• Korean Journal of Microbiology
• /
• v.32 no.3
• /
• pp.202-207
• /
• 1994

A mutant strain PRM1 defective in light-activated heterotrophic growth was isolated from Synechocystis sp. PCC 6803. PRM1 could be grown at growth rate equivalent to Synechocystis 6803 under mixotrophic growth conditions. However, PRM1 could not be grown under light-activated heterotrophic conditions, in which a daily pulse of light for 5 min was given. These results suggest that PRM1 is not defective in heterotrophic metabolism, but in the transduction pathway of light signal essential to the growth. Plasmid patterns, absorption spectra of whole cells, and the exterior and interior structures of PRM1 were similar to those of Synechocystis 6803, except that PRM1 could not produce amorphous slime holding cells together.

• Journal of Life Science
• /
• v.33 no.6
• /
• pp.481-489
• /
• 2023

The taste and quality of soy sauce, a fermented liquid condiment, is greatly influenced by microbial metabolism during fermentation. To investigate the microbiological characteristics of ganjang during the initial fermentation process, we prepared meju (fermented soybean) blocks fermented with starter cultures and solar salts and analyzed the microbial community quantitively using 16S rRNA gene profiling from ganjang that had been fermented over a five-week period. The ganjang samples were collected and analyzed after soaking for week one (1W), three (3W), and five (5W) weeks. We found that Halomonadaceae was significantly higher in the 1W group (89.83%) than the 3W and 5W groups (14.46%, and 13.78%, respectively). At a species level, Chromohalobacter beijerinckii and Chromohalobacter canadensis were the dominant species in the 1W group but several taxa such as Bacillus subtilis, Pediococcus acidilactici, and Enterococcus faecalis were more abundant in the 3W and 5W groups. Pearson correlation analysis of the relative abundance of the bacteria showed a negative correlation between Chromohalobacter and two bacterial genera Bacillus and Enterococcus. Beta-diversity showed a statistical distinction between the 1W and the 3W and 5W groups, while no significance was evident between the 3W and 5W groups. Linear discriminant effect size analysis was used to identify biomarkers and significant differences in the relative abundance of several halophilic bacteria, Bacillus sp. and lactic acid bacteria at 1W, 3W, and 5W, recpectively, which indicates the important role of the bacterial community at these time points.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.1
• /
• pp.29-36
• /
• 2007

The xynA gene encoding the xylanase A of Paenibacillus sp. DG-22 was isolated with a DNA probe obtained by PCR amplification, using degenerated primers deduced from the amino acid residues of the known N-terminal region of the purified enzyme and the conserved region in the family 11 xylanases. The positive clones were screened on the LB agar plates supplemented with xylan, by the Congo-red staining method. The xynA gene consists of a 630-bp open reading frame encoding a protein of 210 amino acids, and the XynA preprotein contains a 28-residues signal peptide whose cleavage yields a l82-residues mature protein of a calculated molecular weight of 20,000Da and pI value of 8.77. The cloned DNA fragment also has another ORF of 873 nucleotides that showed 76% identity to the putative transcriptional activator of Bacillus halodurans C-125. Most of the xylanase activity was found in the periplasmic space of E. coli. The xynA gene was subcloned into pQE60 expression vector to fuse with six histidine-tag. The recombinant xylanase A was purified by heating and immobilized metal affinity chromatography. The optimum pH and temperature of the purified enzyme were 6.0 and $60^{\circ}C$, respectively. This histidine-tagged xylanase A was less thermostable than the native enzyme.

• Preventive Nutrition and Food Science
• /
• v.9 no.2
• /
• pp.138-143
• /
• 2004

Soybean curd residues (SCR) obtained from hot and cold manufacturing processes were fermented by indigenous microorganisms, Lactobacillus rhamnosus LS and Bacillus firmus NA-l for 15 h at 37$^{\circ}C$. The pH, acidity, viable cell counts, and tyrosine content were evaluated in samples with variations in sugar, starter and type of SCR. The raw Doowon SCR (D-SCR, cold-processed) fermented by indigenous microorganism had a 0.9% acidity and 6.7 ${\times}$ 10$^{7}$ CFU/g viable cell counts, compared with the 0.11 % acidity and 6.7 ${\times}$ 10$^{6}$ CFU/g viable cell counts of raw fermented Pulmuwon SCR (P-SCR, hot-processed). After fermentation of raw P-SCR with 1 % glucose and 1 % L. rhamnosus LS starter, the viable cell counts, tyrosine content and acidity were 4.7 ${\times}$ 10$^{8}$ CFU/g, 16.3 mg% and 0.9%, respectively. In addition, the raw P-SCR fermented with Bacillus firmus NA-l as co-starter had a 0.45% acidity, 2.4 ${\times}$ 10$^{8}$ CFU/g lactic acid bacteria, and 3.3 ${\times}$ 10$^{6}$ CFU/g Bacillus sp. In particular, the tyrosine content was increased 5 fold. The drying of fermented SCR was completed by hot-air drying (5$0^{\circ}C$) within 12 h; the dried P-SCR and D-SCR had 1.8 ${\times}$ 10$^{7}$ CFU/g and 5.3 ${\times}$ 10$^{6}$ CFU/g viable cell counts, respectively. The concentrate of methanol extract from fermented D-SCR inhibited the initial cell growth of E. coli, Staphylococcus aureus and Pseudomonas aeruginosa in liquid culture.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.4
• /
• pp.673-679
• /
• 2004

A microbial cryoprotectant formulation using a W/O/W multiple emulsion system was developed. The psychrotolerant microorganism, B4, isolated from soil in South Korea, was observed by the drop freezing method, in which the microorganism sample inhibited ice nucleation activity. The antifreeze activity was eliminated when the microorganism sample was treated with protease, indicating that the antifreeze activity was due to the presence of antifreeze protein. The result of the l6S rDNA sequencing indicated the B4 strain was most closely related to a species of the genus Bacillus. Culture broth of B4 strain (Bacillus sp.) and rapeseed oil containing 1 % polyglycerine polyricinolate (PGPR) were used as core and wall material, respectively. The most stable W/O emulsion was prepared at a core/oil ratio of 1:2. The highest W/O/W emulsion stability was achieved when the primary emulsion to external aqueous phase containing 0.5% caster oil polyoxyethylene ether $(COG25^{TM})$ ratio was 1:1. Microcrystalline cellulose showed better W/O/W emulsion stability than other polymer types. The viability of cells in a W/O/W emulsion was higher than free cells during storage at $37^\circ{C}$. An acidic pH and UV exposure decreased the viability of free cells, but cells in W/O/W emulsion were more stable under these conditions.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.1
• /
• pp.65-71
• /
• 2001

A gene from Paenibacillus sp. KCTC 8848P encoding ${\beta}-amylase$ was cloned and expressed in Escherichia coli. The Paenibacillus ${\beta}-amylase$ gene cosisted of a 2,409-bp open reading frame without a translational stop codon, encoding a protein of 803 amino acids. The presumed ribosime-binding site, GGAGG, was located 10 bp upstream from the TTG initiation codon. The deduced amino acid sequence of the ${\beta}-amylase$ gene had a 95% similarity to the ${\beta}-amylase$ of Bacillus firmus. The ${\beta}-amylase$ gene was introduced into wild-type strains of Saccharomyces cerevisiae using a linearized yeast integrating vector containing a geneticin resistance gene and its product was secreted into the culture medium.

• Microbiology and Biotechnology Letters
• /
• v.32 no.1
• /
• pp.96-100
• /
• 2004

Chlorothalonil is a wide-spectrum fungicide that is widely used in the world. Chlorothalonil is known as a potential toxic pollutant due to its high application rate, persistence, and toxicity to humans and other species. With the Increase of necessity of bioremediation, this study was conducted to isolate the chlorothalonil dissipation bacteria from soil. Soil samples were collected from 184 sites of farmland and wastewater disposal soil.661 strains resistant to chlorothalonil were isolated by dilution method from chlorothalonil-containing enrichment culture. After incubating at $30^{\circ}C$ in 1/10 LB media containing 10 ppm of chlorothalonil for a week, dissipation ability of chlorothalonil was investigated by HPLC. Finally, a strain SH35B, capable of dissipating chlorothalonil efficiently, was selected. The strain SH35B was identified as Ochrobactrum sp. Ten ppm of chlorothalonil In 1/10 LB media were completely dissipated by the growth of Ochrobactrum sp. SH35B for 30 h at $30^{\circ}C$. In the isolated strain, the content of glutathione and the activity of glutathione S-transferase were supposed to be ones of the Important factors for chlorothalonil dissipation and were higher than those of control strains, Escherichia coli and Bacillus subtilis.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.12
• /
• pp.1982-1992
• /
• 2019

The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 10⁸ and 1.25 ± 0.12 × 10⁸ CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 10⁹ CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 10⁶ CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.

• Fashion & Textile Research Journal
• /
• v.8 no.2
• /
• pp.239-244
• /
• 2006

For studies of fibrinolytic enzyme strain K-54 was isolated from the Korean traditional food chungkook-jang. Isolated strains K-54 was identified as Bacillus subtilis. The molecular weight of fibrinolytic enzyme from B. subtilis K-54 was 27 kDa. Optimum temperature for fibrinolytic enzyme of B. subtilis K-54 was $50-70^{\circ}C$ and optimum pH for producing the enzyme of this strain was ranging from 8 to 12. Also, it was found out enzyme activity was completely inhibited by 1mM PMSF. The result indicated this enzyme was thermo-stable alkaline serine protease with strong fibrinolytic activity. The wool and silk were treated with protease of B. subtilis K-54. As a result, the property of dyeing of wool fabrics was increased. By the increasing of treatment time became smoothened. But the change of mechanical properties were not changed.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.4
• /
• pp.437-447
• /
• 2012

Natural and beneficial associations between plants and bacteria have demonstrated potential commercial application for several agricultural crops. The sunflower has acquired increasing importance in Brazilian agribusiness owing to its agronomic characteristics such as the tolerance to edaphoclimatic variations, resistance to pests and diseases, and adaptation to the implements commonly used for maize and soybean, as well as the versatility of the products and by-products obtained from its cultivation. A study of the cultivable bacteria associated with two sunflower cultivars, using classical microbiological methods, successfully obtained isolates from different plant tissues (roots, stems, florets, and rhizosphere). Out of 57 plant-growth-promoting isolates obtained, 45 were identified at the genus level and phylogenetically positioned based on 16S rRNA gene sequencing: 42 Bacillus (B. subtilis, B. cereus, B. thuringiensis, B. pumilus, B. megaterium, and Bacillus sp.) and 3 Methylobacterium komagatae. Random amplified polymorphic DNA (RAPD) analysis showed a broad diversity among the Bacillus isolates, which clustered into 2 groups with 75% similarity and 13 subgroups with 85% similarity, suggesting that the genetic distance correlated with the source of isolation. The isolates were also analyzed for certain growth-promoting activities. Auxin synthesis was widely distributed among the isolates, with values ranging from 93.34 to 1653.37 ${\mu}M$ auxin per ${\mu}g$ of protein. The phosphate solubilization index ranged from 1.25 to 3.89, and siderophore index varied from 1.15 to 5.25. From a total of 57 isolates, 3 showed an ability to biologically fix atmospheric nitrogen, and 7 showed antagonism against the pathogen Sclerotinia sclerotiorum. The results of biochemical characterization allowed identification of potential candidates for the development of biofertilizers targeted to the sunflower crop.