Indigenous yeast with cellulose-degrading activity in napa cabbage (Brassica pekinensis L.) waste: Characterisation and species identification

Napa cabbage waste contains an organic component, cellulose, which can be utilised as an ingredient for cellulose-degrading enzyme production with the help of indigenous yeast. The aim of the research was to identify and characterise potential indigenous yeast isolated from napa cabbage waste, which has cellulose-degrading activity. Indigenous yeast were isolated and characterised using the RapID Yeast Plus System, then turbidity was used to determine the yeast total population. Indigenous yeast was grown at napa cabbage waste at 27, 37, and 40°C for three days, and cellulose-degrading activity was determined by the Dinitrosalicylic Acid (DNS) method. The potential yeast isolate with the highest cellulose-degrading activity was identified by a sequence analysis of the rRNA gene internal transcribed spacer (ITS) region with using primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′- TCCTCCGCTTATTGATATGC-3′). The results were compared to the GenBank database using the Basic Local Alignment Search Tools/BLAST algorithm. Three species of indigenous yeast were isolated from napa cabbage waste (S2, S6, and S8). S8, incubated at 37ºC for three days, demonstrated the highest cellulose-degrading enzyme activity (1.188 U/mL), with the average activity of 0.684U/mL. Species identification results indicated that the S8 isolate had a 100% similarity to Pichia fermentans UniFGPF2 (KT029805.1).