate and volumetric productivity in batch cultures at 37°C were 1.7-fold and 2-fold higher, respectively, than those at 28°C. Glycerol was superior to glucose as a carbon source. Maximum β-carotene production (titer of 663 mg/L and overall volumetric productivity of 24.6 mg/L × h) resulted from the simultaneous addition of 500 g/L glycerol and 50 g/L yeast extract in pH-stat fed-batch culture.     

CRISPR/Cas9编辑大肠杆菌工程菌生产氨基葡萄糖

【背景】氨基葡萄糖(glucosamine, GlcN)及其衍生物N-乙酰氨基葡萄糖(N-acetylglucosamine,GlcNAc)是合成糖胺聚糖的重要前体物质,在医药、化妆品和保健品领域具有广泛的应用价值。传统的生产方式存在诸多弊端,如环境污染、原料限制、不适于海鲜易过敏人群等问题,因此利用微生物发酵法生产GlcN和GlcNAc越来越受到青睐。【目的】利用微生物发酵生产并提高N-乙酰氨基葡萄糖的产量,探索分子改造及发酵条件优化策略。【方法】以大肠杆菌MG1655为出发菌株,首先利用表达载体共表达大肠杆菌来源的glmS和酿酒酵母来源的gna1,构建GlcNAc的生物合成路径,然后利用CRISPR/Cas9技术敲除GlcNAc的分解代谢与转运途径,以提高GlcNAc的产量,最后结合发酵条件优化使GlcNAc的产量得到进一步提升。【结果】通过分子改造得到一株产GlcNAc菌株RY-5,发酵20 h后GlcNAc的产量达到了2.36 g/L,相较于初始构建的菌株RY-1提高了29倍,进一步对装液量和诱导剂IPTG的添加时间等条件进行发酵优化,GlcNAc产量达到了7.74g/L,与优...     

Effect of anaerobic promoters on the microaerobic production of polyhydroxybutyrate (PHB) in recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis>

Nine anaerobic promoters were cloned and constructed upstream of PHB synthesis genes phbCAB from Ralstonia eutropha for the micro- or anaerobic PHB production in recombinant Escherichia coli. Among the promoters, the one for alcohol dehydrogenase (P _adhE ) was found most effective. Recombinant E. coli JM 109 (pWCY09) harboring P _adhE and phbCAB achieved a 48% PHB accumulation in the cell dry weight after 48 h of static culture compared with only 30% PHB production under its native promoter. Sixty-seven percent PHB was produced in the dry weight (CDW) of an acetate pathway deleted (Δpta deletion) E. coli JW2294 harboring the vector pWCY09. In a batch process conducted in a 5.5-l NBS fermentor containing 3 l glucose LB medium, E. coli JW2294 (pWCY09) grew to 7.8 g/l CDW containing 64% PHB after 24 h of microaerobic incubation. In addition, molecular weight of PHB was observed to be much higher under microaerobic culture conditions. The high activity of P _adhE appeared to be the reason for improved micro- or anaerobic cell growth and PHB production while high molecular weight contributed to the static culture condition.     

Continuous <Emphasis Type="SmallCaps">d</Emphasis>-lactic acid production by a novelthermotolerant <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis> subsp. <Emphasis Type="Italic">lactis</Emphasis> QU 41

We isolated and characterized a d-lactic acid-producing lactic acid bacterium (d-LAB), identified as Lactobacillus delbrueckii subsp. lactis QU 41. When compared to Lactobacillus coryniformis subsp. torquens JCM 1166 ^T and L. delbrueckii subsp. lactis JCM 1248 ^T, which are also known as d-LAB, the QU 41 strain exhibited a high thermotolerance and produced d-lactic acid at temperatures of 50 °C and higher. In order to optimize the culture conditions of the QU 41 strain, we examined the effects of pH control, temperature, neutralizing reagent, and initial glucose concentration on d-lactic acid production in batch cultures. It was found that the optimal production of 20.1 g/l d-lactic acid was acquired with high optical purity (>99.9% of d-lactic acid) in a pH 6.0-controlled batch culture, by adding ammonium hydroxide as a neutralizing reagent, at 43 °C in MRS medium containing 20 g/l glucose. As a result of product inhibition and low cell density, continuous cultures were investigated using a microfiltration membrane module to recycle flow-through cells in order to improve d-lactic acid productivity. At a dilution rate of 0.87 h⁻¹, the high cell density continuous culture exhibited the highest d-lactic acid productivity of 18.0 g/l/h with a high yield (ca. 1.0 g/g consumed glucose) and a low residual glucose (<0.1 g/l) in comparison with systems published to date.     

Enhancement of human granulocyte-colony stimulating factor production in recombinant E. coli using batch cultivation

Development of inexpensive and simple culture media is always favorable for recombinant protein over-expression in E. coli. The effects of medium composition on the production of recombinant human granulocyte-colony stimulating factor (rh-GCSF) were investigated in batch culture of E. coli BL21 (DE3) [pET23a-hgcsf]. First, the optimum medium for production of rh-GCSF was determined; and, then it was shown that mixture of amino acid addition at induction time, which was determined on the basis of amino acids frequency in the recombinant protein, increases recombinant protein expression level significantly. Furthermore, the effect of glucose concentration on productivity of rh-GCSF was investigated; 20 g/l of glucose will result in maximum attainable biomass and rh-GCSF in this process. At optimum conditions, a cell dry weight of 10.5 g/l, an expression level of about 35% of total cellular protein, rh-GCSF concentration of 1.75 ± 0.1 g/l, and overall rh-GCSF yield of 165 ± 5 mg/g were obtained.     

Mass production of nitrifying bacterial consortia for the rapid establishment of nitrification in saline recirculating aquaculture systems

Two distinct nitrifying bacterial consortia, namely an ammonia oxidizing non-penaeid culture (AMONPCU-1) and an ammonia oxidizing penaeid culture (AMOPCU-1), have been mass produced in a nitrifying bacterial consortia production unit (NBCPU). The consortia, maintained at 4°C were activated and cultured in a 2 l fermentor initially. At this stage the net biomass (0.105 and 0.112 g/l), maximum specific growth rate (0.112 and 0.105/h) and yield coefficients (1.315 and 2.08) were calculated respectively, for AMONPCU-1 and AMOPCU-1 on attaining stationary growth phase. Subsequently on mass production in a 200 l NBCPU under optimized culture conditions, the total amounts of NH₄ ⁺–N removed by AMONPCU-1 and AMOPCU-1 were 1.948 and 1.242 g/l within 160 and 270 days, respectively. Total alkalinity reduction of 11.7–14.4 and 7.5–9.1 g/l were observed which led to the consumption of 78 and 62 g Na₂CO₃. The yield coefficient and biomass of AMONPCU-1 were 0.67 and 125.3 g/l and those of AMOPCU-1 were 1.23 and 165 g/l. The higher yield coefficient and growth rate of AMOPCU-1 suggest better energy conversion efficiency and higher CO₂ fixation potential. Both of the consortia were dominated by Nitrosomonas-like organisms. The consortia may find application in the establishment of nitrification within marine and brackish water culture systems.     

Modeling of <Emphasis Type="Italic">Fusarium redolens</Emphasis> Dzf2 mycelial growth kinetics and optimal fed-batch fermentation for beauvericin production

Beauvericin (BEA) is a cyclic hexadepsipeptide mycotoxin with notable phytotoxic and insecticidal activities. Fusarium redolens Dzf2 is a highly BEA-producing fungus isolated from a medicinal plant. The aim of the current study was to develop a simple and valid kinetic model for F. redolens Dzf2 mycelial growth and the optimal fed-batch operation for efficient BEA production. A modified Monod model with substrate (glucose) and product (BEA) inhibition was constructed based on the culture characteristics of F. redolens Dzf2 mycelia in a liquid medium. Model parameters were derived by simulation of the experimental data from batch culture. The model fitted closely with the experimental data over 20–50 g l⁻¹ glucose concentration range in batch fermentation. The kinetic model together with the stoichiometric relationships for biomass, substrate and product was applied to predict the optimal feeding scheme for fed-batch fermentation, leading to 54% higher BEA yield (299 mg l⁻¹) than in the batch culture (194 mg l⁻¹). The modified Monod model incorporating substrate and product inhibition was proven adequate for describing the growth kinetics of F. redolens Dzf2 mycelial culture at suitable but not excessive initial glucose levels in batch and fed-batch cultures.     

Optimization of culture on the overproduction of TRAIL in high-cell-density culture by recombinant Escherichia coli

Different nutrient-feeding cultures were carried out in producing recombinant protein of truncated tumor necrosis factor related apoptosis-inducing ligand (TRAIL) (114–281 amino acids of TRAIL) in Escherichia coli strain C600/pBV-TRAIL. The effects of preinduction specific growth rate, postinduction carbon source (glucose and glycerol), and feeding strategies were investigated. The higher preinduction specific growth rate (μ=0.22 h⁻¹) contributed to the increase in the TRAIL production, at which TRAIL was accumulated in bacterial cells as 7.2% of total cellular protein, corresponding to 1.99 g l⁻¹ in contrast with 5.1% (1.29 g l⁻¹) at preinduction specific growth rate (μ=0.1 h⁻¹) during high-cell-density culture. Glycerol was superior to glucose as the postinduction carbon source for TRAIL production. Under similar culture conditions, the final concentration of TRAIL was produced 1.59-fold more when glycerol was used as postinduction carbon source than when glucose was used. At the same time, the results showed that it is efficient to adopt the pH-stat feeding strategy at postinduction for the overproduction of TRAIL. The TRAIL production was increased up to 4.51 g l⁻¹, approximately 16.1% of total cellular protein. The mechanisms behind the preinduction specific growth rate effect on the expression level may be ascribed to the leakage secretion of acetate.     

Effective and stable porcine interferon-α production by Pichia pastoris fed-batch cultivation with multi-variables clustering and analysis

Efficient porcine interferon-α (pIFN-α) expression in high density recombinant Pichia pastoris cultivation was achieved in a 5 l bench-scaled bioreactor. The results indicated that a high and stable oxygen uptake rate (OUR) during induction phase was closely related with pIFN-α production efficiency. The multi-variables clustering and analysis results showed that the achievement of a high and stable OUR relied on a higher glycerol consumption rate during fed-batch culture phase and a moderate methanol level (around 10 g/l) during induction phase. In the high and stable OUR environments (200–300 mmol/l/h), the highest pIFN-α antiviral activity could reach a level of 6.7 × 10⁶ IU/ml, which was more than 10–300-folds higher than those obtained at lower OUR (80–200 mmol/l/h) using the same bioreactor and those obtained in shaking flasks. Clustering and analysis of the specific growth and glycerol consumption rates data during culture phase could detect the ill fermentation state at early stage, potentially provided a simple and effective fault alarming/diagnosis method for the achievement of stable pIFN-α production.     

Increase of xylitol yield by feeding xylose and glucose in Candida tropicalis

Candida tropicalis, a strain isolated from the sludge of a factory manufacturing xylose, produced a high xylitol concentration of 131 g/l from 150 g/l xylose at 45 h in a flask. Above 150 g/l xylose, however, volumetric xylitol production rates decreased because of a lag period in cell growth. In fed-batch culture, the volumetric production rate and xylitol yield from xylose varied substantially with the controlled xylose concentration and were maximum at a controlled xylose concentration of 60 g/l. To increase the xylitol yield from xylose, feeding experiments using different ratios of xylose and glucose were carried out in a fermentor. The maximum xylitol yield from 300 g/l xylose was 91% at a glucose/xylose feeding ratio of 15%, while the maximum volumetric production rate of xylitol was 3.98 g l⁻¹ h⁻¹ at a glucose/xylose feeding ratio of 20%. Xylitol production was found to decrease markedly as its concentration rose above 250 g/l. In order to accumulate xylitol to 250 g/l, 270 g/l xylose was added in total, at a glucose/xylose feeding ratio of 15%. Under these conditions, a final xylitol production of 251 g/l, which corresponded to a yield of 93%, was obtained from 270 g/l xylose in 55 h. Received: 20 April 1998 / Received revision: 29 May 1998 / Accepted: 19 June 1998     

Metabolic engineering of <Emphasis Type="Italic">Escherichia coli</Emphasis> for improving <Emphasis Type="SmallCaps">l</Emphasis>-3,4-dihydroxyphenylalanine (<Emphasis Type="SmallCaps">l</Emphasis>-DOPA) synthesis from glucose

l-3,4-dihydroxyphenylalanine (l-DOPA) is an aromatic compound employed for the treatment of Parkinson's disease. Metabolic engineering was applied to generate Escherichia coli strains for the production of l-DOPA from glucose by modifying the phosphoenolpyruvate:sugar phosphotransferase system (PTS) and aromatic biosynthetic pathways. Carbon flow was directed to the biosynthesis of l-tyrosine (l-Tyr), an l-DOPA precursor, by transforming strains with compatible plasmids carrying genes encoding a feedback-inhibition resistant version of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase, transketolase, the chorismate mutase domain from chorismate mutase-prephenate dehydratase from E. coli and cyclohexadienyl dehydrogenase from Zymomonas mobilis. The effects on l-Tyr production of PTS inactivation (PTS⁻ gluc⁺ phenotype), as well as inactivation of the regulatory protein TyrR, were evaluated. PTS inactivation caused a threefold increase in the specific rate of l-Tyr production (q _l-Tyr), whereas inactivation of TyrR caused 1.7- and 1.9-fold increases in q _l-Tyr in the PTS⁺ and the PTS⁻ gluc⁺ strains, respectively. An 8.6-fold increase in l-Tyr yield from glucose was observed in the PTS⁻ gluc⁺ tyrR ⁻ strain. Expression of hpaBC genes encoding the enzyme 4-hydroxyphenylacetate 3-hydroxylase from E. coli W in the strains modified for l-Tyr production caused the synthesis of l-DOPA. One of such strains, having the PTS⁻ gluc⁺ tyrR ⁻ phenotype, displayed the best production parameters in minimal medium, with a specific rate of l-DOPA production of 13.6 mg/g/h, l-DOPA yield from glucose of 51.7 mg/g and a final l-DOPA titer of 320 mg/l. In a batch fermentor culture in rich medium this strain produced 1.51 g/l of l-DOPA in 50 h.     

Production of <Emphasis Type="SmallCaps">l</Emphasis>-lactic acid by <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> using semicontinuous fermentation in bioreactor

Semicontinuous fermentation using pellets of Rhizopus oryzae has been recognized as a promising technology for l-lactic acid production. In this work, semicontinuous fermentation of R. oryzae AS 3.819 for l-lactic acid production has been developed with high l-lactic acid yield and volumetric productivity. The effects of factors such as inoculations, CaCO₃ addition time, and temperature on l-lactic acid yield and R. oryzae morphology were researched in detail. The results showed that optimal fermentation conditions for the first cycle were: inoculation with 4% spore suspension, CaCO₃ added to the culture medium at the beginning of culture, and culture temperature of 32–34°C. In orthogonal experiments, high l-lactic acid yield was achieved when the feeding medium was (g/l): glucose, 100; (NH₄)₂SO₄, 2; KH₂PO₄, 0.1; ZnSO₄·7H₂O, 0.33; MgSO₄·7H₂O, 0.15; CaCO₃, 50. Twenty cycles of semicontinuous fermentation were carried out in flask culture. l-lactic acid yield was 78.75% for the first cycle and 80–90% for the repeated cycles; the activities of lactate dehydrogenases (LDH) were 7.2–9.2 U/mg; fermentation was completed in 24 h for each repeated cycle. In a 7-l magnetically stirred fermentor, semicontinuous fermentation lasted for 25 cycles using pellets of R. oryzae AS 3.819 under the optimal conditions determined from flask cultures. The final l-lactic acid concentration (LLAC) reached 103.7 g/l, and the volumetric productivity was 2.16 g/(l·h) for the first cycle; in the following 19 repeated cycles, the final LLAC reached 81–95 g/l, and the volumetric productivities were 3.40–3.85 g/(l·h).     

Significantly enhanced production of recombinant nitrilase by optimization of culture conditions and glycerol feeding

The production of a recombinant nitrilase expressed in Escherichia coli JM109/pNLE was optimized in the present work. Various culture conditions and process parameters, including medium composition, inducer, induction condition, pH and temperature, were systematically examined. The results showed that nitrilase production in E. coli JM109/pNLE was greatly affected by the pH condition and the temperature in batch culture, and the highest nitrilase production was obtained when the fermentation was carried out at 37°C, initial pH 7.0 without control and E. coli was induced with 0.2 mM isopropyl-β-d-thiogalactoside at 4.0 h. Furthermore, enzyme production could be significantly enhanced by adopting the glycerol feeding strategy with lower flow rate. The enzyme expression was also authenticated by sodium dodecyl phosphate polyacrylamide gel electrophoresis analysis. Finally, under the optimized conditions for fed-batch culture, cell growth, specific activity and nitrilase production of the recombinant E. coli were increased by 9.0-, 5.5-, and 50-fold, respectively.     

Conversion of glucose‐xylose mixtures to pyruvate using a consortium of metabolically engineered Escherichia coli

Two strains of Escherichia coli were engineered to accumulate pyruvic acid from two sugars found in lignocellulosic hydrolysates by knockouts in the aceE, ppsA, poxB, and ldhA genes. Additionally, since glucose and xylose are typically consumed sequentially due to carbon catabolite repression in E. coli, one strain (MEC590) was engineered to grow only on glucose while a second strain (MEC589) grew only on xylose. On a single substrate, each strain generated pyruvate at a yield of about 0.60 g/g in both continuous culture and batch culture. In a glucose‐xylose mixture under continuous culture, a consortium of both strains maintained a pyruvate yield greater than 0.60 g/g when three different concentrations of glucose and xylose were sequentially fed into the system. In a fed‐batch process, both sugars in a glucose‐xylose mixture were consumed simultaneously to accumulate 39 g/L pyruvate in less than 24 h at a yield of 0.59 g/g.     

Production of bioethanol from organic whey using <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis>

Ethanol production by K. marxianus in whey from organic cheese production was examined in batch and continuous mode. The results showed that no pasteurization or freezing of the whey was necessary and that K. marxianus was able to compete with the lactic acid bacteria added during cheese production. The results also showed that, even though some lactic acid fermentation had taken place prior to ethanol fermentation, K. marxianus was able to take over and produce ethanol from the remaining lactose, since a significant amount of lactic acid was not produced (1–2 g/l). Batch fermentations showed high ethanol yield (~0.50 g ethanol/g lactose) at both 30°C and 40°C using low pH (4.5) or no pH control. Continuous fermentation of nonsterilized whey was performed using Ca-alginate-immobilized K. marxianus. High ethanol productivity (2.5–4.5 g/l/h) was achieved at dilution rate of 0.2/h, and it was concluded that K. marxianus is very suitable for industrial ethanol production from whey.     

Production of pediocin SM-1 by Pediococcus pentosaceus Mees 1934 in fed-batch fermentation: Effects of sucrose concentration in a complex medium and process modeling

Production of pediocin SM-1 by Pediococcus pentosaceus Mees 1934 was investigated in semi-aerobic, pH-controlled, batch and fed-batch fermentations using a complex medium containing sucrose as the main source of carbon. The effects of sucrose concentration were studied in fed-batch fermentations in which a sucrose solution was added at stable feeding rates (5, 7, 9 and 10 g/l/h). The results showed that pediocin is produced as a product of the primary metabolism and its titer could be greatly improved by adjusting the sucrose feeding rate in fed-batch fermentation. The maximum titer of pediocin of 145 AU/ml was obtained in the fed-batch culture with 7 g/l/h feeding rate and that was 119% higher compared to the titer obtained in batch culture. Higher feeding rates (9 and 10 g/l/h) resulted in decreased pediocin yields while biomass levels appeared to be rather unaffected. The specific rate of pediocin formation was also sensitive to sucrose concentration levels. A mathematical model developed on the basis of well-known rate equations for batch and fed-batch cultures and growth associated production, described successfully cell growth, sucrose assimilation, lactate production and pediocin production in fed-batch culture.