• Journal of Plant Biotechnology
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• v.3 no.3
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• pp.151-157
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• 2001

In order to breed barley lines with reduced viscosity of wort, a fractured starch mutant of naked barley cultivar, Nubet, was obtained from the M2 seeds mutated by the diethyl sulfate treatment. Seeds of this fractured starch mutant were opaque and the endosperm consists of angular, irregular and fractured starch. The mutant was caused by single recessive mutation and assigned by the symbol fra. The gene was located on chromosome 4, distal in long arm by linkage recombinations using translocation homozygote lethal test set. The linkage value between the fractured starch mutant and 72-4a, 72-4d were 26.0$\pm$4.9, 34.2$\pm$3.1 percent respectively. In addition to the reduced seed size, fewer kernels per spike and higher tillering ability, lower $\beta$-glucan viscosity and higher lysine content of the grain were associated with this mutant. $\beta$-glucan viscosity of the Nubet grains increased from 3 weeks after anthesis to matury and most of the viscose substances appeared to be stored in the middle of the endosperm tissue. Since the mutant grains showed better milling property as compared to Nubet, it can be used as breeding resources to develope new barley cultivars for maltins and milling purpose.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.288-292
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• 1992

Kinetics of anaerobic ethanol fermentation by Clostridium thermohydrosulfuricum were investigated for the one-step production of ethanol from starch. A mutant strain with a high ethanol yield was induced from C. thermohydrosulfuricum. The mutant, designated as ME4, produced anaerobically 6.1 g/l of ethanol, 3.1 g/l of lactate and 0.1 g/l of acetate from 20 g/l of starch at $68^{\circ}C.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.718-726
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• 2010

A selected fungal strain, for production of the raw-starchdigesting enzyme by solid-state fermentation, was improved by two repeated sequential exposures to ${\gamma}$-irradiation of $Co^{60}$, ultraviolet, and four repeated treatments with Nmethyl-N'-nitrosoguanidine. The mutant strain Aspergillus sp. XN15 was chosen after a rigorous screening process, with its production of the raw-starch-digesting enzyme being twice that of usual wild varieties cultured under preoptimized conditions and in an unsupplemented medium. After 17 successive subculturings, the enzyme production of the mutant was stable. Optimal conditions for the production of the enzyme by solid-state fermentation, using wheat bran as the substrate, were accomplished for the mutant Aspergillus sp. XN15. With the optimal fermentation conditions, and a solid medium supplemented with nitrogen sources of 1% urea and 1% $NH_4NO_3$, 2.5 mM $CoSO_4$, 0.05% (v/w) Tween 80, and 1% glucose, the mutant Aspergillus sp. XN15 produced the raw-starch-digesting enzyme in quantities 19.4 times greater than a typical wild variety. Finally, XN15, through simultaneous saccharification and fermentation of a raw rice corn starch slurry, produced a high level of ethanol with $Y_{p/s}$ of 0.47 g/g.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.95-98
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• 1993

This study was carried out to isolate and characterize the mutant strains of Schwanniomyces castellii NRRL Y-2477. Mutants were prepared with the treatment of ethyl methane sulfonate. 2-deoxy-D-glucose resistant mutants were isolated and two mutants were selected based on their high production of amylolytic enzymes and their ability to ferment starch. The mutants selected had higher a-amylase and glucoamylase activities than the wild type strain from several other carbon sources. Especially, it was revealed that mutant strain M-9, when cultured in the presence of glucose as a sole carbon source, shows relatively high activities of a-amylase and glucoamylase compared to those of the wild type strain. In result, this mutant strain can be considered as a constitutive producer of amylolytic enzymes. To compare the ethanol production ability of wild type strain and of mutant strains selected, an alcohol fermentation was carried out using 100 g/l soluble starch. Mutant strain M-9 did not improve the direct alcohol fermentation of starch, despite its excellent amylolytic activities performance. On the other hand, mutant strain M-6 produced 37.9 g/l (4.8%, v/v) ethanol by utilizing about 82% of substrate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.9
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• pp.1388-1393
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• 2014

To enzymatically prepare amylopectin cluster (APC), cyclodextrin glucanotransferase (CGTase I-5) and its mutant enzyme from alkalophilic Bacillus sp. I-5 were employed, after which the hydrolysis patterns of CGTase wild-type and its mutant enzyme toward amylopectin were investigated using multi-angle laser light scattering. CGTase wild-type dramatically reduced the molecular weight of waxy rice starch at the initial reaction, whereas the mutant enzyme degraded waxy rice starch relatively slowly. Based on the results, the molecular weight of one cluster of amylopectin could be about $10^4{\sim}10^5g/mol$. To determine production of cyclic glucans from amylopectin, matrix-assisted laser desorption ionization time-of-flight mass spectrometry was performed. CGTase I-5 produced various types of cyclic maltooligosaccharides from amylopectin, whereas the mutant enzyme hardly produced any.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.395-401
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• 2005

The dlm (disease lesion mimic) mutant of soybean (Glycine max L. Merr) shows the similar lesion of a soybean disease caused by a fungus, Corynespora cassilcola. The lesion was examined at cellular and molecular level. Trypan blue staining result indicated that cell death was detectable in the entire region of leaves excluding veins when the lesions had already been developed. We found that the mesophyll cells of palisade layer in the dim mutant appeared to be wider apart from each other. The chloroplasts of the dim mutant cells contained bigger starch granules than those in normal plants. We also found that the lesion development of dlm plant was light-dependent and the starch degradation during the dark period of diurnal cycle was impaired in the mutant. Three soybean pathogenesis-related genes, PR-1a, PR-4, and PR-10, were examined for their expression patterns during the development of disease lesion mimic. The expression of all three genes was up-regulated to some extent upon the appearance of the disease lesion mimic. Although the exact function of DLM protein remains elusive, our data would provide some insight into mechanism underling the cell death associated with the dim mutation.

• BMB Reports
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• v.28 no.5
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• pp.375-381
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• 1995

Two forms of glucoamylase (GI and GII) from starch-grown Lipomyces kononenkoae CBS 5608 mutant were purified to apparent homogeneity by means of ultrafiltration, Sephacryl S-200 gel filtration and DEAE Sephadex A-50 chromatography. The apparent molecular weight was calculated as ca. 150 kDa for GI and ca. 128 kDa for GII, respectively. Both enzymes were glycoproteins with isoelectric points of 5.6 (GI) and 5.4 (GII). They had a pH optimun of 4.5 and were stable from pH 5 to 8. The temperature optimum for both enzymes was $60^{\circ}C$, but they were rapidly inactivated above $70^{\circ}C$. The $K_m$ values toward starch were estimated to be 6.57 mg per ml for GI and 4.52 mg per ml for GII, and the $V_{max}$ values were 16.28 ${\mu}M$ per mg for GI and 32.25 ${\mu}M$ per mg for GII, respectively. The $K_m$ and $V_{max}$ values of GII for ${\alpha}-$ or ${\beta}-cyclodextrin$ were estimated to be 0.15 mg per ml and 2.0 mg per ml, respectively ($K_m$) and 1.02 ${\mu}M$ per mg or 1.02 ${\mu}M$ per mg, respectively ($V_{max}$). Neither enzyme exhibited pullulanase activity but they released only glucose from starch or cyclodextrin. Amino acid analysis indicated that both glucoamylases were enriched in proline and acid amino acids. Glucoamylase GII strongly cross-reacted with a monoclonal antibody raised against GI enzymes, and the two enzymes shared very similar amino acid composition. Western blot analysis indicated that L. kononenkoae CBS 5608 mutant produced two forms of glucoamylase on starch, and that synthesis of them was subject to glucose repression.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.854-866
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• 2016

The production cost of biodiesel from microalgae is still not competitive, compared with that of petroleum fuels. The genetic improvement of microalgal strains to increase triacylglycerol (TAG) accumulation is one way to reduce production costs. One of the most promising approaches is the isolation of starch-deficient mutants, which have been reported to successfully increase TAG yields. To date, such a stable mutant is not available in an oleaginous marine microalga, despite several advantages of using marine species for biodiesel production. Algae in the genus Dunaliella are known to tolerate high salt concentration and other environmental stresses. In addition, the cultivation processes for large-scale outdoor commercialization have been well established for this genus. In this study, Dunaliella tertiolecta was used to screen for starch-deficient mutants, using an iodine vapor-staining method. Four out of 20,016 UV-mutagenized strains showed a substantial reduction of starch content. A significantly higher TAG content, up to 3-fold of the wild-type level, was observed in three of the mutants upon induction by nitrogen depletion. The carotenoid production and growth characteristics of these mutants, under both normal and oxidative stress conditions, were not compromised, suggesting that these processes are not necessarily affected by starch deficiency. The results from this work open up new possibilities for exploring Dunaliella for biodiesel production.

• KSBB Journal
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• v.9 no.2
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• pp.147-156
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• 1994

A study was carried out for production of a pigment : bluish purple, using a mutant Streptomyces californicus KS-89-7. The mutant was induced from Streptomyces californicus KS-89 with N-methyl-N-nitro-N-nitrosoquanidin(MNNG). It was immobilized on an inert substance made of colloidal sillica and 3.5% sodium alginate with 1 to 10 ratio. The diameter of inert bead was 2mm, and number of immobilized mutant spore was approximately $1.0{\times}10^7$/ml. It was packed in a column reactor and fermentation was conducted with a substrate made of soluble starch 1%, glycerol 1.0%, sodium glutamate 0.1%, sodium nitrate 0.05%, L-prolin 0.025% and with some trace elements. The aeration for production of the pigment was 2.5m1/min with semi-continuous fermentation. The pigment production reached at peak on 8 days of fermentation, and the mutant produced the pigment 1.8 times more than its parent strain with the maximum pigment production of $1.72g/\ell$. The pigment production continued for 24 hours of fermentation, and at the end of the fermentation the mutant produced the pigment $1.52g/\ell$.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.166-185
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• 1983

Aspergillus niger IFO 8541 (NRRL 3112) was investigated through a series of UV rays and N-Methyl-N'-Nitro-N-Nitrosoguanidine (NTG) treatments to induce mutants that produce highly active raw starch saccharifying enzyme, and two mutants with strong enzymatic productivity were obtained. The mutants obtained were investigated for their fungal characters, condition of enzyme production, and other activities. Furthermore, the raw starch saccharifying enzyme was purified and the characteristics of purified enzyme were studied. The results obtained were summarized as follows; 1. The color of conidial head of UV-46 mutant obtained from UV rays treatment was changed to tan type and the gelatinated starch saccharifying enzyme productivity and the raw starch saccharifying enzyme productivity increased up to twice and 1.8 times compared to the productivities of original Aspergillus niger IFO 8541 cultured on the wheat bran, respectively. 2. The conidial head color of NG-41 mutant obtained from NTG treatment became lighter than that of parent strain. The gelatinated starch saccharifying enzyme productivity and raw starch saccharifying enzyme productivity increased about 1.8 times, and twice over the Aspergillus niger IFO 8541 parent strain cultured on wheat bran, respectively. The productivity of ${\alpha}$-amylase increased about 3 times more than the parent strain. 3. Two peaks of glucoanlylase and a peak of ${\alpha}$-amylase were obtained when enzyme solution of mutants and parent strain were passed through DEAE-Sephadex A-50 column chromatography. Glucoamylase I showed only gelatinated starch saccharifying enzyme activity. However, glucoamylase II (raw starch saccharifying enzyme) showed both raw starch saccharifying enzyme activity and gelatinated starch saccharifying enzyme activity. 4. Mutant, UV-46 was strengthened in glucoamylase II productivity and mutant NG-41 was strengthened in ${\alpha}$-amylase productivity. 5. Glucoamylase II of mutants and parent strain were appeared to have the same enzymatic properties. 6. Glucoamylase II of mutants and parent strain were recognized as simple enzyme through electrophoresis. 7. The glucoamylase II crystallized showed rhombic board type. 8. The molecular weight, isoelectric point, optimum pH, and optimum temperature of the glucoamylase II crystallized were estimated as 76,000, 3.4, 3.5 and $60^{\circ}C$, respectively.