• Journal of Environmental Science International
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• v.17 no.3
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• pp.343-350
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• 2008

The fate of two cyclic ethers, THF(Tetrahydrofuran) and 1,4-Dioxane, in conventional biological wastewater treatment plants was investigated using sequential activated sludge process. Removal efficiency of THF were about 86% in average, which was greater than that of 1,4-Dioxane, 30%. However, it was not clear whether the removal of cyclic ethers in biological system was caused by microbial activity or not. Thus treatability tests were conducted by batch experiments. The effects of mixing, aeration and the addition of activated sludge on the removal of cyclic ethers were investigated in batch experiments. THF was totally removed by mixing and aeration in 24 hours while removal ratio of 1,4-Dioxane was at most 30% for the same period. This results could be ascribed to the differences in Henry's law constants between the two chemicals. In addition, biological degradation including biosorption was not obviously observed in these batch tests.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.3-6
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• 2002

Electron transfer is the major natural process governing the behavior of contaminants in soils and groundwaters. Biological degradation of contaminants, i.e., microbial transformation of hazardous compounds, is a well known irreversible electron transfer process. Although it is not well defined as a separate process, abiotic electron-transfer is also an important process for mobilizing/demobilizing inorganic contaminants in soils and groundwaters. Therefore, numerous remedial technologies have been developed on the basis of electron transfer concept. Among them,

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.11
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• pp.1523-1529
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• 2016

Soybean meal (SBM), a commonly used protein source for animal feed, contains anti-nutritional factors such as trypsin inhibitor, phytate, oligosaccharides among others, which limit its utilization. Microbial fermentation using bacteria or fungi has the capability to improve nutritional value of SBM by altering the native composition. Both submerged and solid state fermentation processes can be used for this purpose. Bacterial and fungal fermentations result in degradation of various anti-nutritional factors, an increase in amount of small-sized peptides and improved content of both essential and non-essential amino acids. However, the resulting fermented products vary in levels of nutritional components as the two species used for fermentation differ in their metabolic activities. Compared to SBM, feeding non-ruminants with fermented SBM has several beneficial effects including increased average daily gain, improved growth performance, better protein digestibility, decreased immunological reactivity and undesirable morphological changes like absence of granulated pinocytotic vacuoles.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.31-34
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• 1990

Dibenzothiophene, crude oil and bunker C oil were used in the microbial desulfurization experiments using thermophilic and mesophilic strains of Desulfovibrio and Desulfotomaculum. Mesophilic Desulforvibrio desulfuricans M6 showed the degrees of sulfur removal about 42% and 17% from dibenzothiophene and crude oil, respectively. Thermophilic Desulfovibrio thermophilus showed the degrees of sulfur removal about 68% and 33% from dibenzothiophene and bunker C oil. The strains of Desulfotomaculum were much less efficient than strains of Desulfovibrio. The latter have more complex and stronger gydrogen metabolism. These results showed that desulfurization is closely related to the hydrogen metabolism of the sulfate reducing bacteria.

• Journal of Microbiology and Biotechnology
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• v.22 no.4
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• pp.457-461
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• 2012

Members of candidate division OP3 were detected in 16S rRNA gene clone libraries from methanogenic enrichment cultures that utilized limonene as a carbon and energy source. We developed probes for the visualization of OP3 cells. In situ hybridization experiments with newly designed OP3-specific probes [OP3-565 and Eub-338(VI)] revealed abundant small OP3 cocci attached to larger cells. Syntrophic Deltaproteobacteria, OP3 cells, and methanogens affiliating with Methanoculleus and Methanosaeta formed the limonene-degrading community.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1774-1778
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• 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.

• Molecules and Cells
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• v.28 no.4
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• pp.369-373
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• 2009

Heterologous secretory expression of endoglucanase E (Clostridium thermocellum) and ${\beta}$-glucosidase 1 (Saccharomycopsis fibuligera) was achieved in Saccharomyces cerevisiae fermentation cultures as an ${\alpha}$-mating factor signal peptide fusion, based on the native enzyme coding sequence. Ethanol production depends on simultaneous saccharification of cellulose to glucose and fermentation of glucose to ethanol by a recombinant yeast strain as a microbial biocatalyst. Recombinant yeast strain expressing endoglucanase and ${\beta}$-glucosidase was able to produce ethanol from ${\beta}$-glucan, CMC and acid swollen cellulose. This indicates that the resultant yeast strain of this study acts efficiently as a whole cell biocatalyst.

• Journal of Microbiology
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• v.43 no.6
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• pp.572-576
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• 2005

This study focused on detecting catabolic genes for polycyclic aromatic hydrocarbons (PAHs) distributed in the reed rhizosphere of Sunchon Bay, Korea. These marsh and mud environments were severely affected by human activities, including agriculture and fisheries. Our previous study on microbial roles in natural decontamination displayed the possibility that PAH-degrading bacteria, such as Achromobacter sp., Alcaligenes sp., Burkholderia sp. and Pseudomonas sp. play an important decontamination role in a reed rhizosphere. In order to gain further fundamental knowledge on the natural decontamination process, catabolic genes for PAH metabolism were investigated through PCR amplification of dioxygenase genes using soil genomic DNA and sequencing. Comparative analysis of predicted amino acid sequences from 50 randomly selected dioxygenase clones capable of hydroxylating inactivated aromatic nuclei indicated that these were divided into three groups, two of which might be originated from PAH-degrading bacteria. Amino acid sequences of each dioxygenase clone were a part of the genes encoding enzymes for initial catabolism of naphthalene, phenanthrene, or pyrene that might be originated from bacteria in the reed rhizosphere of Sunchon Bay.

• Journal of Microbiology
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• v.43 no.spc1
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• pp.101-109
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• 2005

To gain maximal benefit in a competitive environment, single-celled bacteria have adopted a community genetic regulatory mechanism, known as quorum sensing (QS). Many bacteria use QS signaling systems to synchronize target gene expression and coordinate biological activities among a local population. N-acylhomoserine lactones (AHLs) are one family of the well-characterized QS signals in Gram-negative bacteria, which regulate a range of important biological functions, including virulence and biofilm formation. Several groups of AHL-degradation enzymes have recently been identified in a range of living organisms, including bacteria and eukaryotes. Expression of these enzymes in AHL-dependent pathogens and transgenic plants efficiently quenches the microbial QS signaling and blocks pathogenic infections. Discovery of these novel quorum quenching enzymes has not only provided a promising means to control bacterial infections, but also presents new challenges to investigate their roles in host organisms and their potential impacts on ecosystems.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.53-58
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• 1996

The characterstics of the soy protein curd(eczyme-, HCI- and Ca-surd) were shown by scanning electron micrographs and gel electrophoreis. The emulsion stability of enzyme-curd showed high value in the range of pH 2~10and wide range of temperature(20~8$0^{\circ}C$). While at the isoelectric point(pH5.0), the emulsion stability of the HCI-and Ca-curd was decreased remarkably, and the emulsion stability of temperature was reduced quickly to the 60% and 40% at the 4$0^{\circ}C$. The foam stability of enzyme-curd was slightly higher than that HCI-and CA-curd in all ranges of pH and temperature. The feature of SEM of enzyme-cured produced degradation products faster than that of the HCI- and Ca-curd.