• 농업과학연구
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• 제47권3호
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• pp.645-655
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• 2020

Bacteria are a very common cause of food poisoning. Moreover, bacteria form biofilms to protect themselves from harsh environments. Conventional detection methods for foodborne bacterial pathogens including the plate count method, enzyme-linked immunosorbent assays (ELISA), and polymerase chain reaction (PCR) assays require a lot of time and effort. Hyperspectral imaging has been used for food safety because of its non-destructive and real-time detection capability. This study assessed the feasibility of using hyperspectral imaging and machine learning techniques to detect biofilms formed by Escherichia coli. E. coli was cultured on a high-density polyethylene (HDPE) coupon, which is a main material of food processing facilities. Hyperspectral fluorescence images were acquired from 420 to 730 nm and analyzed by a single wavelength method and machine learning techniques to determine whether an E. coli culture was present. The prediction accuracy of a biofilm by the single wavelength method was 84.69%. The prediction accuracy by the machine learning techniques were 87.49, 91.16, 86.61, and 86.80% for decision tree (DT), k-nearest neighbor (k-NN), linear discriminant analysis (LDA), and partial least squares-discriminant analysis (PLS-DA), respectively. This result shows the possibility of using machine learning techniques, especially the k-NN model, to effectively detect bacterial pathogens and confirm food poisoning through hyperspectral images.

• 한국식품저장유통학회지
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• 제10권3호
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• pp.411-416
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• 2003

쌀에 존재하며 토양미생물인 Pseudomonas putida 21025를 미강에 배양하여 생성되는 bacteriocin을 미강 필름에 첨가하여 미강필름의 저상성향상을 조사하였다. Pseudomonas putida 21025를 접종한 미강 액체배지는 초기배지 pH 6.48로 자연그대로의 미강 액체배지를 이용하여 항온 배양기에 3$0^{\circ}C$, 150 rpm으로 33시간 배양하여 bacteriocin을 생성하였다. bacteriocin 첨가 후, 필름 가공시에는 bacteriocin의 생산과 안정성을 고려하여 pH 9.4로 조절한 후 한 시간 이내 교반, 8$0^{\circ}C$로 가열 후 2분간 유지의 총시간을 20분 이내로 하여 미강 단백질 필름을 제조하였다. 이러한 방법으로 제조한 미강 단백질 필름의 아미노태 질소함량을 조사한 결과 20% bacteriocin을 첨가한 미강 단백질 필름이 첨가하지 않은 단백질 필름 보다 아미노태 질소함량이 낮은 것으로 나타났다. 따라서 bacteriocin이 미강 단백질 필름 코팅재의 저장기간 향상에 도움을 줄 것으로 보인다.

• 한국토양비료학회지
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• 제48권5호
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• pp.485-491
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• 2015

This study was performed to investigate thermophilic bacteria from soil having broad antifungal spectrum against Rhizoctonia solani, Colletotrichum gloeosporioides, Phytophthora capsici, Fusarium oxysporum f.sp. lycopersici, and Botrytis cinerea. One isolate selected could resist heat shock of $60^{\circ}C$ for one hour, and had broad antifungal activity in dual culture assay against all tested fungal pathogens and was identified as Bacillus amyloliquefaciens Y1 using 16S rRNA gene sequence. Further investigation for antifungal activity of bacterial culture filtrate (BCF) and butanol crude extract (BCE) of various concentrations showed broad spectrum antifungal activity and fungal growth inhibition significantly increased with increasing concentration with highest growth inhibition of 100% against R. solani with 50% BCF and 11 mm of zone of inhibition against R. solani with 4 mg BCE concentration. Treatment of butanol crude extract resulted in deformation, lysis or degradation of C. gloeosporioides and P. capsici hyphae. Furthermore, B. amyloliquefaciens Y1 produced volatile compounds inhibiting growth of R. solani (70%), C. gloeosporioides (65%) and P. capsici (65-70%) when tested in volatile assay. The results from the study suggest that B. amyloliquefaciens Y1 could be a biocontrol candidate to control fungal diseases in crops.

• Journal of Animal Science and Technology
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• 제63권3호
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• pp.575-592
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• 2021

In livestock nutrition, natural feed additives are gaining increased attention as alternatives to antibiotic growth promoters to improve animal performance. This study investigated the effects of dietary turmeric supplementation on the growth performance and gut health of weaned piglets. A total of 48 weaned piglets (Duroc × [Landrace × Yorkshire]) were used in a 6-week feeding trial. All piglets were allotted to two dietary treatments: corn-soybean meal basal diet without turmeric (control) and with 1% weight per weight (w/w) turmeric powder (turmeric). The results showed that dietary inclusion of turmeric with the basal diet improved final body weight and total average daily gain (p < 0.05). The concentrations of short-chain fatty acids in the fecal samples, including acetic, butyric, and propionic acids, were higher in the turmeric group (p < 0.05). The villus height-to-crypt depth ratio was higher in the ileum of turmeric-fed piglets (p = 0.04). The 16S rRNA gene sequencing of fecal microbiota indicated that, at the phylum level, Firmicutes and Bacteroidetes were the most predominant taxa in all fecal samples. Bacteroidetes were significantly decreased in the turmeric group compared to the control group (p = 0.021). At the genus level, turmeric showed a decreased abundance of Prevotella (p = 0.021) and an increasing trend of Lactobacillus (p = 0.083). Among the total detected species, nine bacterial species showed significant differences between the two groups. The results of this study indicated that turmeric altered the gut microbiota and shortchain fatty acid production. This suggests that turmeric could be used as a potential alternative growth promoter for piglets.

• Journal of Animal Science and Technology
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• 제62권6호
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• pp.912-921
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• 2020

We examined the rates of pathogenic bacterial cross-contamination from gloves to meat and from meat to gloves during pork processing under meat-handling scenarios in transfer rate experiments of inoculated pathogens. The inoculated pork contained ~5-6 Log10 CFU/g pathogenic bacteria like Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes), and Salmonella enterica subsp. enterica (Sal. enteritidis). On cotton gloves, after cutting the pork, the cutting board, knife, and cotton gloves showed 3.07-3.50, 3.29-3.92 and 4.48-4.86 Log10 CFU/g bacteria. However, when using polyethylene gloves, fewer bacteria (3.12-3.75, 3.20-3.33, and 3.07-3.97 Log10 CFU/g, respectively) were transferred. When four pathogens (6 Log10 CFU/g) were inoculated onto the gloves, polyethylene gloves showed a lower transition rate (cutting board 2.47-3.40, knife 2.01-3.98, and polyethylene glove 2.40-2.98 Log10 CFU/g) than cotton gloves. For cotton gloves, these values were 3.46-3.96, 3.37-4.06, and 3.55-4.00 Log10 CFU/g, respectively. Use of cotton gloves, polyethylene gloves, knives and cutting boards for up to 10 hours in a meat butchering environment has not exceeded HACCP regulations. However, after 10 h of use, 3.09, 3.27, and 2.94 Log10 CFU/g of plate count bacteria were detected on the cotton gloves, cutting board, and knives but polyethylene gloves showed no bacterial count. Our results reveal the transfer efficiency of pathogenic bacteria and that gloved hands may act as a transfer route of pathogenic bacteria between meat and hands. The best hand hygiene was achieved when wearing polyethylene gloves. Thus, use of polyethylene rather than cotton gloves reduces cross-contamination during meat processing.

• 상하수도학회지
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• 제22권5호
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• pp.571-580
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• 2008

The influence of bacterial stress on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Several physical and chemical stresses (i.e., heating, adding methane producing inhibitor and chemical acidification) were adapted as a pretreament of the seed sludge. In this experiment, the cultivation temperature were set at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) with adjusting pH at 5, 6, and 7 when using the mixture of food waste and activated sludge as a substrate. In conjunction with the pretreatment, hydrogen production was significantly enhanced as compared with that from untreated sludge. However, less biogas (hydrogen and methane) was produced without the pH control, resulted from the decrease of pH to below 4, mainly due to the formation of VFAs. Hydrogen and carbon dioxide gas were analyzed as main components of the biogas while methane not detected. With an application of chemical acidification, the highest hydrogen production value of 248 ml/l/day achieved at pH 7 and $35^{\circ}C$. In addition, more hydrogen gas produced when the ratio of butyric/acetic acid ratio increased. The optimum pH and temperature for hydrogen production were found to be 7 and $35^{\circ}C$, respectively.

• 한국식품위생안전성학회지
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• 제21권2호
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• pp.70-75
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• 2006

서울시 송파구 가락동에 위치한 가락 농수산물 도매 시장에서 구입한 건포류 32건(오징어류 14건, 명태류 10건, 쥐치포 4건, 대구포 그리고 조개류 각각 2건씩)을 조사한 결과를 보면, 그 평균치가 수분 17.28%, 회분 4.92%, 일반 세균수 $1.1{\times}10^7$ CFU/ml, 대장균군수 $9.0{\times}10^3$ CFU/ml, 그리고 포도상구균수 $5.4{\times}10^6$ CFU/ml로 각각 나타났다. 분리 동정된 111주를 살펴보면, 72주의 대장균군속균에서는 21주의 Pantoea spp, 14주의 Enterobacter cloacae, 그리고 13주의 Ranella aquatilis 등이 주로 나타났고, 포도상구균속균 12주 중에서는 Staphylococcus xylosus가 4주로 가장 많았다.

• 한국식품영양학회지
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• 제25권4호
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• pp.951-956
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• 2012

This research was carried out in order to discover acid-forming bacteria during fermentation of Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. In Makgeolli kept at $25^{\circ}C$, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, whereas the total cell count and bacterial type remained unchanged; the result implies that a succession of bacterial types, including acid forming bacteria, occurred. Two acid-forming bacteria were isolated from acidified Makgeolli and were identified as Acetobacter pasteurianus and Lactobacillus casei. When fresh and heat-treated Makgeolli were inoculated with Acetobacter pasteurianus and/or Lactobacillus casei, the greatest amount of acid was formed in Makgeolli inoculated with Acetobacter pasteurianus and Lactobacillus casei and also in Makgeolli with Acetobacter pasteurianus alone. This result indicates that Acetobacter pasteurianus is the main acidifier; furthermore, it shows the synergy effect in acid formation with Lactobacillus casei.

• 한국지역사회생활과학회지
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• 제28권1호
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• pp.131-141
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• 2017

This study was carried out to perform genotoxicological safety evaluation of crude antifungal compounds produced by Bacillus subtilis SN7 (B. subtilis SN7) isolated from meju. Bacterial reverse mutation assay with Salmonella typhimurium TA98, TA100, TA1535, and TA1537 or Escherichia coli WP2uvrA in the presence and absence of the S9 metabolic activation system was carried out, and the crude antifungal compounds produced by B. subtilis SN7 showed no significant increase in the number of revertant colonies. In the chromosomal aberration tests using Chinese hamster lung (CHL) cells, sample treatment groups showed no increase in the frequency of chromosome aberrations compared to the negative control group. Furthermore, in the micronucleus formation test, the crude antifungal compounds showed no significance increase in the frequency of polychromatic erythrocytes with micronuclei. These results suggest that the crude antifungal compounds produced by B. subtilis SN7 isolated from meju showed no harmful genotoxic effects.

• Applied Biological Chemistry
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• 제36권6호
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• pp.476-480
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• 1993

제초성항생물질인 maculosin과 phenylacetic acid를 생산하는 균주를 Streptomyces rochei로 동정하였다. 동정은 형태학적 및 생리학적 특성시험에 기초하였다. 이 균주는 진균류인 Alternaria altenata 외에 maculosin의 생성이 보고된 최초의 Streptomyces 속 균주이다.