欧李(Cerasus humilis)内生固氮细菌筛选、鉴定及特性研究

为探究荒漠草原灌木欧李(Cerasus humilis)根系内生细菌固氮能力和其它特性。采用无氮培养基,从欧李根内分离获得20株内生固氮菌,并结合乙炔还原法测定固氮酶活性,钼锑抗比色法测定溶磷特性,Salkowski法测定分泌植物生长素(Indole acetic acid,IAA)能力,对筛选出固氮酶活性较高的菌株进行16S rDNA序列比对,确定其分类地位。结果表明,分离的内生固氮细菌均具溶磷和分泌IAA能力。所分离菌株固氮酶活性在31.45~424.81 nmol C₂H₄·h^-1·mL^-1之间(NS 25最高),解有机磷量在26.62~99.18 μg·mL^-1之间(YNS 4最高),溶无机磷量在1.10~20.31 μg·mL^-1之间(WNS 21最高),分泌IAA量在3.86~47.00 μg·mL^-1之间(NS 22最高)。10株固氮酶活性较高菌株经初步鉴定NS1 14-1和NS1 14-2为Bacillus pumilus,NS 25和NS 26为Bacillus paralicheniformis,YNS 1为Brevibacterium frigoritolerans,菌株WNS 21和NNS 15为Bacillus velezensis,NS 8为Paenibacillus catalpae,YNS 6为Cytobacillus firmus,NNS 19为Bacillus sp.。研究分离的内生固氮细菌具有溶磷和分泌IAA的能力,有望通过后续研制微生物菌剂为干旱地区植被恢复与生态重建发挥积极作用。

Screening,Identification and Characteristics of Endophytic Nitrogen-Fixing Bacteria in Cerasus humilis

In order to explore the nitrogen-fixing ability and other characteristics of the endophytic bacteria in the roots of the desert steppe shrubs Cerasus humilis.20 endophytic nitrogen-fixing strains were isolated from the roots of Cerasus humilis using a nitrogen-free medium,and their nitrogenase activity was determined by acetylene reduction assay,phosphorus solubility was determined by molybdenum antimony colorimetric method,and auxin (Indole acetic acid,IAA) secretion capacity was determined by Salkowski method.The 16S rDNA sequence alignment was performed on the strains with higher nitrogenase activity to determine their taxonomic status.The results showed that all isolated endophytic nitrogen-fixing strains had the characteristics of solubilizing phosphorus and secreting IAA.The nitrogenase fixation activity of the isolated strains was 31.45~424.81 nmol C₂H₄·h^-1·mL^-1(NS 25 was the highest);the amount of dissolving organic phosphorus was 26.62~99.18 μ g·mL^-1(YNS 4 was the highest);the amount of solubilizing inorganic phosphorus was 1.10~20.31 μ g·mL^-1(WNS 21 was the highest);the secretion of IAA was 3.86~47.00 μ g·mL^-1(NS 22 was the highest).10 strains with higher nitrogenase activity were preliminarily identified:NS1 14-1 and NS1 14-2 were Bacillus pumilus,NS 25 and NS 26 were Bacillus paralicheniformis,YNS 1 was Brevibacterium frigoritolerans,WNS 21 and NNS 15 were Bacillus velezensis,NS 8 was Paenibacillus catalpae,YNS 6 was Cytobacillus firmus,and NNS 19 was Bacillus sp.The endogenous nitrogen-fixing strains isolated from the study had characteristics of solubilizing phosphorus and secreting IAA.It is expected to play a positive role in vegetation restoration and ecological reconstruction in arid areas through the subsequent development of microbial agents.