Xenorhabdus spp.菌株的菌落、菌体多样现象及抗菌特性

COLONIAL AND CELLULAR POLYMORPHISM AND ANTIMICROBIAL ACTIVITIES OF XENORHABDUS ISOLATES

本文报道了二十多株Steinernema和Heterorhabditis线虫共生细菌在指示培养基上的菌落形态、菌体形态的多样性及菌株的色素与抗菌特性。试验发现菌株出现树枝状菌落,折光性内含物及粒状菌体(比正常菌体小1/4至1/8)的现象,在各菌株中有很大的不同。所有试验菌株都可出现树枝状菌落,但非所有菌株都可见折光性内含物和粒状菌体。实验还观察到H06及CB2B菌株在肉汤培养基中所产生的色素颜色随pH值而变化,但G12及ED/1的色素对酸碱度的变化不敏感,表明菌株产生的色素物质是不同的。直接比较Xenorhaadus菌株之间的抗菌活动显示各菌株间具拮抗作用。菌株产生的抗菌物质是不同的,抗菌物的产生可能与菌株的培养条件有关。

Colonial and cellular polymorphism of more than twenty Xenorhabdus isolates associated with Steinernema and Heterorhabditis nematodes, as well as their pigment and antibiotics production were observed. There were great differences among bacterial isolates tested in the occurrence of swarming colonies, cellular inclusions and small particle cells (cellular variants of the isolates with cell size 1/4 to 1/8 smaller than their parental cells on 96-h-old culture plates). All tested isolates formed swarming colonies, but not every isolate included inclusions in their cells or developed small particle cells. In the culture media H06 (associated with Heterorhabditis bacterophora H06) and CB2B (associated with Steinernema sp. CB2B) produced pigments whose color change depended on pH value. However, G12 (with H. sp. G12) and ED/1 (with S. Sp. ED/1) produced non-pH-sensitive pigments, i. e. H06 was red and CB2B dark green (pH>8.0); when pH=5, H06 was yellow and CB2B red, which indicated that bacterial isolates may produce different pigments. Comparision of the antimicrobial activity of Xenorhabdus isolates against each other confirmed that some Xenorhabdus bacterial isolates could produce antimicrobial compounds against others and the production of compounds was related with the bacterial culture conditions.