• Food Science and Biotechnology
• /
• 제17권4호
• /
• pp.794-798
• /
• 2008

Guar gum and $\kappa$-carrageenan were investigated as a substitutes for phosphate in pork meat processing. Emulsion-type pork sausages were prepared in which 0.5% phosphate was used for the control, and either $\kappa$-carrageenan or guar gum were added at levels of 0.1 or 0.5% for comparison. The hydrocolloid compounds significantly enhanced water holding capacity and cooking loss. However, hardness, cohesiveness, and chewiness were not well-maintained when compared to the control; this was attributable to the altered water distribution as well as enhanced water holding capacity of the sausages by the addition of $\kappa$-carrageenan and guar gum. Furthermore, the phosphate-free sausages had similar storage stability as the phosphate-added sausage. Overall, the results suggest that $\kappa$-carrageenan or guar gum can be used in place of phosphate in conventional processing to successfully prepare phosphate-tree pork sausages.

• 자연과학논문집
• /
• 제11권1호
• /
• pp.55-63
• /
• 1999

효모세포의 원형질체 최적형성을 위한 stabilizer의 종류 및 농도, pH 그리고 lysis 방법을 조사하는 한편, intact cell과 protoplast사이의 효소활성도 및 poly-P 생합성율을 비교하였다. 그 결과 protoplast 형성에 있어 snail gut enzyme은 5시간, drisielase는 3시간 정도의 incubation 시간이 필요했으며, stabilizer로는 0.8 M mannitol, 6 M KCl이 좋았다. Protoplast는 intact cell에 비해 ALPase 활성은 22-27%, ACPase는 4-15% 정도 감소하였으며, poly-P 형성은 protoplast에서 유의한 증가가 일어나지 않았다.

• Environmental Engineering Research
• /
• 제24권2호
• /
• pp.309-317
• /
• 2019

This study evaluated the kinetics of acrylamide (AM) biodegradation by mixed culture bacteria and Enterobacter aerogenes (E. aerogenes) in sequencing batch reactor (SBR) systems with AQUASIM and linear regression. The zero-order, first-order, and Monod kinetic models were used to evaluate the kinetic parameters of both autotrophic and heterotrophic nitrifications and both AM and chemical oxygen demand (COD) removals at different AM concentrations of 100, 200, 300, and 400 mg AM/L. The results revealed that both autotrophic and heterotrophic nitrifications and both AM and COD removals followed the Monod kinetics. High AM loadings resulted in the transformation of Monod kinetics to the first-order reaction for AM and COD removals as the results of the compositions of mixed substrates and the inhibition of the free ammonia nitrogen (FAN). The kinetic parameters indicated that E. aerogenes degraded AM and COD at higher rates than mixed culture bacteria. The FAN from the AM biodegradation increased both heterotrophic and autotrophic nitrification rates at the AM concentrations of 100-300 mg AM/L. At higher AM concentrations, the FAN accumulated in the SBR system inhibited the autotrophic nitrification of mixed culture bacteria. The accumulation of intracellular polyphosphate caused the heterotrophic nitrification of E. aerogenes to follow the first-order approximation.

• Journal of Ceramic Processing Research
• /
• 제20권4호
• /
• pp.411-417
• /
• 2019

Graphene doped zinc oxide nanoparticles (G-ZnO) were prepared using modified hummer's technique together with the ultrasonic method and characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), fourier-transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM). Different samples of epoxy resin nanocomposites reinforced with G-ZnO nanoparticles were prepared and were marked as F1 (without adding nanoparticles), F2 (1% w/w G-ZnO), and F3 (2% w/w G-ZnO) in combination of ≈ 56:18:18:8w/w% with epoxy resin/hardener, ammonium polyphosphate, boric acid, and Chitosan. The peak heat release rate (PHRR) of the epoxy nanocomposites was observed to decrease dramatically with the increasing G-ZnO nanoparticles. However, the LOI values increased significantly with the increase in wt % of G-ZnO nanoparticles. From the UL-94V data, it was confirmed that the F2 and F3 samples passed the flame test and were rated as V-0. The results obtained in the present work clearly revealed that the synthesized samples can be used as efficient materials in fire-retardant coating technology.

• Journal of Microbiology and Biotechnology
• /
• 제33권10호
• /
• pp.1370-1375
• /
• 2023

In this study, we aimed to enhance the accumulation of chorismate (CHR) and anthranilate (ANT), key intermediates in the shikimate pathway, by modifying a shikimate over-producing recombinant strain of Corynebacterium glutamicum [19]. To achieve this, we utilized a CRISPR-driven genome engineering approach to compensate for the deletion of shikimate kinase (AroK) as well as ANT synthases (TrpEG) and ANT phosphoribosyltransferase (TrpD). In addition, we inhibited the CHR metabolic pathway to induce CHR accumulation. Further, to optimize the shikimate pathway, we overexpressed feedback inhibition-resistant Escherichia coli AroG and AroH genes, as well as C. glutamicum AroF and AroB genes. We also overexpressed QsuC and substituted shikimate dehydrogenase (AroE). In parallel, we optimized the carbon metabolism pathway by deleting the gntR family transcriptional regulator (IolR) and overexpressing polyphosphate/ATP-dependent glucokinase (PpgK) and glucose kinase (Glk). Moreover, acetate kinase (Ack) and phosphotransacetylase (Pta) were eliminated. Through our CRISPR-driven genome re-design approach, we successfully generated C. glutamicum cell factories capable of producing up to 0.48 g/l and 0.9 g/l of CHR and ANT in 1.3 ml miniature culture systems, respectively. These findings highlight the efficacy of our rational cell factory design strategy in C. glutamicum, which provides a robust platform technology for developing high-producing strains that synthesize valuable aromatic compounds, particularly those derived from the shikimate pathway metabolites.

• 한국양식학회:학술대회논문집
• /
• 한국양식학회 2003년도 추계학술발표대회 논문요약집
• /
• pp.19-19
• /
• 2003

This presentation reviewed the dietary vitamin C requirements in main marine finfish culture in Korea. In experiment I, an II-week feeding trial was conducted to study the effects of the different levels of dietary vitamin C on growth, tissue ascorbic acid concentrations and histopathological changes in parrot fish. Casein and gelatin based diets were formulated to contain 0, 60, 120, 240, 480 and 2000mg L-ascorbic acid (AA)kg diets on Ah equivalent basis in the form of L-ascorbyl-2-monophosphate (AMP), 60 and 240 mg AA/kg diet as L-ascorbic acid. Broken line analysis of weight gain indicated that the dietary vitamin C requirement of parrot fish is l18$\pm$12 mg AA/kg diet in the form of L-ascorbyl-2-monophosphate for maximum growth. In experiment II, a 12-week experiment was conducted to compare L-ascorbyl-2-monophosphate-Ca (AMP-Ca) with L-ascorbyl-2-monophosphate-Na/Ca (AMP-Na/Ca) for supplying the dietary vitamin C for juvenile Korean rockfish Sebastes schlegeli. Fish were fed one of 11 semi-purified diets containing equivalent of 0, 50, 100, 200, 400, and 800 mg ascorbic acid (AA)kg diet in the form of AMP-Ca or AMP-Na/Ca for 12 weeks. Broken line analysis of weight gain indicated that the dietary vitamin C requirement of Korean rockfish is 100 mg AA/kg diet in the form of AMP-Na/Ca, and 117 nag AA/kg diet in the form of AMP-Ca. In experiment III, a 12-week experiment was conducted to study the effects of different dietary levels of vitamin C, L-ascorbyl-2-polyphosphate (ASPP), on growth and tissue vitamin C concentrations in juvenile olive flounder. Fish were fed one of six semi-purified diets containing an equivalent of 0, 25, 50, 75, 150, or 1500 mg ascorbic acid (AA) kg 1 diet in the form of ASPP for 12 weeks. Based on broken line analyses for WG and PER, the optimum dietary levels of vitamin C were 91 and 93 mg AA/kg diet, respectively.

• 자원환경지질
• /
• 제38권6호
• /
• pp.657-662
• /
• 2005

Extractions fro fertilizer and soil samples were performed to yield the operationally defined fractions 'soluble' chromate (extractable with $NH_4NO_3$), 'exchangeable' chromate (extractable with phosphate buffer pH 7.2), and these results were compared with the data obtained by extractions with ammonium sulfate, borate buffer pH 7.2, saturated borax pH 9.6, and polyphosphate (Graham's salt). In order to maintain the pH of extractant solution about constant, the concentration of extractant buffer had to be raised to at least 0.5 M. The results strongly depended on the kind of extractant, and the solid: liquid ratio. For most of the samples investigated, the extraction efficiency increased in the order borate-sulfate-nitrate-phosphate. Whereas the recovery of $K_2CrO_4\;and\;CaCrO_4$ added to the samples of basic slags prior to the extraction was about complete, the recovery of added $PbCrO_4$ was highly variable. In soil extracts, the color reaction was interfered from co-extracted humics, which react with the chromate in weak acid solution during the time period necessary for color reaction (1 hour). However, this problem can be overcome by standard addition and subtraction of the color of the extractant solution. In soil extract of about pH < 7, organic material reduced chromate during the extraction period also, and standard addition of soluble chromate is recommended to prove recovery and the stability of chromate in the samples. In admixtures of soils and basic slags, results for hexavalent chromium were lower than from the mere basic slags. This effect was more pronounced in phosphate than in nitrate extracts. As a proficiency test, samples low in organic carbon from contaminated sites in Hungary were tested. The results from $NH_4NO_3$ extracts satisfactorily matched the results of the Hungarian labs obtained from $CalCl_2$ extractants.

• 한국수산과학회지
• /
• 제48권4호
• /
• pp.454-458
• /
• 2015

This study compared the effects of dietary supplementation of citrus by-product (CBP) and CBP fermented with Bacillus subtilis (F-CBP) on growth performance, feed utilization, intestinal histology and innate immunity of red seabream Pagrus major with three commercial immune-boosting products. The six experimental diets were supplemented with L-ascorbyl-2-polyphosphate (LAPP; the control diet), CBP or F-CBP at a concentration of 100 mg vitamin C equivalent/kg diet or one of three commercial immune boosters. The Experimental diets were fed to triplicate groups of 17 fish (initial body weight, 116 g) for 8 weeks. The water temperature during the feeding trial was maintained at $13-15^{\circ}C$. Growth and feed utilization did not differ significantly among the six dietary treatments, nor did the phagocytic activity, superoxide dismutase or total immunoglobulin concentrations. However, myeloperoxidase activity was significantly higher in the CBP groups. For the intestinal histology, the intestine diameter, villi and enterocyte heights and number of goblet cells did not differ significantly among groups. Therefore, CBP or F-CBP can be used as a valuable eco-friendly byproduct in diets for fishes including red seabream to maintain their normal growth and health.

• Journal of Microbiology and Biotechnology
• /
• 제12권6호
• /
• pp.929-935
• /
• 2002

The 5-stage biological nutrient removal (BNR) process with step feed system showed a very stable organic carbon and nutrient removal efficiency ($87\%\;COD\,;79\%\;nitrogen,\;and\;87\%$ phosphorus) for an operation period of 2 years. In each stage at the pilot plant, microbial communities, which are important in removing nitrogen and phosphorus, were investigated using fluorescence in-situ hybridization (FISH) and 165 rDNA characterization. All tanks of 5-stage sludge had a similar composition of bacterial communities. The totat cell numbers of each reactor were found to be around $2.36-2.83{\times}10^9$ cells/ml. About $56.5-62.0\%$ of total 4,6-diamidino-2-phenylindol (DAPI) cells were hybridized to the bacterial-specific probe EUB388. Members of ${\beta}$-proteobacteria were the most abundant proteobacterial group, accounting for up to $20.6-26.7\%$. The high G+C Gram-positive bacterial group and Cytophaga-Flexibacter cluster counts were also found to be relatively high. The beta subclass proteobacteria did not accumulate a large amount of polyphosphate. The proportion of phosphorus-accumulating organisms (PAOs) in the total population of the sludge was almost $50\%$ in anoxic-1 tank. The high G+C Gram-positive bacteria and Cytophaga-Flexibacter cluster indicate a key role of denitrifying phosphorus-accumulating organisms (dPAOs). Both groups might be correlated with some other subclass of proteobacteria for enhancing nitrogen and phosphorus removal in this process.

• Composites Research
• /
• 제30권1호
• /
• pp.59-64
• /
• 2017

향상된 특성을 갖는 환경친화적인 복합재료의 개발은 고분자재료의 미래에 있어 필수적이며, 부분적으로 또는 완전히 재생가능한 기지재 또는 보강재에 단지 몇 %의 첨가제를 첨가함으로써 쉽게 제작할 수 있다. 본 연구에서는 마닐라삼 섬유를 보강재로, 비닐에스터를 기지재로 사용하였으며, VARTM 공정을 이용하여 복합재료를 제조하였다. 또한 마닐라삼 섬유의 알칼리표면처리를 수행하고, APP, HNT를 난연제를 첨가함으로써 기계적 물성과 난연 물성을 향상시키고자 하였다. 실험을 통하여 표면처리가 천연섬유의 친수성을 감소시키고 소수성인 기지재와의 계면접착력을 향상시켰으며, 이는 개발된 복합재료의 기계적 물성 향상을 이끌었다. 유사하게, 복합재료의 난연성도 난연제의 함량이 증가함에 따라 크게 향상되는 결과를 얻을 수 있었다.