說(shuō)明：不同溫度下趨磁細(xì)菌群落的系統(tǒng)發(fā)育樹(shù)（A）和群落相似性的主坐標(biāo)分析（B）,，a,、b和c表示同一溫度下的三個(gè)平行樣品。從圖中可以看出,，37°C下趨磁細(xì)菌的種群多樣性與其余溫度下的樣品明顯不同,。
近日，國(guó)際雜志MicrobiologyOpen在線(xiàn)刊登了中科院地質(zhì)與地球物理研究所研究人員的最新研究成果“Short-term effects of temperature on the abundance and diversity of magnetotactic cocci.,，”,，文章中，研究者發(fā)現(xiàn)生長(zhǎng)溫度影響趨磁細(xì)菌數(shù)量和種群多樣性,。
古溫度是古環(huán)境重建的重要參數(shù),。已有研究表明，全球變暖對(duì)高等動(dòng)植物的多樣性具有顯著影響,，但是,，溫度變化對(duì)微生物有何影響目前尚不十分清楚。微生物分布廣,、數(shù)量大,、多樣性高，在全球元素循環(huán)和生態(tài)系統(tǒng)功能維持等方面發(fā)揮十分重要的作用,，能否用微生物變化反映環(huán)境溫度是一個(gè)非常值得研究的科學(xué)問(wèn)題,。
趨磁細(xì)菌是一類(lèi)能沿地磁場(chǎng)磁力線(xiàn)方向運(yùn)動(dòng)的微生物的總稱(chēng)，它們?cè)隗w內(nèi)合成磁鐵礦 (Fe3O4) 或膠黃鐵礦 (Fe3S4) 磁小體,，多呈鏈狀排列,。這類(lèi)細(xì)菌在自然界分布十分廣泛、易于磁收集且多樣性適中，可以作為研究微生物響應(yīng)氣候和環(huán)境變化的理想模式生物類(lèi)群,。
中科院地質(zhì)與地球物理研究所地球深部結(jié)構(gòu)與過(guò)程研究室古地磁與年代學(xué)實(shí)驗(yàn)室,、中-法生物礦化與納米結(jié)構(gòu)聯(lián)合實(shí)驗(yàn)室林巍博士及其合作導(dǎo)師潘永信研究員等通過(guò)實(shí)驗(yàn)室模擬研究，揭示了溫度變化對(duì)趨磁細(xì)菌數(shù)量和種群多樣性的影響,。他們將相同來(lái)源的沉積物樣品在實(shí)驗(yàn)室置于不同溫度下,，保存約一個(gè)月后發(fā)現(xiàn)，9-26°C樣品中趨磁細(xì)菌的群落結(jié)構(gòu)非常相似,，而37°C下趨磁細(xì)菌的多樣性有明顯差異,，樣品中趨磁細(xì)菌的數(shù)量也顯著降低，這表明溫度升高可以顯著影響趨磁細(xì)菌數(shù)量及其種群多樣性,。
這項(xiàng)研究意義在于,，可以利用沉積物中趨磁細(xì)菌古DNA信息反映其種群多樣性，作為古溫度估計(jì)的約束,。有報(bào)道稱(chēng)趨磁細(xì)菌合成磁小體磁鐵礦晶體的氧同位素比值也能反映細(xì)菌生長(zhǎng)環(huán)境的溫度,。因此，趨磁細(xì)菌及磁小體在古環(huán)境研究中具有潛力,。
本研究工作得到中國(guó)科學(xué)院和國(guó)家自然科學(xué)基金資助,。（生物谷Bioon.com）
doi:10.1002/mbo3.7
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Short-term effects of temperature on the abundance and diversity of magnetotactic cocci
Wei Lin1,2,*, Yinzhao Wang1,2, Yongxin Pan1,2
Temperature is one of the most important climate factors that can regulate the activity and growth of organisms. However, it is so far unclear how temperature influences the abundance and community composition of magnetotactic bacteria (MTB) that mineralize intracellular magnetite and/or greigite magnetosomes and play significant roles in the global iron cycling and sediment magnetization. To address this specific problem, in this study we have assessed the impact of temperature on freshwater magnetotactic cocci through laboratory microcosm simulations. Microcosms containing MTB were exposed to four constant temperatures ranging from 9°C to 37°C. After 10 days and 28 days of incubation, no significant differences in abundance were detected in microcosms at 9°C, 15°C, and 26°C (Student's t-test, P > 0.05); however, microcosms exposed to 37°C exhibited a significant decrease of magnetotactic cocci abundance (P < 0.05). Dendrogram analysis of community-amplified ribosomal DNA restriction analysis (community ARDRA) banding patterns distinguished the 37°C samples from samples at lower temperatures regardless of incubation periods. Furthermore, clone library analysis revealed that most of the operational taxonomic units (OTUs) detected in samples from 9°C to 26°C were absent from the 37°C microcosms, whereas six OTUs were exclusively detected in the 37°C samples. Community compositions from four incubation temperatures were further compared using statistical phylogenetic methods (UniFrac and LIBSHUFF), which revealed that the 37°C samples harbored phylogenetically distinct MTB communities compared to those found in 9°C, 15°C, and 26°C samples. Taken together, our results indicate that elevated temperature can influence the abundance and diversity of dominant members of magnetotactic cocci. This linkage further infers that the abundance and diversity of MTB (e.g., based on the fossil magnetosomes) may be useful in reconstruction of paleotemperature.
