• Journal of Microbiology and Biotechnology
• /
• v.28 no.1
• /
• pp.87-94
• /
• 2018

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at $22^{\circ}C$ and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.

• Journal of Welding and Joining
• /
• v.35 no.1
• /
• pp.89-94
• /
• 2017

The microstructure and dilatation for 0.15C steels were investigated to define the phase transformation during the quenching and partitioning (Q&P) process. For the one step Q&P dilatation, the isothermal martensite/bainite transformation occurred because the holding temperature was between $M_s$ and $M_f$. The isothermally transformed martensite/bainite and the athermally transformed martensite were produced by a loss of retained austenite. As the holding time increased, new martensite-start ($M_s$) temperature produced from the final quenching process decreased due to the carbon partitioning from the martensite to the retained austenite. This was the direct evidence of increment for the retained austenite stability. For the two step Q&P dilatation, the isothermal bainitic transformation occurred because the partitioning temperature was larger than the $M_s$ and new $M_s$. The partitioning at $400^{\circ}C$ indicated the short incubation period for the bainite transformation than the $350^{\circ}C$ partitioning because the partitioning at $400^{\circ}C$ should acquire the larger thermal driving force for carbon partitioning than the $350^{\circ}C$ partitioning. A quick drop of $M_s$ and short period of bainite incubation for the $400^{\circ}C$ partitioning steel were also the direct evidence of significant effects of carbon partitioning on the stability of retained austenite.

• Korean journal of food and cookery science
• /
• v.8 no.3
• /
• pp.333-341
• /
• 1992

The physicochemical, rheological and sensory characteristics of 'BACKSULGIES', which was added with potato peel, guar gum or polydextrose, were investigated. The maximum acceptable addition ratio of dietary fiber to 'BACKSULGI' was 10%. And optimal addition ratio was 3% for all samples. The water binding capacity was affected by dietary fiber sources and incubation conditions (temperature and time). The Guar gum had me highest value of water binding capacity. The solubility was highly related with water binding capacity and me swelling power was increased with temperature increment. The degree of gelatinization was not significantly different with dietary fiber sources. But me values of gelatinization of 'BACKSULGIES' added with dietary fibers were significantly higher than mose of 'BACKSULGI' with no dietary fiber. Generally hardness and brittleness incresed along with storage time. But me hardness of 'BACKSULGIES' added with dietary fibers was significantly lower man those of 'BACKSULGI' with no dietary fiber. The retardation effect of dietary fibers for retrogradation of 'BACKSULGIES' was also proved by time constant determination of Avrami equation. Sernsory evaluation revealed that me addition of dietary fibers did not reduce the organoreptic quality. Therefore potato peel 3%, guar gum 3%, polydextrose 3% were optimum addition ratio which could be accepted as conventional 'BACKSULGI'. As me results of this study, it was proved mat the additions of dietary fibers to 'BACKSULGI' had the retardation effect of retrogradation.

• Food Science of Animal Resources
• /
• v.28 no.2
• /
• pp.154-159
• /
• 2008

To investigate the rheological properties of protein mixed gels mediated by microbial transglutaminase (MTGase), pork myofibrillar protein (MFP), sodium caseinate (SC) and their mixture (MS), the various gels were incubated at different temperatures for various times. Extracted MFP, SC and their mixture (MS, 1:1) were incubated at different temperatures ($4^{\circ}C$ vs $37^{\circ}C$) for various times (0, 0.5, 2, 4 hr), and assessed for viscosity, gel strength and other characteristics using differential scanning calorimeter (DSC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). DSC measurements showed that incubation at $37^{\circ}C$ rather than $4^{\circ}C$ caused marked changes in thermal transition, and MS displayed similar thermal curves (three endothermic transitions) to MFP and SC alone. After incubation at $37^{\circ}C$ for 2 hrs, the viscosity (cP) of MS increased (p<0.05) due to induction by MTGase, whereas no differences were observed at $4^{\circ}C$. However, gel strength values were no different, regardless of incubation temperatures and times. Future research will address how longer incubation times affect the functionality of protein mixed gels mediated by MTGase.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.4
• /
• pp.10-14
• /
• 2009

Objective of this study was to examine the effects of grouts and temperature change on microorganisms in geothermal heat pump. Groundwater samples were obtained from wells in the heat pump system during installation (Oriental medicine hospital) and in the heat pump system under operation (Business incubation center). Grouts are the volclay sodium bentonite. Real-time PCR was used to evaluate total bacterial number and 16S rDNA. The results showed that total bacterial number of groundwater in the heat pump operation was greater than that of non-operation case, which indicates a temperature effect on the bacterial culture. In addition, high concentration of grout showed an elevated bacteria number. In the mean time, a long-term field monitoring is essentially required to confirm the effects of the grouts and the temperature changes.

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.4
• /
• pp.29-40
• /
• 2000

Highly purified Cerrena unicolor laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) caused the demethoxylation of milled wood lignin and several lignin related substances. The constitutive form of the enzyme produced extracellularly by C. unicolor fermenter culture was isolated and purified by ion-exchange chromatography on the DEAE-Toyopearl column and by affinity chromatography on a ConA-Sepharose and Syringyl-AH-Sepharose 4B columns. The enzyme was further immobilized on functionalized porous glass (CPG) and keratin coated CPG. The demethylating activity was monitored both by estimation of released methanol and by detection of the level of methoxyl groups (also in some water miscible solvents) after incubation of lignin materials with laccase preparations (free and immobilized). The effects of the incubation time and temperature on the demethoxylating activity of immobilized laccase preparations were also studied.

• Journal of Applied Biological Chemistry
• /
• v.50 no.2
• /
• pp.46-51
• /
• 2007

Lipases are industrially useful versatile enzymes that catalyze numerous different reactions. Among lipases functioning under extreme conditions, alkaline lipase is useful in detergent industry. Lipase from yeast strain Yarrowia lipolytica NRRL Y-2178 was most active under alkaline condition, and initial medium pH for most lipase production was also alkaline [Lee et al., 2007, J Microbiol Biotechnol, 17(6)]. High lipase production was achieved using Y. lipolytica NRRL Y-2178. Optimal incubation time for lipase production at $25^{\circ}C$ was 72 h. Optimal temperature, when incubated for 72 h, was $27.5^{\circ}C$. Lipase production but not cell growth was very sensitive to concentrations of glucose and glycerol as efficient carbon sources, showing optimal concentrations of 1.0 and 1.5% (w/v), respectively. Lipase production was highly stimulated by $Ca^{2+},\;K^+,\;and\;Na^+$, but was inhibited by $Co^{2+},\;Cu^{2+},\;Mn^{2+},\;Na^+,\;and\;Fe^{2+}$. Maximum lipase production at 0.1 mM $Ca^{2+}$ for 72 h incubation at $27.5^{\circ}C$ was 649 units/mL.

• Journal of Microbiology
• /
• v.33 no.2
• /
• pp.160-164
• /
• 1995

The splicing activity of T4 phage td intron RNA has been examined with various Mg$^{2+}$ ions such as MGCl$_{2}$, MgS $O_{4}$ and magnesium acetate using various splicing conditions such as different incubation time and temperature. The maximum splicing of td intron RNA occurred at the concentration of 5 mM MgCl$_{2}$. Raising the Mg$^{2+}$ concentration up to 15 mM appeared to promote P2 delection mutant to overcome the loss of some splicing activity. In both wild type and mutant, a complete hydrolysis of RNA occurred at 30 mM MgCI$_{2}$ MgS $O_{4}$ and magnesium acetate exhibited the rate and pattern of RNA splicing identical to MGCI$_{2}$. The optimal splicing conditions involve the incubation of RNA with 5 mM MgCI$_{2}$ at 58 .deg.C for 15 min. The results suggest that Mg$^{2+}$ may play a key role in the catalytic mechanism of td intron RNA.n RNA.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.20 no.4
• /
• pp.282-292
• /
• 1987

In order to exploit a new type of food source, enzamatically modified hydrolysates and the plasteins synthesized from the filefish (Nevoden modestus) protein hydrolysates by plastein reaction were investigated. The optimum conditions for enzymatic hydrolysis of filefish muscle and synthesis of plasteins using papain, pepsin, $\alpha-chymotrypsin$ and protease (from Streptomyces griceus) were determined. The optimum temperature and pH for the hydrolysis of filefish muscle by papain, pepsin, $\alpha-chymotrypsin$ and protease were $50^{\circ}C,\;40^{\circ}C,\;55^{\circ}C\;and\;50^{\circ}C$; and 6, 2, 7 and 8, respectively. Those for incubation time and enzyme concentration were 4hr, $0.5\%$ for papain and protease, 24hrs $1.0\%$ for pepsin and $\alpha-chymotrypsin$. The pepsin was found to be more reasonable substrate for plastein synthesis from the economic point of view. The enzyme-induced plastein reaction could be optimized, namely, pH 4 for pepsin, pH 7 for $\alpha-chymotrypsin$, pH 6 for papain and protease: substrate concentration $40\%$ for pepsin, $\alpha-chymotrypsin$ and protease, $50\%$ for papain; the time of incubation, 24hr; enzyme/substrate ratio, 1 : 100(W/V) ; incubation temperature, $50^{\circ}C$.

• Korean Journal of Microbiology
• /
• v.20 no.4
• /
• pp.173-182
• /
• 1982

From FGSC 159 strain of Aspergillus nidulans, temperature sensitive mutants that are defective in growth and differentiation have been isolated by N-methyl-N'-nitroN-nitrosoguanidine (NTG) treatment. The optimum concentration of NTG and incubation time to get the highest mutation frequency was $100{\mu}g$ per ml and 1 hour, respectively. The survival frequency was 1%. Among the isolated mutants, five strains that were affected in early steps of differentiation were selected for further studies and named smK, smY, smB, smF, and smZ. The execution point of each mutant was determined and the growing pattern of each mutant at the restrictive temperature was observed under the microscope. Growth of mutant was arrested near at the execution point. From genetic analysis, each temperature-sensitive mutants was thought to have a single recessive gene. The genes of smK, smY, smB, smF, and smZ are linked to the chromosome VII, IV, VIII, I, and VI, respectively. It can be concluded that the genes controlling the differentiation are widely dispersed in the genome. From the results of mutant, smK, it is considered that a single gene can affect a function (functions) which act(s) at two different steps during differentiation.