bacterial and fungal community in the rhizosphere microbiome after introducing biocontrol agents Raw sequence reads. bacterial and fungal community in the rhizosphere microbiome after introducing biocontrol agents

Two separate pot experiments were conducted. The first studied the temporal persistence of Bcsl strains on cucumber roots and in rhizosphere soil and the second investigated the impact of the antagonist B. cereus s.l. S-25 on the rhizosphere microbial community composition, concomitant to evaluating suppression of damping-off disease caused by R. solani.In both experiments, overnight suspensions of Bcsl strains were platted on LB agar and incubated for 24 h at 30 Celsius. The bacteria were resuspended in 0.9% NaCl in sterile 50ml tubes, and centrifuged (14,000 rpm, 10 min, 4 Celsius with Heraeus multifuge X1R, Thermo scientific) and the bacterial pellet was weighed, and subsequently diluted in 0.9% NaCl to reach an optical density equivalent to 109 cells ml-1 (based on preliminary experiments). Cucumber seeds (CV Mani, Genesis Seeds, Israel) were surface sterilized in 50% of sodium hypochlorite for 3 min, washed three times with sterile DDW, and soaked in the above bacterial suspensions or in 0.9%NaCl, at 25 Celsius for 2 h. The coated seeds were sown into a planting tray (408 cells) containing wet peat for up to 5 days at 26 Celsius to facilitate germination. Cucumber seedlings at the 2-leaf stage were then transplanted into 12 cm pots (3 seedlings per pot) filled with commercial potting mixture.

本研究开展了两组独立的盆栽试验。第一组试验旨在探究Bcsl菌株在黄瓜根系及根际土壤中的时间留存特性；第二组试验则以拮抗菌蜡样芽孢杆菌群（Bacillus cereus sensu lato, B. cereus s.l.）S-25为研究对象，分析其对根际微生物群落组成的影响，同时评估其对由立枯丝核菌（Rhizoctonia solani, R. solani）引起的猝倒病的防治效果。

两组试验中，均将Bcsl菌株的过夜培养液涂布于LB琼脂（Luria-Bertani agar）平板，于30℃下培养24小时。随后将菌体重悬于无菌50mL离心管的0.9%氯化钠溶液中，采用赛默飞世尔科技旗下贺利氏Multifuge X1R离心机，于4℃、14000 rpm条件下离心10分钟；称量菌体沉淀后，用0.9%氯化钠溶液将其稀释至光密度对应10^9个细胞/mL（该浓度依据预实验确定）。

供试黄瓜种子（品种Mani，购自以色列Genesis Seeds公司）经50%次氯酸钠溶液表面灭菌3分钟，用无菌双蒸水（double distilled water, DDW）洗涤3次后，于25℃下分别浸入上述菌悬液或0.9%氯化钠溶液中浸泡2小时。将包衣后的种子播种于装有湿润泥炭的408孔育苗盘中，于26℃下培养至多5天以促进萌发。待幼苗长至两叶期时，将其移栽至装有商品栽培基质的12cm口径花盆中（每盆3株幼苗）。