造礁珊瑚黑病之菌相分佈研究

Bacterial consortium associated with the“black disease＂of reef-building corals

廖敏惠(Ming-Hui Liao)

指導教授 ： 陳昭倫

共同指導教授 ： 湯森林

國立臺灣大學/理學院/海洋研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02573

摘要

目前全世界的珊瑚礁都受到破壞，而珊瑚疾病為主要威脅因素之ㄧ。然而受
限於傳統微生物學方法限制，過去對於珊瑚疾病爆發的原因和感染機制仍不清
楚。2006 年，台灣綠島發生大量珊瑚死亡事件，原因為受到如黑色覆蓋物之海綿
（Terpios hoshinota）入侵所引起，簡稱「黑病」。本研究將利用電子顯微鏡方法與
非依賴培養式的微生物分子生物技術，細菌16S rDNA 序列和變性梯度電泳法
(denaturing gradient gel electrophoresis, DGGE)，分析T. hoshinota 特有菌相，並比
較受海綿覆蓋之珊瑚（Porites lutea）與未受海綿覆蓋之珊瑚（P. lutea）其菌相變
化情形，期望發現與疾病有關微生物，以利往後病態監測所用。
結果發現，不論珊瑚或海綿，其菌相分布都與周遭海水菌相不同。T. hoshinota
細菌群相專一，主要為具光合作用的單細胞球形藍綠菌，經分子序列及外觀比對，
可能是新種藍綠菌。此藍綠菌數量極大應該是和T. hoshinota 存有某種程度的共生
關係。另外，利用DOTUR、LIBSHUFF 軟體來分析珊瑚P. lutea 的細菌群相之間
的多樣性和組成相似度。結果發現未罹病珊瑚P. lutea 的菌相分佈，主要以
Gammaproteobacteria、Cyanobacteria、unclassified bacteria 為主；而罹病珊瑚P. lutea
的菌相是以Gammaproteobacteria、Alphaproteobacteria 為主，而Cyanobacteria 以
及unclassified bacteria 則大量減少。過去研究發現，珊瑚上有許多共生細菌，當珊
瑚受到環境壓力時，可能改變或抑制原本正常菌叢，導致菌相會以某一類群細菌
為主， 而非專一性的細菌也會伺機而生； 本研究發現罹病珊瑚上
Gammaproteobacteria 大量增加，可能和環境壓力有關(受海綿覆蓋或海水污染)，
而Alphaproteobacteria 則可能為伺機生長的細菌，而這樣的改變，影響正常菌叢對
珊瑚的功能，推測可能影響珊瑚健康。由於珊瑚上共生細菌易受環境壓力而改變，
未來若能建立珊瑚共生菌相長期監測資料，應可作為珊瑚的健康指標。

關鍵字

海綿 ； 藍綠菌 ； 珊瑚疾病 ； 珊瑚微生物菌相 ； 非培養式微生物分子技術

並列摘要

Coral diseases are one of the major natural disturbances that threat the survival
of coral reefs worldwide. However, the characterization and mechanism of infection
have been difficult in understanding the outbreak of coral diseases due to the
limitation of applying classical microbiological assays. In this thesis, the bacteria
consortium of the “black disease” caused by a black mat-like sponge, Terpios
hoshinota, was characterized by electronic microscopy, denaturing gradient gel
electrophoresis (DGGE), and 16S ribosomal DNA library construction. In order to
understand the possible pathogenic bacteria in “black disease”, the specificity of T.
hoshinota associated bacterial community and the variation between sponge-infected
(SI) and non-sponge-infected (NSI) Porites lutea associated bacterial community
were investigated in the fringing reef of the Green Island (Lutao), where outbreak of
Terpios sponge was first reported in 2006.
Result shows that the bacterial communities from seawater, sponge, and coral
were specific. T. hoshinota associated bacterial community was specific and the
dominant bacteria group was autotrophic Cyanobacteria. The Cyanobacteria
associated with T. hoshinota were supposedly a new Cyanobacteria species as
demonstrated by 16S rDNA sequence with a unique morphology. Furthermore, the
high abundance of cyanobacteria in T. hoshinota may contribute positively to T.
iii
hoshinota outbreak. On the other hand, the diversity and composition similarity of
bacterial community associated with SI and NSI P. lutea were analyzed using
DOTUR and LIBSHUFF. In NSI P. lutea, the dominant bacterial groups were
Gammaproteobacteria, Cyanobacteria, and unclassified bacteria; however, in SI P.
lutea, Gammaproteobacteria and Alphaproteobacteria were major groups and the
abundance of Cyanobacteria and unclassified bacteria were low. In previous studies,
there were diverse coral holobiont on a coral. The natural coral holobiont changed to
dominant bacteria group with abundance of opportunistic bacteria when corals
experience environmental stress; similar situation was observed in SI P. lutea. The
increase of the abundance of Gammaproteobacteria is probably related to
environmental stress (sponge or seawater pollution). In addition, the unexpected
emergence of alphaproteobacteria could be opportunistic bacteria because of
disturbance of natural bacterial community. Disturbance of coral holobiont possible
loss the normal symbiont function for coral and it directly or indirectly supposed to
result in coral disease. Coral associated microbes were variable in different
environment and may be a good bioindicator for environmental stress; therefore,
building up a bioindicator, a long term investigation is apparently essential.

並列關鍵字

sponge ； Cyanobacteria ； coral disease ； coral microbiology ； uncultured molecular method

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