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06Paganoetal.MicrobialPigments

129

Tab. 6.1:

 Journal articles dealing with pigments and different organisms.



Key words

Number of journal articles

Pigments


136,705

Plant pigments

14,517

Bacterial pigments 



5,752

Microbial pigments

2,230

Fungal pigments 



1,551

Microbial natural pigments

261

Database survey conducted on April 2015 (SCOPUS).



Moreover, a variety of strains are well known. This will depend on market and consumer’s 

expectations, industrial prices and availability (Dufossé et al., 2014). Another expectative is 

to use cheaply available organic residues from industries as substrate (See Babitha, 2009).

6.3 Microbial pigments in natural sites

The high number of ecosystems and plant diversity described worldwide suggest that, most 

habitats are underexplored for microbial occurrence. Interest in natural sites to be prospected 

is increasing in parallel with the recognition that novel compounds from fungi to obtain 

several drugs will valuate the fungal bio-prospecting market. Moreover, researchers have 

stressed the urgent need to search for sites and substrates with high fungal richness towards 

protection of fungal resources for unique compound detection (Tang et al., 2007). Preserving 

ecosystem biodiversity will help to maintain its multifunctionality, which can be decisive to 

obtaining new compounds against microorganisms. For example, Dark septate endophytes 

(DSE) are frequently associated to roots of numerous endemic and endangered plants, still 

more in tropical regions where many fungi remain new to science (Hawksworth, 2001).

The kingdom Fungi (yeasts and filamentous fungi) are a promising source able to produce 

different both primary and secondary metabolites, which include peptides, enzymes, acids, 

antibiotics and pigments. Fungi called “black fungi” includes different species are able to 

produce a mixture of several different pigments to survive adverse conditions (carotenoids, 

lycopene and xanthophylls can predominate). For example, carotenoids protect the fungus 

from damaging sunlight and UV light; melanin and sporopollenin found in the spores and 

hyphal walls protect from radiation and drought (Reviewed by Pagano and Dhar, 2015).

Additionally, fungal pigments have been reported as bioactive compounds with antioxi-

dative, free radical scavenging, anticancer, immunomodulatory, antiviral and antibacterial 

activities, many of these pigments are quinones or similar conjugated structures (Velísek and 

Cejpek, 2011).

One of the most important pigments produced by fungi are the melanins (Fig. 6.1), which 

are high molecular weight pigments and displayed different biological functions (Hill, 1992). 




130

 6 Microbial Pigments



Several fungal species are able to produce melanin, which seems to confer advantage to 

survive in the environment by protecting against environmental predators, heavy metals 

toxicity, and physical insults such as UV and solar radiation (Nosanchuk and Casadevall, 

2003). Melanized fungi were found on the walls of damaged reactor in Chernobyl, which 

were consequently exposed to high levels of radiation (Mironenko et al., 2000). After that, 

further studies were made to investigate the radioprotective activity of microbial melanins 

(Dadachova et al., 2007).

Researchers have bio-explored for stressed and extreme habitats worldwide. Vaz et al. (2011) 

investigated yeasts diversity from different sites in Antarctica. They studied rhizospheric Des-

champsia Antarctica soil, ornithogenic (penguin guano) soil, water from lakes, seawater and 

sediments. Besides possible novel species identification, they found that ten yeast isolates 

produced mycosporines and that more than 40 % produced pigments and could be considered 

adapted to survive in the continent. The adaptation of yeasts to cold habitats reveals struc-

tural and biochemical characteristics, such as the production of photoprotective compounds 

(carotenoids and mycosporines), as possible strategy to survive in extreme environments 

(Libkind et al., 2009; Thomas-Hall et al., 2010). Mycosporines (watersoluble, UV-absorbing 

compounds) in yeasts from high-altitude lakes have been correlated with the survival of some 

species adapted to these environments (Libkind et al., 2005; Libkind et al., 2009).

In addition, Fernández et al. (2012) analyzed the yeast and yeast-like fungi present on 



Nothofagus nervosa (raulí) dry fruits. In this work, a total of 171 isolates corresponding to 

17 species were recovered, most of which belonged to the phylum Ascomycota (78 % of the 

isolates and 61 % of the species). All the ascomycetous species were dark pigmented melanin 

containing yeast-like fungi, while only one basidiomycetous species was pigmented (Rhodo-



torula colostri, a pink carotenogenic yeast). Besides, most of the species present on N. nervosa 

fruits (71 %) were capable of synthesizing mycosporines. It is important to mention that the 

three most abundant species (which accounted for 73 % of the isolates) corresponded to 

melanin and mycosporine producing yeast-like fungi (Ascomycetous yeast sp. 1, Aureobasi-



dium pullulans and Dothichiza sp. 1), being two of them novel species (Tab. 6.2). It has been 

described that mycosporines, as well as pigments such as melanin and carotenes, play an 

(a)

(b)


Fig. 6.1:

 Fungal colonies isolated from environmental samples showing 

different pigments (Photographs by L H Rosa).



 

6.3 Microbial pigments in natural sites 



131

antioxidant role in addition to UV protection (Pagano and Dhar, 2015; Moliné et al. 2011, 

Fernández et al. 2012). Altogether, these results highlight how important these components 

(carotenes, melanin, mycosporines) are for surviving in harsh environments, usually char-

acterized by reduced access to nutrients, high fluctuations in temperature and exposure 

to desiccation and/or high UV radiation. Considering the adaptation strategies (carotenes, 

melanin, mycosporines) of different microorganisms to this type of environments together 

with the high proportion of novel species present in them, they should be considered one of 

the main research targets for looking for species capable of synthetizing molecules of bio-

technological importance, appropriate for the bio-prospecting market.



Tab. 6.2:

 Fungal species isolated from Nothofagus nervosa dry fruits surface. % = percentage out of the total 

number of isolates, Pig = pigments, M = melanin, C = carotenes, Myc = mycosporines, +/– = presence/

absence.  




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