Production of xylitol and bio-detoxification of cocoa pod husk hemicellulose hydrolysate by Candida boidinii XM02G.

Nivio Batista Santana,Rachel Passos Rezende,Lucas Oliveira Souza,Marcelo Franco,Larissa Karen Silva Oliveira,João Carlos Teixeira Dias,Pankaj Kumar Arora

doi:10.1371/journal.pone.0195206

Nivio Batista Santana, Rachel Passos Rezende + Show 5 more

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https://doi.org/10.1371/journal.pone.0195206

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Abstract

The use of cocoa pod husk hemicellulose hydrolysate (CPHHH) was evaluated for the production of xylitol by Candida boidinii XM02G yeast isolated from soil of cocoa-growing areas and decaying bark, as an alternative means of reusing this type of waste. Xylitol was obtained in concentrations of 11.34 g.L-1, corresponding to a yield (Yp/s) of 0.52 g.g-1 with a fermentation efficiency (ε) of 56.6%. The yeast was tolerant to inhibitor compounds present in CPHHH without detoxification in different concentration factors, and was able to tolerate phenolic compounds at approximately 6 g.L-1. The yeast was also able to metabolize more than 99% (p/v) of furfural and hydroxymethylfurfural present in the non-detoxified CPHHH without extension of the cell-growth lag phase, showing the potential of this microorganism for the production of xylitol. The fermentation of cocoa pod husk hydrolysates appears to provide an alternative use which may reduce the impact generated by incorrect disposal of this waste.

Highlights

Xylitol is used as a sweetener in the food, pharmaceutical and personal care industries, and its commercial production is currently limited to chemical synthesis by catalytic hydrogenation of xylose extracted from vegetable fibers [1,2]
Considering the above, the present study investigates the use of cocoa pod husks as a source of xylose for the production of xylitol using the Candida boidinii XM02G yeast, which has a high tolerance to inhibitor compounds, isolated from soils in the cocoa cultivation area and from the decaying husks
The content of sugars and xylitol were determined by high performance liquid chromatography (HPLC), using a Shimadzu system equipped with refractive index detector, Shimpack CLC-NH2 column and acetonitrile/water (80/20) as the mobile phase at 1.0 mL.min-1(30 ̊C)

Summary

Introduction

Xylitol is used as a sweetener in the food, pharmaceutical and personal care industries, and its commercial production is currently limited to chemical synthesis by catalytic hydrogenation of xylose extracted from vegetable fibers [1,2]. Its organic synthesis by microorganisms has been studied with the aim of reducing the disadvantages presented by chemically reducing the xylose purification steps and removing waste from the catalyst. Various types of agro-industrial waste have been studied as a potential source of substrate for fermentation and generation of this compound [3,4,5,6]. The biotransformation of xylose into xylitol using yeast requires the production of hydrolysates from the residues, which are rich in sugars, and it is required to reduce their.

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