**5. Collection methodologies**

In October 2009, from 19th to 23rd, an expedition composed by 5 researchers from Ecuador, Brazil and Spain went to the Galapagos Islands in order to start a pioneer study mostly on yeasts biodiversity within the still natural environments of four inhabited islands. This chapter is the first report of such expedition that explored Santa Cruz, Isabela, Floreana and San Cristóbal Islands, where a number of substrates were sampled by using different culture media and techniques.

**Santa Cruz Island Isabela Island Floreana Island San Cristóbal Island Total Isolates 321** 269 177 114 **881**

An Overview of the Yeast Biodiversity in the Galápagos Islands and Other Ecuadorian Regions

http://dx.doi.org/10.5772/58303

201

**Table 1.** Number of yeast isolates collected in four islands of the Galápagos Archipelago during an expedition carried

The difference in the abundance of yeast isolates collected in each island is due to different conditions of time and logistics of the expedition and does not have any relationship with the

The present chapter reports the isolates and biodiversity recovered in a number of substrates including: flowers, rotten wood, excrement, insects, fruits, exudates, leafs, one sugar cane mill (Santa Cruz Island) and others. Figure 1 shows the shares of yeast isolates by substrate we

The Catholic University Yeasts Collection in Quito, in its database presents 118 yeast species belonging to the Ecuador mainland and the Galápagos Islands as shown in Table 4. By establishing a comparison between these two regions, there is not a big difference in number of species registered in the mainland and the islands (82 and 78 respectively). It is important to remark that the yeasts registers in this work were taken only from natural environments

In Mainland Ecuador, about 50% of the characterized isolates preserved in the CLQCA (c.a. 250 yeast isolates) belong to four species: *Candida tropicalis, Meyerozyma guilliermondii, Kodamaea ohmeri,* and *Pichia kudriavzevii.* In contrast, the more represented isolates from the Galápagos Islands in the CLQCA (c.a. 615 yeast isolates) correspond to the species: *Candida tropicalis, Hanseniaspora* sp*., Pichia norvegensis, Candida parazyma, Kodamaea transpacifica, Hanseniaspora*

*Candida tropicalis* in both cases is the most abundant yeast species registered in CLQCA: in mainland it is about 21% of the total identified isolates, while in the Galápagos Islands it represents about 18%. *C. tropicalis* is a cosmopolite yeast species that is ubiquitous in a wide range of substrates: from beetles to fermented beverages, but predominantly it is found in

Between the three regions of mainland there are also registers of 10 species that have been collected from different substrates. These species are quite adaptable to a wide range of climatic conditions and substrates. Table 2 shows the species that are ubiquitous in Amazonia, Andes

Matching the coincidences of yeast species between any individual mainland region with the Galápagos Islands yeast isolates it is noticeable an increase in the number of coincident yeast species if compared to the matching between the three regions within the mainland (Table 3).

have preserved in the Catholic University Yeasts Collection (CLQCA).

and substrates (no clinical or industrial samples are taken into account).

*uvarum, Barnettozyma californica, Candida intermedia,* and *Galactomyces geotrichum*.

**6.2. Yeast species in Ecuador Mainland and Galápagos Islands**

out in October 2009

abundance or diversity of yeasts in each island.

rotten vegetal matter, flowers and excrements.

and Pacific Coast.

Yeast sampling in substrates like flowers, fruits, excrement or fugus was carried out using sterile cotton wool swabs, to inoculate in liquid and solid YM media. In the case of sampling the insect's gut content a technique of catching the living insect in plastic bags for further inoculation by the living insect walking on the surface of Petri dishes containing YM agar medium. Eventually the insects were liberated alive. Additionally a number of substrates were collected in plastic sterile tubes for further culturing in selective culture broths such as YNB-CMC, YNB-D-xylose; YNB-xylan; YNB-L-arabinose, and YNB-raffinose the CLQCA labora‐ tory in Quito, Ecuador. The selective culture media were used especially in the search of yeast strains that exhibit some biotechnological potential use in xylose fermentation as well as cellulose degradation/fermentation.
