Optimal C:N ratio for the production of red pigments by Monascus ruber

Abstract

The carbon-to-nitrogen (C:N) ratio in the biomass of microfungi tends to be quite different (e.g. 10-15) compared with the C:N ratio in the red pigments (e.g. >20) of the fungus Monascus ruber. Therefore, determining an optimal C:N ratio in the culture medium for maximizing the production of the pigments is important. A culture medium composition is established for maximizing the production of the red pigment by the fungus M. ruber ICMP 15220 in submerged culture. The highest volumetric productivity of the red pigment was 0.023 AU L(-1) h(-1) in a batch culture (30 °C, initial pH of 6.5) with a defined medium of the following composition (g L(-1)): glucose (10), monosodium glutamate (MSG) (10), MgSO4·7H2O (0.5), KH2PO4 (5), K2HPO4 (5), ZnSO4·7H2O (0.01), FeSO4·7H2O (0.01), CaCl2 (0.1), MnSO4·H2O (0.03). This medium formulation had a C:N mole ratio of 9:1. Under these conditions, the specific growth rate of the fungus was 0.043 h(-1) and the peak biomass concentration was 6.7 g L(-1) in a 7-day culture. The biomass specific productivity of the red pigment was 1.06 AU g(-1) h(-1). The best nitrogen source proved to be MSG although four other inorganic nitrogen sources were evaluated.

Fungal Communities Along a Small-Scale Elevational Gradient in an Alpine Tundra Are Determined by Soil Carbon Nitrogen Ratios

“…Soil C/N ratio is generally thought as a proxy for nutrient availability ( Cleveland and Liptzin, 2007 ) and as such, the change in ambient C/N ratio can substantially influence the fungal anabolism and foraging strategies ( Prevost-Boure et al, 2011 ; Drake et al, 2013 ; Grosso et al, 2016 ). In terms of stoichiometry, the C/N ratio of a typical fungal biomass in soils was at 10–15 ( Said et al, 2014 ), while the highest soil C/N ratio reached 18.44 in this study. High C/N ratio may broke the stoichiometric balance between soil and mycelia, restraining the activity of exoenzymes and accumulation of fungal biomass ( Sinsabaugh et al, 2013 ).…”

Production of Bio-Based Pigments from Food Processing Industry By-Products (Apple, Pomegranate, Black Carrot, Red Beet Pulps) Using Aspergillus carbonarius

“…Nevertheless, the highest initial C:N ratio was red beet (20.63/1), pomegranate (16.87/1) and apple (11.53/1), respectively. This could be attributed to the decreasing pH levels during the fermentation of red beet pulps [45]. In this study, a more complex substrate such as a real industrial pulp was used for pigment production.…”

Pigment Production by the Edible Filamentous Fungus Neurospora Intermedia

“…The addition of nitrate [34] or ammonium [35] has previously been reported to promote pigment production in Monascus species. The pH was not controlled in these studies, suggesting that the nitrogen source may have an indirect effect on pigment production by changing the pH of the medium.…”