• Journal of Life Science
• /
• v.19 no.11
• /
• pp.1617-1622
• /
• 2009

Optium conditions for the production of mycelia and extracellular polysaccharide (EXPS) from submerged mycelial culture of Inonotus obliquus and their immunomodulating activities were investigated. The optmium production of mycelia and EXPS from I. obliquus was observed in mushroom complete medium (MCM). The optimum pH, temperature, and agitation speed for the production of mycelia and EXPS were 5.5, $25^{\circ}C$, and 150 rpm, respectively. The culture period for maximum production of mycelia (10.89 g/l) and EXPS (1.25 g/l) in shake flask cultivation was 11 days. The anticomplementary activity of intracellular polysaccharide (INPS) and EXPS form I. obliquus increased in a dose-dependent manner. Lysosomal enzyme activity of EXPS and INPS increased by 2.0- and 2.2-fold at $100{\mu}g/ml$ concentration, respectively, compared to the control group.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.11
• /
• pp.1908-1917
• /
• 2016

Wild strain L-6 was subjected to combined mutagenesis, including UV irradiation, atmospheric and room temperature plasma, and ion beam implantation, to increase the yield of 1,3-dihydroxyacetone (DHA). With application of a high-throughput screening method, mutant Gluconobacter oxydans I-2-239 with a DHA productivity of 103.5 g/l in flask-shake fermentation was finally obtained with the starting glycerol concentration of 120 g/l, which was 115.7% higher than the wild strain. The cultivation time also decreased from 54 h to 36 h. Compared with the wild strain, a dramatic increase in enzyme activity was observed for the mutant strain, although the increase in biomass was limited. DNA and amino acid sequence alignment revealed 11 nucleotide substitutions and 10 amino acid substitutions between the sldAB of strains L-6 and I-2-239. Simulation of the 3-D structure and prediction of active site residues and PQQ binding site residues suggested that these mutations were mainly related to PQQ binding, which was speculated to be favorable for the catalyzing capacity of glycerol dehydrogenase. RT-qPCR assay indicated that the transcription levels of sldA and sldB in the mutant strain were respectively 4.8-fold and 5.4-fold higher than that in the wild strain, suggesting another possible reason for the increased DHA productivity of the mutant strain.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.2
• /
• pp.306-315
• /
• 2017

Metabolic engineering with a high-yielding mutant, A. terreus AN37, was performed to enhance the production of itaconic acid (IA). Reportedly, the gene cluster for IA biosynthesis is composed of four genes: reg (regulator), mtt (mitochondrial transporter), cad (cis-aconitate decarboxylase), and mfs (membrane transporter). By overexpressing each gene of the IA gene cluster in A. terreus AN37 transformed by the restriction enzyme-mediated integration method, several transformants showing high productivity of IA were successfully obtained. One of the AN37/cad transformants could produce a very high amount of IA (75 g/l) in shake-flask cultivations, showing an average of 5% higher IA titer compared with the high-yielding control strain. Notably, in the case of the mfs transformants, a maximal increase of 18.3% in IA production was observed relative to the control strain under the identical fermentation conditions. Meanwhile, the overexpression of reg and mtt genes showed no significant improvements in IA production. In summary, the overexpressed cis-aconitate decarboxylase (CAD) and putative membrane transporter (MFS) appeared to have positive influences on the enhanced IA productivity of the respective transformant. The maximal increases of 13.6~18.3% in IA productivity of the transformed strains should be noted, since the parallel mother strain used in this study is indeed a very high-performance mutant that has been obtained through intensive rational screening programs in our laboratory.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.11
• /
• pp.1670-1679
• /
• 2020

The substantial use of fungal enzymes to degrade lignocellulosic plant biomass has widely been attributed to the extensive requirement of powerful enzyme-producing fungal strains. In this study, a two-step screening procedure for finding cellulolytic fungi, involving a miniaturized culture method with shake-flask fermentation, was proposed and demonstrated. We isolated 297 fungal strains from several cellulose-containing samples found in two different locations in Thailand. By using this screening strategy, we then selected 9 fungal strains based on their potential for cellulase production. Through sequence-based identification of these fungal isolates, 4 species in 4 genera were identified: Aspergillus terreus (3 strains: AG466, AG438 and AG499), Penicillium oxalicum (4 strains: AG452, AG496, AG498 and AG559), Talaromyces siamensis (1 strain: AG548) and Trichoderma afroharzianum (1 strain: AG500). After examining their lignocellulose degradation capacity, our data showed that P. oxalicum AG452 exhibited the highest glucose yield after saccharification of pretreated sugarcane trash, cassava pulp and coffee silverskin. In addition, Ta. siamensis AG548 produced the highest glucose yield after hydrolysis of pretreated sugarcane bagasse. Our study demonstrated that the proposed two-step screening strategy can be further applied for discovering potential cellulolytic fungi isolated from various environmental samples. Meanwhile, the fungal strains isolated in this study will prove useful in the bioconversion of agricultural lignocellulosic residues into valuable biotechnological products.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.3
• /
• pp.434-439
• /
• 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
• /
• v.11 no.6
• /
• pp.636-641
• /
• 1996

The production of extracellular mannitol by a new mannitol-producing bacterium, Leuconostoc sp. KY-002 was studied in shake flask cultures. The new isolate has a capability of utilizing fructose and sucrose for mannitol formation. Maximum mannitol production was obtained with fructose as the sole carbon source. Under the optimal culture conditions, within 70 hours of incubation, a final concentration of 26 g/L of mannitol from 50 g/L fructose was obtained with an indicated yield of 52% based on fructose consumed. However, higher concentrations of fructose ranging from 100 to 250 g/L could not effectively be transformed to mannitol due to a lack of osmotolerance. The strain produced no other polyols such as glycerol and sorbitol as by-products. Yeast extract was the best nitrogen source and high levels of inorganic phosphate up to 10 g/L promoted mannitol formation. Any mineral ions and salts did not play important role in both cell growth and mannitol production. Nicotinic acid enhanced mannitol production by 16%. The optimum culture temperature and initial pH were $35^{\circ}C$ and 6, respectively.

• The Journal of Natural Sciences
• /
• v.11 no.1
• /
• pp.159-164
• /
• 1999

The study was investigated to the effect of antimicrobial finishing of towel treated by organic antimicrobial agent. It was measured for the optimal condition such as treated time, treated concentration and temperature. After amtimicrobial treatment, mechanical and fastness properties, anti-laundering property were measured.The antimicrobial activity of samples was analyzed quantitatively by masureing the number of colonies of Staphylococcus aureus using the shake flask method. Towel samples treated with the optimal condition such as treated time of 10 minute, and treated temperature of $30^{\circ}C$, concentration of organic antimicrobial agent of 3.5% were shown a high reduction rate in the number of colonies grown and clear zones of inhibition.The effect of reduction rate for laundering until the number of 20 times was shown high reduction rate of over 80%. And the mechanical properties of samples treated with organic antimicrobial agent were not changed approximately.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.6
• /
• pp.637-645
• /
• 2011

Production of recombinant proteins by excretory expression has many advantages over intracellular expression in Escherichia coli. Hyperexpression of a secretory exoglucanase, Exg, of Cellulomonas fimi was previously shown to saturate the SecYEG pathway and result in dramatic cell death of E. coli. In this study, we demonstrated that overexpression of the PspA in the JM101(pM1VegGcexL-pspA) strain enhanced excretion of Exg to 1.65 U/ml using shake-flask cultivation, which was 80% higher than the highest yield previously obtained from the optimized JM101(pM1VegGcexL) strain. A much higher excreted Exg activity of 4.5 U/ml was further achieved with high cell density cultivation using rich media. Furthermore, we showed that the PspA overexpression strain enjoyed an elevated critical value (CV), which was defined as the largest quotient between the intracellular unprocessed precursor and its secreted mature counterpart that was still tolerable by the host cells prior to the onset of cell death, improving from the previously determined CV of 20/80 to the currently achieved CV of 45/55 for Exg. The results suggested that the PspA overexpression strain might tolerate a higher level of precursor Exg making use of the SecYEG pathway for secretion. The reduced lethal effect might be attributable to the overexpressed PspA, which was postulated to be able to reduce membrane depolarization and damage. Our findings introduce a novel strategy of the combined application of metabolic engineering and construct optimization to the attainment of the best possible E. coli producers for secretory/excretory production of recombinant proteins, using Exg as the model protein.

• Korean Journal of Food Science and Technology
• /
• v.31 no.1
• /
• pp.224-230
• /
• 1999

The ddh gene encoding meso-DAP-dehydrogenase (DDH) involved in the dehydrogenase pathway is essential for high-level lysine production in Brevibacterium lactofermentum. To investigate its influence on lysine production by overexpression of the ddh gene in a lysine-producing B. lactofermentum, recombinant plasmid pRK1 and pRK31 containing the ddh gene of B. lactofermentum were constructed and they were introduced into B. lactofermentum by electroporation. Multiple copies of pRK1 and pRK31 caused 7-fold and 14-fold increase of DDH activity in B. lactofermentum cell extracts, respectively. As determined in shake flask fermentation, lysine production of B. lactofermentum harboring pRK1 or pRK31 was 22% or 19% higher than that of the control, respectively.

• The Korean Journal of Mycology
• /
• v.33 no.2
• /
• pp.59-63
• /
• 2005

Altogether twenty isolates were collected from Wakayama, Japan. The optimum mycelial growth of I. obliquus was observed in BMYA and MCM. The optimum temperature and pH for the mycelial growth were $25^{\circ}C\;and\;6.0{\sim}7.0$, respectively. The optimum carbon and nitrogen sources were dextrose and yeast extract, respectively. Similarly, the optimum mineral salt was $K_{2}HPO_{4}$. The optimum number of mycelial discs for the mycelial growth was $6{\sim}7$ per 100 ml. Similarly, the optimum culture period was $21{\sim}22$ days in liquid broth. The optimum brown rice : water ratio was 1 : 1. No difference in mycelial growth was observed in all the four types of tree stumps used.