• Journal of Mushroom
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• v.6 no.1
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• pp.27-31
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• 2008

The optimization of submerged culture conditions for mycelial growth and exopolysaccharide (EPS) production in an edible mushroom Tremella fuciformis were studied in shake flasks and bioreactors. The temperature of $28^{\circ}C$ and pH 8 in the beginning of fermentation in agitated flasks was the most efficient condition to obtain maximum mycelial biomass and EPS. The optimal medium constituents were as follows (g l-1): glucose 20, tryptone 2, $KH_2PO_4$ 0.46, $K_2HPO_4$ 1 and $MgSO_4H_2O$ 0.5. The fungus was cultivated under various agitation and aeration conditions in a 5L stirred-tank bioreactor. The maximum cell mass and EPS production were obtained at a relatively high agitation speed of 200 rpm and at an aeration rate of 2 vvm. The flow behavior of the fermentation broth was Newtonian and the maximum apparent viscosity (35 cP) was observed at a highly aerated condition (2 vvm). The EPS productivity in an airlift reactor was higher than that in the stirred-tank reactor. The EPS was protein-bound polysaccharides consisted of mainly mannose, xylose, and fructose. The molecular weights of EPS were determined to be $1.3{\sim}1.5{\times}10^6$.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.236-242
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• 2010

The objective of this study was to investigate the potential of the application of kimchi LAB as starter culture in the production of fermented sausages. For this, the solid-state model media composed to simulate the substantial conditions of meat mixtures were fermented for 120 h after the treatment with different concentrations of kimchi (0.5, 1.0, 1.5, 3.0, and 5.0%) and lyophilized kimchi-powder (0.2 % and 0.5%). During the fermentation period, the growth of total viable cells and LAB, and the changes of pH and titratable acidity were investigated. The initial LAB counts ranged from 7.18 to 8.34 Log CFU/ mL for kimchi media and from 6.93 to 6.94 Log CFU/mL for kimchi-powder media depending on the added concentrations. The kimchi LAB in this study were not influenced by the immobilized condition for their adaptation and growth by showing no lag phase and thus acted similar as in the submerged medium. The initially increased counts reached around 9 Log CFU/ mL in 12 h independent of the concentrations of a ded kimchi. However, the growth and metabolic activity of kimchi-powder LAB were influenced by the immobilized condition. Supposedly, as the nutrient supply in solid-state depended solely on diffusion, these differences in the souring properties were caused by the LAB topography in the medium matrix. Nevertheless, the differences in the numbers of LAB between two media were less than 0.5 Log units and the pH drop in the solidstate batches was quite rapid and reached low values. Therefore, it can be assumed that kimchi and kimchi-powder LAB showed the utility as the substitute of commercial starter culture even without a rehydrating pretreatment.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.140-146
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• 1991

Mutation experiments were performed to select the mutant of Aspergillus niger 55, which had lost almost all the ability to produce transglucosidases but retained that of high productivity of raw meal saccharifying enzyme, by means of successive induction with N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), ultraviolet(UV) light, and ${\gamma}$-rays. Also, we used the mutant enrichment techniques, such as liquid culture-filtration procedure and differential heat sensitivity of conidia, in order to increase the possibility of obtaining a mutant. The glucoamylase productivity of mutant PFST-38 was 11 times higher than that of the parent strain. The mutant PFST-38 was morphologically identical to the parent strain, except for the size of conidia, the tendency to form conidia and the lenght of conidiophore. Asp. niger mutant PFST-38 apeared to be useful for the submerged production of the raw corn meal saccharifying enzyme.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.111-118
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• 1996

For the screening and the development of the new bio-material, cultural conditions for the exo-biopolymer (EBP) production throught the submerged cultivation of Ganoderma lucidum mycelium were investigated. Also, the fractionations and the purifications of the exo-biopolymer were carried out and the chemical compositions of the exo-biopolymer were examined. The optimal culture conditions for the exo-biopolymer production were pH 5.0, 30$^{\circ}C$ and 100 rpm of agitation speed in the medium containing of 5% (w/v) glucose, 0.5%(w/v) yeast extract, 0.1% (w/v) ($(NH_4)_2HPO_4$, and 0.05% (w/v) $KH_2PO_4$. In the flask cultivation for 7 days under these conditions, the concentration of the maximum exo-biopolymer and the cell mass were 15.4g/l and 18.8g/l, respectively. The specific growth rate was 0.039 $hr^{-1}$. In addition, the substrate consumption rate, and the exo-biopolymer production rate were 0.043$gg^{-1}$$hr^{-1}$ and 0.025$gg^{-1}$$hr^{-1}$, respectively. The exo-biopolymer was fractionated into BWS (water soluble exo-biopolymer) and BWI (water insoluble exo-biopolymer) by the water extraction, and the sugar contents of two fractions were higher than 97% (based on dry basis). The components sugar of BWS and BWI fractions were glucose, galactose, mannose, xylose, and fucose. Their molar ratios were 3.6:1.5:2.1:0.5: trace and 2.9:3.1:2.0:1.6:0.3, respectively.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.15-20
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• 2005

The unstructured model was tested to describe mycelial growth, exopolysaccharide formation, and substrate consumption in submerged mycelial culture of Paeeiliomyees tenuipes C240. The Logistic equation for mycelial growth, the Luedeking-Piret equation for exopolysaccharide formation, and Luedeking­Piret-like equations for glucose consumptions were successfully incorporated into the model. The value of the key kinetic constants were: maximum specific growth rate ${\mu}m,\;0.7281\;h^{-1};$ growth­associated constant for exopolysaccharide production $(\alpha),\;0.1743g(g\;cells)^{-1}$; non-growth associated constant for exopolysaccharide production $(\beta),\;0.0019g(g\;cells)^{-1}\;;$ maintenance coefficient $(m_s),\;0.0572g\;(g\;cells)^{-1}$. When compared with batch experimental data, the model successfully provided a reasonable description for each parameter during the entire growth phase. The model showed that the production of exopolysaccharide in P. tenuipes C240 was growth-associated. The model tested in the present study can be applied to the design, scale-up, and control of fermentation process for other kinds of basidiomycetes or ascomycetes.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.869-873
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• 2011

Most medium formulations for improving culture of entomopathogenic nematodes (EPN) based on protein sources have used enriched media like animal feed such as dried egg yolk, lactalbumin, and liver extract, among other ingredients. Most results, however, showed unstable yields and longer production time. Many of the results do not show the detailed parameters of fermentation. Soy flour, cotton seed flour, corn gluten meal, casein powder, soytone, peptone, casein hydrolysates, and lactalbumin hydrolysate as protein sources were tested to determine the source to support optimal symbiotic bacteria and nematode growth. The protein hydrolysates selected did not improve bacterial cell mass compared with the yeast extract control, but soy flour was the best, showing 75.1% recovery and producing more bacterial cell number ($1.4{\times}10^9$/ml) than all other sources. The highest yield ($1.85{\times}10^5$ IJs/ml), yield coefficient ($1.67{\times}10^6$ IJs/g medium), and productivity ($1.32{\times}10^7$ IJs/l/day) were also achieved at enriched medium with soybean protein.

• Mycobiology
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• v.34 no.1
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• pp.22-29
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• 2006

Forty-one fungal species belonging to 15 fungal genera isolated from Egyptian soil and sugar cane waste samples were tested for their capacity of producing acidity and gluconic acid. For the tests, the fungi were grown on glucose substrate and culture filtrates were examined using paper chromatography analysis. Most of the tested fungi have a relative wide potentiality for total acid production in their filtrates. Nearly 51% of them showed their ability of producing gluconic acid. Aspergillus niger was distinguishable from other species by its capacity to produce substantial amounts of gluconic acid when it was cultivated on a selective medium. The optimized cultural conditions for gluconic acid yields were using submerged culture at $30^{\circ}C$ at initial pH 6.0 for 7 days of incubation. Among the various concentrations of substrate used, glucose (14%, w/v) was found to be the most suitable carbon source for maximal gluconic acid during fermentation. Maximum values of fungal biomass (10.02 g/l) and gluconic acid (58.46 g/l) were obtained when the fungus was grown with 1% peptone as sole nitrogen source. Influence of the concentration of some inorganic salts as well as the rate of aeration on the gluconic acid and biomass production is also described.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1534-1538
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• 2010

Fed-batch cultures of Hansenula polymorpha were studied to develop an efficient biosystem to produce recombinant human serum albumin (HSA). To comply with this purpose, we used a high-purity oxygen-supplying strategy to increase the viable cell density in a bioreactor and enhance the production of target protein. A mutant strain, H. polymorpha GOT7, was utilized in this study as a host strain in both 5-l and 30-l scale fermentors. To supply high-purity oxygen into a bioreactor, nearly 100% high-purity oxygen from a commercial bomb or higher than 93% oxygen available in situ from a pressure swing adsorption (PSA) oxygen generator was employed. Under the optimal fermentation of H. polymorpha with highpurity oxygen, the final cell densities and produced HSA concentrations were 24.6 g/l and 5.1 g/l in the 5-l fermentor, and 24.8 g/l and 4.5 g/l in the 30-l fermentor, respectively. These were about 2-10 times higher than those obtained in air-based fed-batch fermentations. The discrepancies between the 5-l and 30-l fermentors with air supply were presumably due to the higher contribution of surface aeration over submerged aeration in the 5-l fermentor. This study, therefore, proved the positive effect of high-purity oxygen in enhancing viable cell density as well as target recombinant protein production in microbial fermentations.

• Food Science and Preservation
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• v.12 no.6
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• pp.583-590
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• 2005

Dough fermentation characteristics and quality characteristics of bread added with different concentration(0, 30, 40 and $50\%$ against water) of submerged-culture broth of Fomitopsis pinicola mycelium (CM) were investigated There were positive correlations between CM concentration and dough pH(r=0.98), acidity(r=-0.88), dough thickness(r=0.95) and dough strength(r=0.95). Baking loss rate was decreased with increasing of CM concentration. There was no significant difference between loaf volume index and CM concentration ($30\~40\%$, but the index of CM $50\%$ bread was lower than that of control. L* value of top crust in the CM $50\%$ bread was significantly lower than those of CM $0\~40\%$ bread, while the value of internal tissue was increased with increasing of CM concentration. In the CM $30\~40\%$ bread, hardness was lower, but there were no significant difference in cohesiveness, springiness, chewiness and brittleness compared with control. Appearance, color, taste, texture and overall acceptability of CM $30\~40\%$ bread were similar to those of control. In the results estimated by correlation analysis, the increased pH of the dough by adding CM allowed lowering hardness of the bread By adding CM in bread, retrogradations were delayed, and growth of mold was decreased during storage. In conclusion, the optimum concentration of CM in bread which showed anti-diabetic effect as well as not dropped quality characteristics were $30\~40\%$.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3104-3104
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• 2001

The research described here was undertaken with the aim of monitoring, optimizing and ultimately controlling the production of heterofermentative microbes used as starters in the salami industry. The use of starter cultures in the fermented meats industry is a well-established technique used to shorten and standardize the ripening process, and to improve and control the organoleptic quality of the final product. Starter cultures are obtained by the submerged cultivation of suitable microorganisms in stirred, and sometimes aerated, fermenters where monitoring of key physiological parameters such as the concentration of biomass, substrates and metabolites suffers from the general lack of real-time measurement techniques applicable to aseptic processes. In this respect, the results of the present work are relevant to all submerged fermentation processes. Previous work on the application of on-line NIR spectroscopy to the lactic acid fermentation (Dosi et al. - Monreal NIR1995) had successfully used a system based on a measuring cell included in a circulation loop external to the fermenter. The fluid handling and sterility problems inherent in an external circulation system prompted us to explore the use of an in-line system where the NIR probe is immersed in the culture and is thus exposed to the hydrodynamic conditions of the stirred and aerated fluid. Aeration was expected to be a potential source of problems in view of the possible interference of air bubbles with the measurement device. The experimental set-up was based on an in-situ sterilizable NIR probe connected to the instrument by means of an optical fiber bundle. Preliminary work was carried out to identify and control potential interferences with the measurement, in particular the varying hydrodynamic conditions prevailing at the probe tip. We were successful in defining the operating conditions of the fermenter and the geometrical parameters of the probe (flow path, positioning, etc.) were the NIR readings were reliable and reproducible. The system thus defined was then used to construct and validate calibration curves for tile concentration of biomass, carbon source and major metabolites of two different microorganisms used as salami starters. Real-time measurement of such parameters coupled with the direct interfacing of the NIR instrument with the PC-based measurement and control system of the fermenter enabled the development of automated strategies for the interactive optimization of the starter production process.