Characterization of the LP28 strain-specific exopolysaccharide biosynthetic gene cluster found in the whole circular genome of Pediococcus pentosaceus

Abstract

We have previously isolated a lactic acid bacterium (LAB), Pediococcus pentosaceus LP28, from the longan fruit Euphoria longana. Since the plant-derived LAB strain produces an extracellular polysaccharide (EPS), in this study, we analyzed the chemical structure and the biosynthesizing genes for the EPS.The EPS, which was purified from the LP28 culture broth, was classified into acidic and neutral EPSs with a molecular mass of about 50 kDa and 40 kDa, respectively. The acidic EPS consisted of glucose, galactose, mannose, and N-acetylglucosamine moieties. Interestingly, since pyruvate residue was detected in the hydrolyzed acidic EPS, one of the four sugars may be modified with pyruvate. On the other hand, the neutral EPS consisted of glucose, mannose, and N-acetylglucosamine; pyruvate was scarcely detected in the polysaccharide molecule.As a first step to deduce the probiotic function of the EPS together with the biosynthesis, we determined the whole genome sequence of the LP28 strain, demonstrating that the genome is a circular DNA, which is composed of 1,774,865 bp (1683 ORFs) with a GC content of 37.1%. We also found that the LP28 strain harbors a plasmid carrying 6 ORFs composed of 5366 bp with a GC content of 36.5%. By comparing all of the genome sequences among the LP28 strain and four strains of P. pentosaceus reported previously, we found that 53 proteins in the LP28 strain display a similarity of less than 50% with those in the four P. pentosaceus strains. Significantly, 4 of the 53 proteins, which may be enzymes necessary for the EPS production on the LP28 strain, were absent in the other four P. pentosaceus strains and displayed less than 50% similarity with other LAB species. The EPS-biosynthetic gene cluster detected only in the LP28 genome consisted of 12 ORFs containing a priming enzyme, five glycosyltransferases, and a putative polysaccharide pyruvyltransferase.

Selection of cereal-sourced lactic acid bacteria as candidate starters for the baking industry

“…pentosaceus isolates assayed produced EPS containing from 2.4% (isolate FF78) to 6.7% (isolate FF71) mannose. Again, these results agreed with those of a research study [ 70 ] carried out on the EPS extracted from fruit-sourced isolates ascribed to P . pentosaceus , which were mainly composed of glucose, galactose, and mannose.…”

“…This could be explained by a possible variation in one or both the primer binding sites of the EPS genes, which in turn might have hindered the successful amplification of these target genes. An alternative explanation relies on the involvement of other genes in EPS synthesis, as suggested by a recent investigation [70] on the EPS-biosynthetic gene cluster of a P. pentosaceus strain (LP28) isolated from Euphoria longana, where 12 open reading frames (ORFs) containing a priming enzyme, five glycosyltransferases, and a putative polysaccharide pyruvyl transferase were identified.…”

Characterization of Exopolysaccharides Produced by Thermophilic Lactic Acid Bacteria Isolated from Tropical Fruits of Thailand

“…7,8) In fact, the LY45 strain isolated from lychee can also grow at that concentration of NaCl. The LY45 and PY45 strains grew even at 50°C, whereas P. pentosaceus LP28, which produces an EPS modified by pyruvate residue, 14) did not (data not shown).…”

“…9,10) EPSs have been shown to benefit human health by their immunomodulation, anti-gastritis, anti-ulcer, and anti-virus activities. [11][12][13] We have shown that P. pentosaceus LP28 has the strain-specific EPS biosynthetic gene cluster, 14) and intake of the strain is effective to improve the high fat diet-induced obesity and fatty liver of the mice. 6) Furthermore, the strain is also useful to reduce body fat and body weight in human clinical study.…”

Exopolysaccharide Produced by Lactobacillus paracasei IJH-SONE68 Prevents and Improves the Picryl Chloride-Induced Contact Dermatitis

“…paracasei IJH-SONE68. A modified semi-defined medium (SDM) supplemented with a vitamin mixture (0.2 v / v %) and trace element solution (0.1 v / v %) instead of yeast nitrogen bases was used as a main culture medium [55,56,57].…”