Improved xylitol production by the novel inhibitor-tolerant yeast Candida tropicalis K2

ABSTRACT

Production of potential value-added products from different lignocellulosic biomass is becoming more common due to the availability of the feedstocks in abundance and the environment- friendly nature of the microbial production process. Due to the large array of its applications in the pharmaceutical and food sectors, xylitol is considered as potential value-added compound for production. In this study, organic waste samples were collected from various habitats and screened for potential yeast isolates for xylitol production. Among 124 tested isolates, Candida tropicalis K2 showed the highest potential for xylitol production as well as inhibitors tolerance (Furfural, 5-hydroxymethyl furfural and acetic acid) phenotypes. C. tropicalis K2 produced 90 g/L of xylitol in batch fermentation (100 g/L xylose supplemented with 20 g/L of glycerol as co-substrate) with the yield and productivity of 0.90 g/g and 1.5 g/L.h, respectively, at pH 5.5 and 30°C temperature. Together, >10% higher xylitol yield was achieved when glycerol was used as a co-substrate with pure xylose. Moreover, with non-detoxified corncob and Albizia pod hydrolysates, C. tropicalis K2 isolate produced 0.62 and 0.69 g/g of xylitol yields and 1.04 and 0.75 g/L.h xylitol productivities, respectively. Thus, C. tropicalis K2 isolate could be considered as promising candidate for xylitol production from different lignocellulosic biomass.

HIGHLIGHTS

• Candia tropicalis K2 isolate was screened from natural sites of biomass degradation and characterized for xylitol production.

• Non-detoxified Albizia pod and corncob hydrolysates were explored for xylitol production using selected C. tropicalis K2 isolate.

• A maximum of 0.90 g/g yield and 1.07 g/L.h xylitol productivity was achieved with pure xylose.

• A >10% increase in xylitol yield was achieved using glycerol as a co-substrate.

GRAPHICAL ABSTRACT

Keywords:

• Xylose
• hemicellulose
• fermentation
• Albizia
• inhibitors

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

Data not available due to [ethical/legal/commercial] restrictions.

Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data are not available.

Additional information

Funding

The authors acknowledge the International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi and Department of Biotechnology, Ministry of Science and Technology, India, (Grant No: BT/PB/Centre/03/ICGEB/2011 Phase II), Anup Kumar Singh acknowledges the University Grants Commission, india for providing fellowship (Grant No: 329064).