Department of Plant Pathology, University of California, Davis, California 95616.
Appl Environ Microbiol. 1990 Dec;56(12):3855-60. doi: 10.1128/aem.56.12.3855-3860.1990.
The chemotaxis towards sucrose and yeast extract of nine strains of Xanthomonas campestris representing pathovars campestris, armoraciae, translucens, vesicatoria, and pelargonii was analyzed by using swarm plates. Unexpectedly, each of these strains formed small or reduced swarms typical of nonmotile or nonchemotactic bacteria. With time, however, chemotactic cells appeared on the swarm plates as blebs of bacteria. These cells were strongly chemotactic and were concomitantly deficient in exopolysaccharide production. The switch from the wild type (exopolysaccharide producing and nonchemotactic) to the swarmer type (exopolysaccharide deficient and chemotactic) appeared irreversible ex planta in bacteriological medium. However, in radish leaves swarmer-type strains of X. campestris pv. campestris were able to revert to the wild type. Swarmer-type derivatives of two X. campestris pv. campestris wild-type isolates showed reduced virulence and growth in the host plants cauliflower and radish. However, exocellular complementation of X. campestris pv. campestris Hrp (nonpathogenic) mutant was achieved by coinoculation with a swarmer-type strain.
采用泳动平板法分析了 9 株代表野油菜黄单胞菌致病变种、鳞茎野油菜黄单胞菌、胡萝卜软腐欧文氏菌、透明质酸欧文氏菌和天竺葵欧文氏菌的蔗糖和酵母提取物趋化性。出乎意料的是，这些菌株中的每一株都形成了小的或减少的菌丛，这是无动力或非趋化性细菌的典型特征。然而，随着时间的推移，趋化性细胞会在泳动平板上作为细菌的气泡出现。这些细胞具有强烈的趋化性，同时缺乏胞外多糖的产生。在细菌培养基中，从野生型（产生胞外多糖和非趋化性）到泳动型（缺乏胞外多糖和趋化性）的转变似乎是不可逆转的。然而，在萝卜叶片中，野油菜黄单胞菌 pv. campestris 的泳动型菌株能够恢复为野生型。两种野油菜黄单胞菌 pv. campestris 野生型分离株的泳动型衍生物在宿主植物花椰菜和萝卜中的毒力和生长都有所降低。然而，通过与泳动型菌株共同接种，可以实现对野油菜黄单胞菌 Hrp（非致病性）突变体的胞外互补。
