Isolation and identification of Talaromyces purpurogenus and preliminary studies on its pigment production potentials in solid state cultures

摘要

Pigments from various sources such as annatto seeds, cochineal, beet root, and microalgae are widely used in food, pharmaceutical, cosmetics, textile and other industries. However, these sources of pigments have various limitations such as toxicity and environmental pollution of synthetic pigments, and low productivity of pigments from higher organisms due to long period of growth. The objective of this study was to screen for pigment producing fungi to overcome some of the above limitations. A pigment producing fungus was isolated from soil sample collected from cassava processing site and was identified as Talaromyces purpurogenus based on the colony morphology and characteristics, microscopic observation of the conidia and conidiophores and analysis of the gene sequence of internal transcribed spacer (ITS) region of the rDNA. The nucleotide sequence was deposited in Genbank (DDBJ/ EMBL) and was assigned the accession number LC128689. Pigment production by the isolate in solid state cultures using PDA as substrate in Petri dishes was investigated. The optima culture conditions were pour plating method with agar overlay (4 mm thick) and sealed edges, inoculum spore concentration of 2×108 spores/Petri dish and incubation in dark at 30°C. Under these culture conditions, the red, orange and yellow pigments produced were 11.2, 7.3 and 8.21 unit optical densities per gram of wet agar respectively after 96 h of cultivation. The isolate has good potential for production of different shades of pigments for various applications.