• Journal of Microbiology and Biotechnology
• /
• v.25 no.2
• /
• pp.152-161
• /
• 2015

CodY is a highly conserved protein in low G+C gram-positive bacteria that regulates genes involved in sporulation and stationary-phase adaptation. Bacillus thuringiensis is a grampositive bacterium that forms spores and parasporal crystals during the stationary phase. To our knowledge, the regulatory mechanism of CodY in B. thuringiensis is unknown. To study the function of CodY protein in B. thuringiensis, BMB171codY^- was constructed in a BMB171 strain. A shuttle vector containing the ORF of cry1Ac10 was transformed into BMB171 and BMB171codY^-, named BMB171cry1Ac and BMB171codY^-cry1Ac, respectively. Some morphological and physiological changes of codY mutant BMB171codY^-cry1Ac were observed. A comparative proteomic analysis was conducted for both BMB171codY^-cry1Ac and BMB171cry1Ac through two-dimensional gel electrophoresis and MALDI-TOF-MS/MS analysis. The results showed that the proteins regulated by CodY are involved in microbial metabolism, including branched-chain amino acid metabolism, carbohydrate metabolism, fatty acid metabolism, and energy metabolism. Furthermore, we found CodY to be involved in sporulation, biosynthesis of poly-β-hydroxybutyrate, growth, genetic competence, and translation. According to the analysis of differentially expressed proteins, and physiological characterization of the codY mutant, we performed bacterial one-hybrid and electrophoretic mobility shift assay experiments and confirmed the direct regulation of genes by CodY, specifically those involved in metabolism of branched-chain amino acids, ribosomal recycling factor FRR, and the late competence protein ComER. Our data establish the foundation for in-depth study of the regulation of CodY in B. thuringiensis, and also offer a potential biocatalyst for functions of CodY in other bacteria.

• Journal of Veterinary Clinics
• /
• v.28 no.1
• /
• pp.101-107
• /
• 2011

This study aimed to determine dose-response (DR) curve of avian influenza (AI) virus to predict the probability of illness or adverse health effects that may result from exposure to a pathogenic microorganism in a quantitative microbial risk assessment. To determine the parametric DR relationship of several strains of AI virus, 7 feeding trial data sets challenging humans (5 sets) and chickens (2 sets) for strains of H3N2 (4 sets), H5N1 (2 sets) and H1N1 (1 set) from the published literatures. Except for one data set (study with intra-tracheal inoculation for data set no. 6), all were obtained from the studies with intranasal inoculation. The data were analyzed using three types of DR model as the basis of heterogeneity in infectivity of AI strains in humans and chickens: exponential, beta-binomial and beta-Poisson. We fitted to the data using maximum likelihood estimation to get the parameter estimates of each model. The alpha and beta values of the beta-Poisson DR model ranged 0.06-0.19 and 1.7-48.8, respectively for H3N2 strain. Corresponding values for H5N1 ranged 0.464-0.563 and 97.3-99.4, respectively. For H1N1 the parameter values were 0.103 and 12.7, respectively. Using the exponential model, r (infectivity parameter) ranged from $1.6{\times}10^{-8}$ to $1.2{\times}10^{-5}$ for H3N2 and from $7.5{\times}10^{-3}$ to $4.0{\times}10^{-2}$ for H5N1, while the value was $1.6{\times}10^{-8}$ for H1N1. The beta-Poisson DR model provided the best fit to five of 7 data sets tested, and the estimated parameter values in betabinomial model were very close to those of beta-Poisson. Our study indicated that beta-binomial or beta-Poisson model could be the choice for DR modeling of AI, even though DR relationship varied depending on the virus strains studied, as indicated in prior studies. Further DR modeling should be conducted to quantify the differences among AI virus strains.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.10
• /
• pp.1533-1538
• /
• 2013

The objective of this study is to select an effective microbial strain to enhance the sensory qualities and functionalities of fermented ginseng soymilk. For this purpose, soybean were ground with water extracts of ginseng and fermented with five Lactobacillus strains. All strains grew well in ginseng soymilk, and viable cell counts reached greater than 8 log CFU/mL after 18 h of fermentation. The contents of total ginsenosides were higher in soymilk fermented with L. casei ATCC 393 than those in the other strains. The sensory qualities of the fermented soymilk were observed to increase with the intensity of sourness and showed the best sensory acceptability of soymilk fermented with L. kefir ATCC 35411. Moreover, the antioxidant activities, superoxide and hydroxyl radical scavenging activities were significantly enhanced by 2~4 and 4~5 times, respectively, compared to the non-fermented soymilk. In particular, the antioxidant activities of the fermented soymilk by L. kefir ATCC 35411 were the highest among the samples. This result suggests that soymilk fermented by L. kefir ATCC 35411 allowed obtaining a soymilk with enhanced sensory quality and antioxidant activity was able to contribute to the health benefit.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.4
• /
• pp.569-576
• /
• 2007

Four hundred and fifty tilapias ($6.77{\pm}0.23$ g) were assigned randomly to six groups to evaluate the feasibility of the tested antibacterial peptides (ABPs) and oligosaccharides as substitutes for antibiotics. The control group was fed with a commercial tilapia diet; other five groups were fed with the same commercial diet supplemented with konjac glucomannan (KGLM), cluster bean galactomannan (CBGAM), and three animal intestinal ABPs derived from chicken, pig and rabbit at 100 mg/kg respectively. After 21 days of feeding, growth, disease resistance, and in vivo anti-adherence were determined. Furthermore, the inhibitory effect of tested agents on adhesion of Aeromonas veronii biovar sobria (A.vbs) strain BJCP-5 to tilapia enteric epithelia in vitro was assessed by cell-ELISA system. As a result, the tested agents supplemented at 100 mg/kg show significant benefit to tilapia growth and disease resistance (p<0.05), and the benefit may be correlated with their interfering in the contact of bacteria with host mucosal surface. Although none of the tested agents did inhibit the growth of BJCP-5 in tryptic soy broth at $100{\mu}g/ml$, all of them did inhibit the adhesion of A.vbs to tilapia enteric epithelia in vivo and in vitro. In vitro mimic assays show that three ABPs at low concentrations of $25{\mu}g/ml$ and $2.5{\mu}g/ml$ have the reciprocal dose-dependent anti-adherence effect. The inhibition of ABPs may be correlated with a cation bridging and/or receptor-ligand binding, but not with hydrophobicity. The KGLM and CBGAM inhibited the adherence of BJCP-5 to tilapia enteric epithelia with dose-dependent manner in vitro, and this may be through altering bacterial hydrophobicity and interfering with receptor-ligand binding. Our results indicate that the anti-adherence of the tested ABPs and oligosaccharides may be one of the mechanisms in promoting tilapia growth and resistance to A.vbs.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.10
• /
• pp.1606-1610
• /
• 2005

The effects of Whangkumtang extract and Scutellariae radix extract on the microbial growth were investigated. The antimicrobial activities and cell growth inhibiting effects were investigated to selected strains with different concentrations of Whangkmtang and Scutellariae radix extracts. Whangkmtang and Scutellariae radix extracts showed the antimicrobial activities on Staphylococcus aureus, Bacillus cereus, Shigella sonnei, Shigella flexneri, Salmonella Typhimurium, Salmonella Enteritidis, Vibrio parahaemolyticus, Escherichia coli O111 and Escherichia coli O126. Whangkumtang and Scutellariae radix extracts did not show the antimicrobial activity on Listeriamonocytogenes. Scutellariae radix extract showed the antimicrobial activity on Escherichia coli O157 but Whangkumtang extract did not, Minimum inhibitory concentrations (MIC) of Whangkumtang extract for each strain appeared to 40 mg/mL on Staphylococcus aureus and Bacillus cerus, 100 mg/mL on Shigella Flexneri and Salmonella enteritidis. The MICs of Sutellariae radix extract appeared to 10 mg/mL on Bacillus cereus, 20 mg/UL on Staphylococn aureus, Shigellanexneri and Salmonella Enteritidis. Scutellariae radix extract showed the higher antimicrobial activity than Whangkumtang extract. The cell growth inhibitions by Whangkumtang and Scutellariae radix extracts were observed from Staphylococcus aureus and Bacillus cereus, repectively, during 48-hr incubation period.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.7
• /
• pp.1122-1132
• /
• 2018

In this study, we attempted to find new and efficient microbial enzymes for producing rare sugars. A ribose-5-phosphate isomerase B (OsRpiB) was cloned, overexpressed, and preliminarily purified successfully from a newly screened Ochrobactrum sp. CSL1, which could catalyze the isomerization reaction of rare sugars. A study of its substrate specificity showed that the cloned isomerase (OsRpiB) could effectively catalyze the conversion of $\text\tiny{L}$-rhamnose to $\text\tiny{L}$-rhamnulose, which was unconventional for RpiB. The optimal reaction conditions ($50^{\circ}C$, pH 8.0, and 1 mM $Ca^{2+}$) were obtained to maximize the potential of OsRpiB in preparing $\text\tiny{L}$-rhamnulose. The catalytic properties of OsRpiB, including $K_m$, $k_{cat}$, and catalytic efficiency ($k_{cat}/K_m$), were determined as 43.47 mM, $129.4sec^{-1}$, and 2.98 mM/sec. The highest conversion rate of $\text\tiny{L}$-rhamnose under the optimized conditions by OsRpiB could reach 26% after 4.5 h. To the best of our knowledge, this is the first successful attempt of the novel biotransformation of $\text\tiny{L}$-rhamnose to $\text\tiny{L}$-rhamnulose by OsRpiB biocatalysis.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.4
• /
• pp.177-183
• /
• 2016

Sewage treatment using microorganisms is affected by multiple factors such as microbial properties, characteristics of sewage and operating conditions, and nanoparticles inflow may cause negative effects on sewage treatment system especially on the system stability and efficiency. It was studied to assess the toxic effects of nanoparticles on microorganism growth. The activated sludge in the sewage treatment plant of university was cultured in the optimized medium for each strain. Bacillus (gram-positive), Pseudomonas and E.coli (gram-negative) in the activated sludge were selected as target microorganisms, and ZnO and $TiO_2$ were chosen as nanoparticles. For same concentration of nanoparticles, average growth inhibition rate of Bacillus was 60% or more, while that of Pseudomonas was less than 10%. The toxicity of nanoparticles was shown to be higher for gram-positive bacteria than gram-negative bacteria because of their differences on structure of cell wall, components of cell wall protein, physiology of cells and metabolism. ZnO affected 3 times more negative on the growth of microorganisms as compared to $TiO_2$. It was assumed that, therefore, toxicity of ZnO was found to be greater than $TiO_2$.

• Journal of Plant Biotechnology
• /
• v.29 no.4
• /
• pp.287-293
• /
• 2002

We are trying to develop a transgenic carrot with aims of production and delivery of oral vaccine against microbial enteropathogen using a K88ac pilin gene. A K88ac antigen (pilin) gene was isolated by PCR from the K88ac genomic DNA. The pilin gene was constructed in pGA748 and introduced via Agrobacterium tumefaciens to the explants of carrot hypocotyl and then 494 transgenic lines were established. The amounts of the K88ac antigen produced in each of the cell lines were determined by western and two elite cell lines (M1-17, Y14-1) were selected based on higher levels of expression of the antigens as well as rate of cell growth and efficiency of embryogenesis. In order to test an immunization induced by oral administration of the transgenic carrot, serum of the mice fed with the carrot vaccine were tested in ELISA. It tumed out that the mice fed with 3 g of transgenic carrot showed a similar level of antibody compared to those applied with 10 $\mu\textrm{g}$ of the purified recombinant pilin protein. Besides, various clinical responses were measured after challenging with ETEC K88ac strain to the piglets experiencing an oral immunization with the transgenic carrot. The piglets fed with carrot vaccine showed a lower level of diarrhea in fecal score compared to those fed with non-transgenic carrot. A higher level of increase in weight of the piglets fed with the transgenic carrot vaccine was observed comparing to those fed with non-transgenic carrot as control.

• Journal of Life Science
• /
• v.25 no.12
• /
• pp.1339-1346
• /
• 2015

The aim of this study is to increase production of carotenoids in recombinant Escherichia coli by Archaea chaperonin. The carotenoids are a widely distributed class of structurally and functionally diverse yellow, orange, and red natural pigments. These pigments are synthesized in bacteria, algae, fungi, and plants, and have been widely used as a feed supplement from poultry rearing to aquaculture. Carotenoids also exhibit diverse biological properties, such as strong antioxidant and antitumor activities, and enhancement of immune responses. In the microbial world, carotenoids are present in both anoxygenic and oxygenic photosynthetic bacteria and algae and in many fungi. We have previously reported cloning and functional analysis of the carotenoid biosynthesis genes from Paracoccus haeundaensis. The carotenogenic gene cluster involved in astaxanthin production contained seven carotenogenic genes (crtE, crtB, crtI, crtY, crtZ, crtW and crtX genes) and recombinant Escherichia coli harboring seven carotenogenic genes from Paracoccus haeundaensis produced 400 μg/g dry cell weight (DCW) of astaxanthin. In order to increase production of astaxanthin, we have co-expressed chaperone genes (ApCpnA and ApCpnB) in recombinant Escherichia coli harboring the astaxanthin biosynthesis genes. This engineered Escherichia coli strain containing both chaperone gene and astaxanthin biosynthesis gene cluster produced 890 μg/g DCW of astaxanthin, resulting 2-fold increased production of astaxanthin.

• Microbiology and Biotechnology Letters
• /
• v.33 no.3
• /
• pp.194-199
• /
• 2005

In oder to select an antifungal substance-producing antagonistic bacterium against Fusarium oxysporum casuing fusarium wilt on tomato, strain BK4 was isolated from local soil of Gyeoungbuk and was identified as Bacillus thuringiensis by 16s rDNA analysis, biochemical test, and Mcirolog TM 3.0 System. The antibiotic of B. thuringiensis BK 4 was highly produced at $30^{\circ}C$ in nutrient broth (pH 9.0). The crude antibiotic was even stable at $121^{\circ}C$ and more stable at slight alkalic condition than acid condition. It was also remained $50{\%}$ activity at pH 3.0. B. thuringiensis BK4 showed the inhibition of spore germination and the biocontrol ability against F. oxysporum causing fusarium wilt of tomato in vivo test. According to these results, B. thuringiensis BK4 was enough to use with a microbial agent for biocontrol against fusarium wilt.