High lactic acid and fructose production via Mn2+-mediated conversion of inulin by Lactobacillus paracasei

Abstract

Lactobacillus paracasei DSM 23505 is able to produce high amounts of lactic acid (LA) by simultaneous saccharification and fermentation (SSF) of inulin. Aiming to obtain the highest possible amounts of LA and fructose, the present study is devoted to evaluate the impact of bivalent metal ions on the process of inulin conversion. It was shown that Mn strongly increases the activity of the purified key enzyme β-fructosidase. In vivo, batch fermentation kinetics revealed that the high Mn concentrations accelerated inulin hydrolysis by raise of the inulinase activity, and increased sugars conversion to LA through enhancement of the whole glycolytic flux. The highest LA concentration and yield were reached by addition of 15 mM Mn-151 g/L (corresponding to 40% increase) and 0.83 g/g, respectively. However, the relative quantification by real-time reverse transcription assay showed that the presence of Mn decreases the expression levels of fosE gene encoding β-fructosidase. Contrariwise, the full exclusion of metal ions resulted in fosE gene expression enhancement, blocked fructose transport, and hindered fructose conversion thus leading to huge fructose accumulation. During fed-batch with optimized medium and fermentation parameters, the fructose content reached 35.9% (w/v), achieving yield of 467 g fructose from 675 g inulin containing chicory flour powder (0.69 g/g). LA received in course of the batch fermentation and fructose gained by the fed-batch are the highest amounts ever obtained from inulin, thus disclosing the key role of Mn as a powerful tool to guide inulin conversion to targeted bio-chemicals.

Metagenomic reconstructions of gut microbial metabolism in weanling pigs

“…In contrast to the complex and partially redundant starch-degrading enzymes in Bacteriodetes , fructans degraders carried fewer fructanases. Fructan utilization is not conserved within members of a specific species [ 41 , 42 , 70 ]. Three GH32 enzymes, including BT1760 (extracellular), BT3082 (periplasmic), and BT1765 (intracellular), as well as hybrid two-component (HTC) signaling system, BT1754 are required for fructan utilization in B .…”

“…GH68 family enzymes in lactobacilli are extracellular levansucrases which are necessary for biofilm formation on non-secretary epithelia of the upper GI tract; these enzymes synthesize levan but do not contribute to fructan hydrolysis [ 71 ]. Intracellular GH32 β-fructofuranosidases of lactobacilli (ScrB) utilize only di- and trisaccharides that are transported across the membrane [ 36 , 70 , 72 ]. The metagenomic analysis is the first to report the presence of extracellular fructanases (FruA) in intestinal lactobacilli.…”

Effects of inulin on the growth performance and tolerance in adverse environments of several probiotics

“…Lactobacillus paracasei can produce large amounts of lactic acid through simultaneous sacchari cation and fermentation of inulin. Studies have shown that high concentrations of Mn 2+ accelerate the hydrolysis of inulin by increasing the activity of β-fructosidase, and increasing the conversion of sugar to lactic acid by increasing the overall glycolytic ux (Petrov et al 2017).…”

Butanol Tolerance of Lactiplantibacillus plantarum: A Transcriptome Study

“…We also observed a striking effect regarding the LacI family. Two members were 4.76-and 3.73-fold downregulated in 8-1, the central catabolite regulator CcpA in several genera of LAB [64,65] and a repressor of the maltose operon, respectively. Another member from the same family, the evolved β-galactosidase operon repressor EbgR, was 2.51-fold upregulated in Ym1.…”