• Animal Bioscience
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• v.35 no.10
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• pp.1461-1478
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• 2022

The maintenance of poultry gut health is complex depending on the intricate balance among diet, the commensal microbiota, and the mucosa, including the gut epithelium and the superimposing mucus layer. Changes in microflora composition and abundance can confer beneficial or detrimental effects on fowl. Antibiotics have devastating impacts on altering the landscape of gut microbiota, which further leads to antibiotic resistance or spread the pathogenic populations. By eliciting the landscape of gut microbiota, strategies should be made to break down the regulatory signals of pathogenic bacteria. The optional strategy of conferring dietary fibers (DFs) can be used to counterbalance the gut microbiota. DFs are the non-starch carbohydrates indigestible by host endogenous enzymes but can be fermented by symbiotic microbiota to produce short-chain fatty acids (SCFAs). This is one of the primary modes through which the gut microbiota interacts and communicate with the host. The majority of SCFAs are produced in the large intestine (particularly in the caecum), where they are taken up by the enterocytes or transported through portal vein circulation into the bloodstream. Recent shreds of evidence have elucidated that SCFAs affect the gut and modulate the tissues and organs either by activating G-protein-coupled receptors or affecting epigenetic modifications in the genome through inducing histone acetylase activities and inhibiting histone deacetylases. Thus, in this way, SCFAs vastly influence poultry health by promoting energy regulation, mucosal integrity, immune homeostasis, and immune maturation. In this review article, we will focus on DFs, which directly interact with gut microbes and lead to the production of SCFAs. Further, we will discuss the current molecular mechanisms of how SCFAs are generated, transported, and modulated the pro-and anti-inflammatory immune responses against pathogens and host physiology and gut health.

• Animal Bioscience
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• v.35 no.11
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• pp.1698-1710
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• 2022

Objective: Raw potato starch (RPS) is resistant to digestion, escapes absorption, and is metabolized by intestinal microflora in the large intestine and acts as their energy source. In this study, we compared the effect of different concentrations of RPS on the intestinal bacterial community of weaned piglets. Methods: Male weaned piglets (25-days-old, 7.03±0.49 kg) were either fed a corn/soybean-based control diet (CON, n = 6) or two treatment diets supplemented with 5% RPS (RPS5, n = 4) or 10% RPS (RPS10, n = 4) for 20 days and their fecal samples were collected. The day 0 and 20 samples were analyzed using a 16S rRNA gene sequencing technology, followed by total genomic DNA extraction, library construction, and high-throughput sequencing. After statistical analysis, five phyla and 45 genera accounting for over 0.5% of the reads in any of the three groups were further analyzed. Furthermore, short-chain fatty acids (SCFAs) in the day 20 fecal samples were analyzed using gas chromatography. Results: Significant changes were not observed in the bacterial composition at the phylum level even after 20 d post feeding (dpf); however, the abundance of Intestinimonas and Barnesiella decreased in both RPS treatment groups compared to the CON group. Consumption of 5% RPS increased the abundance of Roseburia (p<0.05) and decreased the abundance of Clostridium (p<0.01) and Mediterraneibacter (p< 0.05). In contrast, consumption of 10% RPS increased the abundance of Olsenella (p<0.05) and decreased the abundance of Campylobacter (p<0.05), Kineothrix (p<0.05), Paraprevotella (p<0.05), and Vallitalea (p<0.05). Additionally, acetate (p<0.01), butyrate (p<0.05), valerate (p = 0.01), and total SCFAs (p = 0.01) were upregulated in the RPS5 treatment group Conclusion: Feeding 5% RPS altered bacterial community composition and promoted gut health in weaned piglets. Thus, resistant starch as a feed additive may prevent diarrhea in piglets during weaning.

• Journal of Microbiology and Biotechnology
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• v.27 no.8
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• pp.1392-1400
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• 2017

Galactooligosaccharides (GOSs) are known to be selectively utilized by Bifidobacterium, which can bring about healthy changes of the composition of intestinal microflora. In this study, ${\beta}-GOS$ were synthesized using bifidobacterial ${\beta}-galactosidase$ (G1) purified from recombinant E. coli with a high GOS yield and with high productivity and enhanced bifidogenic activity. The purified recombinant G1 showed maximum production of ${\beta}-GOSs$ at pH 8.5 and $45^{\circ}C$. A matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the major peaks of the produced ${\beta}-GOSs$ showed MW of 527 and 689, indicating the synthesis of ${\beta}-GOSs$ at degrees of polymerization (DP) of 3 and DP4, respectively. The trisaccharides were identified as ${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-glucopyranose, and the tetrasaccharides were identified as ${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-glucopyranose. The maximal production yield of GOSs was as high as 25.3% (w/v) using purified recombinant ${\beta}-galactosidase$ and 36% (w/v) of lactose as a substrate at pH 8.5 and $45^{\circ}C$. After 140 min of the reaction under this condition, 268.3 g/l of GOSs was obtained. With regard to the prebiotic effect, all of the tested Bifidobacterium except for B. breve grew well in BHI medium containing ${\beta}-GOS$ as a sole carbon source, whereas lactobacilli and Streptococcus thermophilus scarcely grew in the same medium. Only Bacteroides fragilis, Clostridium ramosum, and Enterobacter cloacae among the 17 pathogens tested grew in BHI medium containing ${\beta}-GOS$ as a sole carbon source; the remaining pathogens did not grow in the same medium. Consequently, the ${\beta}-GOS$ are expected to contribute to the beneficial change of intestinal microbial flora.

• The Korean Journal of Mycology
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• v.32 no.2
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• pp.105-111
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• 2004

The changes of microflora and chemical characteristics during fermentation process of cotton waste for oyster mushroom cultivation were investigated with 5 l bench-scale reactors placed in an incubator at different temperatures ($40,\;50\;and\;60^{\circ}C$). Cotton waste was wetted to 70% moisture, and air flow rates to the substrate were 50, 100 and 300 cc/min. In processing of composting, the mesophilic bacterial population decreased sharply but thermophilic bacterial population increased. In case of fungi, both mesophilic and thermophilic population decreased. The daily $CO_2$ evolution showed little difference in all treatments, while $NH_3$ dropped sharply after 3 days. The desirable composting temperature and air flow based on the mycelial growth of oyster mushroom were $50^{\circ}C$ and 100 cc/min, respectively.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.901-906
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• 1997

In order to reproduce and improve quality of traditional kochujang, various raw materials were added to prepare kochujang by replacing part of the glutinous rice. Chemical composition, microbial characteristics and enzyme activities were investigated during fermentation. Crude protein and salt contents of kochujang did not change significantly during fermentation, but moisture contents increased linearly. The pH and titratable acidity of kochujang changed little in garlic added group. The viable cell counts of aerobic bacteria and yeasts in the kochujang increased until 60 days of fermentation and then decreased slowly except for the garlic added group in which they increased during the last period of fermentation. Aerobic bacterial count did not show any remarkable differences among the samples and slowly decreased after 60 days of fermentation. The activities of liquefying and saccharifying amylases decreased until 45 days, but increased at 60th day. Acidic protease activities of each group were strong during the initial period, but neutral protease showed the highest activity from the 30 to 45 days of fermentation. Protease activities increased by addition of soy sauce, Chinese matrimony vine and purple sweet potato.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.1
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• pp.7-11
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• 1990

As the putrefaction of fish is greatly relied on the microorganisms inhabited in the viscera of them, we investigated the microfloral changes in the viscera of sardine, Sardinops melanosticta, which has been caught a lot in adjacent sea of Korea but showed rapid spoilage, after storages with various temperature. The following results were obtained. Viable cell counts at $25^{\circ}C$ of the viscera of sardine were $1.6\times10^5/g$ at the fresh sample, $1.5\times10^5/g$ at the frozen sample, $2.9\times10^8/g$ at the spoiled samples. The most predominant microbial genera from the fresh sardine were Moraxella spp.($31.4\%$) and Pseudomonas spp.($28.6\%$), but Enterobacteriaceae($83.1\%$) was in spoiled sample. While Moraxella spp.($46.2\%$) and Flavobacterium-Cytophaga($21.0\%$) were predominant in the frozen sample and Enterobacteriacear($69.6\%$) was in the thawed-spoiled sample. The rates of proteolytic enzyme producing bacteria were $20\%$ in the fresh sample, $22\%$ in the frozen sample but the rates were increased to $52\%,\;29\%$ in the spoiled sample and the thawed-spoiled sample respectively.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.94-99
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• 2001

Kochujangs(fermented hot pepper-soybean paste) were prepared either using traditional meju (koji for kochujang) or controlled meju fermented by pure isolates (P-1, P-2), which were screened from traditional meju collected at Sunchang area. The isolates were characterized for their superiority on amylase and protease activities, and overall flavor of the culture on cooked soybean. Bacterial cell counts were not different in all treatments of kochujang during fermentation. The mold counts of each treatment dropped to undetectable level after 40 and 60 days of fermentation, respectively. Heat treatment($60^{\circ}C$, 15 min) before fermentation stopped gas formation and had no effect on bacterial cell count, but the growth of yeast was depressed. Total accumulative volume of gas produced during kochujang fermentation was depended on load of yeast in kochujang and the kochujang using P-2 koji produced least amount of gas among all treatments. The amylase and protease activities of kochujang were not significantly different among traditional and controlled kochujangs.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.671-679
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• 2003

Effects of sun-dried, refined, seaweed, and bamboo salts on the quality of kochujang were studied by measuring enzymatic, microbial, and physicochemical characteristics of kochujang during 12 weeks of fermentation. Yeast count was low in the bamboo-salt kochujang, whereas that of aerobic bacteria was low in the seaweed-salt kochujang. Acid protease activity was high in the bamboo-salt kochujang, whereas amylase activity did not show any remarkable difference. Color change was lowest in the bamboo-salt kochujang. Water activities of all kochujangs decreased during fermentation with the lowest shown in the refined-salt kochujang. Consistency of seaweed-salt kochujang was the highest. Total sugar content was higher, whereas ORP was lower in the seaweed- and bamboo-salt kochujangs. Titratable acidity changed slightly in the bamboo-salt kochujang. Reducing sugar content was the lowest, whereas ethanol content was the highest in the refined-salt kochujang. Amino and ammonia nitrogen contents of kochujangs increased up to the middle of fermentation period then decreased with lower changes observed in the sun-dried and refined-salt kochujangs. Results of sensory evaluation indicated that the bamboo-salt kochujang was more acceptable than the sun-dried salt kochujang in taste, color, and overall acceptabilities.

• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.727-734
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• 2013

Makgeolli mashes that were brewed using five different commercial nuruks (fermentation starters) were investigated for changes in physicochemistry, microbial diversity, and biogenic amine (BA) production. Mash A brewed with the nuruk (Gaeryang-nuruk) had the highest level of alcohol concentration and the greatest number of yeast cells, whereas mash E had the greatest number of bacterial cells. Only three biogenic amines were detected in the makgeolli mashes: tyramine, putrescine, and cadaverine. Using a PCR-DGGE technique, we observed that mash E had the highest BA production, and had the greatest number of bands on the denaturing gradient gels. We also observed that the numbers of bacterial cells correlated significantly with the putrescine and the total BA content, and that the BA content correlated significantly with the color values (L, a, b). This study shows that the quality of a makgeolli can depend on the type of nuruk. Therefore, we suggest that the quality management of makgeolli should start with the stage of nuruk manufacture.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.666-672
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• 2002

Changes in chemical characteristic, microflora, and sensory evaluation of fish sauce extracted at an interval of one week from fermented solution were investigated. pH was reduced from 6.0 to 4.5, and trimethylamine oxide from 132.5 to 87.2 mg/100g during fermenting periods. Trimethylamine increased from 5.6 to 50.2 mg/100g, and volatile basic nitrogen from 48.3 to 232.5 mg/100g. Bacterial flora isolated from the fish sauce were 70% Lactobacillus sp. and 13% Bacillus sp. Among the free amino acids, alanine, glutamic acid, valine, and methionine contents constitute 40% of the total free amino acids. Major non-volatile organic acid of the fish sauce was lactic acid (76%). Sensory evaluation results of the fish sauce were higher than the traditional soybean sauce after 28 days of fermentation.