Lignocellulolytic Potential of the Recently Described Species Aspergillus olivimuriae on Different Solid Wastes

Abstract

The genus Aspergillus encompasses several species with relevant lignocellulose-degrading capacity, and a novel species, denominated A. olivimuriae, was recently discovered after its isolation from table olive brine. The acquisition of insight into this species and the assessment of its potential relied on a bioinformatics approach, based on the CAZy database, associated with enzymatic activity profiles in solid-state cultures on four different types of waste, including residual thistle biomass (RTB), spent coffee grounds (SCG), digestate solid fraction and barley straw. The CAZy analysis of A. olivimuriae genome showed that the number of predicted genes for each family was close to that of other Aspergillus species, except for cellobiose dehydrogenase, acetyl xylan esterase and polygalacturonases. In A. olivimuriae solid-state cultures, hemicellulose degradation outperformed that of cellulose, and lignin removal did not occur, regardless of the growth substrate. This is in line with its CAZy content and the extent of hemicellulolytic, and ligninolytic activities detected in its solid-state cultures. RTB and barley straw were the substrates enabling the best glycosyl hydrolase production levels. The exception was SCG, the hemicellulose composition of which, mainly made of glucomannans and galactomanans, led to the highest β-mannanase and β-mannosidase production levels (3.72 ± 0.20 and 0.90 ± 0.04 IU g−1 substrate, respectively).