Sunish Kumar R, Sakthivel N
Department of Biotechnology, Pondicherry University, Kalapet, India.
Appl Microbiol Biotechnol. 2001 Jun;55(6):782-6. doi: 10.1007/s002530000563.
In order to understand the mode of action of the taxonomically related pathogens Xanthomonas campestris pv. translucens, Xanthomonas oryzae pv. oryzae, and Xanthomonas oryzae pv. oryzicola, which attack wheat and rice crops, we examined the compositional differences of their exopolysaccharides (EPSs). Maximum production of polysaccharide in shake cultures of these pathogens was observed between 24 and 72 h. X. campestris pv. translucens, the leaf streak pathogen of wheat, produced a higher amount of polysaccharide (46.97 microg/ml) at 72 h compared to X. oryzae pv. oryzae (42.02 microg/ml), the bacterial blight pathogen of rice, and X. oryzae pv. oryzicola (41.91 microg/ml), the bacterial leaf streak pathogen of rice. Infrared (FTIR) spectra suggested that the polysaccharides of all three Xanthomonas pathovar strains have an -OH group with intermolecular hydrogen bonding, a C-H group of methyl alkanes, an aldehyde (RCHO) group, a C=C or C=O group, and a C-O group. FTIR spectra also revealed the presence of an acid anhydride group in X. oryzae pv. oryzae, a secondary aromatic or aliphatic amine group in X. campestris pv. translucens, and a primary aromatic or aliphatic amine group in X. oryzae pv. oryzae and X. oryzae pv. oryzicola. Nuclear magnetic resonance (NMR) spectra revealed the presence of unsubstituted sugars, an acetyl amine of hexose or pentose, and a beta-anomeric carbon of hexose or pentose in the polysaccharides of all bacteria. NMR spectra also identified the alpha-anomeric carbon of hexose or pentose in all strains, and a branching at the fourth carbon of the sugar only in X. campestris pv. translucens; the presence of an uronic acid molecule (acid anhydride group) in X. oryzae pv. oryzae; and a deoxy sugar, rhamnose, in X. oryzae pv. oryzicola.
为了解分类学上相关的病原体野油菜黄单胞菌小麦致病变种、稻黄单胞菌稻致病变种和稻黄单胞菌稻生致病变种（它们侵袭小麦和水稻作物）的作用模式，我们检测了它们胞外多糖（EPS）的成分差异。在这些病原体的摇瓶培养中，多糖产量在24至72小时之间达到最高。小麦条斑病病原体野油菜黄单胞菌小麦致病变种在72小时时产生的多糖量（46.97微克/毫升）高于水稻白叶枯病病原体稻黄单胞菌稻致病变种（42.02微克/毫升）和水稻细菌性条斑病病原体稻黄单胞菌稻生致病变种（41.91微克/毫升）。红外（FTIR）光谱表明，所有三种黄单胞菌致病型菌株的多糖都含有通过分子间氢键相连的-OH基团、甲基烷烃的C-H基团、醛（RCHO）基团、C=C或C=O基团以及C-O基团。FTIR光谱还显示，稻黄单胞菌稻致病变种中存在酸酐基团，野油菜黄单胞菌小麦致病变种中存在仲芳香族或脂肪族胺基团，稻黄单胞菌稻致病变种和稻黄单胞菌稻生致病变种中存在伯芳香族或脂肪族胺基团。核磁共振（NMR）光谱表明，所有细菌的多糖中都存在未取代的糖、己糖或戊糖的乙酰胺以及己糖或戊糖的β-异头碳。NMR光谱还鉴定出所有菌株中己糖或戊糖的α-异头碳，并且仅在野油菜黄单胞菌小麦致病变种中糖的第四个碳处存在分支；稻黄单胞菌稻致病变种中存在糖醛酸分子（酸酐基团）；稻黄单胞菌稻生致病变种中存在脱氧糖鼠李糖。
