• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.707-712
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• 1994

Yeast screening for effective production of alcohol from Jerusalem artichoke tubers as an alternative energy source was performed. Inulin assimilative strains with high alcohol tolera- nce were isolated from wild sources and cultured in the liquid media of Jerusalem artichoke powder varying its concentraion from 15 to 30%. As a result, four strains of 2,445 isolates showing the inulin assimilation were selected as alcohol fermentative and alcohol tolerant yeasts. These strains were assignated to be Kluyveromyces marxianus F043 and Kluyveromyces sp. F173, E040, and F334, respectively, by their cultural and physiological characteristics. The F043 strain produced ethanol of 98.1 g/l in the 25% Jerusalem artichoke medium for 3 days.

• Korean Journal of Microbiology
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• v.29 no.3
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• pp.189-194
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• 1991

The degree of the genetic variations among Clostridium thermocellum ATCC 27405 and the wild type strains was investigated by the mehtod of GC ratio, DNA-DNA hybridization and RFLP (Restriction Fragment Length Polymorphism) patterns by ribosomal RNA and M13 probe. GC ratio and KNA homology values of th three isolates were approximately equal to those of ATCC type strain. The RFLP patterns by the rRNA and M13 probe showed some differences among C. thermocellum ATCC 27405, wild type strains and Clostridium thermohydrosulfuricum ATCC 33223, indicating that the two probes can be useful in subspecies- and apecies-identification.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.15-18
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• 1998

The entanol productivity of superoxide dismutase (SOD)-deficient mutants of Saccharo-Myces cerevisiae was examined under the oxidative stress by Paraquat. It was observed that MnSOD-deficient mutant of S. cerevisiae had higher ethanol productivity than wild type or CuZnSOD-deficient yeast both in aerobic and in anaerobic culture condition. Pyruvated dehydrogenase activity decreased by 35% and alcohol dehydrogenase activity increased by 32% were observed in MnSOD-deficient yeast grown aerobically. When generating oxygen radicals by Paraquat, the ehanol productivity was increased by 40% in CuZnSOD-deficient or wild strain, resulting from increased activity of alcohol dehydrogenase and decreased a activity of pyruvate dehydrogenase. However, the addition of ascorbic acid with Paraquat returned the enzyme activities at the level of control. These results imply that SOD-deficiency in yeast strains may cause the metabolic flux to shift into anaerobic ethanol fermentation in order to avoid their oxidative damages by Paraquat.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.309-316
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• 2008

Mycelium of Ophiostoma quercus albino strain cultured in liquid culture media was harvested, lyophilized, and stored for examining biocontrol efficacy against wood discoloration by staining fungi in the laboratory and field conditions. Dry weight of mycelium grown in brown sugar yeast extract broth(BYB) showed 3.8 times higher than that grown in potato dextrose broth(PDB). The optimum culture period in BYB was 4 weeks. In vitality test of the albino strain, the lyophilized mycelium stored in liquid nitrogen($-196^{\circ}C$) or in a refrigerator($4^{\circ}C$) kept the vitality until 13 months after storage; however, the mycelium stored at room temperature lost the vitality completely after 13 months. The mycelium stored in liquid nitrogen or in a refrigerator protected wood chips from the discoloration by pretreating mycelial suspension on pine wood chips. The mycelium stored at room temperature for 7 months also showed complete protection. These results suggest that the lyophilized mycelium have a biocontrol efficacy only if it keeps the least vitality. In the field conditions, both albino strain and $Woodguard^{(R)}$(commercial chemical protectant) showed significant differences(p=0.05) in discoloration rate as compared to the non-treated control when these were treated on the wood logs of Pinus rigida. The albino strain showed better protection than $Woodguard^{(R)}$. Isolation frequency of blue stain fungi from the chips of wood logs treated with the albino strain was 0% at three months after treatment, while that treated with $Woodguard^{(R)}$ was 76.7%. In another experiment, pre-treatment of mycelial suspension on the cut surface of wood logs also showed significant protection from wood discoloration. Spraying of both albino strain on the cut surface and insecticides on the bark also showed relatively good control effects as compared to insecticide alone on the bark or nontreated control.

• Journal of Microbiology and Biotechnology
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• v.32 no.11
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• pp.1485-1495
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• 2022

The development of a yeast strain capable of fermenting mixed sugars efficiently is crucial for producing biofuels and value-added materials from cellulosic biomass. Previously, a mutant Pichia stipitis YN14 strain capable of co-fermenting xylose and cellobiose was developed through evolutionary engineering of the wild-type P. stipitis CBS6054 strain, which was incapable of co-fermenting xylose and cellobiose. In this study, through genomic and transcriptomic analyses, we sought to investigate the reasons for the improved sugar metabolic performance of the mutant YN14 strain in comparison with the parental CBS6054 strain. Unfortunately, comparative whole-genome sequencing (WGS) showed no mutation in any of the genes involved in the cellobiose metabolism between the two strains. However, comparative RNA sequencing (RNA-seq) revealed that the YN14 strain had 101.2 times and 5.9 times higher expression levels of HXT2.3 and BGL2 genes involved in cellobiose metabolism, and 6.9 times and 75.9 times lower expression levels of COX17 and SOD2.2 genes involved in respiration, respectively, compared with the CBS6054 strain. This may explain how the YN14 strain enhanced cellobiose metabolic performance and shifted the direction of cellobiose metabolic flux from respiration to fermentation in the presence of cellobiose compared with the CBS6054 strain.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1101-1107
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• 2015

The role of CRE1 in a thermophilic fungus, Myceliophthora thermophila ATCC42464, was studied using RNA interference. In the cre1-silenced strain C88, the filter paper hydrolyzing activity and β-1,4-endoglucanase activity were 3.76-, and 1.31-fold higher, respectively, than those in the parental strain when the strains were cultured in inducing medium for 6 days. The activities of β-1,4-exoglucanase and cellobiase were 2.64-, and 5.59-fold higher, respectively, than those in the parental strain when the strains were cultured for 5 days. Quantitative reverse-transcription polymerase chain reaction showed that the gene expression of egl3, cbh1, and cbh2 was significantly increased in transformant C88 compared with the wild-type strain. Therefore, our findings suggest the feasibility of improving cellulase production by modifying the regulator expression, and an attractive approach to increasing the total cellulase productivity in thermophilic fungi.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1171-1179
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• 2017

Butanol is a promising alternative to ethanol and is desirable for use in transportation fuels and additives to gasoline and diesel fuels. Microbial production of butanol is challenging primarily because of its toxicity and low titer of production. Herein, we compared the transcriptome and phenome of wild-type Escherichia coli and its butanol-tolerant evolved strain to understand the global cellular physiology and metabolism responsible for butanol tolerance. When the ancestral butanol-sensitive E. coli was exposed to butanol, gene activities involved in respiratory mechanisms and oxidative stress were highly perturbed. Intriguingly, the evolved butanol-tolerant strain behaved similarly in both the absence and presence of butanol. Among the mutations occurring in the evolved strain, cis-regulatory mutations may be the cause of butanol tolerance. This study provides a foundation for the rational design of the metabolic and regulatory pathways for enhanced biofuel production.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.2
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• pp.185-189
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• 2001

Wild type Bacilus thuringiensis subsp. israelensis and B. sphaericus toxins have been used separately as active in ingredients for bacterial insecticides to control mosquito larvae due to their comparable toxicity to chemical insecticides. Cry11B, recently cloned from B. thuringiensis subsp. jegathesan, shows higher toxicity against three major species of mosquito larvae than Cry11A, one of the major component of B. thuringiensis subsp. israelensis inclusion body. To determine whether the combination of cry11B and B. sphaericus binary toxins is as toxic as B. thuringiensis subsp. israelensis parental strain, cry11B and B. sphaericus binary toxins genes were co-expressed as an operon using cytlA promoters/STAB-SD hybrid expression system in B. thuringiensis subsp. israelensis acrystalliferous strain 4Q7. However, unexpectedly, B. sphaericus binary toxins were barely produced, whereas relatively large amount of Cry11B was produced. When this strain was grown in four different media, NB+G and Peptonized Milk produced more toxin proteins and spores per unit of media than GYS and G-Tris. Toxicity of this strain against fourth instar Culex quinquefasciatus was ranged from of 8.3 to 45.7 ng/ml, with NB+G culture being the highest, and GYS culture was the lowest.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.959-965
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• 2013

Monascus species have been used to produce fermented rice called Monascus-fermented rice (MFR). To improve a Monascus strain via activation of secondary metabolite (SM) gene clusters for use in the production of MFR, we overexpressed an ortholog of the laeA gene, which encodes a global positive regulator of secondary metabolism under the control of the strong heterologous Aspergillus nidulans alcA promoter in Monascus pilosus. The OE::laeA transformant produced more SMs, including those not detected under uninduced conditions. MFR produced using the M. pilosus OE::laeA strain contained 4 times more monacolin K, a cholesterol-lowering agent, than MFR produced using the wild-type strain. In addition, pigment production was remarkably increased, and the antioxidant activity was increased as well. The results from this study suggest that Monascus species, which are important industrial fermentative fungi in Asia, can be improved for the production of functional foods by overexpressing the laeA gene.