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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/48673

Title: 海生疫病菌屬 (Halophytophthora) 在台灣紅樹林之多樣性及脂肪酸概相分析
Diversity of Halophytophthora in selected Taiwan mangroves and their fatty acids profile analysis.
Authors: Ju, Wen-Ting
朱文廷
Contributors: NTOU:Institute of Marine Biology
國立臺灣海洋大學:海洋生物研究所
Keywords: 海生疫病菌屬;多樣性;多元不飽和脂肪酸;親源關係分析
Halophytophthora;Diversity;Polyunsaturated;Phylogenetic analysis
Date: 2017
Issue Date: 2018-08-22T06:14:55Z
Abstract: 海生疫病菌屬 (Halophytophthora) 隸屬於卵菌綱,其棲地環境主要集中在紅樹林。海生疫病菌種營養方式為腐生,若其游動孢子被做為其他紅樹林生物之食物來源,此時為二次生產者。海生疫病菌屬已被證實能夠產生多元不飽和脂肪酸,其中含量居高者為二十碳五烯酸 (eicosapentaenoic acid, EPA) 及花生四烯酸 (arachidonic acid, ARA)。脂肪酸在化學結構上擁有兩個以上的雙鍵時,此化學物就稱為多元不飽和脂肪酸 (polyunsaturated fatty acids, PUFAs)。隨著脂肪酸鏈的長度和雙鍵位置的差異,會形成不同種類的不飽和脂肪酸。EPA及ARA是人體所需之多元不飽和脂肪酸,其中ARA對於嬰兒時期的大腦及神經系統發育有良好的幫助;而EPA適量的補充可以保持血液流動性,能夠預防中風及心肌梗塞的發生。主要的多元不飽和脂肪酸來源是魚甘油,但隨著近年魚類過度捕撈,導致魚甘油的來源逐漸稀少,而情況只會越來越不樂觀,這也告訴我們需要另闢新源。 因此,本研究前往臺灣五個大型紅樹林,分別為新竹新豐、苗栗竹南、彰化芳苑、嘉義朴子和台南四草,採集落葉並分離海生疫病菌。利用孢子囊形態和18S及internal transcribed spacers (ITS) rDNA序列分折兩種方式進行鑑種,探討其在臺灣之多樣性,並進行親源關係分析,探討所分離海生疫病菌株與其不飽和脂肪酸概相的關係。最後以液態發酵,分析所得之菌株菌絲脂肪酸含量。從臺灣五處紅樹林共取得16株、五種海生疫病菌 (H. avicenniae、H. batemanensis、H. exoprolifera、H. polymorphica、H. spinosa var. spinosa)。最高多樣性為台南四草紅樹林,共發現四種H. avicenniae、H. batemanensis、H. exoprolifera、H. spinosa var. spinosa。菌絲脂肪酸組成分析結果顯示,各菌株ARA在總脂肪酸所占百分比含量為4.16-29.94%,而EPA所占百分比為0-14.16%,其中H. spinosa var. spinosa全部菌株皆沒有生產EPA,推測此菌種缺少了轉化ARA成EPA的酵素。親源關係分析發現大部分海生疫病菌菌種組成Halophytophthora sensu stricto 單系群,僅H. spinosa var. spinosa 形成一獨立分支,這也與其獨特的脂肪酸概相互相呼應,這結果成為是否需要為H. spinosa var. spinosa成立一新屬的重要依據。目前已有六種 (H. vesicula、H. avicenniae、H. batemanensis、H. exoprolifera、H. polymorphica、H. spinosa var. spinosa) 海生疫病菌種接受脂肪酸概相測定,發現不同菌種脂肪酸概相皆有差異,未來若能測定此屬其他菌種脂肪酸概相,期望可發現高脂肪酸含量以及不同的脂肪酸組成概相之海生疫病菌種。
Halophytophthora is an oomycetous genus and predominantly inhabits mangrove environment. Halophytophthora species mainly are saprobic but their spores can be food for other organisms in the mangrove food web, thus serving as secondary producers. A previous study has shown the production of polyunsaturated fatty acids in mycelia of Halophytophthora, especially eicosapentaenoic acid (EPA, 22:5 (n=3)) and arachidonic acid (ARA, 20:4 (n=6)). Fatty acids with double bonds in the fatty acid carbon chain are called polyunsaturated fatty acids (PUFAs). With the differences in the length of the carbon chain and the position of the double bonds, these fatty acids correspond to different PUFAs,e.g. docosahexaenoic acid (DHA, 22:6 (n=3)), EPA and ARA. These fatty acids have been reported to have beneficial health effects on human including loweringblood pressure, preventing cardiovascular disease and reducing inflammation. Traditionally, PUFAs can be consumed through marine fish but overfishing in recent years has prompted discovery of alternative sources of PUFAs. In this study, diversity of Halophytophthora in five different mangroves of Taiwan and their fatty acid profile were studied. A total of 14 isolates representing 5 different species were collected based on identification through morphology and sequence analysis of the nuclear 18S and internal transcribed spacers (ITS) rDNA, including H. avicenniae, H. batemanensis, H. exoprolifera, H. polymorphica and H. spinosa var. spinosa. Liquid fermentation of the 14 isolates of Halophytophthora in glucose/yeast extract/peptone broth was used to analyse the fatty acid composition of mycelia; ARA in total fatty acids ranged between 4.16%-29.94% while EPA ranged between 0%-14.16%. No EPA was detected in all isolates of H. spinosa var. spinosa, suggesting that they may lack specific enzymes to transform ARA to EPA. Phylogenetic analysis of the 18S and ITS rRNA gene showed that majority of the Halophytophthora sequences generated in this study and those from the GenBank constitute the Halophytophthora sensu stricto clade with the type species H. vesicula. However, H. spinosa var. spinosa is distantly related with the Halophytophthora sensu stricto clade and other genera in the Pythiaceae. This observation corroborates the result of the fatty acid analysis; Halophytophthora sensu stricto clade produced ARA and EPA while no EPA was produced by H. spinosa var. spinosa.
URI: http://ethesys.lib.ntou.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=G0010334008.id
http://ntour.ntou.edu.tw:8080/ir/handle/987654321/48673
Appears in Collections:[海洋生物研究所] 博碩士論文

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