• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1202-1207
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• 2012

A gene, ClCDA, encoding chitin deacetylase from Colletotrichum lindemuthianum, was optimized according to the codon usage bias of Pichia pastoris and synthesized in vitro by overlap extension PCR. It was secretorily expressed in P. pastoris GS115 using the constitutive expression vector pHMB905A. The expression level reached the highest with 110 mg/l culture supernatant after 72 h of methanol induction, which comprised 77.27 U/mg chitin deacetylase activity. SDS-PAGE, mass spectrometry, and deglycosylation assays demonstrated that partial recombinant protein was glycosylated with an apparent molecular mass of 33 kDa. The amino acid sequences of recombinant proteins were confirmed by mass spectrometry.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1405-1412
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• 2014

Lysozyme is a protein found in egg white, tears, saliva, and other secretions. As a marketable natural alternative to preservatives, lysozyme can act as a natural antibiotic. In this study, we have isolated Bacillus licheniformis TIB320 from soil, which contains a lysozyme gene with various features. We have cloned and expressed the lysozyme in E. coli. The antimicrobial activity of the lysozyme showed that it had a broad antimicrobial spectrum against several standard strains. The lysozyme could maintain efficient activities in a pH range between 3 and 9 and from $20^{\circ}C$ to $60^{\circ}C$, respectively. The lysozyme was resistant to pepsin and trypsin to some extent at $40^{\circ}C$. Production of the lysozyme was optimized by using various expression strategies in B. subtilis WB800. The lysozyme from B. licheniformis TIB320 will be promising as a food or feed additive.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.350-354
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• 2000

The growth promotion of a Taxus brevifolia cell suspension culture was investigated using conditioning factors. The conditioning factors produced and secreted from cultured cells usually stimulate cell division and the production of secondary metabolites. Therefore, the effective incubation time for the optimal secretion of conditioning factors was firstly determined for the promotion of cell growth. Conditioned media obtained by cultivating for 2 and 5 days showed the promotion of initial cell growth during the early cell growth period. However, the positive effect of the conditioning factors on the initial cell growth did not continue because of the depletion of the medium nutrients. Accordingly, the addition of a carbon source to the conditioned medium prolonged the positive effect on the cell growth. The addition of sucrose to the conditioned medium resulted in the maximum cell density being reached 4 days earlier compared to the control group and an increased substrate yield.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1890-1896
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• 2006

Lumostatic operation for cultivation of Haematococcus pluvialis was assessed to test the scale-up strategy of photobioreactors. Lumostatic operation is a method of maintaining a proper light condition based on the specific light uptake rate ($q_e$), by cells. Lumostatic operations were performed in 0.4-, 2-, 10-, and 30-1 scale bubble column photobioreactors and the results were compared with cultures illuminated with constant light intensity. Significant differences were observed in the maximal cell concentrations obtained from 0.4-, 2-, 10-, and 30-1 scale photobioreactors under constant light intensity, yielding the maximal cell concentrations of $2.8{\times}10^5$, $2.2\times10^5$, $1.5\times10^5$, and $1.1\times10^5$ cells/ml, respectively. The maximal cell concentration in a 0.4-1 photobioreactor under lumostatic operation was $4.3\times10^5$ cells/ml. Furthermore, those in 2-, 10-, and 30-1 scale photobioreactors were about the same as that in the 0.4-1 photobioreactor. The results suggest that lumostatic operation with proper $q_e$ is a good strategy for increasing the cell growth of Haematococcus pluvialis compared with a constant supply of light energy. Therefore, lumostatic operation is not only an efficient way to achieve high cell density cultures with minimal power consumption in microalgal cultures but it is also a perfect parameter for the scale-up of photobioreactors.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.259-271
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• 2021

Many bacteria metabolize aromatic compounds via catechol as a catabolic intermediate, and possess multiple genes or clusters encoding catechol-cleavage enzymes. The presence of multiple isozyme-encoding genes is a widespread phenomenon that seems to give the carrying strains a selective advantage in the natural environment over those with only a single copy. In the naphthalene-degrading strain Pseudomonas putida ND6, catechol can be converted into intermediates of the tricarboxylic acid cycle via either the ortho- or meta-cleavage pathways. In this study, we demonstrated that the catechol ortho-cleavage pathway genes (catBICIAI and catBIICIIAII) on the chromosome play an important role. The catI and catII operons are co-transcribed, whereas catAI and catAII are under independent transcriptional regulation. We examined the binding of regulatory proteins to promoters. In the presence of cis-cis-muconate, a well-studied inducer of the cat gene cluster, CatRI and CatRII occupy an additional downstream site, designated as the activation binding site. Notably, CatRI binds to both the catI and catII promoters with high affinity, while CatRII binds weakly. This is likely caused by a T to G mutation in the G/T-N11-A motif. Specifically, we found that CatRI and CatRII regulate catBICIAI and catBIICIIAII in a cooperative manner, which provides new insights into naphthalene degradation.

• Proceedings of the Microbiological Society of Korea Conference
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• 2006.05a
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• pp.92-92
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• 2006

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.963-977
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• 2015

The well-characterized gram-positive bacterium Bacillus subtilis is an outstanding industrial candidate for protein expression owing to its single membrane and high capacity of secretion, simplifying the downstream processing of secretory proteins. During the last few years, there has been continuous progress in the illustration of secretion mechanisms and application of this robust host in various fields of life science, such as enzyme production, feed additives, and food and pharmaceutical industries. Here, we review the developments of Bacillus subtilis as a highly promising expression system illuminating strong chemical- and temperatureinducible and other types of promoters, strategies for ribosome-binding-site utilization, and the novel approach of signal peptide selection. Furthermore, we outline the main steps of the Sec pathway and the relevant elements as well as their interactions. In addition, we introduce the latest discoveries of Tat-related complex structures and functions and the countless applications of this full-folded protein secretion pathway. This review also lists some of the current understandings of ATP-binding cassette transporters. According to the extensive knowledge on the genetic modification strategies and molecular biology of Bacillus subtilis, we propose some suggestions and strategies for improving the yield of intended productions. We expect this to promote striking future developments in the optimization and application of this bacterium.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1333-1341
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• 2009

Haematococcus pluvial is, a green alga, accumulates astaxanthin (3,3'-dihydroxy-$\beta$,$\beta$'-carotene-4,4'-dione) upto 2-3% on a dry weight basis. In the present study, identification of carotenoids from Haematococcus cyst cell extract by HPLC and LC-MS (APCI) and their antioxidant properties were evaluated in in vitro model systems. The extract exhibited 89% and 78% antioxidant activities in the $\beta$-carotene linoleate model and the hydroxyl radical scavenging model, at 9 ppm of total carotenoid, respectively. The extract also showed 80%, 85%, and 79% antioxidant activities against lipid peroxidation in the kidney, brain, and liver of rats. Low-density lipoprotein oxidation induced by $Cu^{2+}$ ions was also protected (45%, 64%, and 75%) by the extract in a dose-dependent manner with different carotenoid levels. Thiobarbituric acid reactive substances concentration in the blood, liver, and kidney of rats were also significantly (p<0.005) decreased in H. pluvialis-treated rats. The potent antioxidant activity is attributable to various carotenoids present in the extract.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.832-835
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• 2005

Inhibitory activity of active compound isolated from Ruta chalepensis leaf was examined against alcohol dehydrogenase and, upon comparison to those of four commercially available compounds (quinoline, quinoline-3-carboxaldehyde, quinoline-3-carboxylic acid, and quinoline-4-carboxylic acid) and 1,10-phenanthroline as alcohol dehydrogenase inhibitor, was characterized as quinoline-4-caboxaldehyde by spectral analyses. Inhibitory effects ($IC_{50}$) of quinoline-4-caboxaldehyde and quinoline derivatives varied depending on chemicals and concentrations used. The $IC_{50}$ values of quinoline-4-carboxaldehyde, quinoline-3-carboxaldehyde, quinoline, quinoline-3-carboxylic acid, and quinoline-4-carboxylic acid were 0.04, 0.3, 0.8, >1, and >1 mg/mL, respectively. These results suggest inhibitory action of quinoline-4-carboxaldehyde against alcohol dehydrogenase as prospective therapeutics for treatment of alcoholic liver diseases such as alcohol hepatitis and cirrhosis resulting from chronic alcohol abuse.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.685-688
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• 2005

Antibacterial and antiplatelet activities of Acorus gramineus rhizome-derived asaronaldehyde and asaron were analyzed using platelet aggregometer and six human intestinal bacteria. Active constituent of A. gramineus rhizome was isolated and characterized as asaronaldehyde by spectral analyses. At 2 and 1 mg/disk, asaronaldehyde exhibited strong inhibition of Clostridium perfringens and C. difficile without adverse effects on growth of beneficial bacteria such as Bifidobacterium bifidum, Lactobacillus acidophilus, and L. casei. Asaron also revealed moderate growth inhibition against C. perfringens and C. difficile at 2 mg/disk, no growth-inhibiting activity was observed on B. bifidum, L. acidophilus, L. casei, and E. coli. At 50% inhibitory concentration ($IC_{50}$) value, asaronaldehyde was effective in inhibiting platelet aggregation induced by collagen ($IC_{50}$, $27.6\;{\mu}M$) and arachidonic acid ($IC_{50}$, $53.7\;{\mu}M$). These results suggest asaronaldehyde may be useful as lead compound for inhibiting platelet aggregation induced by collagen and arachidonic acid.