为建立潜育化稻田微生物改良技术,采用MWMM(modified wolfe's mineral medium)培养基富集微好氧FeOB,结合16S rRNA测序等技术鉴定菌株种类,分别采用100 mL 106(T1)、107(T2)、108(T3)CFU/mL菌株发酵液处理潜育化水稻土,评价菌株对潜育化水稻土壤的还原性物质、土壤养分、氮循环功能基因丰度和水稻秧苗生长的影响,并利用16S rRNA高通量测序技术评价该菌株对土壤微生态的影响.结果显示:筛选到的对Fe2+具有较强氧化作用的FeOB为球形赖氨酸芽孢杆菌WH07(Lysinibacillus sphaericus WH07);相比于CK,土壤氧化还原电位(Eh)显著提高(P＜0.05),并由负电位转为正电位;T1、T2、T3处理土壤还原性物质总量分别减少 26.47%、41.53%、53.19%,亚铁含量分别减少 0.37%、21.50%、50.09%,亚锰含量分别减少 7.84%、21.57%、37.25%.土壤碱解氮含量分别显著增加15.50%、27.38%、48.90%(P＜0.05),速效磷分别显著增加12.52%、17.34%、27.38%(P＜0.05),速效钾分别显著增加11.56%、17.20%、19.34%(P＜0.05),有机质分别显著增加8.66%、22.22%、45.05%(P＜0.05),pH显著分别增加3.40%、8.94%、16.99%(P＜0.05).土壤AOA-amoA基因丰度分别增加11.94%、14.68%、33.83%,nosZ基因丰度分别增加42.97%、75.78%、118.75%,nifH基因丰度分别增加38.29%、51.05%、216.13%,UreC基因丰度分别增加16.74%、54.51%、60.94%.水稻株高分别增加 5.44%、10.98%、36.00%,叶龄分别增加 10.21%、23.42%、36.94%,鲜质量增加分别 12.61%、22.52%、28.38%,白根数分别增加10.14%、32.92%、46.81%.土壤微生物多样性指数Chao1和Shannon指数相比于CK均显著降低(P＜0.05).门水平上相对丰度前10的土壤细菌中,有8个显著下调(P＜0.05),如Proteobacteria等、2个(Bacteroidetes和Firmicutes)显著上调.在相对丰度前50的属中,3个处理分别有20、19、22个属显著上调(P＜0.05),包括Macellibacteroides等6个FeOB;25个属在3个处理中均显著下调(P＜0.05),包括MBNT15等4个铁还原菌.调控网络分析显示菌株WH07潜在地与FeOB协同改善土壤理化性质和生物活性,最终促进了秧苗生长.结果表明,应用菌株WH07显著改善了潜育化水稻土壤理化性质,改变了土壤微生物群落结构和功能.
Effects of Lysinibacillus sphaericus WH07 on improving soil and soil microecology in gleyed paddy field
FeOB were enriched with modified wolf's mineral medium(MWMM)to screen microaer-obic Fe2+oxidizing bacteria(FeOB)with better oxidative abilities to Fe2+,evaluate its effects on improv-ing soil and the microbial communities and functions of soil in gleyed paddy field,and lay a foundation for establishing technologies of improving microorganism in gleyed paddy fields.The FeOB strain was taxonom-ically identified with combined technologies including 16S rRNA sequencing.The 100 mL fermentation liq-uid of the strain with different concentration of 106(T1),107(T2),108(T3)CFU/mL was used to treat the soil in gleyed paddy field and evaluate the effects of the strain on the reducing substances,nutrients,abundances of functional genes for nitrogen cycling(NCFG)and rice seedlings of soil in gleyed paddy field.16S rRNA high-throughput sequencing technology was used to evaluate the effect of this strain on the soil microecology.The results showed that the FeOB strain screened with strong oxidative effect on Fe2+was identified as Lysinibacillus sphaericus WH07.Compared to CK,the soil redox potential(Eh)was sig-nificantly increased(P＜0.05)and shifted from negative potential to positive potential.The total amount of reducing substance in soil treated with T1,T2,and T3 decreased by 26.47%,41.53%,and 53.19%,re-spectively.The content of ferrous decreased by 0.37%,21.50%,and 50.09%,while the content of manga-nese decreased by 7.84%,21.57%,and 37.25%.The content of alkaline hydrolyzed nitrogen in soil signifi-cantly increased by 15.50%,27.38%,and 48.90%(P＜0.05),while the available phosphorus significantly increased by 12.52%,17.34%,and 27.38%(P＜0.05).The available potassium significantly increased by 11.56%,17.20%,and 19.34%(P＜0.05),and the organic matter significantly increased by 8.66%,22.22%,and 45.05%(P＜0.05).The pH significantly increased by 3.40%,8.94%,and 16.99%(P＜0.05).The abundance of AOA-amoA gene in soil increased by 11.94%,14.68%,and 33.83%,respective-ly.The abundance of nosZ gene increased by 42.97%,75.78%,and 118.75%,while the abundance of nifH gene increased by 38.29%,51.05%,and 216.13%.The abundance of UreC gene increased by 16.74%,54.51%,and 60.94%.The plant height of rice increased by 5.44%,10.98%,36.00%,the leaf age of rice in-creased by 10.21%,23.42%,36.94%,the fresh weight of rice increased by 12.61%,22.52%,28.38%,and the white root number of rice increased by 10.14%,32.92%,and 46.81%.The Chao1 and Shannon index of microbial diversity in soil was significantly decreased compared to CK(P＜0.05).Among the top 10 bac-teria in soil with relative abundance at the Phylum level,8 phyla including Proteobacteria were significantly downregulated(P＜0.05),while 2 phyla including Bacteroidetes and Firmicutes were significantly upregu-lated.Among the top 10 bacteria in soil with relative abundance at the Phylum level,8 phyla including Pro-teobacteria were significantly downregulated(P＜0.05),while 2 phyla including Bacteroidetes and Fir-micutes were significantly upregulated.Among the top 50 bacteria in soil with relative abundance at the ge-nus level,20,19,and 22 genera including 6 FeOBs such as Macellibacteroides et al were significantly up-regulated(P＜0.05)in the three treatments,while 25 genera including 4 Fe reducing bacteria such as MBNT15 et al were significantly down-regulated in all three treatments(P＜0.05).The results of analyz-ing regulatory network showed that the strain WH07 had the potential to synergistically improve the physi-cochemical properties and biological activity of soil with FeOB,ultimately promoting the growth of rice seedlings.It is indicated that the application of strain WH07 significantly improves the physicochemical prop-erties of soil in the gleyed paddy field and change the structure and function of microbial community in soil.
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