Transformation of sugarcane molasses into fructooligosaccharides with enhanced prebiotic activity using whole-cell biocatalysts from Aureobasidium pullulans FRR 5284 and an invertase-deficient Saccharomyces cerevisiae 1403-7A

Most Sheauly Khatun,Morteza Hassanpour,Solange I Mussatto,Mark D Harrison,Robert E Speight,Ian M O’Hara,Zhanying Zhang

doi:10.1186/s40643-021-00438-7

Abstract

Fructooligosaccharides (FOS) can be used as feed prebiotics, but are limited by high production costs. In this study, low-cost sugarcane molasses was used to produce whole-cell biocatalysts containing transfructosylating enzymes by Aureobasidium pullulans FRR 5284, followed by FOS production from molasses using the whole-cells of A. pullulans. A. pullulans in molasses-based medium produced cells and broth with a total transfructosylating activity of 123.6 U/mL compared to 61.0 and 85.8 U/mL in synthetic molasses-based and sucrose-based media, respectively. It was found that inclusion of glucose in sucrose medium reduced both transfructosylating and hydrolytic activities of the produced cells and broth. With the use of pure glucose medium, cells and broth had very low levels of transfructosylating activities and hydrolytic activities were not detected. These results indicated that A. pullulans FRR 5284 produced both constitutive and inducible enzymes in sucrose-rich media, such as molasses while it only produced constitutive enzymes in the glucose media. Furthermore, treatment of FOS solutions generated from sucrose-rich solutions using an invertase-deficient Saccharomyces yeast converted glucose to ethanol and acetic acid and improved FOS content in total sugars by 20–30%. Treated FOS derived from molasses improved the in vitro growth of nine probiotic strains by 9–63% compared to a commercial FOS in 12 h incubation. This study demonstrated the potential of using molasses to produce FOS for feed application.

Highlights

Fructooligosaccharides (FOS) are used as prebiotics in food and feed (Bali et al 2015; Flores-Maltos et al 2016)
Transfructosylating enzymes can be constitutive enzymes which are always produced with the growth of the microorganisms, or inducive enzymes which are only expressed in the presence of inducers
A. pullulans DSM 2404 (ATCC 9348) produced five types of FFases, one of which was constitutively expressed, and its expression was not inhibited by glucose (Yoshikawa et al 2006; 2007)

Summary

Introduction

Fructooligosaccharides (FOS) are used as prebiotics in food and feed (Bali et al 2015; Flores-Maltos et al 2016). FTase mainly has Ut and its hydrolytic activity is very low because of its low affinity towards water as an acceptor (Antosova and Polakovic 2002). Filamentous fungi such as Aspergillus strains and yeast such as Aureobasidium strains are the most studied microorganisms to produce transfructosylating enzymes for FOS production (Bali et al 2015; Flores-Maltos et al 2016). A wide range of carbon sources, such as sucrose, glucose and glycerol have been used to produce transfructosylating enzymes by filamentous fungi and yeast (Bali et al 2015; FloresMaltos et al 2016). One Aspergillus strain cultivated on glucose-based medium led to the highest U t among several carbon sources including glucose, sucrose and raffinose (Nascimento et al 2019)

Methods

Results

Conclusion