Abstract
Considering the high biotechnological potential of yeasts associated to edible fruits, a screening for these microorganisms, capable of alcoholic fermentation, was performed in ripe fruits of camu-camu (Myrciaria dubia, Kunth). The fruits were collected from north of Brazilian Amazon, in the floodplain of the Cauamé River. Yeasts were isolated, and fermentation capability was evaluated using Durham tubes. Quantitative assays were performed to calculate ethanol yield (g g−1), specific growth rate (h−1), and ethanol productivity (g L−1·h−1). Taxonomic identification was performed by ribosomal gene nucleotide sequence analysis by alignment using BLASTN. A total of fifteen yeast colonies were isolated, and three of them presented promising ability to ferment glucose to ethanol. These isolates were identified as Candida orthopsilosis, Pichia kudriavzevii, and Meyerozyma caribbica. When cultured in broth containing 180 g·L−1 of glucose, M. caribbica CC003 reached 91.7 percent of the maximum theoretical ethanol concentration (84.4 g·L−1), presenting an ethanol yield and productivity of 0.4688 g·g−1 and 0.781 g·L−1·h−1, respectively. These results indicate a promising potential of this isolate for bioprocess applications. This paper is a rare report of C. orthopsilosis with endophytic habit because most of the references indicate it as a human pathogen. Besides this, M. caribbica is a promising fermenter for alcoholic beverages due to its osmotolerance and high ethanol yield. This is the first paper reporting endophytic yeasts associated with fruits of Myrciaria dubia.
Highlights
Yeasts are microorganisms from the fungi kingdom that present asexual reproduction by fission or budding and with sexual reproductive structure not presenting fruiting bodies [1]. ere are more than 2500 species described and recognized in the specialized literature [2], but despite this number, there are only about 80 species used in bioprocesses in the laboratory scale and a few more than twelve used in industrial processes [3].Amazon is the greatest tropical rainforest of the world, containing about 220 edible fruit species [4], including camucamu (Myrciaria dubia, Myrtaceae, Myrtales, Magnoliopsida, Magnoliophyta, Plantae)
Discussion e occurrence of P. kudriavzevii was reported to be associated with blossom and ripped fruits of apple, pear, and plum in southwest Slovakia [14]
Its association with natural fermentation of ripped pulp fruits was described when microorganisms associated with Ziziphus mauritiana were screened [15]
Summary
Yeasts are microorganisms from the fungi kingdom that present asexual reproduction by fission or budding and with sexual reproductive structure not presenting fruiting bodies [1]. ere are more than 2500 species described and recognized in the specialized literature [2], but despite this number, there are only about 80 species used in bioprocesses in the laboratory scale and a few more than twelve used in industrial processes [3].Amazon is the greatest tropical rainforest of the world, containing about 220 edible fruit species [4], including camucamu (Myrciaria dubia, Myrtaceae, Myrtales, Magnoliopsida, Magnoliophyta, Plantae). Fruits are potentially the natural habitat to a great variety of microorganisms because of their abundance of sugars and water, being favorable to proliferation of yeasts, mainly those capable of alcoholic fermentation. Despite all these potentials, research studies about yeast communities associated to Amazonian fruits are scarce, some of those dating more than two decades ago [5]. Myrciaria dubia has attracted a lot of attention because of its remarkable quantity of bioactive compounds [6] Because of their antioxidant activity, their fruits have been used for functional food production, including an artisanal beer with high ascorbic acid concentration [7]. There are no specific studies published about the microbiota associated with their leaves, roots, or fruits. e elucidation about yeasts associated to this plant may result in new strains with applicability to both biofuel and food industries
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