• Journal of Microbiology
• /
• 제40권4호
• /
• pp.260-266
• /
• 2002

Bacterial strains were isolated from biofilms formed on glass slides submerged in seawater in Dae-Ho Dike. Eight strains showing fast attaching ability were selected and identified. Their exopolysaccharide (EPS)-producing ability and EPS properties were characterized. Based on Microlog System, 4 among the 8 strains were identified as Micrococcus luteus and the rest were Bacillus thuringiensis, Bacillus megaterium,, Staphylococcus saprophyticus and Agrobacterium vitis. A, vitis was reidentified as Sulfitobacter pontiacus based on 16S rDNA sequence data. The amount of water-soluble EPS produced by the 8 strains ranged from 0.114 to 1.329 g$.$l$\^$-1/ and the productivity was negatively correlated with the cell biomass. The molecular weight of the produced EPS ranged from 0.38 to 25.19$\times$10$\^$4/ Da. Glucose and galactose were ubiquitous sugar components. Mannose, ribose, and xylose were also major sugar components. The molecular weight and composition of the EPS showed strain-specific variation.

• Journal of Microbiology and Biotechnology
• /
• 제23권12호
• /
• pp.1673-1682
• /
• 2013

Citrobacter sp. is a cause of significant opportunistic nosocomial infection and is frequently found in human and animal feces, soil, and sewage water, and even in industrial waste or putrefaction. Biofilm formation is an important virulence trait of Citrobacter sp. pathogens but the process and characteristics of this formation are unclear. Therefore, we employed in vitro assays to study the nutritional and environmental parameters that might influence biofilm formation of C. werkmanii BF-6 using 96-well microtiter plates. In addition, we detected the relative transcript levels of biofilm formation genes by RT-PCR. Our results indicated that the capacity of C. werkmanii BF-6 to form biofilms was affected by culture temperature, media, time, pH, and the osmotic agents glucose, sucrose, NaCl, and KCl. Confocal laser scanning microscopy results illustrated that the structure of biofilms and extracellular polysaccharide was influenced by 100 mM NaCl or 100 mM KCl. In addition, nine biofilm formation genes (bsmA, bssR, bssS, csgD, csgE, csgF, mrkA, mrkB, and mrkE) were found to contribute to planktonic and biofilm growth. Our data suggest that biofilm formation by C. werkmanii BF-6 is affected by nutritional and environmental factors, which could pave the way to the prevention and elimination of biofilm formation using proper strategies.

• Journal of Microbiology and Biotechnology
• /
• 제8권2호
• /
• pp.165-170
• /
• 1998

Lipase-catalyzed esterification of n-butyl oleate was carried out in n-hexane as a model reaction. The optimal activity of Candida rugosa lipase was shown in a water activity ($a_w$) range of 0.52 to 0.65 at $30^{\circ}C$. The water produced from the esterification was removed by a tubular type pervaporation system. The rate of ester formed from the enzymatic esterification was allowed to be the same as the rate of water removal by maintaining an optimal $a_w$ of the reaction system using an on-off dewatering control device. The reaction rate and yield with a$a_w$ control were increased two folds higher than the respective values for the uncontrolled reaction.

• 한국미생물·생명공학회지
• /
• 제23권6호
• /
• pp.633-640
• /
• 1995

As a result of screening the medicinal herbs which selectively control human intestinal microflora, water extract of Akebia quinata Decaisne was proved to have a strong inhibitory activity against the growth of Clostridium pefringens, a major harmful intestinal bacterium. The anti-bacte-rial activity was stable under the thermal treatment at 100$\circ$C for 120 min and in a range of pH 1 to 11. In addition, the water extract of Akebia quinata Decaisne showed the antibacterial activities against five different strains of Clostridia including C. perfringens. On the contrary, the extract did not inhibit the growths of Bifidobacterium, Lactobacillus, Escherichia coli, Enterococcus faecalis. The extract, however, suppressed markedly the growth of Bacteroides fragilis and Staphylococcus aureus in vitro. Alike in the mixed culture inoculated with human feces as starter, in vivo tests using rats showed that the extract tends to increase the numbers of Bifidobacteria and Lactobacilli in the intestinal microflora of rats, whereas those of Clostridia were attenuated.

• Journal of Microbiology and Biotechnology
• /
• 제10권2호
• /
• pp.227-232
• /
• 2000

Fresh pine needles were collected and extracted with 95% methanol and the extract was concentrated to determine its antimicrobial activity. The methanol extract had a considerable inhibitory effect on the tested bacteria, such as Esherichia coli 0157;H7, Listeria monocytogenes, Salmonella typhimurium, and Staphylococcus aureus. The methanol extract of pine needles was further fractionated to chloroform, ethylacetate, butanal, and water fractions. Among these four fractions, the butanol and water fractions, which showed a relatively strong inhibitory effect on all of the tested bacteria, were purified and the minimum ingibitory concentration (MIC) was determined for each microorganism. The MIC raged between 25 mg/ml and 45 mg/ml depending on the microorganism. the purified active fractions were applied to sterilized milk as a model food system to define the antimicrobial effectiveness and it was found that the antimicrobial activities in the water fractions were stronger than those in the butanol fractions.

• 한국미생물·생명공학회지
• /
• 제25권2호
• /
• pp.178-182
• /
• 1997

This study was carried out particutarly focusing on the antitumor effects of extracts obtained from mushroom, Daedalea dickinsii against Hela cell, Hep $G_{2}$, cell, L 929 cell and Sarcoma-180. Antitumor effect of hot water extracts obtained from Daedalea dickinsii against Hela cell showed at the highest level of 70% when adiministrated at the concentration of 1.5 mg/100 ml, however Hep $G_{2}$, cell inhibited 40% at the same concentration of hot water extracts. Antitumor effects of methanol extract of Daedalea dickinsii against Hela cell indicated at the highest level of 60% when 4 mg/ml was administerated. Antitumor effect of hot water extract of Daedalea dickinsii inhibited 51.03% against L929 cell. The solid tumor sarcoma-180 growth inhibition of methanol extract of Deadalea dickinsii inhibited 45.67% when administrated at the concentration of 60mg/kg, and the life prolongation was higher 30.88% than that control group.

• 한국미생물·생명공학회지
• /
• 제8권2호
• /
• pp.135-142
• /
• 1980

The process of biological treatment of organic wastewater is principally associated with those of self-purification in the natural water environment. The treatment system has e intensive function of stabilizing wastewater more effectively than in natural water, which is like natural water concentrated in a small space. Biological treatment of wastewater involves activated sludge and various modified process, trickling filter, rotating disk, oxidation ditch, etc. for aerobic decomposition and anaerobic processes such as anaerobic decomposition and methane fermentation. The basic characteristic of these processes is the use of mixed culture for the conversion of pollutants. This review forcuses on the various kinds of microorganisms related to each treatment processes. Kinetic analysis of the activated sludge process is discussed in order to understand the basis of control and maintenance of the biological treatment process.

• Journal of Microbiology and Biotechnology
• /
• 제23권12호
• /
• pp.1774-1778
• /
• 2013

Methylotrophs within biological activated carbon (BAC) systems have not received attention although they are a valuable biological resource for degradation of organic pollutants. In this study, methylotrophic populations were monitored for four consecutive seasons in BAC of an actual drinking water plant, using ribosomal tag pyrosequencing. Methylotrophs constituted up to 5.6% of the bacterial community, and the methanotrophs Methylosoma and Methylobacter were most abundant. Community comparison showed that the temperature was an important factor affecting community composition, since it had an impact on the growth of particular methylotrophic genera. These results demonstrated that BAC possesses a substantial methylotrophic activity and harbors the relevant microbes.

• Journal of Microbiology and Biotechnology
• /
• 제3권4호
• /
• pp.285-291
• /
• 1993

Growth responses of some intestinal bacteria such as bifidobacteria and Clostridium perfringens to the extracts of certain foodstuffs were investigated in vitro. Among edible mountain herbs, the extracts of several chui-na-muls (Aster tataricus, Ligularia fischeri and Aster scaber) had an inhibitory activity against C. perfringens on the agar plate and the water extract of Aster scaber worked selectively on it among intestinal bacteria. The water extract showed growth-promoting effect toward bifidobacteria such as B. adolescentis, B. animalis, B. bifidum, B. infantis and B. thermophilum in the broth culture. When the faecal inoculum was incubated in the culture with the extract, the population of C. perfringens decreased, whereas that of bifidobacteria increased by $10^3$ scale.$\beta$-glucuronidase activity in the culture with the water extract of Aster scaber digested with pepsin and pancreatin was lower than that in the control culture.

• Journal of Microbiology and Biotechnology
• /
• 제16권9호
• /
• pp.1481-1484
• /
• 2006

In this study, glucose and glutamate (copiotrophic conditions) were used to enrich electrochemically active bacteria (EAB) in a microbial fuel cell (MFC). The enriched population consisted primarily of ${\gamma}$-Proteobacteria (36.5%), followed by Firmicutes (27%) and O-Proteobacteria (15%). Accordingly, we compared our own enrichments done under many different conditions with those reported from the literature, all of which support the notion that electrochemically active bacteria are taxonomically very diverse. Enrichments with different types and levels of energy sources (fuels) have clearly yielded many different groups of bacteria.