• 한국미생물·생명공학회지
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• 제47권4호
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• pp.473-486
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• 2019

In the aquatic environment, microorganisms are predominantly organized as biofilms. Biofilms are formed by the aggregation of microbial cells and are surrounded by a matrix of extracellular polymeric substances (EPS) secreted by the microbial cells. Biofilms are attached to various surfaces, such as the living tissues, indwelling medical devices, and piping of the industrial potable water system. Biofilms formed from a single species has been extensively studied. However, there is an increased research focus on multispecies biofilms in recent years. It is important to assess the microbial mechanisms underlying the regulation of multispecies biofilm formation to determine the drinking water microbial composition. These mechanisms contribute to the predominance of the best-adapted species in an aquatic environment. This review focuses on the interactions in the multispecies biofilms, such as coaggregation, co-metabolism, cross-species protection, jamming of quorum sensing, lateral gene transfer, synergism, and antagonism. Further, this review explores the dynamics and the factors favoring biofilm formation and pathogen transmission within the drinking water distribution systems. The understanding of the physiology and biodiversity of microbial species in the biofilm may aid in the development of novel biofilm control and drinking water disinfection processes.

• The Plant Pathology Journal
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• 제37권4호
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• pp.404-412
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• 2021

Despite the plant microbiota plays an important role in plant health, little is known about the potential interactions of the flower microbiota with pathogens. In this study, we investigated the microbial community of apple blossoms when infected with Erwinia amylovora. The long-read sequencing technology, which significantly increased the genome sequence resolution, thus enabling the characterization of fire blight-induced changes in the flower microbial community. Each sample showed a unique microbial community at the species level. Pantoea agglomerans and P. allii were the most predominant bacteria in healthy flowers, whereas E. amylovora comprised more than 90% of the microbial population in diseased flowers. Furthermore, gene function analysis revealed that glucose and xylose metabolism were enriched in diseased flowers. Overall, our results showed that the microbiome of apple blossoms is rich in specific bacteria, and the nutritional composition of flowers is important for the incidence and spread of bacterial disease.

• 한국해양바이오학회지
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• 제2권1호
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• pp.11-22
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• 2007

This aims to review natural products transformed by mimic intestinal metabolisms with microorganisms and hydrolytic enzymes, which exhibit enforced biological activity, higher extraction yield and identification of active components. In the process, transformation to the smaller active compounds with enzymes and microbes mimics the pharmacological action of natural products by intestinal bacteria. In order to establish conditions for the fermentation and enzyme reaction, it is required to choose several natural products for biotransformation and investigate the optimal conditions for the fermentation or the enzyme reaction such as composition, temperature, pH, inoculum, and cultivation time. It is expected an increase of the internal absorption of the active materials without regard to the intestinal microbes or its ability through biosynthesis of the active materials by the microbes and enzymes. And this techniques can be applied to biotransformation of natural products such as sesaminol, resveratrol, 1-deoxy nojirimycin, naringenin, quercetin, and baicalin and to the metabolism study using the animal model.

• Asian-Australasian Journal of Animal Sciences
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• 제11권3호
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• pp.209-216
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• 1998

The paper presented here is aimed at increasing knowledge on purine metabolism in ruminants and hence the quantification of microbial cells entering the small intestine from urinaη excretion of purine derivatives. Nucleic acid metabolisms of micro-organisms in the rumen, digestion and absorption of nucleic acids entering the intestines, metabolisms of absorbed and endogenous purines involving de novo synthesis of nucleic acids in the ruminants host, and the relationship between absorbed and excreted purines are reviewed. Principal concerns about an amount of purine derivatives excreted in urine in relation to a change in purine-N: total-N ratios in rumen microbes that leave the rumen are discussed. The use of urinary excretion of purine derivatives as an indicator of the amount of microbial biomass leaving the rumen has to be done with some caution since it may be impossible to get a representative sample of microbes entering the intestine and thus yield estimates are relative rather than absolute.

• Journal of Microbiology and Biotechnology
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• 제21권1호
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• pp.43-49
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• 2011

As a rare sugar alcohol, L-arabitol can be used in food and can prevent extra fat deposits in the intestinal tract. Commercially, L-arabitol is prepared from pure L-arabinose by hydrogenation, which needs a high temperature and high pressure, leading to a high production cost for Larabitol. Therefore, this study describes a novel L-arabitol production method based on biological purification from the xylitol mother liquor, a cheap and readily available raw material that contains a high concentration of Larabitol. First, a novel Bacillus megaterium strain was screened that can utilize xylitol, sorbitol, and mannitol, yet not L-arabitol. The isolated strain was inoculated into a medium containing the xylitol mother liquor under formulated culture conditions, where a high L-arabitol yield (95%) and high purity (80%) were obtained when the medium was supplemented with 50 g/l of xylitol mother liquor. Upon further purification of the fermentation broth by ion exchange and decolorization, L-arabitol was crystallized with a purity of 98.5%.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권5호
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• pp.408-417
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• 2005

Increasing numbers of value added chemicals are being produced using microbial fermentation strategies. Computational modeling and simulation of microbial metabolism is rapidly becoming an enabling technology that is driving a new paradigm to accelerate the bioprocess development cycle. In particular, constraint-based modeling and the development of genome-scale models of industrial microbes are finding increasing utility across many phases of the bioprocess development workflow. Herein, we review and discuss the requirements and trends in the industrial application of this technology as we build toward integrated computational/experimental platforms for bioprocess engineering. Specifically we cover the following topics: (1) genome-scale models as genetically and biochemically consistent representations of metabolic networks; (2) the ability of these models to predict, assess, and interpret metabolic physiology and flux states of metabolism; (3) the model-guided integrative analysis of high throughput 'omics' data; (4) the reconciliation and analysis of on- and off-line fermentation data as well as flux tracing data; (5) model-aided strain design strategies and the integration of calculated biotransformation routes; and (6) control and optimization of the fermentation processes. Collectively, constraint-based modeling strategies are impacting the iterative characterization of metabolic flux states throughout the bioprocess development cycle, while also driving metabolic engineering strategies and fermentation optimization.

• Asian-Australasian Journal of Animal Sciences
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• 제22권9호
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• pp.1267-1278
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• 2009

Three beef steers fitted with permanent cannulae in the rumen and duodenum were used to determine the effects of protein supply from soyhulls (SH) and wheat bran (WB) on ruminal metabolism, blood metabolites, nitrogen metabolism, nutrient digestion and concentrations of soluble non-ammonia nitrogen (SNAN) in ruminal (RD) and omasal digesta (OD). In a 3${\times}$3 Latin square design, steers were offered rice straw and concentrates formulated either without (control) or with two brans to increase crude protein (CP) level (9 vs. 11% dietary DM for control and bran-based diets, respectively). The brans used were SH and WB that had similar CP contents but different ruminal CP degradability (52 vs. 80% CP for SH and WB, respectively) for evaluating the effects of protein degradability. Ruminal ammonia concentrations were higher for bran diets (p<0.01) than for the control, and for WB (p<0.001) compared to the SH diet. Similarly, microbial nitrogen and blood urea nitrogen were significantly increased (p<0.05) by bran and WB diets, respectively. Retained nitrogen tended (p<0.082) to be increased by SH compared with the WB diet. Intestinal and total tract CP digestion was enhanced by bran diets. In addition, bran diets tended (p<0.085) to increase intestinal starch digestion. Concentrations of SNAN fractions in RD and OD were higher (p<0.05) for bran diets than for the control, and for WB than for the SH diet. More rumendegraded protein supply resulting from a higher level and degradability of CP released from SH and WB enhanced ruminal microbial nitrogen synthesis and ruminal protein degradation. Thus, free amino acids, peptides and soluble proteins from microbial cells as well as degraded dietary protein may have contributed to increased SNAN concentrations in the rumen and, consequently, the omasum. These results indicate that protein supply from SH and WB, having a low level of protein (13 and 16%, respectively), could affect ruminal metabolism and nutrient digestion if inclusion level is relatively high (>20%).

• 한국식품과학회지
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• 제30권5호
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• pp.1222-1228
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• 1998

스트레스에 의해서 생체는 에너지 대사를 증가시키며, 에너지 대사의 증가는 높은 반응성의 ROS를 생성한다. ROS는 높은 반응성으로 인해 지질, 단백질 등을 과산화시켜 원래의 활성을 잃게함으로 이런 ROS에 대해서 높은 소거능을 지니고 흡수가 쉬운 SOD 유사물질의 투여가 스트레스로 인한 생체내 산화적 손상을 억제할 수 있을 것으로 생각된다. 이것을 확인하기위해서 실험용 흰 쥐에게 4주간의 고정화 스트레스를 가한 결과, 체중 증가량을 감소시켰으며 스트레스 호르몬의 하나인 5-HIAA의 수준을 증가시켰다. 시험관에서 높은 항산화력을 확인한 루이보스티 추출액을 스트레스를 받은 흰 쥐에게 투여한 결과는 체중 증가량 감소는 완화시켰으나 5-HIAA의 수준을 변화시키지 못하여 스트레스 반응 자체를 억제하지 않는 것으로 판명되었다. 루이보스티의 투여는 스트레스로 인해서 유도되는 뇌 조직의 지질과산화와 단백질 산화를 억제하였으나 SOD, GPx 등의 대표적 항산화 효소 활성의 변화를 유발하지 않았다. 따라서, 루이보스티는 스트레스 반응 자체보다는 그에 따른 2차적 독성 대사산물에 대해서 효소 활성의 증가가 아닌 루이보스티 추출액의 구성분 자체가 세포를 보호한 것으로 생각되며, 루이보스티의 추출액이 열수하에서 추출된 것이기 때문에 지질과산화에 대해서보다 단백질 과산화에 대해 더 높은 보호 활성이 나타난 것으로 생각된다.

• 한국수산과학회지
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• 제44권4호
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• pp.325-331
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• 2011

Nonylphenol (NP), which is well known as an endocrine disrupter, has been detected widely in untreated sewage or waste water streams. Given the necessity of discovering an eco-friendly method of degrading this toxic organic compound, this study was conducted to isolate NP-degrading microorganisms from the aqueous environment. NP-degrading microbes were isolated through NP-containing enrichment culture. Finally, a microbial consortium, SW-3, capable of degrading NP with high efficiency, was selected from the mixture sample. The microbial consortium SW-3 was able to degrade over 99% of 100 ppm NP in the culture medium for 40 days at $25^{\circ}C$. The microbial consortium SW-3 seemed to utilize NP as a carbon source, since NP was the sole carbon source in the culture medium. In order to isolate the NP-degrading bacterium, we further conducted single colony isolation using the microbial consortium SW-3. Four strains isolated from SW-3 exhibited lower NP-degradation efficiency than that of SW-3, suggesting that NP was degraded by the co-metabolism of the microbial consortium. We suggest that the microbial consortium obtained in this study would be useful in developing an eco-friendly bioremediation technology for NP degradation.

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.43-49
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• 2003

Metabolism of a new fungicide ethaboxam by soil fungi was studied. Among the fungi tested, Cunninghamelia elegans produced metabolites from ethaboxam, which were not found in the control experiments. M5, a major metabolite from ethaboxam was firmly identified as N-deethylated ethaboxam by LC/MS/MS and NMR. N-Deethylated ethaboxam has been found as a single metabolite in in vitro metabolism with rat liver microsomes. Ml was proved to be 4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboxamide (ETC) by comparing with the authentic compound. In addition, M2, M3, and M4, and M6 were tentatively Identified by LC/MS/MS as hydroxylated and methoxylated ethaboxams, respectively. Production of the major metabolite, N-deethylated ethaboxam, by the fungus suggested that C. elegans would be an efficient eukaryotic microbial candidate for evaluating xenobiotic-driven mammalian risk assessment.