• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.527-532
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• 2023

Brewer's spent grain (BSG) is a waste product of the beer industry, and γ-aminobutyric acid (GABA) is a physiologically active substance important for brain and neuron physiology. In this study, we used the bacterial strains Bacillus velezensis DMB06 and B. licheniformis 0DA23-1, respectively, to ferment BSG and produce GABA. The GABA biosynthesis pathways were identified through genomic analysis of the genomes of both strains. We then inoculated the strains into BSG to determine changes in pH, acidity, reducing sugar content, amino-type nitrogen content, and GABA production, which was approximately doubled in BSG inoculated with Bacillus compared to that in uninoculated BSG; however, no significant difference was observed in GABA production between the two bacterial strains. These results provide the experimental basis for expanding the use of BSG by demonstrating the potential gain in increasing GABA production from a waste resource.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.838-843
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• 2005

Bacterial suspension test was used to establish Standardization Test Method to investigate bactericidal activity of disinfectant/sanitizer product. Using acceptable verification methodology, test substance showing 5 log or higher reduction in viable count against Escherichia coli ATCC 10536 and Staphylococcus aureus ATCC 6538, representing Gram-negative and -positive bacteria, respectively, under test conditions for $5\;min{\pm}10\;sec\;at\;20{\pm}1^{\circ}C$ was considered to have sanitizing capability. All disinfectant/sanitizer products tested under manufacturer's recommended in-use condition gave good reduction values against major food-poisoning bacteria. This standardized method was valuable for evaluating efficacy of disinfectants/sanitizers and could be used as Standardization Test Method for assessing bactericidal activity

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.329-334
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• 2009

Bacterial numbers, such as endospore-formers, and treatment efficiencies were investigated for Rotating Activated Bacillus Contactors (RABC) and other advanced wastewater treatment processes including anaerobic-anoxic-oxic (A2O), sequencing batch reactor (SBR) and biological aerated filter (BAF). Endospore-forming bacterial numbers in the RABC showed 129-fold higher levels than those of the existing advanced systems. RABC process demonstrated the highest bacterial numbers in its bioreactors (paired t-test, p<0.01). RBC biofilms and aeration tanks of the RABC system showed 131- and 476-fold higher than other existing advanced processes, respectively. Mean treatment efficiencies of the existing systems were 83.5% for chemical oxygen demand (COD), 59.1% for total nitrogen (TN) and 76.8% for total phosphorus (TP). However, RABC process removed 96.9% for COD, 96.9% for TN and 91.9% for TP for highly concentrated food wastewater (COD>1,500 mg/L, TN>150 mg/L, TP>50 mg/L). Treatment efficiency was significantly reduced when the numbers of Bacillus genus in the bioreactors decreased below $10^6CFU/mL$. The automated RABC (A-RABC), in which dissolved oxygen concentrations are automatically controlled, showed higher treatment efficiencies compared to the RABC process. The RABC system maintained sufficient bacterial numbers for the effective treatment of highly concentrated food wastewater. Moreover, final effluent was in agreement to water quality standards.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.764-769
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• 1994

This study was performed to obtain fast, consistant and reliable estimation system of bacterial counts of raw milk, which effectively related to the quality of sanitaion and the condition of production at the farm. This study compared regression equation and correlation coefficient relationship between standard plate counts and data of Malthus conductance method for the detection time of total, psychrotrophs, coliform bacterial counts in raw milk. Regression equation (RE) between conductance detection time (Y) and total bacterial log counts (X) was Y=18.27651 - 2.07550X, with correlation coefficient -0.95(n=201). In coliform, RE was Y=9.320848 - 1.15598X with correlation coefficient -0.90 (n=207). Psychrotrophs had the RE of Y=29.96008-3.02487 with correlation coeffecient -0.9 (n=201). This conductance method gave results more quickly and was less labor-intensive than traditional standard plate count method.

• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.823-830
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• 2005

This study was undertaken to evaluate the effect of bacteria-derived $\beta$-glucan fiber on serum lipids, adiposity and uncoupling protein (UCP) expression in rats. In order to induce obesity, Sprague-Dawley weanling male rats were allowed free access to AIN-76A diet until 4 weeks of age, and fed high-fat diet (beef tallow, $40\%$ of calories as fat) for 6 weeks until 10 weeks of age. Rats were then fed with $0\%$ thigh- fat control group), $1\%$, or $5\%$ bacterial ~-glucan supplemented high-fat diets (w/w) for another 6 weeks. For comparison, normal control group was fed with AIN-76 diet $11.7\%$ fat). Supplementation with bacterial $\beta$-glucan resulted in a significant reduction of high-fat-induced white fat (i.e., visceral and peritoneal fat) development, adipocyte hypertrophy, and development of hyperinsulinemia and hyperleptinemia. Serum triglyceride, total cholesterol, and free fatty acid levels were greatly reduced, but, HDL-cholesterol concentrations were increased by bacterial $\beta$-glucan supplementation. Serum leptin level was lower in the $\beta$-glucan groups than in the high-fat group. The expression of UCPs (UCP1, UCP2, and UCP3) in brown adipose tissue (BAT) were significantly increased by $5\%$ bacterial $\beta$-glucan-containing diet. This study suggests that the anti-obesity effect of $5\%$ bacterial $\beta$-glucan is attributed to upregulation of UCPs and inefficient energy utilization.

• Food Science of Animal Resources
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• v.26 no.3
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• Journal of the Korean Society of Food Culture
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• v.23 no.5
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• pp.629-638
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• 2008

The principal objective of this study was to determine the quality characteristics of seasoned sauce and seasoned pork rib to which pine needle powder was added during storage. The pH value, color value, active bacterial cell count, lipid oxidation, shear force, and sensory evaluation of seasoned sauce and seasoned pork rib to which 0, 1, 2, 3 and 4% pine needle powder was added were measured during storage at $5^{\circ}C$. The storage periods for the seasoned sauce were 0, 1, 3, 5, 7, 14, 21 and 30 days, and the storage periods for the seasoned pork ribs were 0, 1, 3, 5, 7 days. We determined that the pH values of both seasoned sauce and seasoned pork rib decreased with increasing quantities of pine needle powder and longer storage periods. The lightness (L) and yellowness (b) of the seasoned sauce were increased and the redness (a) of that decreased with increasing pine needle powder contents and longer storage periods. The L, a, and b values of the seasoned pork rib decreased with increasing pine needle powder contents, whereas the L and b values of that were decreased and the a value increased with longer storage periods. The active bacterial cell count of the seasoned sauce was detected at between $10^2$ to $10^4$ CFU/mL over a storage period of 30 days, regardless of the addition of pine needle powder; additionally, the addition of 4% pine needle powder resulted in the lowest active bacterial cell count among the samples. The active bacterial cell count in the seasoned pork rib decreased with increasing additions of pine needle powder, and was increased during storage. The influence of pine needle powder contents on the active bacterial cell count of seasoned pork rib were minimal, and the active bacterial cell count of that was suppressed by the addition of only 1% pine needle powder. Lipid oxidation in the seasoned pork rib was suppressed by the addition of more than 2% pine needle powder. We noted no difference in the shear force of the seasoned pork rib to which pine needle powder was added. In our sensory evaluation, the intensity of color (greenish brown), flavor (herbal flavor) and taste (bitter & herbal taste) of the seasoned pork rib increased with increasing pine needle powder contents, whereas the texture of the seasoned pork rib evidenced no differences. The overall acceptability of the seasoned pork rib with 0, 1 and 2% added pine needle powder was higher than that of the seasoned pork rib with 3 and 4% added pine needle powder. Thus, the addition of 2% pine needle powder to seasoned pork rib sauce yielded appropriate results with regard to antibacterial, antioxidative, and sensory properties.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.9
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• pp.1362-1370
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• 2015

This study was performed to investigate the effect of different levels of dietary crude protein (CP) on composition of odorous compounds and bacterial communities in pig manure. A total of 48 male pigs (average initial body weight 45 kg) fed diets containing three levels of dietary CP (20%, 17.5%, and 15%) and their slurry samples were collected from the pits under the floor every week for one month. Changes in composition of odorous compounds and bacterial communities were analyzed by gas chromatography and 454 FLX titanium pyrosequencing systems, respectively. Levels of phenols, indoles, short chain fatty acid and branched chain fatty acid were lowest (p<0.05) in CP 15% group among three CP levels. Relative abundance of Bacteroidetes phylum and bacterial genera including Leuconostoc, Bacillus, Atopostipes, Peptonphilus, Ruminococcaceae_uc, Bacteroides, and Pseudomonas was lower (p<0.05) in CP 15% than in CP 20% group. There was a positive correlation (p<0.05) between odorous compounds and bacterial genera: phenol, indole, iso-butyric acid, and iso-valeric acid with Atopostipes, p-cresol and skatole with Bacteroides, acetic acid and butyric acid with AM982595_g of Porphyromonadaceae family, and propionic acid with Tissierella. Taken together, administration of 15% CP showed less production of odorous compounds than 20% CP group and this result might be associated with the changes in bacterial communities especially whose roles in protein metabolism.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.283-289
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• 2002

This study was performed to search for potential microorganism that has rapid fermenting and physiological function from anchovy sauce. We isolated three bacterial strains, JM-1, JM-2, and JM-3 with proteolytic and fibrinolytic activity from anchovy sauce. Among the 3 bacterial strains, JM-3 showed the strongest proteolytic and fibrinolytic activity. Bacterial strain JM-3 was gram-positive rod, motile and formed endospore. The 16S rRNA of bacterial strain JM-3 was amplified by PCR and then its sequence was determined by ABI 310 genetic analyzer. The 16S rRNA sequence of bacterial strain JM-3 was compared to BLAST DNA database and identified to Bacillus subtilis with 99% of homology. The optimum temperature, pH and NaCl concentration for growth of B. subtilis JM-3 were $40^{\circ}C$, 5.0 and 0%, respectively. The optimum temperature, pH and NaCl concentration for proteolytic and fibrinolytic enzyme production of B. subtilis JM-3 were same as optimum conditions for growth. At 20% of NaCl concentration which is common NaCl concentration of fish sauce, B. subtilis JM-3 showed about 60% of proteolytic and fibrinolytic activity of 0% NaCl concentration. From above results, we found that B. subtilis JM-3 will be able to used for starter of functional fish sauce.

• Food Science and Preservation
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• v.17 no.4
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• pp.444-450
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• 2010

We investigated the quality of Dombaeki (shark meat) treated without salting (NS), with salting (S), air-packed (A), and vacuum-packed (V), during storage at $4^{\circ}C$ and $-18^{\circ}C$. We explored water holding capacity, elasticity, total bacterial counts, pH, titratable acidity level, volatile basic nitrogen (VBN) value, and drip loss. Water holding capacity and elasticity values were better when salting and vacuum-packaging were employed than when samples were not salted and were packaged in air. The total bacterial counts in SV meat were significantly lower than in other samples. The pH of all samples increased slowly during storage, and the pH values of NSA samples were significantly higher than the pH values of other samples. The VBN level and drip loss of SV meat were the lowest of all samples during storage. The results show that salted vacuum-packed meat was of better quality than that stored without salting, and air-packed, regardless of storage temperature.