Department of Biochemistry and Microbiology, Slovak University of Technology, Bratislava, Slovak Republic.
Antonie Van Leeuwenhoek. 2011 Jun;100(1):55-66. doi: 10.1007/s10482-011-9564-3. Epub 2011 Feb 20.
Submerged growth of Trichoderma atroviride CCM F 534 on glucose-containing medium was accompanied by the excretion of organic acids (succinate, citrate, alpha-ketoglutarate, fumarate, aconitate). The excretion of succinate was transient. After 48-72 h cultivation, millimolar amounts of succinate disappeared from the medium. We studied the mechanism of the removal of succinate from the medium and demonstrated the activation of the inward transport of succinate by submerged mycelia. This transport was carrier-mediated, had a low solute specificity, and was driven by proton-motive force. The last aspect was provided by the activation of the H(+)-ATPase, as documented by measurements of ATPase activity and expression of the pma gene. The disruption of the pma gene abolished the capacity of the mycelia to re-uptake succinate but not its production. Results show that excreted carboxylates could serve as alternative nutrients in the late phase(s) of submerged growth, explain why inward transport system(s) for carboxylates are induced, and indicate that the inward-directed transport could interfere with the production of carboxylic acids by fungi.
在含有葡萄糖的培养基中，深绿木霉 CCM F 534 的浸没式生长伴随着有机酸（琥珀酸、柠檬酸、α-酮戊二酸、富马酸、乌头酸）的排泄。琥珀酸的排泄是短暂的。在 48-72 小时的培养后，培养基中毫摩尔数量的琥珀酸消失了。我们研究了从培养基中去除琥珀酸的机制，并证明了浸没菌丝体对琥珀酸的内向运输的激活。这种运输是载体介导的，具有较低的溶质特异性，并且由质子动力势驱动。最后一个方面是通过测量 ATP 酶活性和 pma 基因的表达来证明 H(+)-ATP 酶的激活。pma 基因的破坏消除了菌丝体重新吸收琥珀酸的能力，但不影响其产生。结果表明，分泌的羧酸可以在浸没生长的后期作为替代营养物质，解释了为什么诱导了用于羧酸的内向运输系统，并表明内向定向运输可能会干扰真菌产生羧酸。
