Sucrose-Induced Proteomic Response and Carbohydrate Utilization of Lactobacillus sakei TMW 1.411 During Dextran Formation

Abstract

Lactobacillus (L.) sakei belongs to the dominating lactic acid bacteria in indigenous meat fermentations, while diverse strains of this species have also been isolated from plant fermentations. We could recently show, that L. sakei TMW 1.411 produces a high molecular weight dextran from sucrose, indicating its potential use as a dextran forming starter culture. However, the general physiological response of L. sakei to sucrose as carbohydrate source has not been investigated yet, especially upon simultaneous dextran formation. To address this lack of knowledge, we sequenced the genome of L. sakei TMW 1.411 and performed a label-free, quantitative proteomics approach to investigate the sucrose-induced changes in the proteomic profile of this strain in comparison to its proteomic response to glucose. In total, 21 proteins were found to be differentially expressed at the applied significance criteria (FDR ≤ 0.01). Among these, 14 were associated with the carbohydrate metabolism including several enzymes, which enable sucrose and fructose uptake, as well as, their subsequent intracellular metabolization, respectively. The plasmid-encoded, extracellular dextransucrase of L. sakei TMW 1.411 was expressed at high levels irrespective of the present carbohydrate and was predominantly responsible for sucrose consumption in growth experiments using sucrose as sole carbohydrate source, while the released fructose from the dextransucrase reaction was more preferably taken up and intracellularly metabolized than sucrose. Genomic comparisons revealed, that operons coding for uptake and intracellular metabolism of sucrose and fructose are chromosomally conserved among L. sakei, while plasmid-located dextransucrase genes are present only in few strains. In accordance with these findings, all 59 different L. sakei strains of our strain collection were able to grow on sucrose as sole carbohydrate source, while eight of them exhibited a mucous phenotype on agar plates indicating dextran formation from sucrose. Our study therefore highlights the intrinsic adaption of L. sakei to plant environments, where sucrose is abundant, and provides fundamental knowledge regarding the use of L. sakei as starter culture for sucrose-based food fermentation processes with in-situ dextran formation.

A systematic approach to study the pH-dependent release, productivity and product specificity of dextransucrases

“…Diverse studies reported about the sucrose-inducible or pH-dependent release of dextransucrases in LAB [22,[33][34][35][36]. We recently observed that the dextransucrase of L. hordei is released into buffer supernatants efficiently in the presence of sucrose [24].…”

Acetic acid bacteria encode two levansucrase types of different ecological relationship

“…By contrast, Gluconobacter spp. preferably oxidize glucose to gluconic acid(s) and usually occur in sugary environments (Prust et al, 2005). Most species of Gluconacetobacter are N 2 -fixing, endophytic symbionts of plants like sugar cane and coffee (Cavalcante and Dobereiner, 1988;Pedraza, 2008), while Asaia spp.…”

“…While the conversion of monosaccharides by AAB is well understood (Deppenmeier and Ehrenreich, ), the consumption of sucrose being the most abundant carbohydrate in photosynthetic plants (Avigad, ) has not been systematically described in AAB. In general, sucrose can be utilized by bacteria either in phosphorylated form by sucrose‐6‐phosphate hydrolases or non‐phosphorylated form by β‐fructosidases (invertases) or exo‐fructanases (Reid and Abratt, ; Prechtl et al ., ), all of them belonging to the glycoside hydrolase (GH) 32 family defined in the CAZy database (http://www.cazy.org/). Sucrose is also the natural substrate of secreted fructansucrases (GH68) and glucansucrases (GH70), responsible for the synthesis of fructan‐ and glucan‐type homopolymers respectively (van Hijum et al ., ).…”

Comparative Genomics Analysis of Lactobacillus mucosae from Different Niches

“…In addition, the gene clusters associated with lactose [43], trehalose [47], D-fructose [48], and L-arabinose [49,50], emphasizing the importance of glycosyl hydrolase (lacZ and treC), isomerase (araA and araD), and kinases (fruK) in the corresponding operons. It was worth noting that fruK-encoded fructokinase was also important in the degradation of sucrose [51]. In addition, the strain FGSYC17L3, although containing the key gene, treC, was unable to utilize trehalose.…”