氮磷营养盐添加对二甲基巯基丙酸内盐合成与降解细菌及其功能基因的影响  

Effects of nitrogen and phosphorus on the bacterial dimethylsulfoniopropionate production and catabolism

作　　者：谭斯尹 孙浩 梁金昌 张晓华[1,2,3] Siyin Tan;Hao Sun;Jinchang Liang;Xiaohua Zhang(College of Marine Life Sciences,Ocean University of China,Qingdao 266003,Shandong Province,China;Laboratory for Marine Ecology and Environmental Science,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266071,Shandong Province,China;Center for Advanced Science of Deep-Sea Spheres and Earth Systems,Ocean University of China,Qingdao 266100,Shandong Province,China)

机构地区：[1]中国海洋大学海洋生命学院,山东青岛266003 [2]青岛海洋科学与技术试点国家实验室海洋生态与环境科学功能实验室,山东青岛266071 [3]中国海洋大学深海圈层与地球系统前沿科学中心,山东青岛266100

出　　处：《微生物学报》2020年第9期1941-1958,共18页Acta Microbiologica Sinica

基　　金：国家重点研发计划(2016YFA0601303);国家自然科学基金(91751202)。

摘　　要：【目的】二甲基巯基丙酸内盐(dimethylsulfoniopropionate,DMSP)是海洋中主要的有机硫化物之一,是海洋细菌硫的主要来源,海洋细菌将其分解成“冷室气体”二甲基硫(dimethylsulfide,DMS),对调节全球气候变化和驱动地球硫循环有重要作用。本研究通过中国东海水体的现场围隔实验模拟海水富营养化对DMSP、DMS产量以及DMSP合成基因(dsyB和mmtN)和降解基因(dddP和dmdA)及相关功能细菌的影响。【方法】通过流式细胞仪计数92个围隔海水样品中微微型浮游生物的数量,采用Illumina MiSeq测序技术对海水样品中细菌的16S rRNA基因进行高通量测序,利用荧光定量PCR技术定量测定16S rRNA基因、DMSP合成及降解基因的丰度。【结果】研究发现,同时添加硝酸盐(6.00μmol/L)和磷酸盐(0.375μmol/L)能促进叶绿素a、DMSP、DMS的浓度上升。对于DMSP合成基因,只加磷酸盐能促进dsyB及Phaeobacter等相应物种的富集,虽然同时添加硝酸盐和磷酸盐使dsyB富集,但相对只加磷酸盐却不利于dsyB积累;同时添加硝酸盐和磷酸盐也抑制Alteromonas的生长,进而抑制了mmtN的富集。对于DMSP降解基因,同时加入硝酸盐和磷酸盐促进了dddP及Thalassococcus、Thalassobius、Loktanella和Shimia等物种的富集,却抑制了SAR11、Sulfitobacter等的富集,从而导致dmdA无法被富集。【结论】氮限制能更好地促进DMSP合成基因的表达,从而迫使细菌增加DMSP的合成以应对氮营养条件不足的生存环境,并进而提高DMSP脱甲基化的比例为细菌提供更多能量;而在硝酸盐和磷酸盐充足情况下,细菌相对减少DMSP的合成且更倾向于裂解DMSP产生DMS来降低硫同化的比例。本研究结果强调了海水富营养化对细菌合成与降解DMSP过程的影响。[Objective]Dimethylsulfoniopropionate(DMSP)is one of the main organic sulfides in the ocean,and the main source of sulfur for marine bacteria.DMSP is catabolized by bacteria into dimethylsulfide(DMS),driving the sulfur cycle of the Earth.This study simulated the effect of seawater eutrophication on DMSP/DMS,DMSP producing genes(dsyB and mmtN),catabolising genes(dddP and dmdA)and corresponding functional bacteria through the mesocosm.[Methods]We used flow cytometry to quantify the abundance of microplankton of 92 water samples.We sequenced bacterial 16S rRNA gene of seawater samples by high-throughput sequencing.Then we quantified the abundance of 16S rRNA gene,DMSP producing and catabolising genes by quantitative PCR.[Results]Adding nitrate(6.00μmol/L)and phosphate(0.375μmol/L)simultaneously increased the concentration of chlorophyll a,DMSP and DMS.For DMSP producing genes,phosphate enriched the abundance of dsyB and some DMSP producing genera,such as Phaeobacter.Adding nitrate and phosphate could enrich dsyB simultaneously,inhibit the growth of Alteromonas and the enrichment of mmtN gene,but the effects of phosphate on dsyB enrichment was better than nitrate.In terms of DMSP catabolising genes,adding nitrate and phosphate simultaneously promoted the enrichment of dddP and the DMSP catabolising genera like Thalassococcus,Thalassobius,Loktanella and Shimia,but inhibited the enrichment of SAR11,Sulfitobacter and other species,resulting in the failure of enrichment of dmdA.Nitrogen restriction could better promote the abundance of DMSP producing gene,resulting in the increasing of bacterial DMSP production to cope with the insufficient nutritional conditions,and rising the proportion of DMSP demethylation to provide more energy for bacteria.However,in the case of nitrate and phosphate abundance,bacteria were apt to reduce the synthesis of DMSP and was more inclined to lyse DMSP to produce DMS in order to reduce the ratio of sulfur assimilation.[Conclusion]The results of this study emphasized the effect of seawater

关 键 词：二甲基巯基丙酸内盐 合成和降解细菌 营养盐 围隔实验 

分 类 号：Q938[生物学—微生物学]