• Food Science of Animal Resources
• /
• v.28 no.1
• /
• pp.76-81
• /
• 2008

The objective of this study is to evaluate the microbial safety of raw pork used to produce Korean pork jerky. The raw pork samples harbored large populations of microorganisms. In particular, mesophilic bacteria were found to be most numerous $(3.9{\times}10^2-3.9{\times}10^5cfu/g)$ in the samples. Spore-forming bacteria and coliforms were not detected below detection limit. Yeast and molds were detected at $3.8{\times}10^1-5.1{\times}10^2cfu/g$ in the raw pork. Ten samples of raw pork were analyzed for the presence of pathogenic bacteria. Bacillus cereus was isolated from samples B and J and Staphylococcus aureus was isolated from sample B. The B. cereus isolates from raw pork samples were identified with 99.8% agreement and S. aureus isolate was identified with 97.8% agreement according to the API CHB 50 kit.

• Journal of Food Hygiene and Safety
• /
• v.5 no.1
• /
• pp.13-19
• /
• 1990

The microbial populations of exportable ginseng leaf tea were $3.6{\times}10^{5}/g$ in mesophilic aerobic bacteria, $2.1{\times}10^{3}/g$ in mesophilic aerobic spores, $1.6{\times}10^{4}/g$ in yeast, $1.9{\times}10^{4}/g$ in molds and $1.2{\times}10^{4}/g$ in coliforms, respectively, which are higher levels than the legaJIy permissible loads of microorganisms for ginseng powders in Korea. In a comparative study of the decontaminating effects on microorganisms, ethylene oxide fumigation and 5 kGy irradiation could decrease microorganisms below the detectable level. And there is no growth of microorgllnisms after three months of storage at $30{\pm}1^{circ}C$. The decimal reduction doses (Dw value) for microorganisms contaminated were 0.70 kGy in coliforms, 0.75 kGy in total bacteria, 0.85 kGy in molds. and 0.95 kGy in yeast, respectively. In the organoleptic test for ginseng leaf tea, the irradiated samples showed no significant difference from the control group in overall flavor, taste, color and acceptability. However the extracts of ethylene oxide fumigated sample were significantly different in color and taste from other groups even after three months storage.

• Microbiology and Biotechnology Letters
• /
• v.33 no.3
• /
• pp.159-168
• /
• 2005

Up to date, a number of review papers were reported on intestinal microorganisms that influence the health and disease of human being and diet that directly influence the establishment of intestinal microbial populations. Importance of studying intestinal microorganisms in the neonate arises from the easy approach to studying initial acquisition and settlement of intestinal microorganisms. Despite of the importance, few studies of neonatal intestinal microorganisms have been carried out and there is no paper focusing the factors to influence the development of intestinal microorganisms and molecular ecological methods for the analysis of intestinal ecosystem in the neonate. In this review, we summarized the status of our current knowledge of basic initial acquisition and settlement of intestinal microorganisms. And recent development of molecular ecological methods in studying the intestinal microbiology was also discussed.

• Food Science of Animal Resources
• /
• v.26 no.3
• /
• pp.402-409
• /
• 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 Microbiology and Biotechnology
• /
• v.27 no.7
• /
• pp.1276-1280
• /
• 2017

The mcr-1 gene is a new "superbug" gene discoverd in China in 2016 that makes bacteria highly resistant to the last-resort class of antibiotics. The mcr-1 gene raised serious concern about its possible global dissemination and spread. Here, we report a potential anti-resistant strategy using the CRISPR/Cas9-mediated approach that can efficiently induce mcr-1 gene knockout in Escherichia coli. Our findings suggested that using the CRISPR/Cas9 system to knock out the resistance gene mcr-1 might be a potential anti-resistant strategy. Bovine myeloid antimicrobial peptide-27 could help deliver plasmid pCas::mcr targeting specific DNA sequences of the mcr-1 gene into microbial populations.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.4
• /
• pp.450-458
• /
• 2017

In this study, the antimicrobial activity of black garlic pomace extract (BGPE) was examined, and its washing applicability to spinach was investigated. BGPE had antimicrobial activity against both Gram-positive (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative (Escherichia coli O157:H7 and Salmonella Typhimurium) food-borne pathogens. In particular, antimicrobial activities of BGPE against Gram-positive bacteria were higher than those against Gram-negative bacteria. Spinach samples were treated with 0.5% BGPE to determine the effect of BGPE on reducing naturally existing microorganisms on the surface of spinach leaves. BGPE treatment reduced populations of total aerobic bacteria and yeast/molds in spinach by 1.23~1.35 log CFU/g and 0.82~1.12 log CFU/g during 9 days of storage, respectively, compared with those of control samples. After treatment, there were no significant differences in color quality such as Hunter L, a, and b values and total color difference (${\Delta}E$). These results clearly indicate that BGPE treatment can be useful for improving microbiological safety and maintaining color quality of spinach during storage.

• Journal of the Korean Chemical Society
• /
• v.50 no.2
• /
• pp.123-128
• /
• 2006

Behcet's disease (BD) is a systemic vasculitis characterized by recurrent oral and genital ulcers, and ocular inflammation, and which may involve the joints, skin, central nervous system and gastrointestinal tract. Although the exact pathogenesis for BD is not completely understood, it has been suggested that the disease is triggered in genetically susceptible individuals by environmental factors, such as microbial agents. It is noted that multiple genes, including MHC (major histocompatibility complex) and non-MHC genes, are implicated in the pathogenesis of BD. This study tries to determine whether IL-6 gene polymorphisms are associated with susceptibility to Behcet's disease in Koreans. Gene polymorphisms were typed by VNTR (variable number of tandem repeat), RFLP (restriction fragment length polymorphism), DHPLC (denaturing high performance liquid chromatography).There were no evidences for genetic association conferred by the IL-6prom polymorphism. However, significant differences in the IL-6vntr genotype and allele frequencies were found between patients with BD and controls. The IL-6vntr*C allele appeared to be an additional susceptibility gene to Korean BD. Further studies in other populations and gene are required to confirm these results.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.9
• /
• pp.1566-1575
• /
• 2017

MicroRNAs (miRNAs) are abundant in bovine milk and milk derived from other livestock, and they have functional roles in infants and in the secretion process of mammary glands. However, few studies have evaluated miRNAs in dairy processes, such as during cheese making and ripening. Thus, we investigated the characteristics of milk-derived miRNAs during the manufacturing and ripening of Camembert cheese as well as the microbiota present using the quantitative reverse transcription polymer chain reaction (RT-qPCR) and 16S rRNA pyrosequencing, respectively. Pyrosequencing showed that the cheese microbiota changed dramatically during cheese processing, including during the pasteurization, starter culture, and ripening stages. Our results indicated that the RNA contents per $200mg/200{\mu}l$ of the sample increased significantly during cheese-making and ripening. The inner cheese fractions had higher RNA contents than the surfaces after 12 and 22 days of ripening in a time-dependent manner (21.9 and 13.2 times higher in the inner and surface fractions than raw milk, respectively). We performed a comparative analysis of the miRNAs in each fraction by RT-qPCR. Large amounts of miRNAs (miR-93, miR-106a, miR-130, miR-155, miR-181a, and miR-223) correlated with immune responses and mammary glands were present in aged cheese, with the exception of miR-223, which was not present on the surface. Considerable amounts of miRNAs were also detected in whey, which is usually disposed of during the cheese-making process. Unexpectedly, there were no significant correlations between immune-related miRNAs and the microbial populations during cheese processing. Taken together, these results show that various functional miRNAs are present in cheese during its manufacture and that they are dramatically increased in amount in ripened Camembert cheese, with differences according to depth.

• Journal of Food Hygiene and Safety
• /
• v.3 no.4
• /
• pp.233-239
• /
• 1988

Vegetable mixed codiments, commercial products prepared using soybean,paste and natto, respectively as the ingredients, were used ina study to evaluate the efficacy of gamma irradiationas a means of decontamination and the emphasis was placed upon the determination of the effect of irradiation on the microbiological and some physicochemical properties of the samples. The number of microorganisms contaminated ranged from $10^{6}\;to\;10^{7}$ cells per gram in mesophilic total bacteria, which were composed of thermophilts and acid tolerant bacteria by over 90%. They were reduced by 3 to 4 log cycles with irradiation at 10 kGy. Gamma irradiation at 5 kGy could eliminate the microbial populations of yeasts and molds ($10^{2}\;to\;10^{3}$ cells per gram) and coliforms ($10^{6}\;to\;10^{6}$ cells per gram of natto condiments). However, total destruction of microorganisms in soybean-paste and natto condiments was shown to be possible at a dose-range more than 10 kGy. Irradiationup to 10 kGy was not detrimental to the physicochemical properties of the sample, such as pH. amino nitrogen, rancidity and color, even though some change was brought about in the content of sulfur-containing amino acids.

• Animal Bioscience
• /
• v.35 no.2
• /
• pp.184-195
• /
• 2022

Objective: In this study we aimed to evaluate the effect of dietary live yeast supplementation on ruminal pH pattern, fermentation characteristics and associated bacteria in beef cattle. Methods: This work comprised of in vitro and in vivo experiments. In vitro fermentation was conducted by incubating 0%, 0.05%, 0.075%, 0.1%, 0.125%, and 0.15% active dried yeast (Saccharomyces cerevisiae, ADY) with total mixed ration substrate to determine its dose effect. According to in vitro results, 0.1% ADY inclusion level was assigned in in vivo study for continuously monitoring ruminal fermentation characteristics and microbes. Six ruminally cannulated steers were randomly assigned to 2 treatments (Control and ADY supplementation) as two-period crossover design (30-day). Blood samples were harvested before-feeding and rumen fluid was sampled at 0, 3, 6, 9, and 12 h post-feeding on 30 d. Results: After 24 h in vitro fermentation, pH and gas production were increased at 0.1% ADY where ammonia nitrogen and microbial crude protein also displayed lowest and peak values, respectively. Acetate, butyrate and total volatile fatty acids concentrations heightened with increasing ADY doses and plateaued at high levels, while acetate to propionate ratio was decreased accordingly. In in vivo study, ruminal pH was increased with ADY supplementation that also elevated acetate and propionate. Conversely, ADY reduced lactate level by dampening Streptococcus bovis and inducing greater Selenomonas ruminantium and Megasphaera elsdenii populations involved in lactate utilization. The serum urea nitrogen decreased, whereas glucose, albumin and total protein concentrations were increased with ADY supplementation. Conclusion: The results demonstrated dietary ADY improved ruminal fermentation dose-dependently. The ruminal lactate reduction through modification of lactate metabolic bacteria could be an important reason for rumen pH stabilization induced by ADY. ADY supplementation offered a complementary probiotics strategy in improving gluconeogenesis and nitrogen metabolism of beef cattle, potentially resulted from optimized rumen pH and fermentation.