• Mycobiology
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• v.38 no.4
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• pp.302-309
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• 2010

Formic acid is a representative carboxylic acid that inhibits bacterial cell growth, and thus it is generally considered to constitute an obstacle to the reuse of renewable biomass. In this study, Saccharomyces cerevisiae was used to elucidate changes in protein levels in response to formic acid. Fifty-seven differentially expressed proteins in response to formic acid toxicity in S. cerevisiae were identified by 1D-PAGE and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analyses. Among the 28 proteins increased in expression, four were involved in the MAP kinase signal transduction pathway and one in the oxidative stress-induced pathway. A dramatic increase was observed in the number of ion transporters related to maintenance of acid-base balance. Regarding the 29 proteins decreased in expression, they were found to participate in transcription during cell division. Heat shock protein 70, glutathione reductase, and cytochrome c oxidase were measured by LC-MS/MS analysis. Taken together, the inhibitory action of formic acid on S. cerevisiae cells might disrupt the acidbase balance across the cell membrane and generate oxidative stress, leading to repressed cell division and death. S. cerevisiae also induced expression of ion transporters, which may be required to maintain the acid-base balance when yeast cells are exposed to high concentrations of formic acid in growth medium.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.289-296
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• 2019

A novel rapid procedure with liquid chromatography tandem mass spectrometry (LC-MS/MS) detection has been developed by changing various conditions including sample preparation such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology. This work has been involved the optimization and validation of detection method for fluoroquinolones which are widespread used in livestock especially in the chicken. Five grams of homogenized chicken muscle were extracted with QuEChERS EN and acetonitrile containing 5% formic acid and cleaned with anhydrous magnesium sulfate and C₁₈ sorbent. The separation was performed on Acquity UPLC HSS T3 (2.1 mm×100 mm, 1.8 ㎛) column. The mobile phase A and B were composed of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid, respectively. Flow rate was 0.25 mL/min and column temperate was 40℃. LC-MS/MS with multiple reaction monitoring has been optimized for ten fluoroquinolones (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, marbofloxacin, norfloxacin, ofloxacin, orbifloxacin, pefloxacin and sarafloxacin). The method developed in this study has been presented good linearity with correlation coefficient (R²) of 0.9971~0.9998. LOD and LOQ values ranged from 0.09 to 0.76 ppb and from 0.26 to 2.29 ppb, respectively. The average recoveries were from 77.46 to 111.83% at spiked levels of 10.0 and 20.0 ㎍/kg. Relative standard deviation (%) ranged 1.28~11.90% on intra-day and 3.10~8.38 % on inter-day, respectively. This analysis method was applicable to the livestock residue laboratories and was expected to be satisfactory for the residue surveillance system.

• Culinary science and hospitality research
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• v.22 no.2
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• pp.13-28
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• 2016

This study performed quantitative analysis of isoflavone glycoside contents on Buseoktae, Daewon, Wooram beans and cheonggukjang made of Buseoktae beans from the LC/MS/MS. Also, the experiment carried out by means of RSM(response surface methodology), which included 10 experimental points for the two independent variables addition(40, 55, 70 g) and time(2, 3, 4 min) from the beginning point to boil of cheonggukjang. These were optimized using a Face-centered central composite design. Daidzein contents were $212.16{\mu}g/mL$ in Buseoktae, $212.21{\mu}g/mL$ in daewon, $158.54{\mu}g/mL$ in wooram beans. Genistein contents were $318.84{\mu}g/mL$ in Buseoktae, $310.50{\mu}g/mL$ in daewon, $262.71{\mu}g/mL$ in wooram beans. Total isoflavone contents were $532.50{\mu}g/mL$ in Buseoktae, $524.19{\mu}g/mL$ in Daewon, $422.71{\mu}g/mL$ in Wooram beans. Isoflavone contents of Buseoktae and Daewon were quite similar, relatively contents of Wooram beans were low. Total isoflavone contents of Buseoktae cheonggukjang (for business use) was $430.10{\mu}g/mL$ in A ($32^{\circ}C$, 96 h fermentation), $460.09{\mu}g/mL$ in B ($36{\sim}40^{\circ}C$, 30 h fermentation), $417.46{\mu}g/mL$ in C cheonggukjang($36{\sim}38^{\circ}C$, 72 h fermentation), B cheonggukjang was just a bit more than A, C cheonggukjang. The estimated response surfaces confirmed that the amount and time had significant effects on taste. The optimum condition of Buseoktae cheonggukjang taste was predicted to be 55.20 g addition at 2.92 min.