• Journal of Applied Biological Chemistry
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• 제61권1호
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• pp.83-91
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• 2018

박테리아와 진균의 유전체 정보 탐색을 통하여 이차대사 생합성을 지정하는 다수의 잠재 유전자군을 찾을 수 있으며, 유전체 정보를 기반으로 특정 유전자의 발현을 활성화하여 잠재 유전자군의 생성물을 추론하고, 해당 물질의 생물학적 기능을 연구하는 것이 가능하다. 동아시아 지역에서 잘 알려진 식용 사상진균 홍국에 대하여 몇 몇 유전체 정보가 공개되어있으며, 본 연구에서는 Monascus purpureus ${\Delta}MpPKS5$ 균주에서 polyketide synthase-nonribosomal peptide synthase 유전자 Mpfus1 상단에 Aspergillus gpdA 프로모터를 삽입하는 방식으로 이 유전자의 발현을 활성화하였다. Mpfus1 유전자군은 2-pyrrolidone/conjugated polyene 구조를 갖는 물질의 생합성 유전자군들과 높은 유사성을 보이며, 이들 화합물 그룹에서 진균 독소인 fusarin이 잘 알려져 있다. ${\Delta}MpPKS5$ 균주는 홍국 azaphilone 색소 생산 능력이 소실된 균주이며 색소 및 자외선 흡수 특성을 보이는 화합물들의 동정에 적절한 균주이다. Mpfus1 활성화는 균사체가 노란색을 띠도록 유도하며, 균사체의 methanol 추출액은 365 nm에서 최대 흡광도를 보임을 확인할 수 있었다. 해당 추출액의 HPLC 분석을 통하여 다수의 화합물들이 포함되어 있음을 확인할 수 있었으며 이를 통하여 MpFus1 효소의 생성물이 대사적, 화학적으로 불안정함을 추론할 수 있다. Mpfus1 활성화 균주 추출물을 LC-MS로 분석하여 MpFus1 생성물의 구조를 유추하여 Mpfus1 유전자군이 fusarin의 탈메틸 유사체 생합성을 지정하는 것으로 제안할 수 있었다. 본 연구는 홍국 균주에서 유전체 기반-미지 화합물 발굴 연구의 예를 제시하고 홍국 균주에서 새로운 생리활성의 동정 가능성을 시사하여 준다.

• 펄프종이기술
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• 제46권1호
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• pp.18-28
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• 2014

Renewable Portfolio Standards(RPS) is a regulation that requires a renewable energy generated from eco-friendly energy sources such as biomass, wind, solar, and geothermal. The RPS mechanism generally is an obligatory policy that places on electricity supply companies to produce a designated fraction of their electricity from renewable energies. The domestic companies to supply electricity largely rely on wood pellets in order to implement the RPS in spite of undesirable situation of lack of wood resources in Korea. This means that the electricity supply companies in Korea must explore new biomass as an alternative to wood. Palm kernel shell (PKS) and empty fruit bunch (EFB) as oil palm wastes can be used as raw materials used for making pellets after their thermochemical treatment like torrefaction. Torrefaction is a pretreatment process which serves to improve the properties including heating value and energy densification of these oil palm wastes through a mild pyrolysis at temperature typically ranging between 200 and $300^{\circ}C$ in the absence of oxygen under atmospheric pressure. Torrefaction of oil palms wastes at above $200^{\circ}C$ contributed to the increase of fixed carbon with the decrease of volatile matters, leading to the improvement of their calorific values over 20.9 MJ/kg (=5,000 kcal/kg) up to 25.1 MJ/kg (=6,000 kcal/kg). In particular, EFB sensitively responded to torrefaction because of its physical properties like fiber bundles, compared to PKS and hardwood chips. In conclusion, torrefaction treatment of PKS and EFB can greatly contribute to the implement of RPS of the electricity supply companies in Korea through the increased co-firing biomass with coal.

• 펄프종이기술
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• 제47권1호
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• pp.24-34
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• 2015

Domestic companies supplying electricity must increase obligatory duty to use renewable energy annually. If not met with obligatory allotment, the electricity-supply companies must pay RPS (Renewable Portfolio Standards) penalty. Although the power plants using a pulverizing coal firing boiler could co-fire up to around 3 per cent with wood pellets mixed in with coal feedstock without any major equipment revamps, they recorded only about 60 per cent fulfillment of RPS. Consequently, USD 46 million of RPS penalty was imposed on the six power supplying subsidiaries of GENCOs in 2014. One of the solutions to reduce the RPS penalty is that the power supply companies adopt the co-firing of torrefied lignocellulosic biomass in coal plants, which may contribute to the use of over 30 per cent of torrefied biomass mixed with bituminous coals. Extra binder was required to form pellets using torrefied biomass such as wood chips, PKS (Palm Kernel Shell) and EFB (Empty Fruit Bunch). Instead of corn starch, 30, 50 and 70 per cent of Larix saw dusts were respectively added to the torrefied feedstocks such as Pinus densiflora chips, PKS and EFB. The addition of saw dusts led to the decrease of the calorific values of the pellets but the forming ability of the pelletizer was exceedingly improved. Another advantage from the addition of saw dusts stemmed from the reduction of ash contents of the pellets. Finally, it was confirmed that torrefied oil palm biomass such as PKS and EFB could be valuable feedstocks in making pellets through improved binding ability.

• 한국입자에어로졸학회지
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• 제17권4호
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• pp.125-132
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• 2021

Fresh PM_2.5 smokes emitted from combustion of four biomass materials (pellet, palm fruit fiber (PFF), PKS, and sawdust) in a laboratory-controlled environment were characterized using an attenuated total reflectance-fourier transform infrared (ATR-FTIR) technique. In smoke samples emitted from combustion of pellets, PFF and PKS, which is being used as boiler fuels for greenhouses in rural areas, the organic carbon/elemental carbon (OC/EC) ratios in PM_2.5 were very high (14.0-35.5), whereas in sawdust smoke samples they were significantly low (<4.0) due to the combustion method close to flaming combustion. ATR-FTIR analysis showed that OH(3400-3250 cm^-1), CH₃(2958-2840 cm^-1), CH₂(2910 cm^-1 and 2850 cm^-1), ketone(1726-1697 cm^-1), C=C(1607-1606 cm^-1 and 1515-1514 cm^-1), lignin (1463-1462 cm^-1 and 1430-1428 cm^-1) and -NO₂(1360-1370 cm^-1) peaks were identified in all biomass burning (BB) smoke samples. However, additional peaks appeared depending on the type of biomass. Among the four types of biomass materials, an additional peak of the methylene group CH₃(2872-2870 cm^-1) appeared only in PFF and PKS smoke samples, and a peak of C=O(1685 cm^-1) was also confirmed. And in the case of PKS smoke samples, a peak of aromatic C=C(1593 cm^-1 and 1476 cm^-1) that did not appear in other BB samples was also observed. This indicates that the molecular structure of organic compounds emitted during BB differs depending on the type of biomass materials. The results of this study are expected to provide valuable information to more specifically reveal the effect of BB on PM_2.5 collected in the atmospheric environment.

• 문화기술의 융합
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• 제8권6호
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• pp.921-926
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• 2022

Astree사의 E-Tongue을 이용한 상대적 단맛 평가를 위하여 검토한 7개의 센서 중 PKS 및 NMS 센서가 1차로 선정되었다. PKS 및 NMS 센서를 이용해 설탕을 비롯한, 과당, 포도당 및 자일리톨, 5%, 10% 및 15% 용액을 분석한 결과, 자일리톨 및 과당의 농도 증가에 따른 PKS 센서 감응도의 변화가 미미하여, 최종적으로 NMS 센서를 단맛 측정 센서로 선정하였다. 이들 감미료의 농도 중 5% 용액을 모든 센서를 활용한 PCA(주성분 분석) 통계 방법으로 처리한 결과에서는 DI (식별지수)값이 -0.1로 감미료 상호 간 구분이 힘들었으나, NMS 센서만을 이용한 상대적 센서 감응도는 농도에 관계없이 일정한 수치를 나타내었다. 과당 및 자일리톨의 상대적 센서 감응도는 각각 1.08 및 1.00으로 사람의 미각으로 측정한 문헌상 관능검사의 상대적 감미도 범위에 포함되었으나, 포도당의 경우는 0.99로 문헌상 상대감미도 0.5~0.75보다 높게 나타났다. 5%~15% 농도 범위에서 설탕 대비 3종 감미료에 대한 NMS 단일센서를 이용한 E-Tongue의 우수한 정밀성 (%RSD, 1.53~3.64%)을 고려할 때 향후 가당 음료 등에 대한 신제품 개발 및 품질관리 등에 관능검사를 대체할 수 있는 가능성을 확인하였다.

• Mycobiology
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• 제51권1호
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• pp.36-48
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• 2023

Xanthoria elegans is a lichen symbiosis, that inhabits extreme environments and can absorb UV-B. We reported the de novo sequencing and assembly of X. elegans genome. The whole genome was approximately 44.63 Mb, with a GC content of 40.69%. Genome assembly generated 207 scaffolds with an N50 length of 563,100 bp, N90 length of 122,672 bp. The genome comprised 9,581 genes, some encoded enzymes involved in the secondary metabolism such as terpene, polyketides. To further understand the UV-B absorbing and adaptability to extreme environments mechanisms of X. elegans, we searched the secondary metabolites genes and gene-cluster from the genome using genome-mining and bioinformatics analysis. The results revealed that 7 NR-PKSs, 12 HR-PKSs and 2 hybrid PKS-PKSs from X. elegans were isolated, they belong to Type I PKS (T1PKS) according to the domain architecture; phylogenetic analysis and BGCs comparison linked the putative products to two NR-PKSs and three HR-PKSs, the putative products of two NR-PKSs were emodin xanthrone (most likely parietin) and mycophelonic acid, the putative products of three HR-PKSs were soppilines, (+)-asperlin and macrolactone brefeldin A, respectively. 5 PKSs from X. elegans build a correlation between the SMs carbon skeleton and PKS genes based on the domain architecture, phylogenetic and BGC comparison. Although the function of 16 PKSs remains unclear, the findings emphasize that the genes from X. elegans represent an unexploited source of novel polyketide and utilization of lichen gene resources.

• Journal of Microbiology
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• 제44권6호
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• pp.649-654
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• 2006

A standard type II polyketide synthase (PKS) gene cluster was isolated while attempting to clone the biosynthetic gene for lipstatin from Streptomyces toxytricini NRRL 15,443. This result was observed using a Southern blot of a PstI-digested S. toxytricini chromosomal DNA library with a 444 bp amplified probe of a ketosynthase (KS) gene fragment. Four open reading frames [thioesterase (TE), $\beta$-ketoacyl systhase (KAS), chain length factor (CLF), and acyl carrier protein (ACP)], were identified through the nucleotide sequence determination and analysis of a 4.5 kb cloned DNA fragment. In order to confirm the involvement of a cloned gene in lipstatin biosynthesis, a gene disruption experiment for the KS gene was performed. However, the resulting gene disruptant did not show any significant difference in lipstatin production when compared to wild-type S. toxytricini. This result suggests that lipstatin may not be synthesized by a type II PKS.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.153-157
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• 2006

A soil metagenomic library was constructed using an E. coli-fosmid cloning system with environmental DNAs extracted from Kwangreung forest topsoil. We targeted the genes involved in the biosynthesis of bacterial polyketides. Initially, a total of 36 clone pools (10,800 clones) were explored by the PCR-based method using the metagenomic DNAs from each pool and a degenerate primer set, which has been designed based on the highly conserved regions among ketoacyl synthase (KS) domains in actinomycete type I polyketide synthases (PKS Is). Six clone pools were tentatively selected as positive and further examined through a hybridization-based method for selecting a fosmid clone containing PKS I genes. Colony hybridization was performed against fosmid clones from the 6 positive pools, and finally 4 clones were picked out and confirmed to contain the conserved DNA fragment of KS domains. In this study, we present a simple and feasible sorting method for a desired clone from metagenomic libraries.

• Molecules and Cells
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• 제38권12호
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• pp.1105-1110
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• 2015

Phleichrome, a pigment produced by the phytopathogenic fungus Cladosporium phlei, is a fungal perylenequinone whose photodynamic activity has been studied intensively. To determine the biological function of phleichrome and to engineer a strain with enhanced production of phleichrome, we identified the gene responsible for the synthesis of phleichrome. Structural comparison of phleichrome with other fungal perylenequinones suggested that phleichrome is synthesized via polyketide pathway. We recently identified four different polyketide synthase (PKS) genes encompassing three major clades of fungal PKSs that differ with respect to reducing conditions for the polyketide product. Based on in silico analysis of cloned genes, we hypothesized that the non-reducing PKS gene, Cppks1, is involved in phleichrome biosynthesis. Increased accumulation of Cppks1 transcript was observed in response to supplementation with the application of synthetic inducer cyclo-(${_L}-Pro-{_L}-Phe$). In addition, heterologous expression of the Cppks1 gene in Cryphonectria parasitica resulted in the production of phleichrome. These results provide convincing evidence that the Cppks1 gene is responsible for the biosynthesis of phleichrome.

• KSBB Journal
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• 제22권5호
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• pp.356-361
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• 2007

시아노박테리아 같은 수중 미생물에 대한 2차대사물질에 대한 연구는 육상식물이나 미생물에 관련된 연구방법을 응용하고 있으며 아직까지 체계화 되어있지 않아 시아노박테리아를 보다 효율적으로 조사하기 위한 새로운 연구기술의 모색이 절실히 필요하다. 이 연구에서는 의학적인 관점에서 시아노박테리아를 조사하기 위한 유용한 접근 방법을 모색하였고 체계화시켰다. 균주마다 특성화된 최적 배양을 하였고 PCR 증폭을 이용한 분자생물학적인 방법과 HPLC를 통한 정성분석으로 의학적으로 의미있는 NPs를 생산하는 유망 균주를 선별하였다. 선별된 균주에서 나온 추출액은 SPE와 preparative HPLC를 거쳐 분리 정제되어지고, 정제된 물질들은 질량분석기에 의해 분자량과 구조가 결정되어 졌으며, 생활성 테스트에 의해서 그 생물학적인 활성을 정함으로써 의학적인 가능성이나 활용성에 대해서 고찰하였다. 이번 시험에서 98개의 실험균주 중 46개의 균주가 NRPS 또는 PKS 관련 gene을 함유하고 있었으나 HPLC를 이용한 정성분석에서 단지 5개의 균주가 상당히 의미있는 관련 단백질을 생산하고 있음이 알려졌다. 즉, 41 균주에서 관련 gene은 존재하였지만 그 발현이 미약하였고 또는 프로모터의 활성이 이루어지지 않았다. 이와같은 휴먼 gene의 활성화는 자외선 조사 또는 건조를 이용한 자극과 배양액의 성분 조절로 이루어질 수 있고 이를 통해 흥미있는 결과를 이끌어낼 수 있다(13, 14). 이번 연구에서는 HPLC를 통한 정성분석은 Biomass에 대해서 이루어졌다. 그러므로 배양액으로 유출되는 extracellular substances에 대한 분석은 행해지지 않았다. 시아노박테리아가 NRPS/PKS 관련 유전자를 함유하고 있을 때, 특히 biomass에서 NPs 이 검출되지 않을 경우 배양액 안에서의 존재 가능성 대해서 조사할 필요성이 요구되어진다. 시아노박테리아는 대표적인 photoautotroph 미생물로써 $CO_2$를 탄소성분과 에너지원으로 사용한다. 그러므로 E. coli 같은 미생물보다 배양시 경제적이고 또한 다른 종류의 미생물이 탄소영양분의 부족과 cyanobacterial NPs의 생물학적 환성에 의해서 공생하기 어려워 옥외배양을 통한 대량생산이 가능하다. 그러나, 생산되는 cyanobacterial NPs의 높은 구조적 안정성까지 포함하여 시아노박테리아는 미래의학산업의 중요한 천연소스임에 틀림이 없지만 개체 분화의 시간이 4$\sim$10시간 정도로 다른 미생물에 비해 길고 배양시 광원의 필요성 등 한계 요소를 지니고 있다(15). 그러므로 최근에는 개체 분화가 빠른 시아노박테리아나 또는 다른 미생물에 대해서 cyanobacterial NRPS/PKS gene의 heterologous expression 이 연구되어지고 있다(16).