The State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.
J Appl Microbiol. 2010 Jan;108(1):173-80. doi: 10.1111/j.1365-2672.2009.04415.x.
To find possible approaches to utilize the mechanism of oxalate degradation by Coniothyrium minitans (Cm) in controlling the plant pathogen Sclerotinia sclerotiorum (Ss).
Differences in oxalate degradation by different Cm strains and effects of the initial oxalate concentration, ambient pH and nutrient factors on mycelial growth and oxalate degradation by Cm were studied in shaken cultures. Results showed that two wild-type Cm strains, Chy-1 and ZS-1, did not differ in oxalate degradation in modified potato dextrose broth (mPDB) amended with oxalic acid (OA). Cm could grow in mPDB amended with sodium oxalate (SO-mPDB) at pH 6.5 or with ammonium oxalate (AO-PDB) at pH 6.2, but oxalate degradation was very low; oxalate degradation was greatly enhanced in SO- or AO-mPDB with pH being lowered to 2.8-2.9. Similarly, oxalate degradation was higher than 90% in OA-amended mPDB at pH 4.4 but was reduced to be <22% at pH 7.0. Five carbon sources and three nitrogen sources investigated and nutrients from mycelia and sclerotia of Ss were favorable for the growth of Cm and OA degradation by Cm.
Cm can degrade oxalate under acidic pH. Exudates from mycelia or sclerotia of Ss may serve as nutrients for Cm mycelial growth and degradation of oxalate secreted by Ss.
The finding of oxalate degradation laid a foundation for mining-related genes in Cm for engineering plant resistance against Ss. Elucidation of the importance of acidic pH and nutrients from Ss in oxalate degradation by Cm will help to understand the interaction between Cm and Ss.
寻找利用康氏木霉（Coniothyrium minitans，Cm）降解草酸的机制来控制植物病原菌核盘菌（Sclerotinia sclerotiorum，Ss）的可能途径。
在摇瓶培养中，研究了不同 Cm 菌株的草酸降解差异，以及初始草酸浓度、环境 pH 和营养因素对 Cm 菌丝生长和草酸降解的影响。结果表明，在改良马铃薯葡萄糖肉汤（modified potato dextrose broth，mPDB）中添加草酸（oxalic acid，OA）时，两种野生型 Cm 菌株 Chy-1 和 ZS-1 的草酸降解能力没有差异。Cm 可以在 pH 6.5 的添加草酸钠（sodium oxalate，SO）的 mPDB 或 pH 6.2 的添加草酸铵（ammonium oxalate，AO）的 mPDB 中生长，但草酸降解非常低；当 pH 降低至 2.8-2.9 时，SO 或 AO-mPDB 中的草酸降解大大增强。同样，在 pH 4.4 的添加 OA 的 mPDB 中，草酸降解率高于 90%，但在 pH 7.0 时降至<22%。研究了 5 种碳源和 3 种氮源，以及 Ss 菌丝和菌核中的营养物质，有利于 Cm 的生长和 Cm 对 OA 的降解。
Cm 可以在酸性 pH 下降解草酸。Ss 的菌丝或菌核分泌的分泌物可能作为 Cm 菌丝生长和 Ss 分泌的草酸降解的营养物质。
草酸降解的发现为 Cm 中与工程植物抗 Ss 相关的基因挖掘奠定了基础。阐明 Cm 降解草酸过程中酸性 pH 和 Ss 来源营养物质的重要性，将有助于理解 Cm 与 Ss 之间的相互作用。
