高效解硅菌的分离鉴定及其促生能力

Isolation, identification, and growth-promoting ability of efficient silicate-solubilizing strains

摘要:

【背景】硅具有提高作物抗逆性、提高产量及改善品质的能力而被广泛报道，但传统施肥对硅肥的忽略使耕地土壤有效硅含量不断降低，因此建立高效提高土壤有效硅的方式尤为重要。【目的】土壤中有效硅的含量影响作物对硅的吸收利用，通过施用具有解硅能力的土壤微生物实现土壤有效硅的持续活化，不仅对作物产量和品质有重要意义，同时也可减少化肥的施用。【方法】利用选择培养基进行土壤解硅菌的富集、分离纯化，并测定其解硅能力、耐盐碱性、耐低氧性、解磷、解钾、解纤维素能力；利用孔雀绿染色及沙黄溶液复染法测定高效解硅菌芽孢形成率，最后通过盆栽试验探究高效解硅菌株对玉米的促生作用。【结果】筛选获得2株高效解硅菌，分别为菌株MB22及MB35-5，16S rRNA基因序列测定鉴定为Priestia aryabhattai。培养液有效硅浓度分别为空白处理的1.5倍和1.7倍，为对照菌株胶质类芽孢杆菌Paenibacillus mucilaginosus3016处理的1.1倍和1.2倍。2株高效解硅菌表现出较好的耐盐碱性，MB35-5功能最强，在pH 10.0、10% NaCl、10% KNO₃条件下培养液有效硅浓度为0.28-0.37 mmol/L。MB22和MB35-5产芽孢率分别为68%和55%，分别为对照菌株3016的1.69倍和1.37倍。MB35-5对磷、钾和纤维素都有一定的活化利用能力。盆栽试验表明，2株菌均显著提升了玉米株高及根系干重，其中MB35-5促生效果最好，平均株高是空白处理的1.39倍，是对照菌株3016处理的1.14倍，根系干重为空白处理的1.37倍，是对照菌株3016处理的1.24倍。【结论】筛选得到2株高效解硅菌MB22和MB35-5，其中高芽孢率的MB35-5还具有解磷、解钾、降解纤维素和促生功能，同时具备耐盐碱、耐低氧等抗逆性，表明该菌株具有进一步试验和研发的潜势。

Abstract:

[Background] Silicon, which improves the stress resistance, yield, and quality of crops, has been widely reported. However, the conventional neglect of silicon fertilizer results in the continuous decrease in the content of available silicon in arable land. Therefore, it is an urgent task to raise the content of soil available silicon. [Objective] The content of available silicon in soil affects the absorption and utilization of silicon by crops. Silicate-solubilizing microorganisms can continuously activate available silicon in soil, which helps improve crop yield and quality and reduce the application rate of chemical fertilizer. [Methods] Selective media were used for the enrichment, isolation, and purification of soil silicate-solubilizing strains, and the silicate-solubilizing ability, saline-alkaline tolerance, low-oxygen tolerance, phosphate-solubilizing ability, potassium-releasing ability, and cellulose-degrading ability were determined. With malachite green as the primary stain and safranin as counterstain, the spore yield of high-efficiency silicate-solubilizing strains was measured. Finally, the maize growth-promoting ability of efficient silicate-solubilizing strains was investigated through pot experiment. [Results] Two efficient silicate-solubilizing strains were obtained, MB22 and MB35-5. They were identified as Priestia aryabhattai by 16S rRNA sequencing, and the concentration of available silicon in the culture of them was 1.5 and 1.7 folds that of the blank control, and 1.1 and 1.2 folds that of the control Paenibacillus mucilaginosus 3016, respectively. MB22 and MB35-5 showed high saline-alkaline tolerance, particularly MB35-5. Specifically, under the conditions of pH 10, 10% NaCl, and 10% KNO₃, the concentration of available silicon in the culture of MB35-5 was 0.28–0.37 mmol/L. The spore yield of MB22 and MB35-5 was 68% and 55%, respectively, 1.69 folds and 1.37 folds of the control strain, respectively. MB35-5 had phosphate-solubilizing ability, potassium-releasing ability, and cellulose-degrading ability. Pot experiment showed that the two strains significantly increased the plant height and root dry weight of maize plants, especially MB35-5. To be specific, the average height of plants treated by MB35-5 was 1.39 times that of blank treatment and 1.14 times that of plants treated by control strain. The root dry weight of plants treated by MB35-5 was 1.37 times that of the blank treatment and 1.24 times that of plants treated by control strain 3016. [Conclusion] The silicate-solubilizing strains MB22 and MB35-5 were screened out. Among them, MB35-5 with high spore yield also showed phosphate-solubilizing ability, potassium-releasing ability, cellulose-degrading ability, and growth-promoting function, as well as the saline-alkaline tolerance and low-oxygen tolerance. Thus, this strain should be further tested and developed.