• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.04a
• /
• pp.28-30
• /
• 2005

Because of high population diversity in soil microbial communities, it is difficult to accurately assess the capability of biodegradation of toxicant by microbes in soil and sediment. Identifying biodegradative microorganisms is an important step in designing and analyzing soil bioremediation. To remove non-important noise information, it is necessary to selectively enrich genomes of biodegradative microorganisms fromnon-biodegradative populations. For this purpose, a stable isotope probing (SIP) technique was applied in selectively harvesting the genomes of biphenyl-utilizing bacteria from soil microbial communities. Since many biphenyl-using microorganisms are responsible for aerobic PCB degradation In soil and sediments, biphenyl-utilizing bacteria were chosen as the target organisms. In soil microcosms, 13C-biphenyl was added as a selective carbon source for biphenyl users, According to $13C-CO_2$ analysis by GC-MS, 13C-biphenyl mineralization was detected after a 7-day of incubation. The heavy portion of DNA(13C-DNA) was separated from the light portion of DNA (12C-DNA) using equilibrium density gradient ultracentrifuge. Bacterial community structure in the 13C-DNAsample was analyzed by t-RFLP (terminal restriction fragment length polymorphism) method. The t-RFLP result demonstates that the use of SIP efficiently and selectively enriched the genomes of biphenyl degrading bacteria from non-degradative microbes. Furthermore, the bacterial diversity of biphenyl degrading populations was small enough for environmental genomes tools (metagenomics and DNA microarrays) to be used to detect functional (biphenyl degradation) genes from soil microbial communities, which may provide a significant progress in assessing microbial capability of PCB bioremediation in soil and groundwater.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.4
• /
• pp.43-50
• /
• 2010

In this study, we have isolated MTBE utilizing bacteria at the gasoline contaminated soil and also MTBE degradation patterns were characterized. The 18 bacterial mono-cultures isolated from enrichment cultures were screened for MTBE degradation. Of the 18 strains, the 3 strains (Flavobacterium, Pseudomonas, and Achromobacter) have shown effective MTBE degradation. Experimental parameters affecting the growth conditions (such as temperature, pH, initial cell mass) were optimized. Experimental parameters such as temperature $30^{\circ}C$, pH 7, and initial cell mass 0.6 g/mL in optimal growth conditions for MTBE degradation. The optimal growth conditions of the isolated stains were temperature $30^{\circ}C$, pH 7, and initial cell mass 0.6 g/mL in our experiment, respectively. The first order degradation coefficients of Achromobacter, Mixed culture, Pseudomonas, and Flavobacterium were 0.072, 0.066, 0.047, and $0.032hr^{-1}$, respectively. and also, it could be expressed as a degradation rate considering cell mass (1.302, 1.019, 0.523, and 0.352 mg/TSS g/hr for each microorganism). Although Achromobacter has shown highest MTBE degradation rate, degradation rate for BTEX was relatively lower than other strains. and Mixed culture and Flavobacterium have shown similar degradation pattern for MTBE and BTEX biodegradation.

• Korean Journal of Environmental Biology
• /
• v.17 no.1
• /
• pp.59-69
• /
• 1999

Bacterial population, signal compounds of pollution, bacterial productivity, heterotrophic activity and the activities of extracellular enzymes were analyzed four times from July 1994 to April 1995 at Daejin, Galnam, Pohang, and Ulsan in the coastal area of Bast Sea in order to investigate the state of eutrophication. The population of heavy metal resistant bacteria in Pohang was the highest among all stations. The bacterial populations which could utilize C -P compounds (phosphonate) showed the highest at Pohang that was expected for the industrial and agricultural effluents to inpour. It could be useful as an index of expectation about the influx of industrial sewages and agricultural effluents. The activities of extracellular enzymes for the degradation of organic matter were the highest in the Ulsan Chuyongam, but low in Daejin. These results showed positive relationship with the population of heterotrophic bacteria and bacterial productivity The ratio of poly-P and DNA in Pohang was the highest, and that in Ulsan, Galnam, and Daejin consecutively, corresponding with the distribution of heterotrophic bacteria. In case of the heterotrophic activities, each of the stations gives difference of seasonal variation in heterotrophic activities. Bacterial productivity seemed to be dependent on seasons; the highest in summer and the lowest in fall and winter. These seasonal variations of bacterial productivity seems to be similar with those of heterotrophic bacteria. It is suggested that the state of eutrophication could be evaluated by the criteria of the population sizes and the productivities of microorganisms, the amount of poly-P, heterotrophic activity, the activities of extracellular enzymes, etc.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.10 no.1
• /
• pp.40-46
• /
• 2005

Clostridium bifermentans strain DPH-1 has already been found to dechlorinate perchloroethylene (PCE) to cis-dichloroethylene (cis-DCE) via trichloroethylene (TCE). In this study, our investigation on different culture conditions of this DPH-1 strain was extended to find a more efficient and cost effective growth medium composition for this DPH-1 strain in bioremediation practices. Temperature dependency of strain DPH-1 showed that the growth starting time and PCE degradation at $15^{\circ}C$ was very slow compared to that of $30^{\circ}C$, but complete PCE degradation occurred in both cases. For the proper utilization of strain DPH-1 in more cost effective bioremediation practices, a simpler composition of an effective media was studied. One component of the culture medium, yeast extract, had been substituted by molasses, which served as a good source of electron donor. The DPH-1 strain in the medium containing molasses, in the presence of $K_{2}HPO_4\;and\;KH_{2}PO_4$, showed identical bacterial multiplication (0.135 mg protein $mL^{-1}h^{-1}$) and PCE degradation rates ($0.38\;{\mu}M/h$) to those of the yeast extract containing medium.

• KSBB Journal
• /
• v.22 no.3
• /
• pp.157-161
• /
• 2007

This study is to investigate the biological degradation and the characteristics of MEA, a pH regulator to be put in the cooling water circulation system for power plants, loading to elevate concentrations of COD and N when eluted into the water environment. MEA, $NH_4^+$ and CODcr were monitored in flask cultures and in a batch aerator. MEA was found to be biologically degradable, producing substantial amount of ammonia (max. 78.1%) in a form of $NH_4^+$ and other carboneous intermediates. The degradation reaction rates were similar one another over all MEA concentrations tested as the activated sludge (microbial consortium) was acclimated to MEA with the gradual and stepwise increase in MEA input into the batch aerator. Also, MLVSS kept increasing with increasing MEA input. The COD-based degradation reaction order was determined to be 1.

• Microbiology and Biotechnology Letters
• /
• v.34 no.4
• /
• pp.289-298
• /
• 2006

3',5'-cyclic adenosine monophosphate (cAMP) is an important molecule, which mediates diverse cellular processes. For example, it is involved in regulation of sugar uptake/catabolism, DNA replication, cell division, and motility in various acterial species. In addition, cAMP is one of the critical regulators for syntheses of virulence factors in many pathogenic bacteria. It is believed that cAMP acts as a signal for environmental changes as well as a regulatory factor for gene expressions. Therefore, intracellular concentration of cAMP is finely modulated by according to its rates of synthesis (by adenylate cyclase), excretion, and degradation (by cAMP phosphodiesterase). In the present review, we discuss the bacterial physiological characteristics governed by CAMP and the molecular mechanisms for gene regulation by cAMP. Furthermore, the effect of cAMP on phosphotransferase system is addressed.

• Environmental Engineering Research
• /
• v.25 no.4
• /
• pp.561-570
• /
• 2020

In the present study, dye decolorizing bacteria were isolated from water and soil samples, collected from textile industries in Jodhpur province, India. Two bacterial species namely, Bacillus pumilis and Paenibacillus thiaminolyticus were screened and identified based on biochemical characterization. The degradation efficiency of these two microorganisms was compared through optimization of pH, incubation time, initial dye concentration and inoculum size. B. pumilis and P. thiominolyticus were able to degrade 61% and 67% Red HE3B, 81% and 75% Orange F2R, 49.7% and 44.2% Yellow ME4GL and 61.6% and 59.5% Blue RC CT dyes of 800mg/l concentration respectively. The optimum pH and time were found to be 8 within 24 hours. The FT-IR analysis confirmed that microorganisms were able to degrade toxic azo dyes into a non-toxic product as proved through structural modifications to analyze chemical functions in materials by detecting the vibrations that characterize chemical bonds. It is based on the absorption of infrared radiation by the microbial product. Therefore, Bacillus pumilis and Paenibacillus thiaminolyticus are a promising tool for decolorization of dyes due to its potential to effectively decolorize higher azo dye concentrations (10-800 mg/L) and can be exploited for bioremediation.

• Mycobiology
• /
• v.47 no.2
• /
• pp.250-255
• /
• 2019

In the present study, we aimed to determine the cause of surface film formation in three rice vinegars fermented using the traditional static fermentation method. The pH and total acidity of vinegar were 3.0-3.3 and 3.0-8.7%, respectively, and acetic acid was the predominant organic acid present. Colonies showing a clear halo on GYC medium were isolated from the surface film of all vinegars. Via 16S rDNA sequencing, all of the isolates were identified as Acetobacter pasteurianus. Furthermore, field-emission scanning electron microscopy analysis showed that the bacterial cells had a rough surface, were rod-shaped, and were ${\sim}1{\times}2{\mu}m$ in size. Interestingly, cells of the isolate from one of the vinegars were surrounded with an extremely fine threadlike structure. Thus, our results suggest that formation of the surface film in rice vinegar was attributable not to external contamination, to the production of bacterial cellulose by A. pasteurianus to withstand the high concentrations of acetic acid generated during fermentation. However, because of the formation of a surface film in vinegar is undesirable from an industrial perspective, further studies should focus on devising a modified fermentation process to prevent surface film formation and consequent quality degradation.

• Microbiology and Biotechnology Letters
• /
• v.47 no.1
• /
• pp.69-77
• /
• 2019

Screening microorganisms that can produce glucan hydrolases for industrial, environmental, and biomedical applications is important. Herein, we describe a novel approach to perform glucan hydrolase screening-based on analysis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) spectra-which involves degradation of the oligo- and polysaccharides. As a proof-of-concept study, glucan hydrolases that could break down glucans made of several glucose units were used to demonstrate the MALDI-MS-based enzyme assay. First, the enzyme activities of ${\alpha}$-amylase and cellulase on a mixture of glucan oligosaccharides were successfully discriminated, where changes of the MALDI-MS profiles directly reflected the glucan hydrolase activities. Next, we validated that this MALDI-MS-based enzyme assay could be applied to glucan polysaccharides (i.e., pullulan, lichenan, and schizophyllan). Finally, the bacterial glucan hydrolase activities were screened on 96-well plate-based platforms, using cell lysates or samples of secreted enzyme. Our results demonstrated that the MALDI-MS-based enzyme assay system would be useful for investigating bacterial glucoside hydrolases in a high-throughput manner.

• Korean Journal of Microbiology
• /
• v.51 no.3
• /
• pp.209-220
• /
• 2015

In this study, gut bacterial communities in xylophagous insects were analyzed using the pyrosequencing of 16S rRNA genes for their potential biotechnological applications in lignocelluloses degradation. The result showed that operational taxonomic units (OTUs), species richness and diversity index were higher in the hindgut than in the midgut of all insect samples analyzed. The dominant phyla or classes were Firmicutes (54.0%), Bacteroidetes (14.5%), ${\gamma}-Proteobacteria$ (12.3%) in all xylophagous insects except for Rhinotermitidae. The principal coordinates analysis (PCoA) showed that the bacterial community structure mostly clustered according to phylogeny of hosts rather than their habitats. In our study, the two carboxymethyl cellulose (CMC)-degrading isolates which showed the highest enzyme activity were most closely related to Bacillus toyonensis $BCT-7112^T$ and Lactococcus lactis subsp. hordniae $NCDO\;2181^T$, respectively. Cellulolytic enzyme activity analysis showed that ${\beta}-1,4-glucosidase$, ${\beta}-1,4-endoglucanase$ and ${\beta}-1,4-xylanase$ were higher in the hindgut of Cerambycidae. The results demonstrate that xylophagous insect guts harbor diverse gut bacteria, including valuable cellulolytic bacteria, which could be used for various biotechnological applications.