• KSBB Journal
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• v.13 no.6
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• pp.730-734
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• 1998

The mathematical model of specific growth rate of Saccharomyces cerevisiae ATCC 24858 is proposed as a function of sugar and ethanol concentrations by the combination of Andrew's equation and Aiba's equation. The maximum concentration of sugar Sm, which was the highest concentration of sugar not having any effect on the growth inhibition, was 150 g/L and the substrate inhibition was expressed as a function of (S-Sm). The maximum specific growth inhibition, was 150 g/L and the substrate inhibition was expressed as a function of (S-Sm). The maximum specific growth rate ${\mu}m$, Monod's constant Ks, and Andrew's inhibition constant KI were 0.49 hr-1, 19 g/L, and 139 g/L, respectively. The maximum ethanol concentration, Pm, which did not show any inhibition effect on the specific growth rate was found to be 2 g/L. Therefore, the ethanol inhibition was represented as a function of (P-Pm). The final mathematical model for the specific growth rate of the microorganism in this work is proposed as the following. And the average percent of errors between the calculated specific growth rate and the experimental values was 5.96%.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.3
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• pp.254-261
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• 2005

The over-expression of Bcl-2 has greatly improved the culture period, specific growth rate, and maximum viable cell density of NS0 cells culture under low serum condition. Further analysis of these data suggests that a saturation model of the Monod type can be used to represent the relationships of specific growth rate and initial serum concentration. The ${\mu}_{max}$ and $K_s$ for the Bcl-2 cell line is $0.927day^{-1}\;and\;0.947\%(v/v)$ respectively, which are $21\%$ greate and $7\%$ lower respectively than its control counterpart. Study on the amino acid supplementation revealed that Bcl-2 cell lines possess greater improvement in the specific growth rate and maximum viable cell density compared to the control cell lines. A further increase in the amino acid supplementation has resulted a $17\%$ decrease in specific growth rate and no improvement in maximum viable cell density in the control culture. However, the Bcl-2 cell line exhibited a better growth characteristic in this culture condition compared to that of control cell lines. The higher specific growth rate and maximum viable cell density of the Bcl-2 cell line in medium fortified with serum and MEM EM suggested a more efficient nutrient metabolism compared to that in the control cell line. The low serum and amino acid utilisation rate and the higher cell yield may prove to be important in the development of serum/protein free culture.

• Environmental Engineering Research
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• v.20 no.4
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• pp.347-355
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• 2015

The growth kinetics of phototrophic microorganisms can be controlled by the light irradiance, the concentration of an inorganic nutrient, or both. A multi-component kinetic model is proposed and tested in novel batch experiments that allow the kinetic parameters for each factor to be estimated independently. For the cyanobacterium Synechocystis sp. PCC6803, the estimated parameters are maximum specific growth rate $({\mu}_{max})=2.8/d$, half-maximum-rate light irradiance $(K_L)=11W/m^2$, half-inhibition-rate light irradiance $(K_{L,I})=39W/m^2$, and half-maximum-rate concentration for inorganic carbon $(K_{S,Ci})=0.5mgC/L$, half-maximum-rate concentration for inorganic nitrogen $(K_{S,Ni})=1.4mgN/L$, and half-maximum-rate concentration for inorganic phosphorus $(K_{S,Pi})=0.06mgP/L$. Compared to other phototrophs having ${\mu}max$ estimates, PCC6803 is a fast-growing r-strategist relying on reaction rate. Its half-maximum-rate and half-inhibition rate values identify the ranges of light irradiance and nutrient concentrations that PCC6803 needs to achieve a high specific growth rate to be a sustainable bioenergy source. To gain the advantages of its high maximum specific growth rate, PCC6803 needs to have moderate light illumination ($7-62W/m^2$ for ${\mu}_{syn}{\geq}1/d$) and relatively high nutrient concentrations: $N_i{\geq}2.3 mgN/L$, $P_i{\geq}0.1mgP/L$, and $C_i{\geq}1.0mgC/L$.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.6
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• pp.332-338
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• 2017

The purpose of this study was to determine optimum value of aeration, acetate dosage, and $CO_2$ input for the cultivation of Scenedesmus acuminatus. Highest specific growth rate and maximum biomass productivity was obtained by the aeration of 0.72 vvm and lower specific growth rates and maximum biomass productivity were obtained for other aeration tests. When putting 0.3 M of ammonium acetate in JM medium, the highest specific growth rate and maximum biomass productivity were obtained. $CO_2$ input tests were performed during semi-continuous culturing tests. The highest specific growth rate ($0.460d^{-1}$) and maximum biomass productivity ($0.936gL^{-1}d^{-1}$) were obtained after replacing 50% of solution with 0.3 M of acetate solution for $CO_2$ input tests. However, more dilutions after the first dilution resulted in lower specific growth rate and maximum biomass productivity. In aeration tests, the highest specific growth rate ($0.381d^{-1}$) and maximum biomass productivity ($0.253gL^{-1}d^{-1}$) were obtained when cultivating it with JM medium, but the specific growth rate and maximum biomass producitivty were significantly decreased when 50% of solution was replaced by acetate containing solution.

• KSBB Journal
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• v.9 no.5
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• pp.443-449
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• 1994

Fermentation characteristics of Kluyveromyces fragilis CBS 1555 with Jerusalem artichoke juice, in extractive ethanol fermentation in aqueous two phase systems composed of polyethylene glycol 20000 (PEG) and crude dextran(Dx), were investigated as a function of initial sugar concentrations, concentrations of ethanol formed, or fermentation time. Both specific ethanol production rate increased with decrease in concentrations of PEG and Dx in two-phase systems. Without being related to the compositions of aqueous two-phase system, maximum specific cell growth rate and maximum specific ethanol production rate were showed in the initial sugar concentration fo $80g/\ell$ and $120g/\ell$, respectively. The inhibition effects of ethanol on specific cell growth rate and specific ethanol production rate decreased with decrease in PEG concentration and in the range of 2.5 to 5% Dx. Specific cell growth rate and specific ethanol production rate was fitted as an exponential function and a hyperbolic function, respectively, of the concentrations of ethanol formed. Overall ethanol productivity increased with increase in initial sugar concentrations, and also the required time for the maximum productivity was so. Ethanol production rate by the elapsed fermentation time showed the maximum value in the initial sugar concentration of $160g/\ell$.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.27-31
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• 2000

Characteristics of ethanol production by a xylose-fermenting yeast, Pichia stipitis Y-7124, were studied. The sugar consumption rate and specific growth rate were higher in the glucose-containing medium than in the xylose-containing medium. Specific activities of xylose reductase and xylitol dehydrogenase were higher in the medium with xylose than glucose, suggesting their induction by xylose. Maximum specific growth rate and ethanol yield were achieved at 30 g xylose/L concentration without formation of by-products such as xylitol and acetic acid whereas a maximum ethanol concentration was obtained at 130 g/L xylose. Adding a respiratory inhibitor, rotenone, increased a maximum ethanol concentration by $10\%$ compared with the control experiment. In order to evaluate the pattern of ethanol inhibition on specific growth rate, a kinetic model based on Luong's equations was applied. The relationship between ethanol concentration and specific growth rate was hyperbolic for glucose and parabolic for xylose. A maximum ethanol concentration at which cells did not grow was 33.6 g/L for glucose and 44.7 g/L for xylose.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.2
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• pp.91-95
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• 2009

To understand the effect of attachment substrate on the growth of benthic microalgae, we experimentally investigated the growth of benthic microalgae Nitzschia sp. (Jinhae Bay strain) with additions of glass beads in different sizes. The glass beads used in this study are 0.09-0.15 mm (G1), 0.25-0.50 mm (G2), 0.75-1.00 mm (G3) and 1.25-1.65 mm (G4). No addition of glass beads used as controls. Highest specific growth rate (0.37/day) and maximum cell density ($9,232{\pm}840$ cells/mL) of Nitzschia sp. showed at the smallest glass beads (G1), and the specific growth rate and maximum cell density were decreasing with increasing size of glass beads (specific growth rate and maximum cell density of G4 was 0.24/day and $6,397{\pm}524$ cells/mL, respectively). Moreover, specific growth rate of the control experiment (0.23/day) was significantly lower than their of G1 to G3 experiment. The results indicated that the attachment substrate for benthic microalgae as Nitzschia sp. is important factor which affecting the growth rate as well as cell density. Therefore, the physiological experiment of benthic microalgae seems to be necessary to preliminary experiment, which is addition or not of the attachment suitable substrate and the grain size for the target species of benthic microalgae.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.368-375
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• 2005

Batch cultures were carried out to optimize the exo-polysaccharide production by liquid cultures of Pleurotus ferulae. Among the various carbon sources, when $5\%$ of glucose was used, the maximum mycelial growth and exo-polysaccharide concentration reached were 8.78 g/l and 3.59 g/l, respectively. Yeast extract and polypeptone were identified as the most suitable nitrogen sources. In particular, when a mixture of $1\%$ of polypeptone and $0.8\%$ of yeast extract was used, 9.52 g/l of mycelial growth and 4.09 g/l of exo-polysaccharide were obtained. In the case of mineral sources, K$_2$HPO$_4$ and MgSO$_4$$\codt$7H$_2$0 were found to be the best mineral sources for mycelial growth and exo-polysaccharide production. Under the optimized culture conditions, the agitation speed and aeration were investigated for mycelial growth and exo­polysaccharide production in a jar fermentor. The maximum mycelial growth and exo-polysaccharide concentration at 1.5 vvm and 200 rpm obtained were 13.2 g/l and 4.95 g/l, respectively, after 10 days of culture, which were $76\%$ and $79\%$ higher than those of the basal medium. The specific growth rate was decreased with the increase of mycelial growth. However, the specific production rate of the exo-polysaccharide was proportionally increased with the specific growth rate. The proposed model profiles showed good agreement with the experimental results for the mycelial growth and exo-polysaccharide production. The specific production rate using the optimized medium was higher than that of basal medium.

• Microbiology and Biotechnology Letters
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• v.25 no.3
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• pp.235-239
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• 1997

Chlorococcum littorale has been grown in high $CO_2$ concentrations to utilize $CO_2$ gas in the polluted air. The effect of incident light intensity on the specific growth rate is expressed by a photoinhibition model, showing half- saturation constant, $K_0\;as\;8\;(W/m^2)$ and inhibition constant, Ki as 35 $(W/m^2)$. The maximum specific growth rate was also estimated as 0.095 (1/day) under this condition. This strain maintained the optimum growth rate in 20% of $CO_2$ gas but 50% of input $CO_2$ gas is the maximum concentration considering the economical efficiency. The maximum Specific $CO_2$ consumption rate, $qCO_2$ was measured as 17.48 (mg $CO_2/g$ dry wt./day) in batch cultivation, 11.2 (mg $CO_2/g$ dry wt./day) in fed-batch cultivation and 10.87 (mg $CO_2/g$ dry wt./day) at 0.065 (1/day) of dilution rate in continuous cultivation. The chemical composition of the biomass obtained from this process showed 32.5% of protein, 27.5% of lipid, 16.5% of carbohydrate and ash 11.7%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.434-439
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• 2008

The amount of salt to make seed sorting solution of the specific gravity of 1.13 was reconsidered and determined as 3.8 kg salt in 18 L water, which is lower amount than currently used. Five rice cultivars were examined. Percent germination and seedling emergence were not similar. Seedling emergence rate of Japonica varieties, Nampyungbyeo and Daerypbyeo-1 were 87% and 95% under specific gravity of 1.13, respectively. Seedling emergence rate of Tongil type variety, Dasanbyeo was as high as 67% in specific gravity of 1.06. Seedling emergence rate of waxy rice, Hwasunchalbyeo and Aranghangchalbyeo were examined. Seedling emergence rate was 94% in both cultivars in specific gravity of 1.04. Seedling emergence rate was same in specific gravity of 1.08 which is generally used for selecting seed currently. Early growth (plant height, leaf number, and dry weight) were not significantly different by specific gravity within species. In all cultivars except waxy rice, highest seedling emergence rate was observed in specific gravity of 1.13 which is currently used for selection and decreased as specific gravity is lowed. However, considering total amount of seeds in each group of specific gravity, amount of seed in lower specific gravity group is relatively small and total seedling emergence rate within variety dose not show big difference. However, if seeds with low speicific gravity are produced due to the bad grain filling condition and consequently total seed content of low specific gravity increases, results will be differnt. Reduction in total growth and yield could occur. It will be important to comply with the seed sorting criterion of 1.13 for Japonica, 1.06 for Tongil, and 1.04 for waxy rice variety to ensure the maximum rice growth and yield.