# Effects of VeA Gene on the Growth, Pigment and Citrinin Synthesis of Monascus ruber M7

## TL;DR

This study shows that deleting the VeA gene in Monascus ruber M7 affects its growth, pigment production, and citrinin synthesis, which is important for food safety and industrial use.

## Contribution

The study reveals the role of the VeA gene in regulating growth, pigmentation, and citrinin production in Monascus ruber M7.

## Key findings

- Deleting the VeA gene increased growth rate and mycelium density but reduced pigment and citrinin production.
- Transcriptomic analysis showed DEGs enriched in amino sugar metabolism, MAPK signaling, and carbohydrate metabolism.
- VeA negatively regulates growth and positively regulates reproduction, pigments, and citrinin in M. ruber M7.

## Abstract

Monascus spp. is widely used in food fermentation and additive production, and some of its strains produce citrinin (CIT), which is nephrotoxic. In this study, we constructed a mutant strain of Monascus ruber M7 (M. ruber M7) with a VeA gene deletion (ΔVeA) using the Agrobacterium-mediated transformation technique to investigate the VeA gene in growth and development, pigmentation, and CIT synthesis in M. ruber M7. Compared to the wild-type strain (WT), the ΔVeA strain grew faster, the mycelium was dense, the length was longer, the colony color was lighter, the cleistothecium and conidia were reduced, the ability to produce Monascus pigments (MPs) decreased, and CIT was not produced. Transcriptomic results showed that differentially expressed genes (DEGs) were mainly enriched in amino sugar metabolism, the MAPK signaling pathway and carbohydrate metabolism. These results suggest that the VeA gene negatively regulates the growth and development of M. ruber M7 and positively regulates its sexual/asexual reproduction, MPs, and CIT production. The results of this study can provide a reference for industrial applications of Monascus with low or even no CIT production.