莴笋根部促生菌筛选与促生特性测定

Lettuce root growth promoting bacteria screening and determination of growth promoting properties

为获得莴笋(Lactuca sativa)根部优良促生菌株,为后续研制微生物接种剂(菌肥)提供优良菌种,以莴笋根系为对象,利用选择性培养基分离、筛选莴笋根系溶解有机溶磷、无机溶磷细菌和固氮细菌,测定其溶磷能力、固氮能力、分泌植物生长激素能力以及对植物病原菌的拮抗能力;对性能优良的菌株进行16S rDNA分子生物学鉴定。研究表明:莴笋根部分离到25株溶磷菌株,其溶解无机磷能力为60.83~290.66μg·mL^-1(菌株PGBA2溶磷量最高,为290.66μg·mL^-1),溶解有机磷的能力普遍较低,为8.12~71.87μg·mL^-1;分离出固氮菌株20株,固氮酶活性为8.37~371.54 nmol·h^-1·mL^-1(GNB6固氮酶活性最强,为371.54 nmol·h^-1·mL^-1);分离筛选分泌植物生长激素(IAA)菌株14株,分泌量为0.78~5.29μg·mL^-1(MGBD1分泌IAA的能力最强,为5.29μg·mL^-1);菌株MGNB4、MGBC3、PGBA2对黄瓜枯萎病(Fusarium oxysporum)有抑菌作用,抑菌率达到50%以上。对9株优良PGPR菌株进行分子生物学鉴定,菌株MGBC2、MGBC3、PGBA2为醋酸钙不动杆菌(Acinetobacter calcoaceticus),菌株MGNB3、MGNB4为华夏氏肠杆菌(Enterobacter huaxiensis),菌株MGBD1为铜绿假单胞菌(Pseudomonas brassicacearum),菌株GND5为枯草芽孢杆菌(Bacillus subtilis),菌株GNA6为气泡微细菌(Microbacterium aerolatum),菌株GNB6为放射型根瘤菌(Rhizobium radiobacter)。

In order to obtain excellent strains of lettuce(Lactuca sativa)root growth-promoting bacteria and provide excellent strains for the subsequent development of microbial inoculants(bacterial fertilizers),we took the root system of lettuce as the research object and used selective incubation culture medium to separate and screen the ability of lettuce roots in dissolving organic phosphorus(P),inorganic phosphate solubilizing bacteria,and nitrogen(N)-fixing bacteria,and determine their ability to dissolve P,N fixation,plant growth hormone secretion,and antagonistic ability against plant pathogenic.We also tried to identify excellent strainsby 16S rDNA molecular biology technology.The results shown that 25 strains of P-dissolving strains were isolated from the roots of lettuce,and their ability to dissolve inorganic P was 60.83~290.66μg·mL^-1(the highest amount of P in PGBA2 was 290.66μg·mL^-1);The ability to dissolve organic P was generally low,ranging from 8.12 to 71.87μg·mL^-1.The 20 strains of N-fixing strains were isolated,and the nitrogenase activity was 8.37~371.54 nmol·h^-1·mL^-1(the most active nitrogenase activity of GNB6 was 371.54 nmol·h^-1·mL^-1).Fourteen strains of secreted plant growth hormone(IAA)strains were isolated and screened,and the secretion amount was 0.78~5.29μg·mL^-1(MGBD1 had the strongest ability to secrete IAA at 5.29μg·mL^-1).The strains MGNB4,MGBC3,and PGBA2 had antibacterial activity against Fusarium oxysporum,and the inhibition rate was over 50%.After the molecular biological identification of 9 excellent PGPR strains,the strains MGBC2,MGBC3,and PGBA2 were Acinetobacter calcoaceticus;the strains MGNB3 and MGNB4 were Enterobacter huaxiensis;the strain MGBD1 was Pseudomonas brassicacearum;the strain GND5 was Bacillus subtilis;the strain GNA6 was Microbacterium aerolatum,and the strain GNB6 was Rhizobium radiobacter.The excellent root-growth promoting bacteria selected in this study can provide excellent strains for the future development of lettuce microbial fertilizer,also enriched the PGPR strain resource bank.