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Title:

体外驯化与培养组学策略:从盐角草中分离耐盐核心微生物群

Take home message:

(1)发现叶内微生物的多样性比根际更高,并且分离出15个属,其中8个属是首次从盐角草中培养出来的

(2)驯化后,叶内以假单胞菌门/芽孢杆菌门为主,根际则主要是盐单胞菌

(3) PBSW为盐生植物细菌的培养创造了原位相似环境,并实现了繁殖微生物群的体外驯化,而不是为未来的SynCom应用而费力地构建单一分离物的群体.


Main:

摘要

(1)Microbiome-mediated strategies for future stressed-agriculture entail exploration of repertoires of halophyte microbiota. Culturomics strategies are advanced to improve culturability and extend diversity of microbiota of Salicornia europaea L. 微生物类群介导的未来胁迫农业策略需要探索盐生植物微生物群的宝库。为了提高盐角草的可培养性和扩大微生物区系的多样性,提出了培养组学策略

(2)The plant broth-based-seawater-culture medium (PBSW) was advanced for in vitro domestication of microbiota of endo-rhizosphere/endo-phyllosphere of S. europaea. Populations (Colony Forming Units, CFUs) and biomass production (Optical Density, OD) were monitored throughout successive steps of in vitro cultivation/domestication in liquid batch cultures. 提出了基于植物肉汤的海水培养基(PBSW ),用于菝葜根际/叶内微生物群的体外驯化。在液体分批培养的体外培养/驯化的连续步骤中,监测种群(菌落形成单位,CFUs)和生物量生产(光密度,OD)。

(3)Culture-dependent methods were applied to cultivate and identify (16S rRNA gene sequencing) representative isolates; and culture-independent analyses (DGGE/qPCR) for community composition. 应用培养依赖方法培养和鉴定(16S rRNA基因测序)代表性分离物;和用于群落组成的非培养依赖性分析(DGGE/qPCR)。 

(4)PBSW supported higher CFUs counts; and related to 16S rRNA gene copy numbers (qPCR), increased (>40 fold) culturability compared to NaCl-salted-standard culture medium. PBSW支持更高的cfu数;并且与16S rRNA基因拷贝数(qPCR)相关,与NaCl盐标准培养基相比,可培养性增加(> 40倍)。  

(5)Successive in vitro domestication/batch cultures boosted bacterial growth, diminished differences among tested culture media and shortened doubling times (DT) 连续的体外驯化/分批培养促进了细菌生长,减少了测试培养基之间的差异,并缩短了倍增时间(DT) .

(6)PCR-DGGE showed divergence in culturable community composition primarily attributed to culture media. 16S rRNA gene sequencing of representative isolates indicated: a) greater diversity in endo-phyllosphere than endo-rhizosphere; b) abundant phyla were Pseudomonadota/Bacillota /Actinomycetota; c) dominance of Halomonas among 15 genera identified; d) Gracilibacillus, Metabacillus, Mixta, Salinicoccus, Zhihengliuella, Marinobacter, Marinimicrobium and Planomicrobium were first reported/cultivated for S. europaea. In vitro domestication resulted in dominance of genera of Pseudomonadota/Bacillota for endo-phyllosphere and Halomonas sp. of Pseudomonadota for endo-rhizosphere. PCR-DGGE显示了主要归因于培养基的可培养群落组成的差异。代表性菌株的16S rRNA基因测序表明:a)叶内比根际具有更大的多样性;(2)丰富的门有假单胞菌门/杆菌门/放线菌门;c)盐单胞菌在已鉴定的15个属中的优势;d)纤细芽孢杆菌属、代谢芽孢杆菌属、混合芽孢杆菌属、盐生球菌属、志恒流杆菌属、海洋杆菌属、海洋微生物属和平微生物属首次被报道/培养用于欧洲链霉菌。体外驯化导致叶内假单胞菌属/芽孢杆菌属和盐单胞菌属占优势。假单胞菌内生根际。

(7)PBSW created in situ similis milieu for cultivation of halophyte bacteria, and enabled in vitro domestication for propagating microbiota, instead of laborious construction of consortia of single isolates, for future SynCom applications. PBSW为盐生植物细菌的培养创造了原位相似环境,并实现了繁殖微生物群的体外驯化,而不是为未来的SynCom应用而费力地构建单一分离物的群体.

图片

Effect of in vitro domestication in PBSW batch cultures compared to intact (mother) halophyte microbiota of endo- rhizosphere and endo-phyllosphere at genera level 在属水平上,PBSW分批培养物中的体外驯化与根际和叶内完整(母体)盐生植物微生物群的比较效果

Result

(8) Culturability of S. europaea microbiota as affected by plant compartments and culture media 

(9)In vitro domestication and biomass production of halophyte microbiota associated to Salicornia europaea

(10)Up-scaling of in vitro domesticated biomass production 

(11)Analysis of culture dependant/independent community composition of both intact S. europaea compartments and resulted in vitro-domesticated batch cultures 

(12)Diversity of bacterial isolates representing the culturable community of bacterial endophytes in S. europaea compartments

(13)Isolates representing the original mother cultures, i.e. intact endo-rhizosphere/endo-phyllosphere of S. europaea

(14)Isolates dominated the tested in vitro-domesticated batch cultures 

(15)方法

叶内微生物的分离方法(Endo-phyllosphere)

1. 表面灭菌

采集盐角草地上部分(茎、叶)浸泡在 95% 乙醇 中 1 分钟,再浸泡在 3% 次氯酸钠 中 30 分钟,用无菌海水多次冲洗(每次 5 分钟)

2. 制备母液

将 10 g 表面灭菌后的植物组织,放入 180 mL 无菌海水中,用搅拌机打碎(Waring blender),120 rpm 摇动 30 分钟,制成原始悬液(母液)

3. 稀释与培养

用海水进行 10 倍系列稀释(10⁻¹ 到 10⁻⁵),取 200 μL 稀释液,涂布在 PBSW 琼脂平板 或 1/10 CCM30 琼脂平板 上,25°C 培养 8–12 天

4. 单菌落分离与纯化

挑选所有生长的菌落,转移到 半固体培养基(1.85 g/L 琼脂)中25°C 培养 5–7 天,成功生长的菌落进行进一步鉴定

5. 16S rRNA 基因测序

共获得 535 个菌落(叶内来源),最终成功测序 69 株代表性菌株(叶内)

体外驯化方法

1. 使用的培养基

PBSW(植物肉汤 + 海水培养基):

将盐角草地上部分制成植物肉汤,加入海水(25–50 mL 植物肉汤 / L 海水),pH 7.67,EC 68 dS/m。对照培养基 1/10 CCM30:标准化学合成培养基,加 3% NaCl。

2. 三步连续驯化流程(图1)

第一步(Step 1):取 20 mL 原始母液(来自表面灭菌后的植物组织悬液),接种到 180 mL 液体培养基中(PBSW 或 CCM30)25°C 培养 10–12 天,间歇摇动(120 rpm)

第二步(Step 2):取 5 mL 第一步培养液,接种到 180 mL 新鲜培养基中,同样条件培养 10–12 天,第三步(Step 3):取 5 mL 第二步培养液再次接种到 180 mL 新鲜培养基中,同样条件培养 10–12 天

3. 监测指标

OD₆₀₀(光密度,代表生物量),CFUs(菌落形成单位),倍增时间(Doubling time, DT),pH 和 EC(电导率)

4. 驯化效果

第三步驯化后,PBSW 中的细菌生长显著提升,OD 值和 CFUs 与 CCM30 差异缩小。倍增时间缩短(如叶内微生物 DT 降至 22–24 h)。驯化后,微生物群落结构更适应高盐环境


Words:

Culturomics strategies are advanced to improve culturability and extend diversity of microbiota of Salicornia europaea L.