1. INTRODUCTION
A colorant is any substance added to a product for the purpose of changing its color, enhancing the existing color or restoring lost color. Natural colors are pigments made by living organisms (plants, lichens, algae, insects, bacteria and fungi) [1–3]. There is low consumer interest for the use of the synthetic colorants due to the fact that they are toxic to human health (mutagenic and carcinogenic potential) [4,5]. The current legislation of the European Union, the United States, Brazil, Norway and Sweden also limits the use of synthetic colorants as food additives, and the process used to produce synthetic colorants is toxic to the environment [6,7].
However, natural colorants extracted from plants have a drawback, i.e., they depend on seasonal availability[8]. As a potential bioprocess for the new bioindustry of colorants, the production of colorants using microbial fermentation is rising, since it is possible to reduce production costs by choosing the best growing conditions; in addition, unlike plants microorganisms do not depend on climatic conditions [9–11]. As well as these advantages, many fungi-based colorants have important biological properties, such as antimicrobial, antioxidant, immunosuppressive, antiviral, anticancer and cholesterol-lowering properties, which make them important compounds for numerous industries. As a result, there is growing worldwide interest for the use of natural colorants[12–14] .
Studies have shown the potential of Amazonian fungi for colorant production. One study that can be highlighted isolated fungi-producing pigments [15] and obtained fractions with colors ranging from yellow to red. Penicillium sclerotiorum 2AV2 produced intensely colored pigments and the pigment was identified as sclerotiorin, which has specific biological activities such as the inhibition of aldose reductase enzymes, lipases, integrins and proteases of the human immunodeficiency virus HIV-1[16]. Teixeira et al. [17] evaluated the antibacterial activity and toxicity of organic extracts. The authors identified antimicrobial activity and lack of toxic action of the colorants produced by strains of the genus Aspergillus andPenicillium.
The Amazon Rainforest contains a rich diversity of microorganisms. Despite the richness of biological diversity in the Amazon, few works have been dedicated to researching fungal colorants. Therefore, the present study aimed to identify fungal isolates with the potential for production of colorants.