• Journal of Life Science
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• v.28 no.8
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• pp.969-976
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• 2018

In this study, transglucosidase (TG), an enzyme produced by Aspergillus niger, synthesized isomaltooligosaccharide from ${\alpha}-(1{\rightarrow}4)$ linked substrates. The highest TG-producing A. niger KCTC6913 was selected from six kinds of species, and optimized TG producing conditions were established. Five different carbon sources (potato starch, sweet potato starch, corn starch, wheat starch, and dextrin) and three different nitrogen sources (yeast extract, malt extract, and beef extract) were tested to establish the carbon and nitrogen sources favorable for TG production. Measurements of TG activity after an initial culture at pH 5.0 for 15 days revealed that potato starch and yeast extract, which are basic culture media, resulted in the highest TG activity. In addition, A. niger KCTC6913 increased TG production under aerobic conditions and a controlled carbon/nitrogen ratio. In conclusion, to evaluate TG activity in the established optimal medium, it is confirmed that the basal and potato dextrose broth medium were used as a control, and the highest TG production was measured, which was highlighted in the established optimal medium.

• The Korean Journal of Mycology
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• v.10 no.4
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• pp.193-202
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• 1982

The changes of total carbohydrates and trehalose levels during differentiation of A. niger were studied. Aspergillus niger was cultivated in Czapeck-Dox medium by the method of surface culture and shake culture. Total carbohydrates and trehalose were fractionated and determined by the method of Trevelyan and Harrison (1956). Total carbohydrates and trehalose accumulated in A. niger during sporulation. The influences of nutritional starvation on the levels of cellular carbohydrates in A. niger, which was cultivated in each nitrogen, phosphate and glucose limited Czapeck-Dox medium, were studied. The levels of total carbohydrates and trehalose in A. niger cultivated in nitrogen limited medium increased much than those cultured in full medium. The total carborates and trehalose levels in A. niger cultivated in phosphate limited medium increased, but the increases were less than those cultured in nitrogen limitted medium. In glucose limited medium, any changes of total carbohydrates and trehalose levels were not found. It is considered that the biochemical mechanisms responsible for the changes of total carbohydrates and trehalose levels may be related with differentiation of Aspergillus niger.

• KSBB Journal
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• v.13 no.2
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• pp.214-219
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• 1998

Polymerase chain reaction(PCR) was conducted to obtain the gene encoding glucose oxidase(GOD) from Aspergillus niger(ATCC 2110) and the DNA sequence determined was coincided with published GOD sequence from A. niger. Recombinant transforming vector containing GOD and hygromycin B(hyg.B) resistant gene(hph) was constructed and used for further transformation of A. niger ATCC 2110. Selectivity of hyg.B against A. niger differed depending on which media were used i.e., nutrient-rich media such as potato dextrose agar(PDA) and complete medium(CM) showed only 50% growth inhibition at 400 $\mu$m ml$^-1$ of hyg.B while the minimal media inhibited mycelial growth completely at 200 $\mu$m ml$^-1$ of hyg.B. Twenty to sixty putative transformants were isolated from the hyg.B-containing minimal top agar, transferred successively onto alternating selective and nonselective media for a mitotic stability of hyg.B resistance and, then, single-spored. Among the stable transformants, the transformant(GOD1-6) grown by flask culture showed the considerable increase of extracellular GOD activity, which was estimated to the degree of 50% - 100% comparing to that of wild type. Transformation of tGOD1-6 was resulted from integration of the vectors into heterologous as well as homologous regions of the A. niger genome. Southern blot analysis revealed that there were two independent integrations of vector into fungal genome and one into the GOD gene due to homologous recombination. In addition, GOD activity and sodium gluconate production when tGOD1-6 was fed-batch fermented were enhanced 11 fold and 2.25 fold, respectively, compared to that of the wild type.

• Parasites, Hosts and Diseases
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• v.61 no.4
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• pp.455-462
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• 2023

Since 2015, countries in the Sahel region have implemented large-scale seasonal malaria chemoprevention (SMC). However, the mass use of sulfadoxine-pyrimethamine (SP) plus amodiaquine impacts the genetic diversity of malaria parasites and their sensitivity to antimalarials. This study aimed to describe and compare the genetic diversity and SP resistance of Plasmodium falciparum strains in Mali and Niger. We collected 400 blood samples in Mali and Niger from children aged 3-59 months suspected of malaria. Of them, 201 tested positive (Niger, 111, 55.2%; Mali, 90, 44.8%). Polymorphism of merozoite surface protein 1 (msp1) genetic marker showed 201 allotypes. The frequency of the RO33 allotype was significantly higher in Niger (63.6%) than in Mali (39.3%). There was no significant difference in the frequency of the K1 and MAD20 allotypes between the 2 countries. The multiplicity of infection was 2 allotypes per patient in Mali and one allotype per patient in Niger. The prevalence of strains with the triple mutants Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H and Pfdhfr51I/Pfdhfr59R/Pfdhps437G was 18.1% and 30.2%, respectively, and 7.7% carried the quadruple mutant Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H/Pfdhps437G. Despite the significant genetic diversity of parasite populations, the level of SP resistance was comparable between Mali and Niger. The frequency of mutations conferring resistance to SP still allows its effective use in intermittent preventive treatment in pregnant women and in SMC.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.2
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• pp.179-190
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• 2010

The experiment was conducted to observe the effects of dried whole crop barley treated with cellulolytic microorganisms (Aspergillus niger KCCM 60357 and Bacillus licheniformis KCCM 40934) on the chemical composition, in vitro colonic fermentation and whole tract digestibility in swine. Whole crop barley were fermented with no microorganism addition (control), A. niger, B. licheniformis and co-culture of A. niger and B. licheniformis (Mixture) for 3 days at $30^{\circ}C$. In the feed chemical composition, CP contents of whole crop barley treated with A. niger (7.52%) and B. licheniformis (7.77%) were significantly higher than control (6.81%) (p<0.05). The in vitro colonic fermentation of dried whole crop barley fermented with control showed significantly higher $CH_4$ contents than A. niger, B. licheniformis and Mixture at 18h incubation (p<0.05). Dry matter (DM) digestibilities of A. niger (55%) and Mixture (57.42%) treatments were significantly higher than control (43.74%) (p<0.05). Ammonia-N was significantly increased in A. niger, B. licheniformis and Mixture relative to control at 24 hour incubation (p<0.05). Xylanase activities in A. niger, B. licheniformis and Mixture treatments were significantly higher than control at 24 hour incubation (p<0.05). Concentrations of total VFA were significantly increased in B. licheniformis (12.61 mM) at 24hour incubation (p<0.05). In vitro whole tract digestibility was significantly increased in B. licheniformis (49.61%) compared with the control (45.65%) (p<0.05). In conclusion, whole crop barley treated with cellulolytic microorganisms improved whole tract digestibility and colonic fermentation for swine.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.427-429
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• 1996

We have already cloned an extracellular $\alpha$-glucosidase gene from Aspergillus niger with oligonucleotide probe synthesized on the basis of the peptide sequences determined previously. The DNA sequence revealed an open reading frame of 895 amino acids split by three introns. We are attempting to construct an A. niger strain deficient in the $\alpha$-glucosidase enzyme activity, which would be useful for the glucoamylase production without contamination by the industrially undesirable $\alpha$-glucosidase. For destruction of the $\alpha$-glucosidase gene, we try to make transformations. A cloned partial $\alpha$-glucosidase gene was introduced into Aspergillus niger, and transformants with suppressed $\alpha$-glucosidase activity were isolated. The transformants were cultured on YPD medium which contained Hygromycin B at 30$\circ$C. The activity of $\alpha$-glucosidase of the suppressed transformants was compared to that of wild type activity. As shown by southern-hybridization, we detected that the transformant was a heterocaryon.

• Microbiology and Biotechnology Letters
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• v.15 no.6
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• pp.402-407
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• 1987

Glucose oxidase from Aspergillus niger KUF-04 was purified homogeneously by the procedure of seven steps including crystallization. The ball-like crystalline enzyme was obtained from the 23-fold purified enzyme solution. The glucose oxidase was found to be composed of two identical subunits and the molecular weight of the enzyme and its subunit were estimated to be about 210, 000 and 110, 000 by HPLC and SDS-acrylamide gel electrophoresis, respectively.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.13-17
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• 1993

When mandarin orange peel was used for a substrate of citric aCid fermentation by Aspergillus niger, principal enzyme activities were investigated. Not only the activity of polygalacturonase and pectin esterase being capable of digesting pectin and crude fiber of mandarin orange peel. but also that of carboxymethyl cellulase, xylanase and amylase was high. In carbohydrate metabolism, the activity of enzymes related in HMP pathway was higher than that in EMP pathway at the orange peel medium designed hereby rather than synthetic medium. Productivity of citric acid was significantly increased when the activity of citrate synthetase was high and 5imultaneously those of aconitase and NADP-dependent dehydrogenase were low.

• Natural Product Sciences
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• v.26 no.4
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• pp.283-288
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• 2020

Microbial transformation of a potent progestin, norethisterone (17��-hydroxy-19-nor-17α-pregn-4-en-20-yn-3-one) (1) was carried out by using two filamentous fungi Aspergillus niger and Penicillium citrinum. Biotransformation of 1 with A. niger yielded a hydroxylated transformed product 10��,17��-diydroxy-19-nor-17α-pregn-4-en-20-yn-3-one (2) whereas 11��,17��-diydroxy-19-nor-17α-pregn-4-en-20-yn-3-one (3) was obtained through microbial transformation of 1 by P. citrinum. It is the first report of their production from 1 by using A. niger and P. citrinum with complete 1H- and 13C-NMR assignment. The structures of both metabolites were characterized by various spectroscopic techniques and reported data.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.383-385
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• 1999

Effects of temperature and initial pH of the medium on production of citric acid from cheese whey permeate by Aspergillus niger were investigated. A. niger was cultivated at four different temperatures (27, 30, 33, $36^{\circ}C$) and four different pHs (2, 3, 4, 5) for 15 days. During the fermentation the concentrations of lactose and citric acid in the culture broth were measured. The maximum production of citric acid which was 33.9 g/l (68.26% yield based on lactose utilized) was obtained at $33^{\circ}C$ and pH 3. The production of citric acid was not much affected by shaking speed. However, the shaking speed was found to influence the form of pellets during cell growth.