Cyclopiazonic acid (CPA)-producing Penicillium griseofulvum is usually found on the dry-cured ham surface during its ripening. The objective of this work was to evaluate the effect of temperature and water activity (a_w) of dry-cured ham processing on growth, CPA production, and temporal relative expression of genes involved in CPA biosynthesis on dry-cured meat-based media. P. griseofulvum CECT 2919 grew faster than P. griseofulvum IBT 14319 in all conditions tested, although no growth occurred at 0.85 a_w. Besides, the dry-cured ham-based medium favoured CPA synthesis for both strains compared to the meat-based medium. For the strain CECT 2919, the expression of the mfs-1 and pks-nrps genes were stimulated at 0.90 and 0.95 a_w, respectively, while the dmaT gene expression was inhibited during the incubation time. By contrast, the strain IBT 14319 showed that the dmaT gene expression was stimulated at 0.90 a_w, while the pks-nrps and mfs-1 genes were repressed throughout incubation time. In conclusion, it is necessary to reduce a_w on the surface of the hams below 0.85 during ripening before to increase temperature to reduce growth of P. griseofulvum and CPA production. This information may be useful to design preventive and corrective actions to minimise risks associated with the presence of CPA in dry-cured ham.

中文翻译：

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在干腌火腿加工环境条件下，灰霉青霉中环吡唑酸的产生与基因表达之间的关系。

通常在干熟火腿表面熟化过程中，发现产生环己二酸（CPA）的灰霉青霉。这项工作的目的是评估干腌火腿加工的温度和水分活度（_aw）对干腌肉基培养基上CPA生物合成相关基因的生长，CPA产生以及基因的时间相对表达的影响。在所有测试条件下，灰霉菌CECT 2919的生长都比灰霉菌IBT 14319快，尽管在0.85 a _w时没有生长。此外，与基于肉的培养基相比，两种菌株的干腌火腿培养基均有利于CPA的合成。对于菌株CECT 2919，mfs-1和在孵化期间，分别以0.90和0.95 a _w刺激pks-nrps基因，而dmaT基因表达被抑制。相比之下，IBT 14319菌株显示dmaT基因表达在0.90 a _w时被刺激，而pks-nrps和mfs-1基因在整个孵育时间内均被抑制。总而言之，有必要在成熟过程中将火腿表面的_w降低至0.85以下，然后再升高温度以减少灰霉病菌的生长。和每次转化费用的生成。该信息可能有助于设计预防和纠正措施，以最大程度地减少与干腌火腿中CPA的存在有关的风险。