• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1560-1568
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• 2013

Salmonella, a main cause of foodborne diseases, encounters a variety of environmental stresses and overcomes the stresses by multiple resistance strategies. One of the general responses to hyperosmotic stress is to import or produce compatible solutes so that cells maintain fluid balance and protect proteins and lipids from denaturation. The ProP and ProU systems are the main transport systems for compatible solutes. The OsmU system, recently identified as a third osmoprotectant transport system, debilitates excessive growth as well by reducing production of trehalose. We studied a fourth putative osmoprotectant transport system, YehZYXW, with high sequence similarity with the OsmU system. A Salmonella strain lacking YehZ, a predicted substrate-binding protein, did not suffer from hyperosmolarity but rather grew more rapidly than the wild type regardless of glycine betaine, an osmoprotectant, suggesting that the YehZYXW system controls bacterial growth irrespective of transporting glycine betaine. However, the growth advantage of ${\Delta}yehZ$ was not attributable to an increase in OtsBA-mediated trehalose production, which is responsible for the outcompetition of the ${\Delta}osmU$ strain. Overexpressed YehZ in trans was capable of deaccelerating bacterial growth vice versa, supporting a role of YehZ in dampening growth. The expression of yehZ was increased in response to nutrient starvation, acidic pH, and the presence of glycine betaine under hyperosmotic stress. Identifying substrates for YehZ will help decipher the role of the YehZYXW system in regulating bacterial growth in response to environmental cues.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.57-65
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• 2012

Phosphorous is an essential element for the synthesis of various biomolecules including phospholipids, carbohydrates and nucleic acids. Bacterial cells can uptake it as forms of phosphate and phosphate-containing nutrients from extracellular environments, and reserve extra phosphate to polyphosphate inside the cell. Among five phosphate transport systems, Pst plays central roles in phosphate transport, and its expression is coordinated by the regulation of PhoB-PhoR two component signal transduction system in response to extracellular levels of phosphate. Genomic studies on the response regulator PhoB reveal many genes independent of phosphate metabolism. Based on recent findings on phenotypes of bacteria lacking proper function of each phosphate transport system, this review discusses roles of phosphate transporters in maintaining optimum intracellular phosphate levels, and presents diverse phenotypes of phosphate transporters related with other environmental signals as well as phosphate, then finally points out functional redundancy among phosphate transport systems or their regulators, which emphasize importance of phosphate homeostasis in governing metabolism, adaptation, and virulence of bacteria.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.245-250
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• 2018

Lawsonia intracellularis is the pathogenic agent of porcine proliferative enteritis (PPE). The bacterial pathogen infects the intestinal crypt cells which causes hyperplasia of the infected cells and leads to the process of intestinal pathogenesis. PPE includes some clinical maninfestations, including acute hemorrhagic diarrhea with sudden death in growing pigs and porcine intestinal adenomatosis, to a chronic diarrhea with reduced productivity of the infected pigs. The purpose of the present studies were carried out to determine L. intracellularis in livestock transport car of slaughterhouse. Distribution of L. intracellularis in livestock transport car were conducted using real-time polymerase chain reaction (real-time PCR) testing method, total 300 samples. Of 300 samples, 119 (39.7%) were detected as positive to L. intracellularis in livestock transport car. In seasonal analysis, 42 (28.0%) out of 150 samples in spring and summer season. 77 (51.3%) out of 150 sample in autumn and winter season. In regional analysis, 53 (88.3%) out of 60 cars and the detection ratio showed that regional variation in livestock transport car.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.45-49
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• 1996

A series of in vitro experiments was conducted to investigate response of rumen bacterial deamination to the ionophore salinomycin. Addition of salinomycin to the inoculum, strained rumen fluid, depressed ammonia production from casein, while increased accumulation of ${\alpha}$-amino acids. This suggests an inhibitory effect of salinomycin on ruminal deamination. When the effect in washed bacterial suspension was monitored with individual amino acid, aspartic acid degradation was markedly inhibited by salinomycin. This inhibition was not observed when the mixed rumen bacteria were ultrasonically disrupted and used as the enzyme source. Extent of the inhibition tended to be higher in the bacteria source from sheep on a high roughage diet. From these results it was speculated that the inhibition of deamination with salinomycin is caused by a decreased transport of amino acid into the bacterial cells as well as a decreased proportion of deaminating bacteria in the rumen.

• Environmental Engineering Research
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• v.16 no.4
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• pp.219-225
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• 2011

The objective of this study was to investigate the bacterial adhesion to iron (hydr)oxide-coated sand (IHCS) and aluminum oxidecoated sand (AOCS) in the presence of Tween 20 (nonionic surfactant) and lipopeptide biosurfactant (anionic surfactant) through column experiments. Results show that in the presence of Tween 20, bacterial adhesion to the coated sands was slightly decreased compared to the condition of deionized water; the mass recovery (Mr) increased from 0.491 to 0.550 in IHCS and from 0.279 to 0.380 in AOCS. The bacterial adhesion to the coated sands was greatly reduced in lipopeptide biosurfactant; Mr increased to 0.980 in IHCS and to 0.797 in AOCS. Results indicate that the impact of lipopeptide biosurfactant on bacterial adhesion to metal oxide-coated sands was significantly greater than that of Tween 20. Our results differed from those of the previous report, showing that Tween 20 was the most effective while the biosurfactant was the least effective in the reduction of bacterial adhesion to porous media. This discrepancy could be ascribed to the different surface charges of porous media used in the experiments. This study indicates that lipopeptide biosurfactant can play an important role in enhancing the bacterial transport in geochemically heterogeneous porous media.

• Korean Journal of Microbiology
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• v.21 no.3
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• pp.115-126
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• 1983

The results that the effect of 6 detergents on the structural changes and biochemical composition of bacterial membrane of Escherichia coli and Bacillus cereus are as follows ; 1. Population growth of the bacteria was increased in case of the treatment with palmitoyl carnitine and sodium deoxy cholate but was increased in case of the treatment with palmitoyl carnitine and sodium deoxy cholate but was decreased by sodium dodecyl sulfate and palmitoyl choline, in E.coli and was decreased by palmitoyl carnitine and palmitoyl choline at the low concentration, in B. cereus. 2. The electron micrograph showed that cell wall lysis or cell collapse were observed in the treatment of sodium dodecyl sulfate and palmitoyl choline, and also cell wall was condensed by triton X-100 and sodium deoxy cholate, in E.coli. And in B. cereus, endospore formation of the bacteria was stimulated by palmitoyl choline, and cell lysis or structural changes of the membrane were observed in the treatment of sodium dodecyl sulfate, sodium cholate, and triton X-100, respectively. 3. As to the effect of detergent on the biochemical composition of biomembrane, the content of carnitine, in E.coli, and B.cereus, the content of structural protein and phospholipid were decreased by treatment of sodium dodecyl sulfate and structural protein was denatured by palmitoyl choline. 4. The profile of membrane protein revealed that the bacterial membrane were composed of various proteins. By dint of this result, some of membrane proteins were solubilized or changed to small molecules by the treatment of sodium dodecyl sulfate and palmitoyl choline, in E.coli and membrane protein of the biomembrane by treatment of sodium dodecyl sulfate, sodium deoxy cholate, palmitoyl choline, and palmitoyl carnitine were confirmed to be different profile as compared with those of the control, in B. cereus. Therefore, it is suggested that sodium dfodecyl sulfate and palmitoyl choline soulbilized biomembranes or inhibited membrane transport and that palmitoyl carnitine and sodium deoxy cholate were used as an energy source or stimulating the membrane transport, in E.coli. And, it is suggested that all of detergents were inhibited biomembrane synthesis, expet saponin, in B.cereus.

• Environmental Engineering Research
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• v.13 no.3
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• pp.141-146
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• 2008

Transport of Escherichia coli ATCC 11105 through porous media was investigated in this study using two sets of column experiments to quantify the attachment-related parameters (sticking efficiency, attachment rate coefficient and filter factor). The first set of experiments was performed in quartz sand under different ionic strength conditions (1, 20, 100, 200 mM) while the second experiments were carried out in quartz sand mixed with metal oxyhydroxide-coated sand (0, 5, 10, 25%). The breakthrough curves of bacteria were obtained by monitoring effluent, and then bacterial mass recovery and attachment-related parameters were quantified from these curves. The first experiments showed that the mass recoveries were in the range of 13.3 to 64.7%, decreasing with increasing ionic strength. In the second experiments, the mass recoveries were in the range of 15.0 to 43.4%, decreasing with increasing coated sand content. The analysis indicated that the sticking efficiency, attachment rate coefficient and filter factor increased with increasing ionic strength and coated sand content. The value of filter factor in the first experiments ranged from 1.45 e-2 to 6.72 e-2 1/cm while in the second experiments it ranged from 2.78 e-2 to 6.32 e-2 1/cm. Our filter factor values are one order of magnitude lower than those from other studies. This discrepancy can be attributed to the size of sand used in the experiment. The analysis demonstrated that the travel distance of bacteria estimated using the filter factor can be varied greatly depending on the solution chemistry and charge heterogeneity of porous media.

• Journal of Aquaculture
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• v.16 no.2
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• pp.76-83
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• 2003

To improve the efficiency of removal of bacteria and virus with DynaSand Filters used for treatment of recycling wastewater from aquaculture, effect of biofilm formation on bacterial transport through coated sand was estimated. At the neutral pH (pH 7.0), the coated sand was positive of zeta potential (surface charge). Column experiments were also carried out to test the effect of uncoated sand as well as coated sand with Al and Fe. The coated sand influenced more significantly the surface properties, adsorption and transport than the uncoated sand. The leaching batch system investigated for synthetic water showed concentrations of 7.47, 4.80, 20.89 and 7.23 mg/L for the uncoated sand, coated sand with Al, Fe and Al+Fe, respectively. Hence there are significant differences among the tested coatings with reference to bacterial transport and surface properties.

• International Journal of Oral Biology
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• v.38 no.2
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• pp.61-65
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• 2013

Erythromycin is a macrolide antibiotic and inhibits bacterial protein synthesis by stimulating the dissociation of the peptidyl-tRNA molecule from the ribosomes during elongation. The use of macrolides has increased dramatically over the last few years and has led to an increase in bacterial resistance to these antibiotics. Bacterial resistance to erythromycin is generally conferred by the ribosome methylation and/or transport (efflux) protein genes. Among the identified erythromycin-resistant genes, erm(B) (erythromycin methylation) and mef(A) (macrolide efflux) are generally detectable in erythromycin-resistant streptococcal species. The distribution of these genes in oral streptococcal isolates has been reported in studies from other countries but has not been previously examined in a Korean study. We here examined by PCR the presence of erm(B) and mef(A) in oral streptococci isolated from Korean dental plaques. Among the 57 erythromycin-resistant strains tested, 64.9% harbored erm(B) whereas 40.4% were positive for mef(A). Eleven isolates had both the erm(B) and mef(A) genes. Twenty six isolates had only erm(B) and 12 isolates had only mef(A). Eight of the 57 strains examined were negative for both genes.

• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1543-1551
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• 2023

The recently published high-resolution R388 T4SS structure provides exciting new details about the complete complex of T4SS, including the components making up the stalk and arches, numerous symmetry mismatches between regions of the complex, and an intriguing interpretation of the closed stalk and radial symmetry of the inner membrane complex, which is related to pilus biogenesis assembly. However, there are a few unidentified densities in the electron microscopy map and portions of the identified component sequences for which the structure is not yet known. It is also unclear how well this minimized DNA-transporting T4SS predicts the structure of other T4SSs, such as expanded systems and those that transport proteins rather than DNA. In this review, we evaluate what can be inferred from the recent high-resolution structure of the R388 T4SS with respect to the Cag and Dot/Icm systems. These systems were selected because, given what is currently known about these systems, we expect them to present most structural differences compared to the R388 T4SS structure. Furthermore, we discuss bacterial physiology and diversity, the T4SS structures and their variations between different bacterial species. These insights may prove beneficial for researchers who elucidate the structure and functions of T4SS in different bacterial species.