• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.3
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• pp.161-166
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• 2001

The influence of the consumed carbon to nitrogen (C/N) ratio on mycelial morphology was investigated in cultures of Mortierella alpina using shake flasks. The consumed C/N ratio was varied from 5 to 32 under the condition that the total initial amount of the carbon and nitrogen sources was 50g/L. The whole mycelia and filamentous mycelia exhibited no relationship with the consumed C/N ratio below a consumed C/N ratio of 20 in the presence of either excess carbon or excess nitrogen. However, when the consumed C/N ratio increased higher than 20, the mycelial sizes increased in proportion to the consumed C/N ratio. However, the area ratio of filamentous mycelia to total mycelia was found to be independent of the consumed C/N ratio, and remained constant at 0.82. In the case of a fixed consumed C/N ratio of 20, the whole mycelia and filamentous mycelia increased in proportion to the degree of the medium strength, yet the area ratio of filamentous mycelia to total mycelia remained unchanged at 0.76. Accordingly, these results show that fungal morphology and mycelial size are both affected by the ratio of carbon to nitrogen. The findings of the current study will be helpful in obtaining the efficient production of useful bioproducts from fungal cultures.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.237-242
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• 2004

Cell growth and the production of pullulan by Aureobasidium pullulan HP-2001, the UV-induced mutant of A pullulans ATCC 42023, increased with increased concentration of glucose up to 15.0% (w/v). Maximal production of pullulan in the flask scale was 27.65 g/l, when concentrations of glucose and yeast extract were 15.0 and 0.25% (w/v), respectively. Maximal conversion rate of pullulan from glucose as the carbon source was 0.37, when those of glucose and yeast extract were 5.0 and 0.15% (w/v), respectively. On the basis of total amount of pullulan, the conversion rate of pullulan from glucose, and utilization rate of glucose to cell mass and pullulan by A. pullulans HP-2001, the optimal concentrations of glucose and yeast extract for the mass production of pullulan were determined to be 10.0 and 0.25% (w/v), respectively, at which concentrations the production of pullulan and its conversion rate were 27.14 g/l and 0.27, respectively. Maximal production of pullulan with optimized concentrations of carbon and nitrogen sources by A. pullulans HP-200l in a 7-1 bioreactor was 32.12 g/l for 72 h culture, and that in a 100-1 bioreactor with the inner pressure of $0.4 kgf/cm^2$ was 36.87 g/l. Increased inner pressure of a 100-1 bioreactor resulted in a higher concentration of dissolved oxygen in the medium, which might enhance the production of pullulan by A. pullulans HP-2001.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.261-267
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• 2010

We describe culture conditions for a high-efficiency in vitro regeneration system of Papaver nudicaule through somatic embryogenesis and secondary somatic embryogenesis. The embryogenic callus induction rate was highest when petiole explants were cultured on Murashige and Skoog (MS) medium containing 1.0 mg $1^{-1}$ ${\alpha}$-naphthaleneacetic acid (NAA) and 0.1 mg $1^{-1}$ 6-benzyladenine (BA) (36.7%). When transferred to plant growth regulator (PGR)-free medium, 430 somatic embryos formed asynchronously from 90 mg of embryogenic callus in each 100-ml flask. Early-stage somatic embryos were transferred to MS medium containing 1.0 mg $1^{-1}$ BA and 1.0 mg $1^{-1}$ NAA to germinate at high frequency (97.6%). One-third-strength MS medium with 1.0% sucrose and 1.0 mg $1^{-1}$ $GA_3$ had the highest frequency of plantlet conversion from somatic embryos (91.2%). Over 90% of regenerated plantlets were successfully acclimated in the greenhouse. Secondary somatic embryos were frequently induced directly when the excised hypocotyls of the primary somatic embryos were cultured on MS medium without PGRs. Sucrose concentration significantly affected the induction of secondary embryos. The highest induction rate (89.5) and number of secondary somatic embryos per explant (9.3) were obtained by 1% sucrose. Most secondary embryos (87.2-94.3%) developed into the cotyledonary stage on induction medium. All cotyledonary secondary embryos were converted into plantlets both in liquid and on semisolid 1/3-strength MS medium with 1.0% sucrose.

• Journal of Animal Science and Technology
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• v.51 no.6
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• pp.527-536
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• 2009

A potent protein degrading bacterium was isolated from soil samples of different environments. Polyphasic taxonomic studies and phylogenetic 16S rRNA sequence analyses led to identify the isolate IB No. 11 as a strain of Bacillus subtilis. The isolated strain was recognized to produce protease constitutively, and the maximum production (1.64 units/ml) was attained in a shake flask culture when the isolate was grown at $40^{\circ}C$, for 32 h in basal medium supplemented with starch (0.25%) and gelatin (1.25%) as sole carbon and nitrogen source, respectively. The optimum pH and temperature for the protease activity were determined to be pH 7.0 and $50^{\circ}C$, respectively. $Ca^{2+}$ and $Mn^{2+}$ enhanced remarkably the protease activity but neither showed positive effect on the protease's thermal stability. In addition, it was observed that the protease was fairly stable in the pH range of 6.5-8.0 and at temperatures below $50^{\circ}C$, and it could be a good candidate for an animal feed additive. The inhibition profile of the protease by various inhibitors indicated that the enzyme is a member of serine-proteases. A combination of UV irradiation and NTG mutagenesis allowed to develop a protease hyper-producing mutant strain coded as IB No. 11-4. This mutant strain produced approximately 3.23-fold higher protease activity (6.74 units/mg) than the parent strain IB No. 11 when grown at $40^{\circ}C$ for 32h in the production medium. The protease production profile of the selected mutants was also confirmed by the zymography analysis.

• Journal of Life Science
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• v.6 no.2
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• pp.135-141
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• 1996

Possible yeast strains that could be used as feed for aquaculture were studied. It was shown that the maximum specific growth rate and the biomass yield of Kluyveromyces fragilis yeast and Candida utilis yeast under optimum pH and temperature were much higher than those of Saccharomyces cervisiae yeast which had been as established yeast diet for rotifer culture. Hence, this work was focussed on the growth characteristics of the two yeasts through flask dultures for mass production. With 5% inoculum dosage, the best values of $\mu$$_{max}$ and OD$_{max}$ were obtained with on 2.5% fructose medium and 2% YE medium for K. fragilis and C. utilis, respectively, where the values of $\mu$$_{max}$ and OD$_{max}$ were found to be 0.73 hr$^{-1}$ and 3.00 for K. fragilis and 0.59 hr$^{-1}$ and 2.80 for C. utilis. It was also found that the lag phase of the growth incresed with increasing initial zinc and NaCl concentrations and decreased with increasing inoculum dosage. Both yeasts could survive relatively well at 3.5% NaCl concentration, and only C. utilis yeast could utilize zinc.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.434-439
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• 1995

Chinese radish juice(CRJ) was used as a culture medium for the production of Candida utilis ATCC 42416 biomass. Soluble solid and total sugar contents of Chinese radishes were in the range between 5.5 and $8.8^{\circ}$Brix and 3.5 and 6.5%, respectively. Since sugar in radishes are in readily usable forms, pretreatm ent procedures were not necessary after the extraction of juice from fresh radishes. In shake flask experimetns, C. utilis ATCC 42416 grew well in CRJ and completed growth in 24 hrs at $30^{\circ}C$ and 200 rpm. Maximum cell dry weight obtainable from a liter of CRJ(1.0% sugar $DCRJ{\times}5$) was 21.5g, when the yeast was grown on CRJ diluted 5 times or more with tap water to make sugar content to be eual to or less than 1.0%. Supplementation of 5-fold diluted CRJ with some nutrients did not greatly influence the growth rate, yeast biomass production, or cell protein content significantly, indicating that CRJ itself was a good substrate for the production of biomass by C. utilis ATCC 42416.

• KSBB Journal
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• v.13 no.2
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• pp.214-219
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• 1998

Polymerase chain reaction(PCR) was conducted to obtain the gene encoding glucose oxidase(GOD) from Aspergillus niger(ATCC 2110) and the DNA sequence determined was coincided with published GOD sequence from A. niger. Recombinant transforming vector containing GOD and hygromycin B(hyg.B) resistant gene(hph) was constructed and used for further transformation of A. niger ATCC 2110. Selectivity of hyg.B against A. niger differed depending on which media were used i.e., nutrient-rich media such as potato dextrose agar(PDA) and complete medium(CM) showed only 50% growth inhibition at 400 $\mu$m ml$^-1$ of hyg.B while the minimal media inhibited mycelial growth completely at 200 $\mu$m ml$^-1$ of hyg.B. Twenty to sixty putative transformants were isolated from the hyg.B-containing minimal top agar, transferred successively onto alternating selective and nonselective media for a mitotic stability of hyg.B resistance and, then, single-spored. Among the stable transformants, the transformant(GOD1-6) grown by flask culture showed the considerable increase of extracellular GOD activity, which was estimated to the degree of 50% - 100% comparing to that of wild type. Transformation of tGOD1-6 was resulted from integration of the vectors into heterologous as well as homologous regions of the A. niger genome. Southern blot analysis revealed that there were two independent integrations of vector into fungal genome and one into the GOD gene due to homologous recombination. In addition, GOD activity and sodium gluconate production when tGOD1-6 was fed-batch fermented were enhanced 11 fold and 2.25 fold, respectively, compared to that of the wild type.

• KSBB Journal
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• v.9 no.4
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• pp.428-435
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• 1994

Cell growth and production of ${\alpha}$-amylase, acetic acid and lactic acid were investigated in Bacillus amyloliquefaciens(ATCC 23350) flask culture with various carbon sources. Maximum dry cell density increased with increase in initial maltose concentration. Maximum dry cell density was the highest(1.4g/$\ell$) at 10g/$\ell$ of initial glucose concentration. With 10g/$\ell$ of initial glucose concentration, maximum specific cell growth rate was obtained. Among the various carbon sources maximum ${\alpha}$-amylase production was obtained with 149 unit/ml at 20g/$\ell$ of initial maltose concentration. With 5g/$\ell$ of initial maltose concentration, maximum ${\alpha}$-amylase production rate was obtained. By increasing carbon source concentration, acetic acid formation decreased. Acetic acid formation was higher in glucose than in maltose. By increasing carbon source concentration, lactic acid formation increased. Lactic acid formation was higher in maltose than in glucose.

• KSBB Journal
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• v.15 no.1
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• pp.27-34
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• 2000

A marine bacterium having a high oil-degrading activity was isolated form the oil-polluted southern sea of Korea, and was identified as Pseudomonas aeruginosa and was named Pseudomonas aeruginosa BYK-2. The optimal tmeperatur, culture time, pH and NaCl concentration for biosurfactant production and cell growth showed $25^{\circ}C$, 48h, 7.0 and 0%(w/v), respectively. After cultivation at $25^{\circ}C$, 180 rpm in 250 mL erlenmeyer flask for 7days, 1%(w/v) arabian light crude oil and bunker C oil which are considered to be hardly degradable compounds were degraded 92.1%(w/w) and 76%(w/w) respectively. And then, cell adherence was measured on various carbon sources. The cell adherence indicated over 80% on hydrocarbons(arabian light crude oil, kuwait curde oil, bunker C oil, n-paraffine, n-hexadecane, n-tetradecane) as carbon sources. Lecithin among fatty acids(oleic acid, olive oil, lecithin) showed highest cell adherence of 91.5%. The cell adherence of sugars(arabinose, trehalose, dextrose, galactose, lactose, fructose, maltose, sorbitol, sucrose) observed to be less than 70% except for arabinose, galactose, sorbitol and sucrose.

• Microbiology and Biotechnology Letters
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• v.32 no.2
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• pp.123-127
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• 2004

Pseudomonas sp. MBEL21 was newly isolated from soil samples and found to accumulate medium-chain-length Polyhydroxyalkanoates(MCL-PHAs) using oleic acid as a sole carbon source. Among the various nutrient limiting conditions examined, including nitrogen, sulfur and phosphorus, only phosphorus limitation supported the accumulation of MCL-PHAs up to 15 wt％ of dry cell weight in flask cultures. MCL-PHAs produced by Pseudomonas sp. MBEL21 was mainly composed of 3-hydroxy-5-cis-tetradecenoate. Fed-batch culture of Pseudomonas sp. MBEL21 by novel feeding strategies based on cell growth charcteristics was carried out under phosphorus limitation using oleic acid as a sole carbon source. The final cell concentration and PHA content of 82 g/L and 28 wt％, respectively, were obtained. Furthermore, PHA consisted of MCL-hydroxyalkanoates and 3-hydroxybutyrate could be produced using olive oil as a sole carbon source.