Endophytes as Producers of Xylanase.
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The influential factors of xylanases (EC3.2.1.8) activity were studied. Optimum pH for both xylanase A and xylanase B wns 7.0,
the optimum temperature for xylanase A and xylanase B was 65℃ and 70℃ respectively. The activity of both A and B enzyme was
activited by Fe~(3+) at low concentration, but inhibited by Fe~(3+) at high concentration. Al~(3+) had inhibition on xylanase A, but a promoting effect
on xylanase B. The activity of both xylanase A and xylanase B was inhibited by Cu~(2+). Mn~(2+) activated xylanase A, but inhibited xylanase B.
Xylanase A had K_m of 5.57 mg/mL and V_(max) of 1.98×10~4μmol/ (mL· min ). The K_m and V_(max) for xylanase B were 6.09 mg/mL and 3.64×10~4
μmol/ (mL·min).
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A factorial design was performed to find the best conditions of pH and temperature for #946-xylanase activity and to maintain its activity for prolonged periods of time of pure xylanase produced by newly isolated Thermomyces lanuginosus THKU-49. The central composite design (CCD) used for the analysis of treatment combinations showed that a regression models of optimization of xylanase activity and xylanase stability were good agreement to experimental results with R2 = 0.98 and 0.99, respectively. The maximum activity of xylanase was obtained at 66 o C and pH 6.3. The temperature and pH for maximum enzyme stability was 70 o C and pH 7.3, respectively. Under this condition xylanase having half-life of 825 min indicated the highest thermostable xylanase.
Central composite design
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Fungal Diversity
Marine fungi
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A new extracellular xylanase produced by Streptomyces lividans 66 was isolated from a genetically engineered clone of that strain. This enzyme, named xylanase B, has an Mr of 31,000 and acts specifically on xylan as an endo-type xylanase producing short-chain xylo-oligosaccharides. The activity is optimal at pH 6.5 and at a temperature of 55 degrees C, which is similar to that of the previously characterized xylanase A. Xylanase B is glycosylated and has a pI of 8.4; its Km and Vmax. values are 3.71 mg/ml and 1.96 mmol/mg of enzyme respectively. Specific antibodies raised against xylanase A show no cross-reaction with xylanase B; however, the anti-(xylanase B) antibodies react slightly with xylanase A. A comparison of the hydrolysis products obtained from oat-spelts xylan with both enzymes show that xylanase A preferentially degrades short-chain oligo-xylosides, whereas xylanase B acts on the longer, water-insoluble, molecules.
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본 연구에서는 다양한 곡류전곡립(벼, 보리, 밀, 및 메밀)에서 추출한 식이섬유(dietary fiber, DF)에 cellulase와 xylanase 를 각각 고형분 대비 1, 5 및 10% 처리하여 전곡립별 효소종류 및 농도에 따른 총 식이섬유 함량, 수용성/불용성 식이섬유 조성 변화 및 항산화 활성 분석을 통해 기능성분 변화를 알아보고자 하였다. 아울러 기능성분 결과를 바탕으로 전곡립 종류 및 효소처리 조건을 선정하였으며, 10% xylanase 처리 보리 식이섬유를 밀가루 중량 대비 1-3% 대체한 스펀지 케이크를 제조하여 물리적 특성, 항산화 활성 및 전분 소화율의 건강기능적 특성을 밀가루로 제조한 control 케이크와 native 보리 식이섬유 첨가 케이크와 비교 · 분석하였다. 총 식이섬유 함량은 모든 효소처리 전곡립 식이섬유에서 native 식이섬유에 비해 증가하였으며, cellulase와 xylanase의 1% 처리에서 가장 많이 증가하고, 5-10% 효소처리에서는 효소종류에 관계없이 감소하는 경향을 나타내었다. 특히, 전곡립 중 메밀 총 식이섬유의 증가율 및 식이섬유 조성변화가 가장 컸으며, 전곡립의 종류에 관계없이 xylanase 가 cellulase에 비해 식이섬유 함량 및 조성변화에 더 큰 영향을 주었다. 또한 cellulase와 xylanase의 효소농도에 따라 항산화 활성이 유의적으로 증가했으며(p0.05), 특히 보리 식이섬유의 증가율이 가장 컸고, xylanase가 효과적이었다. 한편, 효소처리 보리 식이섬유를 1, 2 및 3% 대체한 스펀지 케이크의 hardness는 증가하고 색도의 값은 감소하였지만, 효소처리 보리 식이섬유 대체 케이크의 대체율에 따라 항산화 활성이 control과 native 보리식이섬유 첨가 케이크와 비교하여 유의적으로 증가하였고(p0.05), 전분 가수분해율이 낮아져 전분소화 지연에 효과적임을 나타내었다. 이상의 결과로 볼 때, 곡류 전곡립 유래 식이섬유를 효과적으로 변형시키는 효소는 xylanase로 나타났으며, 식이섬유 함량 및 식이섬유의 수용화는 메밀에서, 항산화 유용성분 및 활성변화는 보리 식이섬유에서 가장 많이 증가함을 확인함과 동시에, 효소처리 전곡립 식이섬유를 첨가할 경우, 기존 케이크와 비교하여 품질변화가 최소화 되면서 항산화 특성이 향상됨을 확인하여 건강기능성이 증대된 식품 개발로의 가능성을 제시하였다.
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Catharanthus roseus (L.) is well known for its production of several anticancerous vinca alkaloids such as vincristine, vindesine, vinorelbine, vinblastin, and the recently discovered vinflunine. This plant is a host to a plethora of endophytic fungi. A total 183 endophytic fungi representing 13 fungal taxa were isolated from leaf, stem and root tissues of C. roseus from two sites representing two different ecosystems in North India. Interestingly, with two exceptions (one coelomycete and one ascomycete), all of the isolates were Hyphomycetes. Root tissues were heavily colonized by genera such as Alternaria, Cladosporium and Aspergillus. However, leaf tissues showed a greater diversity of endophytes and Drechslera, Curvularia, Bipolaris, Alternaria and Aspergillus spp. were the dominant fungi isolated. Interestingly, a fungus producing no fruiting structures was the most prevalent, isolated from C. roseus. On the basis of its partial ITS-5.8 S rDNA sequences, it was identified as Chaetomium globossum, with 99% sequence similarity (537/540). The species richness as well as frequency of colonization of endophytic fungi were pronounced in the root tissues at both sites (Loc 1, 38.6%; Loc 2, 33.7%). This study suggests that endophytes are both host- and tissue-specific. It also confirms that despite ecological variations, there were little differences in the species richness of fungal endophytes recovered from plants in the two different ecological sites.
Catharanthus roseus
Hyphomycetes
Endophyte
Chaetomium
Mycology
Bipolaris
Vinca
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Endophyte
Acremonium
Cladosporium
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Endophytic fungi and ectomycorrhizal fungi co-exist in the mycorrhizal root tips of boreal forest trees. However, very little is known about the functional role they play in their host’s biology. The activity of enzymes responsible for important biochemical processes is used to determine the functional role of root-associated mycorrhizal fungi. However, enzyme activity is never studied in the presence of endophytic fungi in-planta. The aims of this study were to investigate the effect of Scots pine (Pinus sylvestris L.) root-isolated fungal endophytes on the host plant root morphology, to determine their functional effects using host root-excreted enzyme activity measurements, and to compare them with roots colonized by decomposer and ectomycorrhizal fungal strains and noncolonised Scots pine root tips. Our results show that endophytic fungi did not damage the pine roots in contrast to the decomposer fungi. The endophytic fungi penetrated the cortical cells of the host plant. The roots colonised by endophytic fungi produce different exo-enzymes compared with those produced by roots colonized by other fungal groups or noncolonized control root tips. Our results indicate that endophytic fungi are clearly a distinctive ecological group of fungi that have functional traits different from those of ectomycorrhizal and decomposer fungi.
Decomposer
Scots pine
Ectomycorrhiza
Endophyte
Mycology
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본 연구에서는 강원도 함백산에 서식하는 잣나무, 전나무, 일본잎갈나무, 산겨릅나무 등 4종의 목본식물의 잎에서 내생균을 분리하여 균의 형태적 특징과 ITS 부위의 염기서열을 이용하여 분자계통 분석을 실시하였다, 그 결과, 국내 미기록종인 Talaromyces radicus, Myceliophthora verrucosa, Cryptosporiopsis diversispora, Sphaerulina berberidis로 동정되었으며, 각 균주의 형태학적, 분자계통학적 특징을 기술하였다. In this study, endophytic fungi were isolated from leaves of four species of woody plants, Acer tagmentosum, Larix kaempferi, Abies holophylla, and Pinus koraiensis, on Mt. Hambaek, Gangwondo, Korea. The endophytic fungi were identified using morphological and sequences analysis of ITS regions. The fungal endophytes were identified as Talaromyces radicus, Myceliophthora verrucosa, Cryptosporiopsis diversispora, and Sphaerulina berberidis, which are the first record in Korea. The morphological and molecular phylogenetic characteristics of each strain were described.
Pinus koraiensis
Larix kaempferi
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Endophytic fungi occupy various ecological niches, which reinforces their diversity. As few studies have investigated the endophytic fungi of alpine conifers, we focused on four species of alpine conifers in this study—Abies nephrolepis, Pinus pumila, Taxus cuspidata var. nana, and Thuja koraiensis—and examined them for endophytic fungi. A total of 108 endophytic fungi were isolated. There were four taxa in A. nephrolepis, 12 in P. pumila, 18 in T. cuspidata var. nana, and 17 in T. koraiensis; these were divided into five classes: Agaricomycetes (3.2%), Dothideomycetes (29.0%), Leotiomycetes (15.0%), Sordariomycetes (41.9%), and Orbiliomycetes (1.6%). The most prevalent fungi were Sydowia polyspora (22.7%) and Xylariaceae sp. (22.7%) in P. pumila, Phomopsis juglandina (16.1%) in T. cuspidata var. nana, and Thuja-endophytes sp. 1 (70.0%) in T. koraiensis. However, there was no dominant species growing in A. nephrolepis. Some host plants were analyzed using next-generation sequencing. We obtained 4618 reads for A. nephrolepis and 2268 reads for T. koraiensis. At the genus level, the top three endophytic fungi were Ophiostomataceae_uc (64.6%), Nectriaceae_uc (15.5%), and unclassified organism (18.0%) in A. nephrolepis and Nectriaceae_uc (41.9%), Ophiostomataceae_uc (41.8%), and Magnaporthaceae_uc (9.2%) in T. koraiensis. Our results show that there are different communities of endophytic fungi among different host plants, even if the host plants are in the same region. Such ecological niches are important in terms of the ecological restoration of alpine conifers.
Pinus koraiensis
Dothideomycetes
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