Low‐Frequency Magnetic Field of Appropriate Strengths Changed Secondary Metabolite Production and Na⁺ Concentration of Intracellular and Extracellular Monascus purpureus

Abstract

Monascus purpureus is used to yield edible pigments accompanied by mycotoxin-citrinin. A low-frequency (<300 Hz) magnetic field (LF-MF) affects microbial metabolism. The link of LF-MF with secondary metabolites and intracellular and extracellular Na + levels in M. purpureus was determined. The fermentation broth was exposed to LF-MF during the first 2 days of fermentation and continuously cultured at 30°C and 200 rpm until the 8th day of fermentation. Results showed that LF-MF treatments didn't affect the growth of M. purpureus in liquid-state fermentation. Compared with the control, citrinin production showed a decrease of 45.0%, while yellow, red, and orange pigment production showed an increase of 72.9, 73.9, and 40.1%, respectively, with LF-MF treatment of 1.6 mT. This was in agreement with downregulation of pksCT and ctnA, and upregulation of pksPT, pigR, veA, and laeA at the transcriptional level. Moreover, 1.6 mT LF-MF exposure caused the transfer of Na + from extracellular to intracellular, which was validated through the upregulation of transmembrane sensor synthesis genes and the changes in the relative expression levels of the P-type ATPase and protein phosphatase genes. This study established that LF-MF could inhibit citrinin and stimulate pigment production and change intracellular and extracellular Na + concentrations. Bioelectromagnetics. 2020;41:289-297.

Role of histone H3K4 methyltransferase in regulating Monascus pigments production by red light‐coupled magnetic field

“…36 LF-MF promoted the biosynthesis of MPs. [40][41][42][43] This study also found that 250 lux red light treatment M. purpureus 24 h significantly promoted the production of water-and alcohol-soluble MPs in WT. The the yield of MPs had a significant increase in WT exposed to RLCMF.…”

“…For M. purpureus, it affected the growth and MPs production. [40][41][42][43] Light and MF, as natural environmental factors, affected the growth, development, and MPs biosynthesis of Monascus. Histone H3K4 methylation was often accompanied by the activation of gene transcription, which also affected the MPs biosynthesis of Monascus.…”

Genetic Regulation of Mycotoxin Biosynthesis

“…Understanding the regulation of gene expression in mycotoxin biosynthesis helps to explain and develop control approaches by linking the environmental factors inducing toxin synthesis. For example, a treatment by a low-frequency (<300 Hz) magnetic field inhibits CIT contamination by reducing the expression of the pathway-specific regulator gene ctnA in M. purpureus [ 139 ]. Another potential strategy is to identify molecules that could inhibit pathway-specific regulators.…”

Strategies on improvement of pigment formation and reduction of citrinin in Monascus fermentation

“…40 In line with the results, Xiong et al further confirmed that under 1.6 mT treatment, the yellow and red pigment yield of M. purpureus was promoted by over 70%, accompanied by decreased citrinin content. 41 Two possible underlying mechanisms were concluded as follows: one is that the low-frequency (<300 Hz) magnetic field (LF-MF) can up-regulate transcriptional levels of some key pigment production genes and significantly suppress the transcriptional levels of citrinin genes. The other is that the LF-MF can alter polyketide metabolic flux from citrinin to pigment synthesis.…”