三株固氮类芽孢杆菌的特点及其对中国青菜的产量和土壤酶活性的影响

【目的】本研究分析三株固氮菌PGPR性状特征及其对中国青菜产量和土壤酶活的影响。【方法】氮(N)-修复(固氮)细菌被认为是一种能够促进植物生长和增产的施氮方式。在本研究中,我们用无氮培养基分离出了30株根际固氮细菌:11株来自小麦根际,16株来自中国青菜根际和3株来自莲花根际。基于16S r DNA序列分析,对小麦、中国青菜和莲花等植物根际中属于类芽孢杆菌属的主要固氮细菌进行研究。【结果】本研究从这30株固氮菌中筛选出三株属于类芽孢杆菌属(Paenibacillus)的细菌,分别命名为P-4、W-7和L-3,它们的固氮酶活性不但高于对照组(圆褐固氮菌),而且可以有效抑制两种或三种植物病原菌的生长,即核盘菌(Sclerotinia sclerotiorum)、玉蜀黍赤霉(Gibberella zeae)和棉花黄萎病菌(Verticillium dahliae)。菌株W-7还具有溶解难溶磷的能力,中国青菜在接种菌株W-7和L-3后,其鲜重显著增加,同时改变了田间土壤蔗糖酶、磷酸酶和过氧化氢酶的活性;而接种了菌株P-4对植物的生长和酶活性没有显著的影响。【结论】土壤蔗糖酶、磷酸酶和过氧化氢酶活性与中国青菜的生物量呈正相关。同时,菌株W-7和L-3具有促进植物产量和提高土壤质量的良好潜力。

Characterizations of three diazotrophic Paenibacillus spp. and their effect on Chinese pakchoi yield and soil enzyme activities

Objective] Nitrogen-fixing (diazotrophic) bacteria are considered possible alternative to nitrogen fertilizers for promoting plant growth and yield. This study was to run a phylogenetic analysis and determine the PGPR traits of the isolated diazotrophic bacteria and characterize the effect of diazotrophic bacteria on Chinese pakchoi yield and soil enzyme activities.Methods] We isolated 30 diazotrophic bacteria from rhizosphere of wheat (11 isolates), Chinese pakchoi (16 isolates), and lotus (3 isolates) on N-free medium plates. Based on 16S rRNA sequence analysis, the dominant diazotrophic bacteria of wheat, Chinese pakchoi, and lotus belonged to the genus Paenibacillus. Results] Three multi-function diazotrophic bacteria designated as Paenibacillus spp. P-4, W-7 and L-3 were screened from these 30 diazotrophic. The nitrogenase activities of P-4, W-7 and L-3 were higher than the that of Azotobacter chroococcum used as the control. Strains P-4, W-7 and L-3 can inhibit the growth of two or three plant pathogens of Sclerotinia sclerotiorum, Gibberella zeae and Verticillium dahliae. Strain W-7 has also the phosphate solubilizing ability. Inoculation with Paenibacillus spp. W-7 or L-3 significantly increased the shoot fresh weight of Chinese pakchoi and changed the activity of soil sucrase, phosphatase, and catalase under field conditions, whereas inoculation with Paenibacillus sp. P-4 had no significant effect on plant growth or enzyme activity. Conclusion] Paenibacillus sp. W-7 and L-3 have good potential to promote plant yield and improve soil quality.