Leudeking Piret Model Research Articles

L-Asparaginase from an acrylamide degrader, Cupriavidus oxalaticus ICTDB921: Production, kinetic modelling, purification and characterization

In the present study, a novel soil isolate and previously reported acrylamide degrader, Cupriavidus oxalaticus ICTDB921, was found to have better and significantly higher l-asparaginase (LAase) activity than other bacterial strains that were screened for the same. The medium and fermentation conditions were optimized for maximizing LAase production followed by its purification and biochemical characterization. The optimum conditions of pH (7), temperature (30 °C) and agitation (180 rpm), showed the highest biomass accumulation (DCW 3.15 g/L) and LAase activity (22.94 IU/mL) after 12 h at 160 mM l-asparagine. Kinetic modelling of optimized batch data showed the biomass accumulation, LAase formation and l-asparagine utilization to best fit with the logistic model, Leudeking-Piret model and exponential decay model, respectively. The crude LAase from this isolate showed high potency at pH 7 to 9, and temperatures from 30 to 40 °C with reasonable pH (6–9) and thermal (up to 50 °C) stability. The LAase was stable against most amino acids and metal ions, and it could degrade aliphatic amides like urea and formamide. A sequential purification by ammonium sulphate precipitation, thermal treatment and chromatographic separation achieved approximately 8-fold purity. The purified subunit showed a molecular weight of 78 kDa, and km and Vmax of 24.1 mM and 40 μmol/min, respectively. The study demonstrates the potential of LAase from Cupriavidus oxalaticus in the mitigation of asparagine in food as well as for therapeutic applications.

Characterization of biosurfactant produced in response to petroleum crude oil stress by Bacillus sp. WD22 in marine environment.

Bacillus sp. WD22, previously isolated from refinery effluent, degraded 71% of C8 hydrocarbons present in 1.0% v/v PCO in seawater (control medium), which reduced to 16.3%, on addition of yeast extract. The bacteria produced a biosurfactant in both media, whose surface was observed to be amorphous in nature under FESEM-EDAX analysis. The biosurfactant was characterized as a linear surfactin by LCMS and FT-IR analysis. The critical micelle concentration was observed as 50mg/L and 60mg/L at which the surface tension of water was reduced to 30 mN/m. Purified biosurfactant could emulsify petroleum-based oils and vegetable oils effectively and was stable at all tested conditions of pH, salinity and temperature up to 80°C. The biosurfactant production was found to be mixed growth associated in control medium, while it was strictly growth associated in medium with yeast extract as studied by the Leudeking-Piret model.

Sequential Dark-Photo Batch Fermentation and Kinetic Modelling for Biohydrogen Production Using Cheese Whey as a Feedstock.

The present work describes the utilisation of cheese whey to produce biohydrogen by sequential dark-photo fermentation. In first stage, cheese whey was fermented by Enterobacter aerogenes 2822 cells in a 2 L double-walled cylindrical bioreactor to produce hydrogen/organic acids giving maximum biohydrogen yield and cumulative hydrogen of 2.43 ± 0.12molmol-1 lactose and 3270 ± 143.5mL at cheese whey concentration of 105mM lactose L-1. The soluble metabolites of dark fermentation when utilised as carbon source for photo fermentation by Rhodobacter sphaeroides O.U.001, the yield, and cumulative hydrogen was increased to 4.22 ± 0.20molmol-1 VFA and 3800 ± 170mL, respectively. Meanwhile, an overall COD removal of about 38.08% was also achieved. The overall biohydrogen yield was increased from 2.43 (dark fermentation) to 6.65 ± 0.25molmol-1 lactose. Similarly, the modelling for biohydrogen production in bioreactor was done using modified Gompertz equation and Leudeking-Piret model, which gave adequate simulated fitting with the experimental values. The carbon material balance showed that acetic acid, lactic acid, and CO2 along with microbial biomass were the main by-products of dark fermentation and comprised more than 75% of carbon consumed.

Isolation and identification of new source of bacteriocin-producing Lactobacillus plantarum C010 and growth kinetics of its batch fermentation.

The control of food-borne pathogens and spoilage organisms in meat and related products is urgently needed. Bacteriocins produced by lactic acid bacteria (LAB) are promising natural food preservatives. In this study, six bacteriocin-producing bacteria were screened from soil and fresh cow dung. Pseudomonas koreensis PS1, a specific spoilage organism from spoiled chilled pork, was used as the indicator bacteria. From the analyses, the strain C010 was selected due to its high yield, broad spectrum, and subculture stability. Through morphological, biochemical, and 16S rDNA gene sequence analysis, this strain was identified as Lactobacillus plantarum. Crude bacteriocin extracted from the cell-free supernatant (CFS) of L. plantarum C010 was stable under high temperature, ultraviolet radiation, and protease attack (pepsin, trypsin, and proteinase K). The kinetics of bacterial growth and bacteriocin production by L. plantarum C010 were analyzed during batch fermentation. Bacteriocin was produced throughout the logarithmic growth phase, and the Leudeking-Piret model characterized the synthesis of bacteriocins. The present study indicates that this novel bacteriocin produced by bacteria is a promising option for reducing spoilage microorganisms and can be widely used as a bio-preservative in meat and other foods.

Exploring the potential of biodiesel derived crude glycerol into high value malic acid: Biosynthesis, process optimization and kinetic assessment

In this study, Zygosaccharomyces rouxii, a sugar tolerant yeast culture was explored for the production of high value malic acid using crude glycerol from biodiesel plant. In addition, the effect of addition of glutamic acid (precursor) (0.25 to 1%), temperature (15 to 30 ​°C) and time (0 to 24 days) of the fermentation process was also investigated by both conventional as well as Response Surface Methodology (RSM). The highest malic acid of 72.1 ​± ​0.05 ​g/L was obtained and RSM predicts the accurate optimized conditions such as 30% crude glycerol concentration in the fermentative media with 0.75% addition of precursor with initial pH 5 ​at 20 ​°C for 20 days. This study reveals that the crude glycerol can be efficiently used and the production of malic acid was raised with 3 folds correspond to no precursor under optimal conditions. The growth and product kinetics were studied by Monod, Logistic, Leudeking Piret as well as Logistic incorporated Leudeking-Piret models with and without precursor and Logistic incorporated Leudeking-Piret model allowed the best fit for the malic acid production.

Optimization of baker`s yeast production on grape juice using response surface methodology

There is an increasing interest in improving biological processes, including fermentation processes, improving fermentation conditions is difficult, as it requires the use of an appropriate improvement method that allows operating the biological fermenter under optimal conditions in order to obtain the largest possible amount of the final product. The aim of this work was to succeed in examples of fermentation conditions to produce the largest possible quantity of dry yeast biomass Saccharomyces cerevisiae using grape juice as the sole carbon source. The optimum values of five factors that have an effect on the production of dry biomass from baker`s yeast were determined. The design of the experiments was carried out using the central composite experimental design (CCD) and the number of experiments according to the design was (54) experiments, the response surface methodology method was used to determine the best possible amount of production of yeast, and has reached (41.44 g/L) after 12 hours of fermentation, under the following optimal conditions (temperature (30.11??), pH (4.75), sugar concentration (158.36 g/L), the ratio of carbon to nitrogen (an essential nutrient for yeast growth ) is (11.9), initial concentration of yeasts (2.5 g/L), the amount of urea was 6.65 g/L and the amount of ammonium sulfate used was 6.65 g/L, so that the concentration of added urea and ammonium sulfate was (50-50)% and the required C/N ratio was achieved, and the used agitation speed was equal to 200 r.p.m during the fermentation process. The fermenter power of the obtained yeast was 470 ml. Three kinematic models (Monod, Verhulst, and Tessier) were also selected for the purpose of studying the kinetic performance of Saccharomyces cerevisiae yeast. Monod and Tessier`s models did not give satisfactory results, while the best results were according to the Verhulst model. Also, the Leudeking Piret model has also been successfully used to predict substrate consumption during fermentation time.

Optimization and modelling of dark fermentative hydrogen production from cheese whey by Enterobacter aerogenes 2822

In India, annually about 3.3–5 million tons of cheese whey is produced which may causes serious problems for the environment if left untreated. In this study, pretreated cheese whey was utilized to produce hydrogen via dark fermentation by Enterobacter aerogenes 2822 cells in 2 L double walled cylindrical bioreactor having working volume of 1.5 L. Effect of change in total carbohydrate concentration in cheese whey (CWTC, 20–45 g L−1), temperature (T, 25–37 °C) and pH (5.5–7.5) was investigated on volumetric hydrogen production rate (VHPR) using Box Behnken design (BBD). Experimental VHPR of 24.7 mL L−1 h−1 was attained at an optimum concentration of 32.5 g L−1 CWTC, 31 °C T and 6.5 pH, which was in good correlation with predicted rate of 23.2 mL L−1 h−1. Mathematical models based on Monod and logistic equations were developed to describe the kinetics of substrate consumption and growth profile of E. aerogenes 2822 under optimum conditions. While for the modelling of fermentative hydrogen production in batch mode, Modified Gompertz equation and Leudeking-Piret models were used which gave proper simulated fitting. These results will add significant values to cheese whey by converting it into a clean form of bioenergy.

Effect of yeast extract supplementation on halotolerant biosurfactant production kinetics coupled with degradation of petroleum crude oil by Acinetobacter baumannii OCB1 in marine environment

The pressing priority is to uncover environmentally secure techniques for abolition of oil spills suited to Indian marine conditions as increase in fuel consumption and demand has resulted in enhanced petroleum crude oil (PCO) transfer via sea route. Acinetobacter baumannii OCB1, isolated from petroleum refinery effluent, when grown in sea water supplemented with PCO (1.0% v/v) and glucose (1.0 g/L) yielded high degradation of C8 hydrocarbons (69.69%). On adding yeast extract (0.05 g/L) it degraded C8–C14 hydrocarbons (3.55–17.48%). Degradation was facilitated by lipopeptide biosurfactant (BS) having needle like surface as depicted by LCMS and FESEM analysis. Yield was higher in presence of yeast extract while there was no significant difference in activity. BS showed excellent stability at wide range of pH, temperature, salinity and high emulsification of petroleum-based oils. BS production modelled by Leudeking Piret model was growth associated and mixed growth associated without and with yeast extract respectively.

New insight into poly (3-hydroxybutyrate) production by Azomonas macrocytogenes isolate KC685000: large scale production, kinetic modeling, recovery and characterization.

About 24h incubation of Azomonas (A.) macrocytogenes isolate KC685000 in 14L fermenter produced 22% poly (3-hydroxybutyrate) (PHB) per cell dry weight (CDW) biopolymer using 1vvm aeration, 10% inoculum size, and initial pH of 7.2. To control the fermentation process, Logistic and Leudeking-Piret models were used to describe the cell growth and PHB production, respectively. These two models were in good agreement with the experimental data confirming the growth associated nature of PHB production. The best method for recovery of PHB was chemical digestion using sodium hypochlorite alone. The characterization of the produced polymer was carried out using FT-IR, 1HNMR spectroscopy, gel permeation chromatography and transmission electron microscope. The analysis of the nucleotide sequences of PHA synthase enzyme revealed class III identity. The putative tertiary structure of PHA synthase enzyme was analyzed using Modular Approach to Structural class prediction software, Tied Mixture Hidden Markov Model server, and Swiss model software. It was deduced that PHA synthases' structural class was multidomain protein (α/β) containing a conserved cysteine residue and lipase box as characteristic features of α/β hydrolase super family. Taken together, all the results of molecular characterization and transmission electron microscope images supported that the PHB formation was attained by the micelle model. To the best of our knowledge, this is the first report on production of growth associated PHB polymer using A. macrocytogenes isolate KC685000, and its class III PHA synthase.

Growth, substrate consumption, and product formation kinetics of Phanerochaete chrysosporium and Schizophyllum commune mixed culture under solid-state fermentation of fruit peels.

Kinetic analysis of solid-state fermentation (SSF) of fruit peels with Phanerochaete chrysosporium and Schizophyllum commune mixed culture was studied in flask and 7kg capacity reactor. Modified Monod kinetic model suggested by Haldane sufficiently described microbial growth with co-efficient of determination (R 2) reaching 0.908 at increased substrate concentration than the classical Monod model (R 2 = 0.932). Leudeking-Piret model adequately described product synthesis in non-growth-dependent manner (R 2 = 0.989), while substrate consumption by P. chrysosporium and S. commune fungal mixed culture was growth-dependent (R 2 = 0.938). Hanes-Woolf model sufficiently represented α-amylase and cellulase enzymes synthesis (R 2 = 0.911 and 0.988); α-amylase had enzyme maximum velocity (V max) of 25.19IU/gds/day and rate constant (K m) of 11.55IU/gds/day, while cellulase enzyme had V max of 3.05IU/gds/day and K m of 57.47IU/gds/day. Product yield in the reactor increased to 32.65mg/g/day compared with 28.15mg/g/day in shake flask. 2.5cm media thickness was adequate for product formation within a 6day SSF in the tray reactor.

Kinetic modeling, recovery, and molecular characterization of poly-beta-hydroxybutyrate polymer in Acinetobacter baumannii isolate P39

To control the poly-β-hydroxybutyrate (PHB) biopolymer production by Acinetobacter baumannii isolate P39 kinetic modeling of the fermentation process, polymer downstream processing, enzymological analysis, and molecular characterization of PHA synthase, key biosynthetic enzyme, should be addressed. A. baumannii isolate P39 produced 0.15g/L PHB after 24h of incubation with a polymer content of 28% per dry weight. Logistic and Leudeking-Piret models were used for describing cell growth and PHB production, respectively. They showed good agreement with the experimental data describing both cell growth and PHB production (average regression coefficient r2:0.999). The growth-associated production of PHB biopolymer as an electron acceptor was confirmed using Leudeking-Piret model and victim substrate experiment. The best method of recovery of PHB biopolymer was chemical digestion using sodium hypochlorite, since it produced the largest amount of polymer and highest molecular weight (16,000g/mole) in comparison to other recovery methods. DTNB assay showed high activity of PHA synthase enzyme, 600U activity, and 153.8U/mg specific activity. Molecular analysis of PHA synthase enzyme confirmed class III identity. Taken together, micelle model was proposed for polyhydroxybutyrate formation in A. baumannii isolate P39.

Solid state fermentation of mixed substrate for l-asparaginase production using tray and in-house designed rotary bioreactor

l-asparaginase cover a broad spectrum of industrial application like food, biosensor and chemotherapeutic drug. In the present work, l-asparaginase production was carried out using tray bioreactor and in-house designed, fabricated rotary bioreactor using previously optimized tri-substrate mixture using Aspergillus tubingensis IBBL1. l-asparaginase production by tray bioreactor was performed in temperature controlled chamber. Enzyme production was also performed in newly designed and fabricated rotary bioreactor at room temperature and effect of variables such as substrate loading, mixing events and particle size were evaluated. Maximum l-asparaginase activity of 20.58 U/gds was observed using tray bioreactor with bed height of 1 cm and by applying intermittent mixing strategy at 120 h of fermentation. In case of in-house designed rotary bioreactor, l-asparaginase activity of 19.96 U/gds was obtained with 1.5 kg substrate loading, 3 min delay time of the drum and on rotation for 30 s. These findings demonstrate that in-house designed rotary bioreactor was easy to handle, and has shown comparable results with tray bioreactor. At optimized conditions growth kinetics were studied in tray and rotary bioreactor using various growth model equations. Correlation between growth dynamics and l-asparaginase production was explained by means of Leudeking-Piret model. Results indicate that under the optimized conditions, l-asparaginase can be produced in bulk quantities.

Optimization of Baker's Yeast Production on Date Extract Using Response Surface Methodology (RSM).

This work aims to study the production of the biomass of S. cerevisiae on an optimized medium using date extract as the only carbon source in order to obtain a good yield of the biomass. The biomass production was carried out according to the central composite experimental design (CCD) as a response surface methodology using Minitab 16 software. Indeed, under optimal biomass production conditions, temperature (32.9 °C), pH (5.35) and the total reducing sugar extracted from dates (70.93 g/L), S. cerevisiae produced 40 g/L of their biomass in an Erlenmeyer after only 16 h of fermentation. The kinetic performance of the S. cerevisiae strain was investigated with three unstructured models i.e., Monod, Verhulst, and Tessier. The conformity of the experimental data fitted showed a good consistency with Monod and Tessier models with R2 = 0.945 and 0.979, respectively. An excellent adequacy was noted in the case of the Verhulst model (R2 = 0.981). The values of kinetic parameters (Ks, Xm, μm, p and q) calculated by the Excel software, confirmed that Monod and Verhulst were suitable models, in contrast, the Tessier model was inappropriately fitted with the experimental data due to the illogical value of Ks (−9.434). The profiles prediction of the biomass production with the Verhulst model, and that of the substrate consumption using Leudeking Piret model over time, demonstrated a good agreement between the simulation models and the experimental data.

Microbial Growth Kinetics in Isobutanol Production by Saccharomyces Cerevisiae

Renewable sources of fuels are important for environmental sustainability. Biofuels are produced from renewable feedstocks through biological processes and can be found in the form of liquid, gas and solid. Isobutanol, a branched chain butanol isomer, is a type of biofuel that can be produced through the fermentation of biomass using microorganisms. In an aerobic fermentation, Saccharomyces cerevisiae (yeast) produced certain amount of isobutanol as by-product during the degradation of valine through the Ehrlich pathway. In the fermentation process, the determination of growth kinetics gives a better explanation regarding the relationship between specific growth rate and the concentration of a substrate. Kinetic coefficients are useful in providing information regarding the progression of either the chemical or biological reaction occurring in a system. In this study, the microbial growth kinetics, glucose utilisation and isobutanol productivity were investigated. The growth kinetics coefficients were determined by the Monod's model while the Ledeuking-Piret's model were used in investigating the parameters involved in substrate's consumption and product's formation. The maximum specific growth rate, μmax and the substrate saturation constant, Ks were determined from the slope and interception point (a plot between 1/μ and 1/S) during 48 h of fermentation period. The value of μmax and Ks obtained were 0.74 h-1 and 57 g/L. The isobutanol yield (YP/S), biomass yield (YX/S) and the correlation between isobutanol production and yeast growth (YP/X) were found to be 4.79 mg/g, 0.1 g/g and 49.4 mg/g. The Monod's and Leudeking-Piret's models were found to be suitable to represent the experimental data of growth kinetics and product's formation kinetics in this study.

English

The growth kinetics and modeling of ethanol production from inulin by Pichia caribbica (KC977491) were studied in a batch system. Unstructured models were proposed using the logistic equation for growth, the Luedeking-Piret equation for ethanol production and modified Leudeking-Piret model for substrate consumption. Kinetic parameters (X0, μm, m, n, p and q) were determined by nonlinear regression, using Levenberg-Marquart method implemented in a Mathcad program. Since the production of ethanol was associated with P. caribbica cell growth, a good agreement between model predictions and experimental data was obtained. Indeed, significant R2 values of 0.91, 0.96, and 0.95 were observed for biomass, ethanol production and substrate consumption, respectively. Furthermore, analysis of variance (ANOVA) was also used to validate the proposed models. According to the obtained results, the predicted kinetic values and experimental data agreed well . Finally, it is possible to predict the development of P. caribbica using these models. Key words : Pichia caribbica, inulin, bioethanol, numerical simulation.

Kinetic modelling of cell growth, substrate utilization, and biosurfactant production from solid agrowaste (Beta vulgaris) by Bacillus licheniformis STK 01

AbstractThe kinetics of cell growth, substrate utilization, and biosurfactant production by Bacillus licheniformis STK 01 from a solid agrowaste substrate (Beta vulgaris) and a refined substrate (mineral salts, MS) was investigated. Data obtained were fitted to the integrated Monod equation, logistic models, and Leudeking–Piret model using nonlinear regression analyses. The maximum cell growth was observed after 72 h of fermentation for both substrates. The highest biosurfactant production was 5.8 ± 0.5 g/L when the B. vulgaris waste substrate was used, while the production increased up to 9.78 ± 1.02 g/L when MS was used. The biosurfactant produced from B. vulgaris and MS lowered the surface tension of the broth to 30 and 23.5 mN/m respectively. Furthermore, from the kinetic data analyses, cell growth and B. vulgaris utilization were described by the logistic model and modified Monod equation, respectively, with the maximum cell growth rate of 0.026 h−1, cell yield of 0.617, and the Monod saturation constant being 0.418 g/L. Similarly, biosurfactant production was best described by the logistic model while the production rate constant was 0.140 h−1. This study is applicable, among other areas, in the design of biological systems augmented with B. vulgaris waste.

GLUCONACETOBACTER HANSENİİ P2A İLE GERÇEKLEŞTİRİLEN BAKTERİYEL SELÜLOZ ÜRETİMİNİN KİNETİK MODELLENMESİ

This study involved the expression of the kinetics of bacterial cellulose production by Gluconacetobacter hansenii P2A (KUEN 1606); a strain which was originally isolated from a rotten plum. Bacterial cellulose production was realized in Hestrin Schramm medium under static and agitated cultivation conditions. The experimental data were fitted to relevant kinetic models for cell growth and cellulose production and model parameters thereof were calculated accordingly. Results proved that the growth of Gluconacetobacter hansenii P2A was best described by Monod equation for both stationary and agitated culture conditions (R21). Monod parameters max and Ks were identified as 0.081 h-1, 45.88 g.l-1 and 0.224 h-1, 22.85 g.l-1 for static and agitated conditions, respectively. For the description of product formation kinetics, Leudeking Piret model was selected according to the relatively high regression coefficients of 0.96 and 0.98, for stationary and agitated culture conditions, respectively. These constructed models of high accuracy are convenient to form the basis for the design of pilot and industrial scale production of bacterial cellulose by Gluconacetobacter hansenii P2A (KUEN 1606)

Comparative study of growth responses and screening of inter-specific OTA production kinetics by A. carbonarius isolated from grapes.

The aim of this work was to assess OchratoxinA (OTA) production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM) similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 aw). Samples for OTA determination were removed at 3, 5, 7, 9, and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50 to 2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density) have been measured and correlated with toxin production by means of principal components analysis (PCA), confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time.

Experimental Investigation of Poly-β-Hydroxybutyrate Production by Azohydromonas lata: Kinetics and Artificial Neural Network Modeling

Batch culture of Azohydromonas lata was investigated for the production of intracellular poly-β-hydroxybutyrate (PHB). In order to determine the C:N value of the culture media for maximizing the microbial productivity of PHB, different concentrations of glucose and ammonium chloride were used as carbon and nitrogen sources, respectively. The optimal temperature and shaking rate was obtained at 30°C and 180 rpm, respectively. The maximum intracellular PHB concentration obtained was 5.09 g/l, which was 20% (w/w) of the cell dry weight (CDW) after 72 h. Also, the synthesis of PHB was growth associated with the C:N ratio of 153.71. The maximum calculated Yp/s was 0.212 (gr/gr) and the specific production rate value after 12 h was 0.264 g/l/h, with 40 and 50 g/l of glucose concentrations, respectively, with 0.5 g/l ammonium chloride kept constant. The chemical composition of the resulting PHB was analyzed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The Leudeking–Piret model was used for kinetic analysis of the PHB production, the statistical analysis of which was modeled by response surface methodology. An artificial neural network technique was applied for modeling of the microbial production of PHB by A. lata as a function of the glucose concentration and CDW, where the minimum mean square error of the model was 0.0012 and 0.0038 for glucose concentrations of 50 g/l and 40 g/l, respectively, when 0.5 g/l ammonium chloride was kept constant.

Biosynthesis of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator H16 from jatropha oil as carbon source

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer that can be synthesized through bacterial fermentation. In this study, Cupriavidus necator H16 is used to synthesize PHB by using Jatropha oil as its sole carbon source. Different variables mainly jatropha oil and urea concentrations, and agitation rate were investigated to determine the optimum condition for microbial fermentation in batch culture. Based on the results, the highest cell dry weight and PHB concentrations of 20.1 and 15.5 g/L, respectively, were obtained when 20 g/L of jatropha oil was used. Ethanol was used as external stress factor and the addition of 1.5 % ethanol at 38 h had a positive effect with a high PHB yield of 0.987 g PHB/g jatropha oil. The kinetic studies for cell growth rate and PHB production were conducted and the data were fitted with Logistic and Leudeking–Piret models. The rate constants were evaluated and the theoretical values were in accordance with the experimental data obtained