Exploring the potential of Epicoccum nigrum for pigment production under variable conditions

Abstract

Purpose: The purpose of this study is to isolate yellow pigment producing fungal strain and to determine the media requirement for growth and secondary metabolite production. Design/methodology/approach: Fifteen soil samples were collected and studied for a pigment producing fungal sources. Selection of a fungus was based on pigment produced and further conditions, such as effect of media composition and light wavelength on pigment production and growth parameters were optimised. Findings: Out of the isolates analysed, Epicoccum nigrum was selected for further study as this strain has the potential for pigment production. Among all the media evaluated, potato dextrose agar (PDA) was found to be the best media for growth and sporulation, whilst sabouraud dextrose agar (SDA) was only 29 per cent as capable as the best medium. The radial growth rate in case of PDA was 3 ± 0.02 mm/day, while in case of SDA, it was only 1.09 mm/day. Whilst starch as a carbon source was found to increase the radial growth to 5.15 ± 0.02 mm/day, sucrose significantly (p < 0.05) influenced the sporulation (224,000 ± 1,550 spores/ml) of Epicoccum nigrum. Amongst the various nitrogen sources analysed, peptone significantly increased (p < 0.05) the radial growth (6.55 ± 0.02 mm/day) as well as sporulation (220,000 ± 2,100 spores/ml). The observations also indicated that E. nigrum is able to sense and differentiate between light in different wavelength ranges and respond differently in growth and sporulation. The light passing through a red colour sheet resulted in better radial growth (8.5 ± 0.02 mm/day) in comparison to unfiltered light (3 ± 0.02 mm/day). Yellow pigment production in terms of hue values was significantly influenced by the presence of dextrose, peptone and darkness. Research limitations/implications: The isolated strain could be studied for variable conditions and stress factors for optimal production of the pigment. Recovery and purification studies could be carried out at pilot and industrial scale. Practical implications: The isolation of a strain producing valuable microbial pigment will increase the alternatives of natural food colours and enhance the its commercial applications Originality/value: This study identifies Epicoccum nigrum as a potential source of microbial pigment and facilitates its growth and production for possible applications in industrial pigment production. © 2019, Emerald Publishing Limited.