• Journal of Microbiology and Biotechnology
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• v.32 no.7
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• pp.877-884
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• 2022

Probiotics are microorganisms that can benefit host health when ingested in a live state, and lactic acid bacteria are the most common type. Among fungi, Saccharomyces boulardii (SB) is the only strain known to have a probiotic function with beneficial effects on colitis; however, information on other probiotic yeast strains is limited. Therefore, this study aimed to discover yeast strains expressing intestinal anti-inflammatory activities by exhibiting probiotic properties in dextran sodium sulfate (DSS)-induced colitis mice model. Nuruk (Korean traditional fermentation starter) containing various microbial strains was used as a source for yeast strains, and S. cerevisiae 28-7 (SC28-7) strain was selected with in vitro and in vivo characteristics to enable survival in the intestines. After 14 days of pretreatment with the yeast strains, DSS was co-administered for six days to induce colitis in mice. The results revealed that the disease activity index score was lowered by SC28-7 treatment compared to the DSS group, and the colon length and weight/length ratio were recovered in a pattern similar to that of the normal group. SC28-7 administration significantly reduced the secretion of pro-inflammatory cytokines in the serum and modified the mRNA expression of inflammatory cytokines (interleukin-1β, transforming growth factor-β, and interferon-γ) and proteins involved in gut barrier functions (mucin 2, mucin 3, zonula occludens-1, and occludin) in colon tissues. These results indicate that SC28-7 attenuates DSS-induced colon damage and inflammation, supporting its future use as a probiotic yeast for treating and preventing intestinal inflammatory diseases such as inflammatory bowel disease.

• Korean Journal of Food Science and Technology
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• v.53 no.5
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• pp.657-668
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• 2021

We prepared the growth and survival models of enterohemorrhagic Escherichia coli (EHEC) and Campylobacter jejuni in milk as a function of temperature and assessed the microbiological risks associated with the consumption of whole milk. EHEC and C. jejuni were not detected in whole milk (n=195) in the retail market. The minimum growth temperature of EHEC in milk was 7℃. The lag time of EHEC in whole milk was longer than that in skim milk. The survival ability of C. jejuni in milk was better at 4℃ than at 10℃. Lower delta values were observed in whole milk than in skim milk, indicating that C. jejuni survived better in skim milk. The probability of foodborne illness from whole milk consumption was 5.70×10^-5 for EHEC and 9.86×10^-9 for C. jejuni. Sensitivity analysis results show that the market temperature of EHEC and the dose-response model of C. jejuni are correlated with the probability of foodborne illness.

• Journal of Korean Academy of Dental Administration
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• v.6 no.1
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• pp.19-27
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• 2018

The purpose of this study was to determine the level of toothbrush bacterial growth, whether the dryness of the toothbrush head differs depending on the number of holes in the head, and to use these results as a reference for future toothbrush design. Two-millimeter holes were created on the head of the toothbrushes in groups of three, one, or zero holes. We made the solution with Streptococcus mutans, and the toothbrushes were placed in the solution and agitated. The toothbrushes were shaken to remove moisture and allowed to air-dry. The toothbrush heads were swabbed with saline and then placed in two inoculation groups. The first group was inoculated with a 102 dilution of the S. mutans culture and the second was inoculated with the original culture. After incubation, bacterial colony numbers were measured. The number of holes on the toothbrush head correlated with a decrease in number of cultured bacterial colonies. Our model of a toothbrush head with holes indicated that these holes in the toothbrush head were effective in reducing the level of microbial contamination and that a greater number of holes creates an improved toothbrush sanitation effect. The average number of colonies on the head of toothbrush by number of holes was high, followed by the number of holes 0, 1 and 3, and the average number of colony among toothbrush heads was same. The use of a toothbrush with holes between the toothbrush head indicates that it is effective in reducing the level of microbial contamination between the toothbrush head and toothbrush and the higher the number of holes, the better the effect.

• Animal Bioscience
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• v.34 no.7
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• pp.1202-1209
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• 2021

Objective: The intestinal microbiota plays an important role in host physiology, metabolism, immunity, and behavior. And host genetics could influence the gut microbiota of hybrid animals. The three-way cross model is commonly utilized in commercial pig production; however, the use of this model to analyse the gut microbial composition is rarely reported. Methods: Two three-way hybrid pigs were selected, with Saba pigs as the starting maternal pig: Duroc× (Berkshire×Saba) (DBS) pig, Berkshire×(Duroc×Saba) (BDS) pig. One hundred pigs of each model were reared from 35 days (d) to 210 d. The body weight or feed consumption of all pigs were recorded and their feed/gain (F/G) ratio was calculated. On day 210, 10 pigs from each three-way cross were selected for slaughter, and cecal chyme samples were collected for 16S rRNA gene sequencing. Results: The final body weight (FBW) and average daily gain (ADG) of DBS pigs were significantly higher than those of BDS pigs (p<0.05), while the F/G ratios of DBS pigs were significantly lower than those of BDS pigs (p<0.05). The dominant phyla in DBS and BDS pigs were Bacteroidetes (55.23% vs 59%, respectively) and Firmicutes (36.65% vs 34.86%, respectively) (p>0.05). At the genus level, the abundance of Prevotella, Roseburia, and Anaerovibrio in DBS pigs was significantly lower than in BDS pigs (p<0.01). The abundance of Eubacterium, Clostridium XI, Bacteroides, Methanomassiliicoccus, and Parabacteroides in DBS pigs was significantly higher than in BDS pigs (p<0.05). The FBWs and ADGs were positively correlated with Bacteroides, ClostridiumXI, and Parabacteroides but negatively correlated with the Prevotella, Prevotella/Bacteroides (P/B) ratio, Roseburia, and Anaerovibrio. Conclusion: These results indicated that host genetics affect the cecal microbiota composition and the porcine gut microbiota is associated with growth performance, thereby suggesting that gut microbiota composition may be a useful biomarker in porcine genetics and breeding.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.84-91
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• 2000

Mycopasma contamination of tissue culture cells easily evades detection and, thus, represents a continous therat to cell biologists. In case where infected cell can not simply be replaced, attempts have to be made to eradicate mycoplacma from the tissue culture cells. A variety of anti-microbial agents have been shown to be toxic to mycoplasma strains ; however, cell associated mycoplasma are often protected from antibiotics at concentrations shown to be effective in vitro. Antibiotic concentrations high enough to be lethal to cell as sociated mycoplasmas frequently are also detrimentrations to the host cells, while moderately increased antibiotic levels tolerated by the host cells often lead to only temporary growth suppression and/or to the emergence of mycoplasma strains resistanct even to high concentrations of the antibiotis applied. Hare, a genetic approach for the elimination of mycoplasma from tissue culture cells that overcomes thens limitations is described. By expression of a selection marker conferring resistance to an otherwise toxic agent, Acholeplasma laidlawii infected BHK-21 cells used as the model system were enabled to temporarily tolerate antibiotic concentrations high enough to be lethal to cell associated mycopalsma while leaving the host cells unharmed. Upon successful mycoplasma eradicated, cultvation of the cured host cells in the absence of the selective agent yielded revertant cell clones that had regained susceptibillity to the toxic agent. Cressation of the selection marker expression was shown to result from the loss of the selection marker DNA, which is a consequence of the fact that the stable and permanent integration of foreign DNA in eucaryotic cell chrosomes is highly inefficient. Thus, the cells were cured from mycoplasma yet remained biochemically unaltered.

• Natural Product Sciences
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• v.23 no.2
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• pp.125-131
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• 2017

Clitoria ternatea or Commonly known blue pea, is a perennial climber crop native to Asian countries. The current study was aimed to evaluate the antimicrobial activity C. ternatea extract on food borne microorganisms and its antifungal effect on Penicillium expansum. The extract showed significant antimicrobial activity against 3 Gram positive bacteria, 2 Gram negative bacteria and 1 filamentous fungus on disc diffusion assay. The extract also showed good biocidal effect on all Gram positive bacteria tested and P. expansum. However, the kill curve analysis revealed that the fungicidal activity of the extract against P. expansum conidia was depend on the concentration of the extract and the time of exposure of the conidia to the extract. The scanning electron micrograph of the extract treated P. expansum culture showed alterations in the morphology of fungal hyphae. The germination of P. expansum conidia was completely inhibited and conidial development was totally suppressed by the extract, suggesting the possible mode of action of anthocyanin. Besides, the extract also exhibited 5.0-log suppression of microbial growth relative to control in the rice model. The results indicate the potential use of the C. ternatea anthocyanin as food biopreservative.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.79-84
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• 2014

Purpose: While single-species biofilms have been studied extensively, we know notably little regarding multispecies biofilms and their interactions. The purpose of this study was to develop and evaluate an in vitro multispecies dental biofilm model that aimed to mimic the environment of chronic periodontitis. Methods: Streptococcus gordonii KN1, Fusobacterium nucleatum ATCC23726, Aggregatibacter actinomycetemcomitans ATCC33384, and Porphyromonas gingivalis ATCC33277 were used for this experiment. The biofilms were grown on 12-well plates with a round glass slip (12 mm in diameter) with a supply of fresh medium. Four different single-species biofilms and multispecies biofilms with the four bacterial strains listed above were prepared. The biofilms were examined with a confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM). The minimum inhibitory concentrations (MIC) for four different planktonic single-species and multispecies bacteria were determined. The MICs of doxycycline and chlorhexidine for four different single-species biofilms and a multispecies biofilm were also determined. Results: The CLSM and SEM examination revealed that the growth pattern of the multispecies biofilm was similar to those of single-species biofilms. However, the multispecies biofilm became thicker than the single-species biofilms, and networks between bacteria were formed. The MICs of doxycycline and chlorhexidine were higher in the biofilm state than in the planktonic bacteria. The MIC of doxycycline for the multispecies biofilm was higher than were those for the single-species biofilms of P. gingivalis, F. nucleatum, or A. actinomycetemcomitans. The MIC of chlorhexidine for the multispecies biofilm was higher than were those for the single-species biofilms of P. gingivalis or F. nucleatum. Conclusions: To mimic the natural dental biofilm, a multispecies biofilm composed of four bacterial species was grown. The 24-hour multispecies biofilm may be useful as a laboratory dental biofilm model system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.340-360
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• 1982

Because of the continuing rapid increase in pesticide usage in Taiwan, much attention has been focus on pesticide contamination of food and effect of pesticides on human and environmental health. The Plant Protection Center (PPC) conducts safety evaluation of pesticides usee! in Taiwan. The pesticides are classified into different groups based on their acute toxicities. Pesticides which are classified into extremely toxic group are not allow to used on short term crops or the continuously harvest crops. The acute toxicity of pesticides to the beneficial insects are also studied, special attention has been paid to the two predators of rice brown planthopper. 60% of cultivated land in Taiwan are paddy field; therefore, acute fish toxicity was taken into consideration when a pesticide was applied for registration to be used in the paddy. Fish toxicities were evaluated by the dangerous rating value which is the amount of pesticide residue in the field water over the TLM value. Mutagenicity of pesticides was continuously evaluated by using Arne's microbial testing method. Island wide survey of residual levels of pesticides of known pollutants such as chlorinated hydrocarbon . insecticides, mercurial compounds in soil, water and biological samples were carried out constantly. The potential of a new1y Imported esticides to pollute the environment were studied by using model ecosystem. Ecological magnification (EM) of a chemical was calculated from model ecosystem. A chemical was considered as a pollutant when its EM value over 5000. In order to ensure the levels of pesticides residue of the crop within the safety limit. The 'tolerance' of pesticides on different crop groupings were established base on 1) acceptable daily intake value of individual pesticides, 2) average daily consumption of each crop groupings by Chinese person, 3) Actual residues of pesticides. on different crops obtained from supervised trials. Total about 79 pesticides for which the tolerances have been established on different crop groupings. Because the intensive agricultural system was adopted in Taiwan. The phytotoxicity of pesticides to the non-target crops was therefore become one of the important factor in the safety evaluation of pesticide usage. These will include 1) direct injury, 2) injury caused by pesticide polluted irrigation water, 3) injury caused by the pesticide polluted soil, 4) reduction of growth caused by the effect of pesticide on the soil microorganisms. This paper will reviewed all the aspects mentioned in the previous .paragraphs. Most the works have done in Taiwan by the PPC.y the PPC.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.858-864
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• 2001

This study was performed to investigate the effect of sodium lactate (SL, 60%) and a mixed fat replacer (FR) on the product quality and shelf-life effect of low-fat bologna sausage (LFBS) in a model system during refrigerated storage. Low-fat and regular-fat bologna sausages had pH values ranged from 6.15 to 6.30 and water activity values ranged from 0.95 to 0.96. LFBS had a moisture content of 74~76%, <2% fat and 14~15% protein, whereas regular-fat bologna had 60% moisture, 22% fat and approximately 12% protein in the final products. Expressible moisture (%) increased (p<0.05) in all bolognas, resulting in the soft texture, as the storage time (weeks) increased. LFBS manufactured with SL and a FR had lower (p<0.05) the cooking loss (%) and had higher (p<0.05) texture profile analysis (TPA) values than the regular-fat counterpart. As the sodium lactate level increased up to 5% in the formulation of LFBS, vacuum purge and TPA hardness values also increased (p<0.05), but thiobarbituric acid (TBA) values decreased (p<0.05). Total plate counts of LFBS were reduced (p<0.05) when the addition level of 60% SL solution was more than 3.3%. This result indicated that the increased level of SL (>3.3%) in the combination of a FR in the formulation of LFBS improved the product quality and did inhibit the total microbial growth of LFBS during storage, as compared to the control.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.208-215
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• 2005

This study was accomplished in order to collect fundamental data on microbial roles in recycling process of reed rhizosphere. Sunchon bay, which is considered as one of the marsh and mud environments severely affected by human activities such agriculture and fisheries, was selected as a model place. In our initial efforts, two bacterial consortia were obtained by enrichment culture using PAH mixtures containing anthracene, naphthalene, phenanthrene and pyrene as the sources of carbon and energy, and four pure bacteria capable of rapid degradation of PAH were isolated from them. Four strains designated as SCB1, SCB2, SCB6, and SCB7 revealed by morphological, physiological and molecular analyses were identified as Burkholderia anthina, Alcaligenes sp., Achromobacter xylosoxidans., and Pseudomonas putida, respectively with over $99{\%}$ confidence. Notably, Burkholderia anthina SCB1 and Alcaligenes sp. SCB2 were found to utilize anthracene and pyrene more quickly than naphthalene and phenanthrene, whereas Achromobacter xylosoxidans SCB6 and Pseudomonas putida SCB7 exhibited similar growth and degradation patterns except for pyrene. These facts suggest that the rhizosphere microorganisms capable of PAH degradation might be used to clean up the contamination sites with polycyclic aromatic hydrocarbons.