• Mycobiology
• /
• v.44 no.4
• /
• pp.269-276
• /
• 2016

Aspergillus luchuensis is known as an industrially important fungal species used for making fermented foods such as awamori and shochu in Japan, makgeolli and Meju in Korea, and Pu-erh tea in China. Nonetheless, this species has not yet been widely studied regarding mating-type genes. In this study, we examined the MAT1-1 and MAT1-2 gene ratio in black koji molds (A. luchuensis, Aspergillus niger, and Aspergillus tubingensis) and in Aspergillus welwitschiae isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea. The number of strains with the MAT1-1 locus was 2 of 23 (A. luchuensis), 6 of 13 (A. tubingensis), 21 of 28 (A. niger), and 5 of 10 (A. welwitschiae). Fungal species A. tubingensis and A. welwitschiae showed a 1 : 1 ratio of MAT1-1 and MAT1-2 mating-type loci. In contrast, A. luchuensis revealed predominance of MAT1-2 (91.3%) and A. niger of MAT1-1 (75%). We isolated and identified 2 A. luchuensis MAT1-1 strains from Meju, although all strains for making shochu in Japan are of the MAT1-2 type. These strains may be a good resource for breeding of A. luchuensis to be used in the Asian fermented-food industry.

• The Korean Journal of Mycology
• /
• v.41 no.2
• /
• pp.132-135
• /
• 2013

Black Aspergillus is important fungus for oriental fermentation industry. Black Aspergillus was frequently isolated from Korean traditional Meju, a fermented soybean starting material for soy sauce and soybean paste. Thirty three strains were isolated from 98 finished Meju collected in various regions of Korea from 2008 to 2011, and 21 strains were isolated from in-process Meju at various farms from 2010 to 2011. The isolated black Aspergillus were identified using DNA sequences of partial ${\beta}$-tubulin and calmodulin genes. Of 54 black Aspergillus strains, 14 strains were identified as A. luchuensis and the others were composed of A. niger (n = 21), A. tubingensis (n = 10), and A. welwitschiae (n = 9).

• Mycobiology
• /
• v.44 no.3
• /
• pp.171-179
• /
• 2016

In the screening of marine mangrove derived fungi for lovastatin productivity, endophytic Aspergillus luchuensis MERV10 exhibited the highest lovastatin productivity (9.5 mg/gds) in solid state fermentation (SSF) using rice bran. Aspergillus luchuensis MERV10 was used as the parental strain in which to induce genetic variabilities after application of different mixtures as well as doses of mutagens followed by three successive rounds of genome shuffling. Four potent mutants, UN6, UN28, NE11, and NE23, with lovastatin productivity equal to 2.0-, 2.11-, 1.95-, and 2.11-fold higher than the parental strain, respectively, were applied for three rounds of genome shuffling as the initial mutants. Four hereditarily stable recombinants (F3/3, F3/7, F3/9, and F3/13) were obtained with lovastatin productivity equal to 50.8, 57.0, 49.7, and 51.0 mg/gds, respectively. Recombinant strain F3/7 yielded 57.0 mg/gds of lovastatin, which is 6-fold and 2.85-fold higher, respectively, than the initial parental strain and the highest mutants UN28 and NE23. It was therefore selected for the optimization of lovastatin production through improvement of SSF parameters. Lovastatin productivity was increased 32-fold through strain improvement methods, including mutations and three successive rounds of genome shuffling followed by optimizing SSF factors.

• Journal of Biomedical and Translational Research
• /
• v.19 no.4
• /
• pp.103-109
• /
• 2018

Aspergillus luchuensis 34-1 was inoculated into wheat pellets with different conditions of raw materials to produce nuruk. The degree of substrate reactivity improvement of steam treated raw materials compared with that of non-heat treated was analyzed. The water content of the pellet was adjusted to 25% and 35%, and steam treatment for 10 minutes improved the substrate reactivity at 2.1-fold and 3.1-fold, and sterilization was also possible. The characteristics of improvement pellet nuruk were investigated according to the degree of crushing and water content of raw materials according to the temperatures and humidities ($23^{\circ}C$, $30^{\circ}C$ and RH 60%, RH 80%). The pH of the pellet nuruk was higher depending on the temperature, humidity and moisture content of the koji were lower, and the pH of the flour-pellet nuruk was lower than that of 2 mm milling wheat-pellet nuruk according to milling degree. It can be seen that the milling degree affects the growth of mold. The acidity and amino acid were generally higher as fermentation time increased. Also, the higher the incubation temperature, humidity and moisture content, the higher the value. Glucoamylase activity was significantly the highest in moisture content 35% D2b nuruk, cultured at $30^{\circ}C$ and 80% RH for 38 hours. This is higher than the previous reports on glucoamylase of rice-koji or commercial nuruk using fungi isolated from traditional nuruk. From these study, it is expected that making of improvement pellet nuruk would save the fermentation time considerably compared with traditional nuruks.

• Mycobiology
• /
• v.43 no.3
• /
• pp.218-224
• /
• 2015

Aspergillus is an important fungal genus used for the fermentation of Asian foods; this genus is referred to as koji mold in Japan and China. A. oryzae, A. sojae, and A. tamari are used in the production of miso and shoyu in Japan, but a comprehensive taxonomic study of Aspergillus isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea, has not been conducted. In this study, various Aspergillus species were isolated during a study of the mycobiota of Meju, and the aspergilli were identified based on phenotypic characteristics and sequencing of the ${\beta}$-tubulin gene. Most strains of Aspergillus were found to belong to the following sections: Aspergillus (n = 220), Flavi (n = 213), and Nigri (n = 54). The most commonly identified species were A. oryzae (n = 183), A. pseudoglaucus (Eurotium repens) (n = 81), A. chevalieri (E. chevalieri) (n = 62), A. montevidensis (E. amstelodami) (n = 34), A. niger (n = 21), A. tamari (n = 15), A. ruber (E. rubrum) (n = 15), A. proliferans (n = 14), and A. luchuensis (n = 14); 25 species were identified from 533 Aspergillus strains. Aspergillus strains were mainly found during the high temperature fermentation period in the later steps of Meju fermentation.

• The Korean Journal of Mycology
• /
• v.43 no.3
• /
• pp.149-157
• /
• 2015

We examined taxonomic characteristics and safety of eight Nuruk molds that are widely used for making soybean paste, soy sauce and alcoholic beverages in Korea. HK1 from Hakyeong Fermentation Co., SW101 from Suwon Fermentation Co., CF1001, CF1002, CF1003 from Chungmoo Fermaentation Co. and KACC 93210 are yellow-Nuruk molds, and SW201 from Suwon Fermentation Co. and CF1005 from Chungmoo Fermentation Co. are white-Nuruk molds. Six strains of yellow-Nuruk molds were identified as Aspergillus oryzae. HK1, SW101, CF1001 and CF1003 of yellow-Nuruk molds have middle length of stipes ($711{\sim}1,121{\mu}m$), and CF1003 (for sake) produced less conidia and more hyphae than HK1, SW101 and CF1001 (for soybean paste). CF 1002 used for soy sauce has shorter stipes ($543{\mu}m$) and is clustered into IBLB-group based on omtA gene analysis although the other yellow-Nuruk molds are clustered into ICAo group. KACC 93210 isolated from traditional Korean Meju has very short stipes (average $270{\mu}m$), and showed velvety colonies although the others showed floccose colonies. The strain has different DNA sequences of omtA gene from other strains in NCBI GenBank as well as strains used in Korea, suggesting that it is unique from other strains published. SW201 and CF1005 of white-Nuruk molds were identified as Aspergillus luchuensis or A. luchuensis mut. Kawachii that is known as safe, non-toxigenic fungus. The six strains of yellow-Nuruk molds did not produce mycotoxins including aflatoxin, cyclopiazonic acid, and sterigmatocystin. Therefore, eight strains of Nuruk molds used for making soy sauce, soybean paste and alcoholic beverages in Korea were proved to be safe in this study.

• Food Science and Preservation
• /
• v.23 no.6
• /
• pp.797-803
• /
• 2016

In this study, we investigated the effect of fermentation conditions on the amylolytic and proteolytic activities of Aspergillus luchuensis strain 74-5 and Aspergillus oryzae strain 75-2, which are used in the preparation of the starter culture, for Takju (Korean traditional rice wine). The starter culture was optimized using different conditions, such as inoculum size, inoculation temperature, and incubation time. The enzyme activities under each condition were measured. In the A. luchuensis strain 74-5 starter culture, the ${\alpha}-amylase$ and glucoamylase activities increased, however the activity of acidic protease decreased as the diluent to starter culture ratio increased. In the A. oryzae 75-2 starter culture, all enzyme activities were maintained at a higher level even at 5% inoculation ratio. Higher enzyme activities were observed in the middle range of inoculation temperature (35, $40^{\circ}C$), than in the lower range (20, $30^{\circ}C$). Enzyme activity in the starter culture varied with incubation time, however it was the highest at 144 and 120 hr, respectively, for A. luchuensis strain 74-5 and A. oryzae strain 75-2. The spore count of the starter culture was approximately $2{\times}10^7$ during fermentation, out of which contamination by aerobic bacteria was about $3{\times}10^3$. The results suggested that the starter culture of each strain could be used as an inoculum for fermentation. However, we needs to conduct further research for the selection of suitable diluting agents as well as drying methods to reduce the contamination by aerobic bacteria, while retaining the enzyme activity.

• Mycobiology
• /
• v.51 no.5
• /
• pp.288-299
• /
• 2023

Aspergillus is one of the largest and diverse genera of fungi with huge economical, biotechnological, and social significance. Taxonomically, Aspergillus is divided into six subgenera comprising 27 sections. In this study, 235 strains of Aspergillus subgenus Circumdati (section: Candidi, Circumdati, Flavi, Flavipedes, Nigri, and Terrei) preserved at the Korean Agricultural Culture Collection (KACC) were analyzed and re-identified using a combined dataset of partial b-tubulin (BenA), Calmodulin (CaM) gene sequences and morphological data. We confirmed nineteen species to be priorly reported in Korea (A. neotritici, A. terreus, A. floccosus, A. allahabadii, A. steynii, A. westerdijkiae, A. ochraceus, A. ostianus, A. sclerotiorum, A. luchuensis, A. tubingensis, A. niger, A. welwitschiae, A. japonicus, A. nomius, A. tamarii, A. parasiticus, A. flavi, and A. oryzae). Among the studied strains, three species (A. subalbidus, A. iizukae, and A. uvarum), previously unreported or not officially documented, were discovered in Korea, to the best of our knowledge. We have given a detailed description of the characteristic features of the three species, which remain uncharted in Korea.

• Mycobiology
• /
• v.35 no.4
• /
• pp.191-195
• /
• 2007

The colonization pattern and extent of decay produced in paddy stubble by soil inhabiting mycoflora were done by using nylon net bag technique. Among the three methods used for isolation of fungi, dilution plate technique recorded the highest number of fungi followed by damp chamber and direct observation method. Nutrient availability and climatic conditions (temperature, humidity and rainfall) influenced the occurrence and colonization pattern of fungi. Maximum fungal population was recorded in October ($48.99{\times}10^4/g$ dry litter) and minimum in May ($11.41{\times}10^4/g$ dry litter). Distribution of Deuteromycetous fungi was more in comparison to Zygomycetes, oomycetes and ascomycetes. In the early stage of decomposition Mucor racemosus, Rhizopus nigricans, Chaetomium globosum and Gliocladium species were found primarly whereas at later stages of decomposition preponderance of Aspergillus candidus, Torula graminis, Cladosporiun cladosporioides and Aspergillus luchuensis was recorded.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.51 no.4
• /
• pp.369-375
• /
• 2018

This study investigated the effects of selected seaweeds on rice koji preparation (rice inoculated with Aspergillus luchuensis) and enzyme activity. Four types of rice koji were prepared using one of three seaweeds (0.5% laver, 0.5% kelp and 0.5% green laver) or a control for 72 h. The changes in the moisture content, water activity, pH, total mold cell count, amylase and protease activities were measured. During preparation, there was no significant difference in the moisture content among the four kojis, whereas the pH in the kojis made with either laver or green laver decreased rapidly compared with the control (P<0.05). This seemed to result from the seaweeds promoting the growth of mold cells. In terms of the activities of both amylase and protease, the koji with laver was superior. Subsequently, the amylase and protease activities of the koji made with laver were evaluated at various pHs (3 to 9), temperatures ($15-55^{\circ}C$) and NaCl concentrations (0-10%). The activities of both enzymes decreased notably at pH 9 and the protease activity decreased at temperatures above $45^{\circ}C$. Although the activities of both enzymes decreased at greater than 2.5% NaCl, activity was present at 10% NaCl.