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Coupling between viruses and heterotrophic bacteria in semi- enclosed and open coastal waters: Does environment make a difference?
|Authors: ||Lin, Yu-Chia|
VLP2;VLP1;Bacteria;Synechococcus spp.;suspending particle
|Issue Date: ||2017-11-15T08:45:44Z
|Abstract: ||先前很多研究認為細菌與病毒之間互動關係良好，但Bettarel et al. (2004)的研究卻發現在法國營養鹽較豐富的高山湖泊Aydat中，其病毒和細菌之間關係卻不強(R2=0.13)。此作者推測可能的原因是小型植物性浮游生物的數量大量增加，使得感染植物性浮游生物的病毒數量增加，致使造成病毒與細菌之間關係薄弱。對此推測，本研究利用台灣東北沿岸兩個不同環境(小艇碼頭及水生動物實驗中心臨海海域)並使用流式細胞儀針對Pico級微生物及病毒數進行計數，同時利用DNA染劑染色後的螢光高低分為低螢光顆粒病毒(VLP1)和高螢光顆粒病毒(VLP2)。研究結果發現小艇碼頭環境中之細菌、藍綠細菌及Pico級真核藻類季節性數量變動明顯高於水生動物實驗中心臨海環境，同時發現小艇碼頭水域亦有較高的病毒顆粒存在。本研究由分析資料推測VLP1病毒在兩水域環境應是以感染細菌而裂解產生，但發現小艇碼頭VLP1病毒和細菌之互動關係較差(R2= 0.37)，其原因本研究認為並非Bettarelet al. (2004)所言，其互動關係較弱是病毒感染藍綠細菌所致，而應是在該水域環境中有較高的懸浮顆粒數量，吸附了表水中的病毒所致。本研究續將VLP1病毒除以細菌之值(VBR)視為兩者之間的動態關係，水生動物實驗中心臨海水域及小艇碼頭水域之VBR值各在1.7 ~ 10.6和0.9 ~ 6.1之間，且兩水域環境的VBR值有明顯的季節性變化。在11月至5月期間兩環境水域VBR值與溫度變化有明顯的正相關，而6月至10月期間，其VBR值與水溫並無關係存在且產生很大的變化範圍，其可能的原因為暖季期間微細鞭毛蟲攝食細菌的能力增加所致。|
To our knowledge, assessments of viral dynamics in marine system around Taiwan are still limited. Therefore, the objectives of this study was to assess the seasonal variations of viral abundance in relation to the dynamics of picoplankton (bacteria, Synechococcus spp. and pico-eukaryotes) and environmental factors at semi- enclosed (station A) and open coastal waters (station B) in the northeast of Taiwan. Picoplankton and viral populations were identified and enumerated by flow cytometry. Furthermore, viral populations were split into two virus- like particle populations (VLP1 and VLP2). During the study, viral and picoplankton abundance were significantly higher at station A than that at station B. Positive correlation occurred between VLP1 and bacterial abundance, suggesting that VLP1 were bacteriophage. However, the R2 value of regression line at station A was smaller than that at station B, one possible explanation of this phenomenon may be that viruses absorbed to suspended material in the surface water may settle out to the deep water. In this study, we suggest that increased abundance of VLP2 viruses seem to be non-bacteriophage viruses, such as these viruses could infect cyanobacteria, pico- eukaryotes and nanoflagellates. Furthermore, we used VLP1 virus to bacteria ratio (VBR) as an important parameter indicating virus- host interactions. Clear seasonal variations of VBR values were observed at both stations, and ranged from 1.7 to 10.6 and 0.9 to 6.1 at station A and B, respectively. Between November and May, we found that there was positive relationship between VBR and temperature. However, there was no relationship between these, and showed that large variations of VBR values during June to October. This could suggest a limited virus effect on bacteria, such as nanoflagellate grazing rates on bacteria increased during the warm season.
|Appears in Collections:||[海洋環境與生態研究所] 博碩士論文|
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