• KSBB Journal
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• v.19 no.4
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• pp.250-256
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• 2004

In this work we have cultivated several B. cereus strains in a complex LB medium in order to study the production of phospholipase C (PLC), and among them B. cereus 318 showed the highest productivity of PLC. Some components, i.e., 5 g/L glucose, 5 g/L yeast extract, 5 g/L peptone, 0.5∼1.0 g/L K$_2$HPO$_4$, 0.02∼0.04 g/L ZnSO$_4$$.$7H$_2$O and 3 g/L NaHCO$_3$ were found to be optimal for the high production of PLC by B. cereus 318. Optimal culture temperature and pH were found to be 30$^{\circ}C$ and pH 7.5 for the PLC production, respectively. Optimum reaction temperature and pH of the PLC produced by B. cereus 11 and 318 were 45$^{\circ}C$ and pH 4.0, while they were 50$^{\circ}C$ and pH 7.0 for the PLC by B. cereus 559. The PLC produced by B. cereus was activated by Mn$\^$2+/, Co$\^$2+/ and dimethyl sulfoxide (DMSO), but its activity was inhibited by Cu$\^$2+/ and partially by glycerol, isopropanol and sodium dodecyl sulfate (SDS).

• Applied Biological Chemistry
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• v.32 no.4
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• pp.424-434
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• 1989

The rationale for the use of fungi in treating waste streams from food processing plants I~as been that of incorporating the dissolved and suspending nutrients into a macroscopic organism which can be filtered out readily. In order for a process using fungi to meet these objectives we examined a strain of fungi, Aspergillus fumigatus, which grew well on a variety of polysaccharide-containing materials and showed both efficient BOD removal and high quality protein recovery. In this experiment the fungal choice was based on the laboratory screening studies where the criteria used was BOD and COD reduction, growth response, mycelial yield, and the ability to compete with the natural flora. In the fermentation system used far the continuous culture of Aspergillus fumigatus the best combination of operating variables, inoculum ratio, temperature, initial pH, fermentation time and agitation rate was 5%(v/v), $35{\sim}40^{circ}C,\;pH\;4.5{\sim}5.0$, 2days and 150rpm, respectively. The fungus reduced BOD and COD to 94.0 and 90.4%, respectively and 3.15g of dry mycelium per liter of alcohol waste was harvested during 48hr of incubation time. The protein efficiency ratios for the control diet and the experimental diet containing the fungal protein were $3.42{\pm}0.15$ and $3.40{\pm}0.43$, respectively.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.172-176
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• 1996

Effect of culture conditions such as pH, temperature, agitation speed and oxygen transfer rate on xylitol production from xylose by Candide parapsilosis ATCC 21019 mutant was investigated in a jar fermentor. The initial concentration of xylosr was fixed at 50 g/l in this experiment. When pH was increased, cell growth and xylose consumption rate were increased, but maximum xylitol production was shown in the range of pH 4.5 and 5.5 with a yield of 0.68 g/g-xylose. The optimal temperature for xylitol production was determined to be $30^{\circ}C$. Considering the importance of dissolved oxygen tension, for xylitol production, the effect of oxygen transfer rate coefficient $(k_La)$ on fermentation parameters was carefully evaluated in the range of $20{\sim}85\;hr{-1}\;of\;k_La$ (corresponding to $100{\sim}300$rpm of agitation speed). The xylitol production was maximized at $30\;hr^{-1}\;of\;k_La$(150 rpm). A higher oxygen transfer rate supported better cell growth with lower xylitol yield. It was determined that maximum xylitol concentration, xylitol yield and productivity was 35.8 g/l, 71.6% and $0.58\;g/l{\sim}hr^{-1}$, respectively, at $30\;hr^{-1}\;of\;k_La$ In order to further increase xylitol productivity, ferementation using the concentrated biomass(20 g/l) was carried out at the conditions of pH 4.5, $30^{\circ}C$ and $30\;hr\;1$ of oxygen transfer rate. The final xylitol concentration of 40 g/l was obtained at 18 hours of culture time. From this result, it was calculated that xylitol yield was 80ft on the basis of xylose consumption and volumetric productivity was $2.22\;g/l{\sim}hr$ which was increased by $3{\sim}4$ fold compared with $0.5{\sim}0.7\;g/l-hr$ obtained in a normal fermentation condition.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.53-56
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• 2000

Two-stage fed-batch culture was peformed to improve the volumetric productivity of erythritol. In the growth phase dissolved oxygen was maintained to 20% and the feed medium was automatically supplied to the fermenter by pH-stat mode. The cell yield was 0.76 g-cell/g-glucose. In two-stage fed-batch culture, 41% of total erythritol conversion yield with 187 g/L of erythritol concentration and 2.79 g/L-h of maximum erythritol Productivity were obtained when 400 g/L of glucose was directly added in the form of non-sterile powder at production phase. The erythritol productivity increased in parallel with cell mass. The metabolic shift in the biosynthetic pathway of erythritol was caused by dissolved oxygen concentration. The production of gluconic acid was observed when the dissolved oxygen in the medium was maintained over 40% during the production phase, whereas the dissolved oxygen concentration lower than 40% caused the production of citric acid. But the butyric acid was produced independently with dissolved oxygen concentration in the medium. The production of organic acids such as gluconic acid, citric acid, and butyric acid was decreased by addition of mineral salts.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.6
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• pp.833-838
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• 2013

In this study, twelve strains of brewing fungi were individually cultivated on wheat extract broth (WEB), potato dextrose broth (PDB) and malt extract broth (MEB) in order to determine the microorganism with good culture characteristics as well as with amylolytic activity. The strain cultured in PDB exhibited mycelia production from 12.6 g/L (Rhizopus oryzae KACC 45714) to a maximum of 48.0 g/L (Aspergillus oryzae KACC 46959), which was 2.3~9.2 times lower than that of the strain cultured in WEB and 1.7~14.6 times lower than that of the strain cultured in MEB. Accorfing the results, We found that the commercial strains of A. oryzae Suwon, CF1001 and CF1003 had a higher dry cell mass than the wild-type strains KACC 46421, 46423, 46424 and 46959. For Rhizopus sp., the acidity levels in WEB, PDB and MEB were 0.12~0.47%, 0.22~1.0% and 0.16~0.68% (equivalent lactic acid concentration) respectively. For A. oryzae, the acidity levels were 0.06~0.11%, 0.03~0.04% and 0.06~0.08% (equivalent lactic acid concentration), respectively. Amylase enzyme from Rhizopus delemar KACC 46419 exhibited an enzyme activity of 0.013 U and 0.019 U in WEB and MEB cultures, respectively. The enzyme activity of the amylase enzyme from A. oryzae was 0.019~0.037, 0.017~0.033 and 0.028~0.046 U in WEB, PDB and MEB cultures, respectively.

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.281-285
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• 2015

An oleaginous fungus was isolated from soil and identified as Mortierella sp. (M-12) for producing arachidonic acid (AA). Cell disruption methods, extraction methods, and particle sizes of freeze-dried biomass were tested to achieve maximum extraction of total lipids and AA. M-12 grown in glucose yeast media at $25^{\circ}C$ for 7 days contained 35.5% total lipid, and 47% of the total lipid was AA. Lipid extraction yield from wet biomass was shown to be similar to that in a dry state. Maximum lipid extraction was achieved using a mixture of chloroform and methanol (2:1) as an extraction solvent. Different mechanical cell disruption methods did not affect lipid extraction yields. The smaller the particle size of the biomass, the better the lipid extraction yield was observed. Particle size of biomass was shown to more strongly affect lipid extraction than extraction time. The highest AA content was observed in the class of neutral lipids.

• KSBB Journal
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• v.23 no.6
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• pp.463-469
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• 2008

During the last decade, monacolin-K biosynthesized by fermentation of red yeast rice (Monascus strains) was proved to have an efficient cholesterol lowering capability, leading to rapid increase in the market demand for the functional red yeast rice. In this study, the production medium composition and components were optimized on a shake flask scale for monacolin-K production by Monascus pilosus (KCCM 60160). The effect of three different soybean flours on the monacolin-K production were studied in order to replace the nitrogen sources of basic production medium (yeast extract, malt extract and beef extract). Among the several experiments, the production medium with dietary soybean flour to replace a half of yeast extract was very good for monacolin-K production. Plackett-Burman experimental design was used to determine the key factors which are critical to produce the biological products in the fermentation. According to the result of Plackett-Burman experimental design, a second order response surface design was applied using yeast extract, beef extract and $(NH_4)_2SO_4$ as factors. Applying this model, the optimum concentration of the three variables was obtained. The maximum monacolin-K production (369.6 mg/L) predicted by model agrees well with the experimental value (418 mg/L) obtained from the experimental verification at the optimal medium. The yield of monacolin-K was increased by 67% as compared to that obtained with basic production medium in shake flasks.

• KSBB Journal
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• v.9 no.2
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• pp.91-97
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• 1994

In this study, Pullulan Production from whey medium by Aureohsidium pullulans was investigated. When the Pullulan production from whey medium was carried outs final cell concentration was similar to sucrose basal medium but Pullulan concentration was less than 5g/$\ell$. For pullulan production from whey medium, adaptation culture technique was tried on lactose and galactose base medium When the adaptation culture technique was not applied, the maximum concentration of pullulan was 3.4g/$\ell$ for lactose, 2.5g/$\ell$ for galactose. Adapted strains produced 10~12g/$\ell$ from lactose, 10~11g/$\ell$ from galactose. The pullulan production from lactose basal medium was 13.5g/$\ell$ for lactose adapted strains and 18.6g/$\ell$ for galactose adapted strains. When the adapted strains were inoculated on whey medium, maximum pullulan production was obtained at initial pH 3.0.

• Journal of Life Science
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• v.21 no.8
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• pp.1083-1093
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• 2011

A microorganism utilizing rice hulls as a substrate for the production of carboxymethylcellulase (CMCase) was isolated from seawater and identified as Bacillus lincheniformis by analyses of its 16S rDNA sequences. The optimal carbon and nitrogen sources for production of CMCase were found to be rice hulls and ammonium nitrate. The optimal conditions for cell growth and the production of CMCase by B. lincheniformis LBH-52 were investigated using the response surface method (RSM). The analysis of variance (ANOVA) of results from central composite design (CCD) indicated that a highly significant factor ("probe>F" less than 0.0001) for cell growth was rice hulls, whereas those for production of CMCase were rice hulls and initial pH of the medium. The optimal conditions of rice hulls, ammonium nitrate, initial pH, and temperature for cell growth extracted by Design Expert Software were 48.7 g/l, 1.8 g/l, 6.6, and 35.7$^{\circ}C$, respectively, whereas those for the production of CMCase were 43.2 g/l, 1.1 g/l, 6.8, and 35.7$^{\circ}C$. The maximal production of CMCase by B. lincheniformis LBH-52 from rice hulls under optimized conditions was 79.6 U/ml in a 7 l bioreactor. In this study, rice hulls and ammonium nitrate were developed to be substrates for the production of CMCase by a newly isolated marine microorganism, and the time for production of CMCase was reduced to 3 days using a bacterial strain with submerged fermentation.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.619-623
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• 1991

To investigate nisin production and resistance of Lactococcus lactis ssp. tactis ML (L. lactis $ML_8$, effects of medium, pH of culture broth, and cell growth on the nisin activity, and effect of nisin with or without $Ca^[2+}$ ion on the growth of L. lactzs were analyzed. In the bio-assay of nisin by the agar diffusion method, inhibition-zone diameter of Micrococcus Javus was propotional to the logarithm of nisin concentration ranged 0.5~20 unitlml (12.5~500 ng/mf). Nisin activity of the pasteurized culture filtrates of L. lactis MLs was high at pH 2!3 but was inactivated completely at pH over 6.0. Nisin production of the L. lactis $ML_8$ cultured on LTB broth increased at late logarithmic phase and reached 10.5 unitlml after 16 hr. The cell growth of L. lactis LM 0230, a plasmid free and nisin sensitive strain, was inhibited on agar medium containing 7 unitlrnl of nisin, while L. lactis $ML_8$ showed high survival ability at 20 unitld of nisin. When 40 mM $Ca^[2+}$ ion was added to Elliker broth with 8 unitlml of nisin, the growth pattern of L. lactis $ML_8$ was similiar to that on control medium which did not contain nisin and $Ca^[2+}$ ion, and this suggested that $Ca^[2+}$ increased the nisin resistance of the L. lactis.