Metabolic activity in dormant conidia of Aspergillus niger and developmental changes during conidial outgrowth.
Metabolic activity in dormant conidia of Aspergillus niger and developmental changes during conidial outgrowth.
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DOI：
10.1016/j.fgb.2016.07.002
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发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
Archer DB
中科院分区：
文献类型：
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作者：
Novodvorska M;Stratford M;Blythe MJ;Wilson R;Beniston RG;Archer DB
休眠分生孢子被证明是代谢活性的。在引发分生孢子生长后，发生发酵，接着是呼吸作用。山梨酸抑制O2摄取并延迟呼吸的开始。通过全基因组基因表达分析（RNAseq）、蛋白质组学、瓦尔堡测压和摄取研究相结合，探索了尼日尔曲霉分生孢子在生长过程中的早期发育阶段。静止的分生孢子悬浮在水中首次被证明是代谢活性的低水平的氧吸收和二氧化碳的产生被检测到，这表明低水平的呼吸代谢发生在分生孢子的维护。孢子萌发后，CO2的产生急剧增加。在短时间内，这与细胞内多元醇海藻糖的动员相一致，O2的摄取没有增加，表明海藻糖通过发酵代谢。从全基因组的mRNA分析数据显示，在休眠分生孢子的发酵和呼吸代谢相关的转录本的存在。触发分生孢子生长后，有一个明确的开关呼吸后25分钟，证实了氰化物抑制。SHAM（水杨基异羟肟酸）对呼吸无影响，表明电子流通过细胞色素c氧化酶。葡萄糖进入孢子是不可检测的1小时前触发萌发后。山梨酸对发芽的影响进行了检查，我们发现，它抑制葡萄糖的吸收。O2的吸收也受到抑制，延迟呼吸的开始，延长发酵期。总之，我们表明，分生孢子悬浮在水中并不完全休眠，分生孢子的生长涉及呼吸前的发酵代谢。
Resting conidia are demonstrated to be metabolically active. After triggering of conidial outgrowth fermentation occurs, followed by respiration. Sorbic acid inhibits O2 uptake and delays the onset of respiration. The early stages of development of Aspergillus niger conidia during outgrowth were explored by combining genome-wide gene expression analysis (RNAseq), proteomics, Warburg manometry and uptake studies. Resting conidia suspended in water were demonstrated for the first time to be metabolically active as low levels of oxygen uptake and the generation of carbon dioxide were detected, suggesting that low-level respiratory metabolism occurs in conidia for maintenance. Upon triggering of spore germination, generation of CO2 increased dramatically. For a short period, which coincided with mobilisation of the intracellular polyol, trehalose, there was no increase in uptake of O2 indicating that trehalose was metabolised by fermentation. Data from genome-wide mRNA profiling showed the presence of transcripts associated with fermentative and respiratory metabolism in resting conidia. Following triggering of conidial outgrowth, there was a clear switch to respiration after 25 min, confirmed by cyanide inhibition. No effect of SHAM, salicylhydroxamic acid, on respiration suggests electron flow via cytochrome c oxidase. Glucose entry into spores was not detectable before 1 h after triggering germination. The impact of sorbic acid on germination was examined and we showed that it inhibits glucose uptake. O2 uptake was also inhibited, delaying the onset of respiration and extending the period of fermentation. In conclusion, we show that conidia suspended in water are not completely dormant and that conidial outgrowth involves fermentative metabolism that precedes respiration.