Exploring yeast biodiversity in fruit waste for cellulose degradation and proteomic profiling

Aims:The aim of this study was to isolate and characterize pineapple waste cellulose-degrading yeasts and assess their enzymatic and proteomic potential for industrial biotechnology and biomass conversion processes.Methodology and results: Pineapple waste was gathered from a Davangere local market in Karnataka and inoculated on Yeast extract peptone dextrose (YEPD) agar with carboxymethyl cellulose (CMC) added for enhancing the growth of cellulolytic yeast.Six yeast isolates with cellulose-degrading activity were obtained from the culture.The isolates were selected for cellulase production by Congo red staining on CMC-supplemented agar for the visual detection of hydrolysis zones.A complete identification process was performed using biochemical and genetic approaches.The isolates were identified to be Galactomyces geotrichum, Geotrichum candidum, Aureobasidium pullulans, Pseudozyma aphidis, Candida tropicalis and Vanrija humicola by 18S rDNA sequencing.Enzyme assays revealed the presence of cellulolytic activity in the form of endoglucanases, exoglucanases, and β-glucosidases with optimal enzymatic activity at pH 5.0 and 30 °C.MALDI-TOF mass spectrometry also confirmed the proteomic findings by the detection of characteristic protein peaks related to cellulase activity. Conclusion, significance and impact of study:The current research confirms that pineapple waste-isolated yeast strains are highly cellulolytic and rich in cellulase-related proteins.The intersection of molecular and proteomic tools confirms their viability as sustainable bioresources.Most importantly, G. candidum and other similar strains are good candidates for use in bioethanol production and green biotechnological processes as a valorization strategy for agroindustrial waste.