• Korean Journal of Microbiology
• /
• v.40 no.2
• /
• pp.94-99
• /
• 2004

The activities of enzymes that act on oxygen derivatives in Rhodobacter sphaeroides D-230 were investigated under various culture conditions. Intracellular SOD activity from the cells grown in aerobic or anaerobic culture conditions was highest at pH 7.0 and pH 8.0, respectively. On the other hand, extracellular SOD activity was highest at pH 6.0. Catalase activity was highest at neutral pH in both cases. Growth of R. sphaeroides D-230 in aerobic or anaerobic culture conditions was inhibited by methyl viologen. As R. sphaeroides D-230 was cul-tured aerobically, SOD activity was increased about 2-fold by addition of iron ion. But $Mn^+2$ had little effect on the SOD activity of R. sphaeroides D-230 grown in aerobically. NaCN, the inhibitor of Cu$.$Zn-SOD, did not inhibit SOD activity. But, $NaN_3$, the inhibitor of Mn-SOD, inhibited SOD activity in anaerobic cultures con-dition. Therefore, R. sphaeroides D-230 produce Mn-SOD in anaerobic condition, although Fe-Sod is produced in aerobic condition. The activity of catalase was induced by methyl viologen, however, extremely inhibited by NaCN and $NaN_3$.

• Korean Journal of Microbiology
• /
• v.50 no.1
• /
• pp.27-32
• /
• 2014

Autophagy is one of the lysosomal degradation pathways to maintain cellular homeostasis. The damaged proteins or organelles are uptaken through extra- and intra-cellular stress, starvation and infected pathogens, subsequently, autophagosomes are fused with lysosomes to break down the molecules. Salmonella enterica serovar Typhimurium (S. Typhimurium), intracellular bacteria, cause acute gastroenteritis and food poisoning. Given that autophagy induced by S. Typhimurium plays an important role in the cells to control the infection, we identify whether the induction of autophagy with rapamycin, chemical inducer of autophagy, before infection regulates S. Typhimurium infection. After treatment of rapamycin or 3-methyladenine (3-MA), autophagy inhibitor, RAW264.7 cells were infected with S. Typhimurium. Pretretment of rapamycin decreased the growth rate of S. Typhimurium in the cells; otherwise, pretreatment of 3-MA increased the growth rate of S. Typhimurium. The expression of autophagy-related genes was significantly increased in the S. Typhimurium-infected cells pretreated with rapamycin. To examine whether induced autophagy by rapamycin control the infection with increase the production of reactive oxygen species (ROS) and nitric oxide (NO), antibacterial radical substrates were measured in infected cells followed by the treatment with either rapamycin or 3-MA. NO production increased in RAW264.7 cells; otherwise, ROS production remained unchanged during the infection. These findings suggest that inducing autophagy with rapamycin reveals antimicrobial activity as producing NO against S. Typhimurium infection in mouse macrophages.

• Korean Journal of Veterinary Service
• /
• v.38 no.4
• /
• pp.233-239
• /
• 2015

Both Q-fever and Toxoplasmosis are zoonosis. Q-fever occurs due to intracellular bacteria, while Toxoplasmosis is created by protozoan. Both of them have a wide range of host including livestock and wild animals and occur sporadically all over in the world. In this study, seroprevalence of Q-fever and Toxoplasmosis was investigated on cows bred in the area of Seoul where there was a fairly high possibility to occur, while vaccine was not used in Korea. As for experiment materials, cattle blood collected from 190 cows from February to September in 2014 was used ELISA. According to the result, there was a positive reaction on Q-fever from 18 cows out of total 190 cows (9.5%) and on Toxoplasmosis from 32 cows (16.8%). Seroprevalence of both diseases per age was turned out to be negative for those aged less than 2. In addition, it was shown to be positive on 4 cows out of 87 (4.6%) cows aged from 3 to 5, on 7 cows out of 30 cows (23.3%) aged from 6 to 7. Finally, it was shown to be positive on 7 cows out of 17 cows (41.2%) aged 8 or above. Toxoplasmosis was turned out to be positive on 1 cow out of 56 cows (1.8%) aged less than 2, on 6 cows out of 87 cows (6.9%) aged from 3 to 5, on 17 cows out of 30 cows (56.7%) aged from 6 to 7. In addition, it was turned out to be 8 cows out of 17 cows (47.1%) aged 8 or above. Seroprevalence of both diseases was turned out to be higher as age increased. Therefore, it seems that a wide range of investigation on the entire disease spreaders as well as livestock is required since infection of Q-fever and Toxoplasmosis, types of zoonosis, has continuously occurred, and the number of insects, wild animals, and stray animals serving as a role of spreading diseases by changes in seasons and environments has been gradually increasing in Korea.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2008.05a
• /
• pp.23-25
• /
• 2008

Serum complement proteins comprise an important system that is responsible for several innate and adaptive immune defence mechanisms. There were three well described pathways known to lead to the generation of a C3 convertase, which catalyses the proteolysis of complement component C3, and leads to the formation of C3 opsonins (C3b, iC3b and C3d) that fix to bacteria. A pivotal step in the complement pathway is the assembly of a C3 convertase, which digests the C3 complement component to form microbial-binding C3 fragments recognized by leukocytes. The spleen clears microorganisms from the blood. Individuals lacking this organ are more susceptible to Streptococcus pneumoniae. Innate resistance to S. pneumoniae has previously been shown to involve complement components C3 and C4, however this resistance has only a partial requirement for mediators of these three pathways, such as immunoglobulin, factor B and mannose-binding lectin. Therefore it was likely that spleen and complement system provide resistance against blood-borne S. pneumoniae infection through unknown mechanism. To better understand the mechanisms involved, we studied Specific intracellular adhesion molecule-grabbing nonintegrin (SIGN)-R1. SIGN-R1, is a C-type lectin that is expressed at high levels by spleen marginal-zone macrophages and lymph-node macrophages. SIGN-R1 has previously been shown to be the main receptor for bacterial dextrans, as well as for the capsular pneumococcal polysaccharide (CPS) of S. pneumoniae. We examined the specific role of this receptor in the activation of complement. Using a monoclonal antibody that selectively downregulates SIGN-R1 expression in vivo, we show that in response to S. pneumoniae or CPS, SIGN-R1 mediates the immediate proteolysis of C3 and fixation of C3 opsonins to S. pneumoniae or to marginal-zone macrophages that had taken up CPS. These data indicate that SIGN-R1 is largely responsible for the rapid C3 convertase formation induced by S. pneumoniae in the spleen of mice. Also, we found that SIGN-R1 directly binds C1q and that C3 fixation by SIGN-R1 requires C1q and C4 but not factor B or immunoglobulin. Traditionally C3 convertase can be formed by the classical C1q- and immunoglobulin-dependent pathway, the alternative factor-B-dependent pathway and the soluble mannose-binding lectin pathway. Furthermore Conditional SIGN-R1 knockout mice developed deficits in C3 catabolism when given S. pneumoniae or its capsular polysaccharide intravenously. There were marked reductions in proteolysis of serum C3, deposition of C3 on organisms within SIGN-$R1^+$ spleen macrophages, and formation of C3 ligands. The transmembrane lectin SIGN-R1 therefore contributes to innate resistance by an unusual C3 activation pathway. We propose that in the SIGN-R1 mediated complement activation pathway, after binding to polysaccharide, SIGN-R1 captures C1q. SIGN-R1 can then, in association with several other complement proteins including C4, lead to the formation of a C3 convertase and fixation of C3. Therefore, this new pathway for C3 fixation by SIGN-R1, which is unusual as it is a classical C1q-dependent pathway that does not require immuno globulin, contributes to innate immune resistance to certain encapsulated microorganisms.

• Applied Biological Chemistry
• /
• v.40 no.6
• /
• pp.484-489
• /
• 1997

The characteristics of growth and esterase activity of bacterial strains isolated from acid hydrolysed soybean protein were examined. All the isolated strains having decomposition activity of p-hydroxybenzoic acid butyl ester and esterase producing activity were identified as Bacillus sp. by morphological and biochemical methods. The specific growth rates, esterase activities and p-hydroxybenzoic acid butyl ester decomposition activities of isolated strains were $0.844{\sim}1.213\;h^{-1}$, $21{\sim}222\;mU/ml$ and $5.4{\sim}8.1\;mU/ml$, respectively. In the fermentation of Bacillus sp. KB8 strain which had the highest esterase producing activity, growth, extracellular excretion and intracellular synthesis of esterase were inhibited by adding NaCl in the culture broth. Esterase producing activity gradually increased after late exponential growth phase, until maximum value of 420 mU/ml reached after 64 hours culture period. Esterase of Bacillus sp. KB8 strain was stable up to $50^{\circ}C$ for 30 minutes, but was inactivated by heating for 30 minutes at $70^{\circ}C$. The enzyme activity exponentially decreased during the incubation time at the temperatures of $60^{\circ}C$ and $65^{\circ}C$.

• Korean Journal of Food Science and Technology
• /
• v.46 no.6
• /
• pp.762-768
• /
• 2014

In this study, the ameliorating effects of lactic acid-fermented garlic extract (LAFGE) on non-alcoholic fatty liver were investigated using oleic acid-induced steatotic HepG2 cells. The ameliorating mechanism was analyzed by RT-PCR and Western blot. Treatment with 1 mg/mL LAFGE decreased intracellular lipid accumulation approximately 1.5-fold, compared to that achieved with non-fermented garlic extract. LAFGE reduced fatty acid influx into hepatocytes through down-regulation of FAT/CD36 mRNA expression in the steatotic HepG2 cells. $PPAR{\alpha}$ and CPT-1 mRNA expression was significantly up-regulated by LAFGE treatment of HepG2 cells as a consequence of activation of beta oxidation. Additionally, the treatment with 1 mg/mL LAFGE highly down-regulated mRNA expression of SREBP-1c and FAS to 51% and 35%, respectively. LAFGE showed concentration-dependent down-regulation patterns in protein expression of SREBP-1c and FAS, as determined by Western blot. These results suggest that LAFGE treatment improves hepatic steatosis triggered by the imbalance of hepatic lipid metabolism owing to oleic acid treatment.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.3
• /
• pp.609-615
• /
• 2005

The safety and immunogenicity of an attenuated recombinant Salmonella vaccine strain, Salmonella enterica serovar Typhimurium llaB, was assessed. This vaccine strain could survive in low pH condition, and its ability of intracellular survival did not differ from that of S. enterica serovar Typhimurium UK1, which is the wild-type of the vaccine strain. The mortality of the mice orally administered with the vaccine strain was $50\%$ at the dose of $10^7$ CFU. All mice administered with $10^5\;or\;10^3$ CFU of the vaccine strain survived for 3 days postinoculation (pi). However, all mice administered with more than $10^3$ CFU of the vaccine strain died within 3 days pi. To examine the protective effect of the vaccine strain, mice were orally immunized with $10^4\;and\;10^6$ CFU of the bacteria. Control mice were given with 0.5 ml of phosphate buffered saline (PBS). After 8 days, the mice were challenged with $10^9$ CFU of S. enterica serovar Typhimurium UK1, and mortality was examined for 5 days. The survival rates of the mice immunized with $10^4\;and\;10^6$ CFU of the vaccine strain were $60\%\;and\;80\%$, respectively, whereas all control mice died within 2 days after challenging. To investigate the immunogenicity of S. enterica serovar Typhimurium llaB, mice were orally immunized with $10^5\;or\;10^6$ CFU ml of the vaccine strain. Five mice of each group were sacrificed at 5 and 12 days after immunization, and results showed that immunization of the vaccine strain led to increases of IgG1, IgG2, and IgM titers against S. enterica serovar Typhimurium UK1 in mouse sera, cytokine expressions such as IL-2, IL-4, IL-6, and IL-10 in spleen, and the lymphocyte proliferation response to mitogens (concanavalin A or LPS) stimulation.

• Korean Journal of Food Science and Technology
• /
• v.34 no.2
• /
• pp.311-318
• /
• 2002

A new bacteriocin producing lactic acid bacteria having antagonistic activity against Lactobacillus plantarum, was isolated from Kimchi. It was identified as Leuconostoc mesenteroides, and designated as Leuconostoc mesenteroides B7. The bacteriocin from Leuconostoc mesenteroides B7 named as bacteriocin B7 was stable in the pH range $2.5{\sim}9.5$. Bacteriocin B7 was active over a wide temperature range from $4^{\circ}C$ to $120^{\circ}C$. It was inactivated by proteinase K, trypsin, ${\alpha}-chymotrypsin$, and protease treatments indicating its proteinous nature. Tricine-SDS-PAGE of the purified bacteriocin B7 showed the presence of a single band, having a molecular mass of about 3,500 dalton. Mixed culture of the producer and the indicator, Lb. plantarum KFRI 464 or Lb. delbruekii KFRI 347, increased production of bacteriocin B7. This result suggested the presence of bacteriocin inducing factor in the indicator strain. The inducing factor was localized in cell debris and intracellular faction of the indicator cell, Lb. plantarum KFRI 464. Treatment of the inducing factor with proteinase K destroyed inducing activity. This result strongly suggested that the inducing factor is a protein.

• Korean Journal of Food Science and Technology
• /
• v.21 no.1
• /
• pp.86-91
• /
• 1989

To investigate the effect of NaCl concentration and nitrogen sources in the medium for the Streptococci on the intra- and extracellular proteinase(ICP and ECP) which have been known as one of the major causes for the bitter peptide formation, Streptococcus lactis $ML_8$ and Streptococcus cremoris $ML_4$ strains were incubated at 0-4% NaCl in the medium and Na-caseinate as a nitrogen source 0-100%, and the cell growth, ICP and ECP activities were analyzed. As the concentration of the NaCl in the medium increased, the growth and ECP activity decreased but the ICP $activity/10^{10}$ cells increased on the contrary. This implied that the NaCl in the medium affects only the ECP which is associated mainly to the cell wall and cell membrane but not the ICP activity. When the content of the caseinate instead of other low molecular nitrogen sources were increased in the medium, the cell growth was lowered while the ECP activities increased probably by induction of proteinase production.

• Journal of Life Science
• /
• v.26 no.10
• /
• pp.1113-1120
• /
• 2016

Two bacterial strains producing extracellular man nanase were isolated from doenjang, a traditionally fermented soybean paste in Korea. The isolates, WL-6 and WL-11, were identified as Bacillus subtiis on the basis of their 16S rRNA gene sequences, morphological, and biochemical properties. Two genes encoding the mannanase of both B. subtilis WL-6 and B. subtilis WL-11 were each cloned into Escherichia coli, and their nucleotide sequences were determined. Both mannanase genes consisted of 1,086 nucleotides, encoding polypeptides of 362 amino acid residues. The deduced amino acid sequences of the two WL-6 and WL-11 mannanases, designated Man6 and Man11, respectively, differed from each other by eight amino acid residues, and they were highly homologous to those of mannanases belonging to the glycosyl hydrolase family 26. The 26 amino acid stretch in the N-terminus of Man6 and Man11 was a predicted signal peptide. Both Man6 and Man11 were localized at the level of 94–95% in an intracellular fraction of recombinant E. coli cells. The enzymes hydrolyzed both locust bean gum and mannooligosaccharides, including mannotriose, mannotetraose, mannopentaose, and mannohexaose, forming mannobiose and mannotriose as predominant products. The optimal reaction conditions were 55°C and pH 6.0 for Man6, and 60°C and pH 5.5 for Man11. Man11 was more stable than Man6 at high temperatures.