• Food Science of Animal Resources
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• v.44 no.4
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• pp.912-933
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• 2024

The objective of this study was to isolate, identify, and evaluate novel Korean starter cultures for use in fermented sausages. A total of 72 strains were isolated from various indigenous sources, including Nuruk, Jeotgal, and mudflats on the west coast of South Korea. Two strains were identified as Penicillium nalgiovense (SD01 and SJ02), a traditional starter used in the production of fermented sausages. A comparative analysis was performed between SD01 and SJ02 using the commercial starter culture (M600). Strain SJ02 exhibited superior lipolytic and proteolytic activities, as well as an enhanced growth rate at the optimal salinity level of 2% NaCl compared to M600. No significant differences were observed in thiobarbituric acid reactive substances values, sausage colors, and texture properties between SJ02 and M600 fermented sausages, except for adhesiveness. Profiles of mycotoxin-related genes were similar for both strains. Electronic nose analysis revealed distinct aroma profiles between SJ02 and M600 fermented sausages, with a relatively higher levels of propan-2-one and butyl butanoate in SJ02, and a higher level of ethanol and propanal in M600. In electronic tongue analysis, there was no significant differences in taste characteristics between SJ02 and M600. These results indicate that P. nalgiovense SJ02 is a potential starter culture to produce dry fermented sausages, enhancing Korean style cured meat processing industry.

• Mycobiology
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• v.42 no.3
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• pp.291-295
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• 2014

Mycoflora was assessed in the commercial meju from four well-separated geographic origins. A total of 112 fungal isolates were identified by phenotypic characteristics and molecular taxonomy using sequencing the internal transcribed spacer of the rDNA and revealed 19 species from 13 genera. Enzymatic characteristics of protease and amylase, and mycotoxin production were analyzed.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.11-11
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• 2015

A total of sixty-six samples of Nuruk, a fermention starter used to make the Korean traditional rice wine, Makgeolli, were collected from central and southern regions of Korea in 2013 and 2014. We classified two groups of the Nuruk samples, "commercial" and "home-made", according to the manufacturing procedure and purpose of use. Commercial Nuruks were made in a controlled environment where the temperature and humidity are fixed and the final product is supplied to Makgeolli manufacturers. Home-made Nuruks were made under uncontrolled conditions in the naturally opened environment and were intended for use in the production of small amounts of home-brewed Makgeolli. We obtained more than five hundred isolates including filamentous fungi and yeasts from the Nuruk samples followed by identification of fungal species. Also we stored glycerol stocks of each single isolate at $-70^{\circ}C$. We identified the species of each isolate based on the sequences of ITS regions amplified with two different universal primer pairs. We also performed morphological characterization of the filamentous fungi and yeast species through observations under the microscope. We investigated the major fungal species of commercial and home-made Nuruks by counting the colony forming units (CFU) and analyzing the occurrence tendency of fungal species. While commercial Nuruks contained mostly high CFU of yeasts, home-made Nuruks showed relatively high occurrence of filamentous fungi. One of the representative Nuruk manufacturers used both domestic wheat bran and imported ones, mainly from US, as raw material. Depending on the source of ingredient, the fungal diversity was somewhat different. Another commercial Nuruk sample was collected twice, once in 2013 and again in 2014, and showed different diversity of fungal species in each year. Nuruks obtained from the southern regions of Korea and Jeju island showed high frequency of yeast such as Saccharomycopsis fibuligera and Pichia species as well as unique filamentous fungus, Monascus species. S. fibuligera was easily found in many Nuruk samples with high CFU. The major filamentous fungi were Aspergillus, Lichtheimia, Mucor and Penicillium species. In order to further our understanding of the isolates and their potential industrial applications, we assayed three enzymes, alpha amylase, glucoamylase and acid protease from 140 isolates out of about five hundred isolates and selected about 10 excellent strains with high enzyme activities. With these fungal isolates, we will perform omics analyses including genomics, transcriptomics, metabolic pathway analyses, and metabolomics followed by whole genome sequencing of unique isolates associated with the basic research of Nuruk and that also has applications in the Makgeolli making process.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.57-66
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• 2017

Aflatoxins are classified as Group 1 (carcinogenic to humans) by the International Agency for Research on Cancer. In this study, a total of 134 fungal strains were isolated from 65 meju samples, and two fungal isolates were selected as potential aflatoxin $B_1$ ($AFB_1$)-biodetoxification fungi. These fungi were identified as Aspergillus oryzae MAO103 and A. oryzae MAO104 by sequencing the beta-tubulin gene. The two A. oryzae strains were able to degrade more than 90% of $AFB_1$ (initial concentration: $40{\mu}g/l$) in a culture broth in 14 days. The mutagenic effects of $AFB_1$ treated with A. oryzae MAO103 and MAO104 significantly decreased to 5.7% and 6.4%, respectively, in the frame-shift mutation of Ames tests using Salmonella typhimurium TA98. The base-substituting mutagenicity of $AFB_1$ was also decreased by the two fungi. Moreover, $AFB_1$ production by Aspergillus flavus was significantly decreased by the two A. oryzae strains on soybean-based agar plates. Our data suggest that the two $AFB_1$-detoxifying A. oryzae strains have potential application to control $AFB_1$ in foods and feeds.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.32-39
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• 2018

Samples of Laru (a fermentation starter) obtained from the upper part of Borneo Island were analyzed for their lactic acid bacteria (LAB) and fungal diversity using both a culture-independent method (PCR-DGGE) and culture-dependent methods (SDS-PAGE and MALDI-TOF MS). Pediococcus pentosaceus, Lactobacillus brevis, Saccharomycopsis fibuligera, Hyphopichia burtonii, and Kodamaea ohmeri were detected by all three methods. In addition, Weissella cibaria, Weissella paramesenteroides, Leuconostoc citreum, Leuconostoc mesenteroides, Lactococcus lactis, Rhizopus oryzae/Amylomyces rouxii, Mucor indicus, and Candida intermedia were detected by PCR-DGGE. In contrast, Lactobacillus fermentum, Lactobacillus plantarum, Pichia anomala, Candida parapsilosis, and Candida orthopsilosis were detected only by the culture-dependent methods. Our results indicate that the culture-independent method can be used to determine whether multiple laru samples originated from the same manufacturing region; however, using the culture-independent and the two culture-dependent approaches in combination provides a more comprehensive overview of the laru microbiota.

• Mycobiology
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• v.50 no.6
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• pp.408-419
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• 2022

Filamentous fungi that could be classified into Aspergillus flavus/oryzae were isolated from traditionally fermented meju commercially available in Korea. The samples were analyzed for aflatoxin B1 and ochratoxin A contamination by HPLC; however, no toxin was detected. In addition, fungal and bacterial metagenomic sequencing were performed to analyze the microbial distribution in the samples. The results revealed that the distribution and abundance of fungi and bacteria differed considerably depending on the production regions and fermentation conditions of the meju samples. Through morphological analysis, ITS region sequencing, and assessment of the aflatoxin-producing ability, a total of 32 A. flavus/oryzae strains were identified. PCR analysis of six regions with a high mutation frequency in the aflatoxin gene cluster (AGC) revealed a total of six types of AGC breaking point patterns. The A. flavus/oryzae strains did not exhibit the high amylase activity detected in the commercial yellow koji strain (starter mold). However, their peptidase and lipase activities were generally higher than that of the koji isolates. We verified the safety of the traditionally fermented meju samples by analyzing the AGC breaking point pattern and the enzyme activities of A. flavus/oryzae strains isolated from the samples. The isolated strains could possibly be used as starter molds for soybean fermentation.

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

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.654-662
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• 2024

To investigate the effect of the predominant fungal species from Korean traditional meju and doenjang on soybean fermentation, the enzymatic activity and amino acid production of twenty-two fungal strains were assessed through solid- and liquid-state soybean fermentation. Enzymatic activity analyses of solid-state fermented soybeans revealed different enzyme activities involving protease, leucine aminopeptidase (LAP), carboxypeptidase (CaP), glutaminase, γ-glutamyl transferase (GGT), and amylase, depending on the fungal species. These enzymatic activities significantly affected the amino acid profile throughout liquid-state fermentation. Strains belonging to Mucoromycota, including Lichtheimia, Mucor, Rhizomucor, and Rhizopus, produced smaller amounts of total amino acids and umami-producing amino acids, such as glutamic acid and aspartic acid, than strains belonging to Aspergillus subgenus circumdati. The genera Penicillium and Scopulariopsis produced large amounts of total amino acids and glutamic acid, suggesting that these genera play an essential role in producing umami and kokumi tastes in fermented soybean products. Strains belonging to Aspergillus subgenus circumdati, including A. oryzae, showed the highest amino acid content, including glutamic acid, suggesting the potential benefits of A. oryzae as a starter for soybean fermentation. This study showed the potential of traditional meju strains as starters for soybean fermentation. However, further analysis of processes such as the production of G-peptide for kokumi taste and volatile compounds for flavor and safety is needed.

• Korean Journal of Microbiology
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• v.7 no.4
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• pp.159-166
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• 1969

It is necessry to develop and strengthen the activity of enzymic source which in low applied for maggerley brewing as an amylolytic and proteolytic starter, recently in this country the active and strong enzymic starter is required for the better brewing and to substitute another starch material for the present wheat flour. In this study, manufacturing method the strong enzymic source have been developed and established with use of raw wheat bran plus fungal strains of Rhizopus sp. and Aspergillus usamii the culture of starter. The results on experimental the activities of enzymic sources (stater) are as following ; 1. Method of making the enzymic source (starter) is to cultivate the strains of Asperguillus orzyae, Asp. kawachii, Asp usamii and Rhizopus sp. in the acid treated raw or heatboiled wheat bran. 2. The saccharogenic pwoer (S.P.) of enzymic source which consisted of raw bran plus fungi and cultured in it is generally stronger than those of heat-boiled bran plus fungi, the strongest power was shown in the culture of Rhizopus plus raw bran, and the next other is in mixture of Asp.usamii and Rhizopus on raw wheat bran. 3. The most strong alpha amylase activity was expressed in the plot of Asp.oryzae on heat-boiled wheat bran, the next was in the culture of Rhizopus nad Aspergillus usamii on raw wheatbran. 4. The most vigourous acidic proteinase activity was expressed in the micture of raw bran plus Asp. usamii and Rhizopus those were independentlu cu;tured before mixing for neutral proteinase activity, it was shown in the mixed culture of Asp. usamii and Rhizopus on raw wheat bran, the msot active alkaline proteinase activity of enzymic source was found in the plot of raw bran material. 5. For poly-preptidase activity in pH 6.5 it is found that the culture of Rhizopus and Asp.usamii on raw bran was most active among them of enzymic sources. 6. Generally, it is concluded that culture of fungi on acid treated raw wheat bran is stronger in its activity than those of heat boiled wheat bran, especially the culture of Rhizopus nad Asp.usamii on raw bran exhibited the most vigorous and non-polarized activity for all aspects, so it is considered to be most desirable enzymic stater in Korean Maggerley brewing and this would be able to substitute brewing material for the present wheat flour because of its strong and wide hand activity of amylolytic and proteolytic action.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.759-766
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• 1997

From Nuruks, a traditional Korean starter for rice wine, collected from 42 different areas in Korea, 111 fungal strains were isolated. These isolates were identified as 25 species belonging to seven genera of Rhizopus oryzae(14 strains), R. oligosporus(8 strains), R. nigricans(5 strains), R. arrhizus (5 strains), Aspergillus oryzae(12 strains),Asp. parasiticus(8 strains), Asp. fumigatus(3 strains), Asp. ochraceus(7 strains), Asp. wentii(5 strains), Asp. parasiticus(8 strains), Asp. penicilloides(3 strains), Asp. clavatus(4 strains), Penicillium purpurogenum(2 strains), Pen. glabrum(1 strain), Pen. granulaturm (1 strsin), Pen. fellutanum(1 strain), Geotrichum candidum(2 strains), Absidia corymbifera(12 strains), Mucor racemosus(2 strains), M. plumbeus(2 strains) and Curvularia lunatus(3 strains).