Diversity and Biotechnological Potential of Xylan-Degrading Microorganisms from Orange Juice Processing Waste

Abstract

The orange juice processing sector produces worldwide massive amounts of waste, which is characterized by high lignin, cellulose and hemicellulose content, and which exceeds 40% of the fruit’s dry weight (d.w.). In this work, the diversity and the biotechnological potential of xylan-degrading microbiota in orange juice processing waste were investigated through the implementation of an enrichment isolation strategy followed by enzyme assays for the determination of xylanolytic activities, and via next generation sequencing for microbial diversity identification. Intracellular rather than extracellular endo-1,4-β-xylanase activities were detected, indicating that peripheral cell-bound (surface) xylanases are involved in xylan hydrolysis by the examined microbial strains. Among the isolated microbial strains, bacterial isolates belonging to Pseudomonas psychrotolerans/P. oryzihabitans spectrum (99.9%/99.8% similarity, respectively) exhibited activities of 280 U/mg protein. In contrast, almost all microbial strains isolated exerted low extracellular 1,4-β-xylosidase activities (<5 U/mg protein), whereas no intracellular 1,4-β-xylosidase activities were detected for any of them. Illumina data showed the dominance of lactic and acetic acid bacteria and of the yeasts Hanseniaspora and Zygosaccharomyces. This is the first report on indigenous xylanolytic microbiota isolated from orange juice processing waste, possessing the biotechnological potential to serve as biocatalysts for citrus biomass valorization through the production of high-added value products and energy recovery.

Improved Sugar Recovery from Orange Peel by Statistical Optimization of Thermo-Alkaline Pretreatment

“…In particular, in an orange peel, cellulase hydrolyzes β-1,4glycosidic bonds into cellulose and cellobiase hydrolyzes cellobiose or oligosaccharides from the non-reducing ends to glucose [34]. Xylanase is used for hydrolysis of xylan, which is a xylose biopolymer [35]. Optimized reaction conditions and enzyme loading were needed to investigate efficient enzyme hydrolysis [36].…”

Xylanase-Producing Microbes and Their Real-World Application

“…Bifdobacteria, a healthy human gut bacteria growth promotion by the use of enzymes has been reported. Ferulic acid along with hydroxycinnamic acids, by-products of xylanolytic enzymes which are the hydrolytic products of xylan hydrolyzed by feruloyl esterase International Journal of Chemical Engineering [73] Bacteroidales bacterium KA00344 [74] International Journal of Chemical Engineering [102] have been reported to show antimicrobial, antiinfammatory, anti-diabetic, antithrombosis, anticancer, and cholesterol lowering agents [68].…”

Agro-Industrial Wastewater Treatment with Decentralized Biological Treatment Methods

“…Furthermore, dairy wastewater recorded the highest attached biomass productivity (5.03 g m −2 day −1 ). Zerva et al [12] isolated xylan-degrading microbiota from orange juice processing waste to access their biotechnological potential to serve as biocatalysts for citrus biomass valorization. The isolated microbial strains included isolates belonging to Pseudomonas psychrotolerans and P. oryzihabitans, while Illumina data showed the dominance of lactic and acetic acid bacteria and of the yeasts Hanseniaspora and Zygosaccharomyces.…”