In this study, the effects of temperature-shift (from 30 to 25 °C) and temperature-constant (at 30 °C) cultivation on the mass of Monascus fuliginosus CG-6 mycelia and concentration of the produced monacolin K (MK) were monitored. The expression levels of the MK biosynthetic genes of M. fuliginosus CG-6 at constant and variable culture temperatures were analysed by real-time quantitative polymerase chain reaction (RT-qPCR). The total protein was collected and determined by liquid chromatography-electrospray ionisation with tandem mass spectrometry (LC-ESI-MS/MS). Results showed that the maximum mycelial mass in temperature-shift cultivation was only 0.477 g of dry cell mass per dish, which was lower than that in temperature-constant cultivation (0.581 g of dry cell mass per dish); however, the maximum concentration of MK in temperature-shift cultivation (34.5 µg/mL) was 16 times higher than that in temperature-constant cultivation at 30 °C (2.11 µg/mL). Gene expression analysis showed that the expression of the MK biosynthetic gene cluster at culture temperature of 25 °C was higher than that at 30 °C, which was similar to the trend of the MK concentration, except for individual MK B and MK C genes. Analysis of differential protein expression revealed that 2016 proteins were detected by LC-ESI-MS/MS. The expression level of efflux pump protein coded by the MK I gene exhibited the same upregulated trend as the expression of MK I in temperature-shift cultivation. Temperature-shift cultivation enhanced the expression of proteins in the secondary metabolite production pathway, but suppressed the expression of proteins involved in the mycelial growth.

中文翻译：

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温移和恒温培养对红曲菌Monacolin K生物合成基因簇表达的影响

在这项研究中，温度变化（从30到25°C）和温度恒定（在30°C）培养对红曲霉CG-6菌丝体质量和产生的莫纳可林K（MK）浓度的影响为受监控。fuliginosus的MK生物合成基因的表达水平。通过实时定量聚合酶链反应（RT-qPCR）分析恒定和可变培养温度下的CG-6。收集总蛋白并通过液相色谱-串联质谱电喷雾电离（LC-ESI-MS / MS）测定。结果表明，温移培养的最大菌丝质量仅为每盘干细胞质量0.477 g，低于恒温培养的最大菌丝质量（每盘干细胞质量为0.581 g）。但是，温度漂移培养（34.5 µg / mL）中MK的最大浓度比30°C恒温培养（2.11 µg / mL）中的MK最高。基因表达分析表明，培养温度为25°C时，MK生物合成基因簇的表达高于30°C，MK B和MK C基因。差异蛋白质表达的分析显示，通过LC-ESI-MS / MS检测到了2016种蛋白质。MK I基因编码的外排泵蛋白的表达水平与温移培养中MK I的表达具有相同的上调趋势。温移培养增强了次级代谢产物产生途径中蛋白质的表达，但抑制了菌丝体生长中涉及的蛋白质的表达。