抗镉并且产吲哚乙酸的细菌的筛选鉴定及其植物促生作用

Screening and Identification of Cadmium-resistant and IAA-producing Bacteria, Their Plant-growth Promoting Effects

植物促生长细菌(plant growth-promoting bacteria,PGPB)在植物修复重金属污染土壤的过程中能够有助于植物生长,从而提高植物的重金属污染土壤的修复能力。作为在重金属污染环境中应用的PGPB首先必须具有重金属抗性。镉是一种毒性很高的重金属,也是常见的环境污染因子之一。在植物中,镉抑制根和茎的生长,影响营养吸收和内环境稳定。现已知的PGPB的作用机制之一是产生植物生长激素如吲哚乙酸(indole acetic acid,IAA)和铁载体(siderophore)。本研究从土壤中筛选获得5株具有镉抗性(>1.55 mmol/L)且产IAA和铁载体的细菌,这5株菌被编号为DJY、TK-2、TK-6、WM-1、PZ-23。在含镉培养基上,所有5种菌对芥菜根均有不同程度的促生长作用,其中TK-2对芥菜幼苗根萌发和下胚轴延伸的促进效果最为显著;促生效应并不由单一因素决定的,而是多种促生因素的统一协调作用的结果。

Plant growth-promoting bacteria（PGPB） are helpful to plant growth during phytoremediation of heavy metal-polluted soils, and can therefore enhance the ability of remediation of heavy metal-polluted soils by plants.However, the PGPB applied in the heavy-metal-polluted environments should first have a resistance to heavy metals. Cadmium is one of common environmental pollution factors which is highly toxic. Cadmium can inhibit the growth of root and stem in plants and affect nutrient absorption and homeostasis. One of the known mechanisms of plant growth promoting effect of the PGPB is to produce plant growth hormone such as IAA and siderophore. Five strains of cadmium-resistant（〉1.55 mmol/L） and IAA-producing, siderophores-producing bacteria were isolated from the soil, which were numbered DJY, TK-2, TK-6, WM-1 and PZ-23. All five kinds of bacteria have different levels of growth-promoting effect on roots of mustard grown on the cadmium-containing medium, of which TK-2 had the best effect of promoting elongation of roots and hypocotyls of plants.Growth-promoting effects by bacteria result from coordinated effects of multiple factors instead of single factor.