凤眼莲根分泌物氨基酸组分对根际肠杆菌属F_2细菌的趋化作用

Chemotaxis of amino acids in root exudates from Eichhornia crassipes to its rhizospheric Enterobacter sp. F_2

凤眼莲（Ｅｉｃｈｈｏｒｎｉａｃｒａｓｓｉｐｅｓ）的根分泌物中含有Ｍｅｔ等多种氨基酸，其中Ｍｅｔ、ＧＡＢＡ、Ｇｌｙ、Ａｌａ、Ａｓｐ、Ｓｅｒ、Ｖａｌ和Ｌｅｕ（１０－７～１０－２ｍｏｌ·Ｌ－１）均对凤眼莲的根际肠杆菌属Ｆ２（Ｅｎｔｅｒｏｂａｃｔｅｒｓｐ．Ｆ２）细菌有强烈的正趋化作用；Ｇｌｕ、Ｔｈｒ和Ｈｉｓ（１０－７～１０－３ｍｏｌ·Ｌ－１）也对该菌有一定的正趋化作用；而Ｌｙｓ、Ｃｙｓ、Ａｒｇ、Ｔｙｒ、Ｐｒｏ、Ａｓｎ、Ｇｌｎ、Ｉｌｅ、Ｐｈｅ和Ｔｙｐ则对该菌表现出一定的负趋化作用．对细菌的正趋化作用存在一个趋化物的最适浓度范围．具有正趋化作用的氨基酸在凤眼莲根际的浓度都较高，而具有负趋化作用的浓度则较低，这正是凤眼莲与该根际细菌结合为根际微生态系统的原因之一．

Many kinds of amino acids are found in root exudates from Eichhornia crassipes. F2 can be strongly attracted to amino acids methionine, gamma amino butyric acid, glycine, alanine, aspartate, serine, valine, and leucine under concentrations from 10-7 to 10-2 mol·L, some degrees to glutamate, threonine and histidine, but not to lysine, cysteine,arginine, tyrosine, proline, asparagine, glutamine, isoleucine, phenylalanine or tryptophan. There exists an optimium chemotaxic concentration range of each positive attractant. The fact that some amino acids caf f attract the bacteria,but others can not is one of the reasons why Eichhornia crassipes and F, can form a microecosystem.