广西红壤区林木根际溶磷菌的筛选与鉴定

Isolation and identification of a strain of phosphate-solubilizing bacteria from forest in red soil region of southern China

南方速生丰产林多为人工纯林,生态系统薄弱,林地产出多,施用大量的化肥,造成林地生态环境恶化,速效磷已成为南方红壤区林木生长的主要限制因子之一,为了减少化肥的施用量,提高南方林木对土壤磷素的利用率,开发林木微生物肥料,利用以磷酸钙为磷源的难溶性无机盐培养基从南方不同红壤区林木根际土壤中筛选分离得到42株溶磷菌,获得其中6株高效菌株探讨其溶磷机理,并用测序技术进行菌株鉴定。结果表明:所筛选得到的6株D/d值大于1.2的菌株在液体发酵条件下均有明显的溶磷能力, L205菌株溶磷量最大达到203.04mg·L^-1。各菌株在发酵过程中pH值不断降低,从6.50~6.78降低到3.13~4.12,与其溶磷量具有一定的相关性。通过16S rDNA序列测序确定L205的系统发育地位,发现该菌株为巨大芽孢杆菌Bacillus megaterium。L205菌株具有很好的溶无机磷效果,在南方林业生产实践中具有较好的应用潜力,同时也为南方速生丰产林的减肥增效扩宽了思路。

With the rapid development of fast-growing and high-yield forests in the south, the southern forests have provided a large amount of timber demand for the country. At the same time, the fast-growing and high-yield forests in the south are mostly pure plantation. The ecosystem is weak, and the output of forest land is large. A large number of fertilizers are applied, resulting in the deterioration of the woodland ecological environment. Available phosphorus has become one of the main limiting factors for tree growth in red soil region of subtropics. To improve efficiency of phosphorus in Guangxi woodland. Phosphorus solubilizing effects of 6 stains of phosphorus solubilizing bacteria screened out of the red soil in Guangxi were studied and compared through incubation in PKO solution containing Ca3(PO4)2 as phosphorus sourse. And the strains were identified by sequencing technology.Result showed that all strains which value of D/d were greater than 1.2 had significant effect of phosphate solubilization under the condition of liquid fermentation. strain L205 had the best ability to dissolve rock phosphates, and the amount of dissolved phosphorus reached 203.04 mg·L^-1. During the fermentation process, pH decreased from 6.50-6.78 to 3.13-4.12, which had a certain correlation with the amount of phosphate solubilization of strains. The phylogenetic status of the strain was determined by sequencing of16 S rDNA sequences. What was identified as Bacillus megaterium. The L205 strain had a good effect of phosphate solubilization, which has great potential for application in the subtropical forest production practice. Meanwhile, the idea of reducing fertilizer application and increasing the effect in the southern forests has been widened.