Abstract
The growing demand for protein-rich food forces humans to search for alternative protein sources. Yeasts are among the preferred candidates due to their well-balanced source of amino acids and vitamins. The present study aimed to identify an indigenous yeast strain that can be used as a protein source. Yeast strains were isolated from Palmyrah toddy sediments collected from different regions in the Jaffna Peninsula. One yeast strain, named A3, was selected as a potential strain based on the maximum cell size and optical density among the 55 yeast strains isolated. The biochemical analysis and sequencing of the ITS region (including 5.8S rRNA gene) and the LSU rRNA gene D1/D2 domains confirmed the yeast isolate as a strain of <em>Saccharomyces cerevisiae</em>. The optimum growth conditions for the yeast strain were determined using Taguchi L16 orthogonal array. Yeast cell autolysis was conducted with and without papain, and the yield of soluble matter and total protein were measured. The strain yielded a maximum of 70.7% soluble mater and 56.9% of total protein when autolysis with papain. The yield is significantly higher (p<0.05) than obtained with the baker's yeast used in the control experiment.
Highlights
The increasing population in developing countries is expected to create a high demand for protein-rich food by 2050 (Boland et al, 2013)
About 30 years ago, a study conducted based on yeast's biochemical and morphological characteristics revealed the association of Saccharomyces cerevisiae, Kloeckera apiculata, Schizosaccharomyces pombe and Saccharomyces chevalieri in the sediments of the toddy (Theivendirarajah and Chrystopher, 1987)
The suspension was transferred on yeast extract peptone dextrose agar (YEPDA) medium (1 L medium contain yeast extract 5.0 g, peptone 10.0 g, dextrose 20.0 g and agar 2.5 g) by spread plate method, and the plates were incubated at 28 oC for 3-5 days
Summary
The increasing population in developing countries is expected to create a high demand for protein-rich food by 2050 (Boland et al, 2013). The yield of extract in standard autolysis usually varies between 19 to 56% for different types of yeast (Sugimoto, 1974; Kollar et al, 1991; Vukasinovic Milic et al, 2007). Several studies have been conducted to optimise factors that influence protein extraction from different types of yeasts (Hongpattarakere and H-kittikun, 1995; Taran and Bakhtiyari, 2013; Lapeña et al, 2020). About 30 years ago, a study conducted based on yeast's biochemical and morphological characteristics revealed the association of Saccharomyces cerevisiae, Kloeckera apiculata, Schizosaccharomyces pombe and Saccharomyces chevalieri in the sediments of the toddy (Theivendirarajah and Chrystopher, 1987). The present study aimed to isolate and identify a potential yeast isolate from the toddy sediment and to increase protein yield from that isolate by optimising the growth and autolysis on a laboratory scale
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