The relationship between the violet pigment PP-V production and intracellular ammonium level in Penicillium purpurogenum

Abstract

Penicillium purpurogenum is the fungus that produces an azaphilone pigment. However, details about the pigment biosynthesis pathway are unknown. The violet pigment PP-V is the one of the main pigments biosynthesized by this fungus. This pigment contains an amino group in a pyran ring as its core structure. We focused on this pigment and examined the relationship between intracellular ammonium concentration and pigment production using glutamine as a nitrogen source. The intracellular ammonium level decreased about 1.5-fold in conditions favoring PP-V production. Moreover, P. purpurogenum was transferred to medium in which it commonly produces the related pigment PP-O after cultivating it in the presence or absence of glutamine to investigate whether this fungus biosynthesizes PP-V using surplus ammonium in cells. Only mycelia cultured in medium containing 10 mM glutamine produced the violet pigment, and simultaneously intracellular ammonium levels decreased under this condition. From comparisons of the amount of PP-V that was secreted with quantity of surplus intracellular ammonium, it is suggested that P. purpurogenum maintains ammonium homeostasis by excreting waste ammonium as PP-V.

Fungal Pigments: Their Diversity, Chemistry, Food and Non-Food Applications

“…P. purpurogenum secretes an azaphilone-like, brick-red pigment. Additionally, violet and orange pigments were obtained by modifying conditions of culturing [74]. Pigment production using Penicillium as a source is more efficient and highly preferred because it secretes water-soluble and stable pigments extracellularly, so it can be easily purified [75].…”

Safety Evaluation of Fungal Pigments for Food Applications

“…It secretes a brick red pigment during growth, which generally diffuses into commonly used media. However, violet pigment (PP-V) and orange pigment (PP-O) were also reported by altering culture conditions [ 78 ]. The production of pigment from Penicillium is more efficient and profitable than any other microorganism.…”