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In 2019, the International Scientific Association for Probiotics and Prebiotics (ISAPP) convened a panel of experts specializing in nutrition, microbial physiology, gastroenterology, paediatrics, food science and microbiology to review the definition and scope of postbiotics. The term ‘postbiotics’ is increasingly found in the scientific literature and on commercial products, yet is inconsistently used and lacks a clear definition. The purpose of this panel was to consider the scientific, commercial and regulatory parameters encompassing this emerging term, propose a useful definition and thereby establish a foundation for future developments. The panel defined a postbiotic as a “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. Effective postbiotics must contain inactivated microbial cells or cell components, with or without metabolites, that contribute to observed health benefits. The panel also discussed existing evidence of health-promoting effects of postbiotics, potential mechanisms of action, levels of evidence required to meet the stated definition, safety and implications for stakeholders. The panel determined that a definition of postbiotics is useful so that scientists, clinical triallists, industry, regulators and consumers have common ground for future activity in this area. A generally accepted definition will hopefully lead to regulatory clarity and promote innovation and the development of new postbiotic products. Postbiotics are emerging substances prepared from inactivated microorganisms, in contrast to probiotics, which must be administered alive. This Consensus Statement outlines a definition for the term ‘postbiotics’ as determined by an expert panel convened by the International Scientific Association for Probiotics and Prebiotics.

ABSTRACT Fructophilic lactic acid bacteria (FLAB) are a group of lactic acid bacteria (LAB) with unique growth characteristics and are regarded as promising candidates for foods or food ingredients. The present study characterized levels of viable FLAB cells in honeybee-based food products, especially focusing on fresh honey. FLAB were recovered from 88% of fresh honey samples (harvested within a week) tested, and 29% of the fresh honey samples contained FLAB with levels of over 105 CFU/g. FLAB species found in the tested fresh honeys were mostly Apilactobacillus kunkeei and Fructobacillus fructosus. FLAB were not recovered from aged honey samples (aged over 2 weeks after harvest). Fresh comb honey and bee pollen samples occasionally contained low levels of FLAB. When FLAB were inoculated into honeys (linden honey and clover honey), their viability markedly reduced during a week. One of the reasons for this decrease was the presence of H2O2 in the honeys, and supplementation of catalase significantly improved their survivability in linden honey. The long history of human consumption of fresh honey suggests that viable FLAB cells do not present health concerns. Fresh honeybee-based food products contain viable fructophilic lactic acid bacteria.

Background Fruit juice is a rich source of vitamins, dietary fiber, and polyphenols; however, it also contains high concentrations of free sugars, such as glucose, fructose, and sucrose. Excessive consumption of these sugars negatively affects human health. For example, high fructose consumption is regarded as a contributing factor to metabolic syndrome. Therefore, various methods have been explored to reduce free sugar content in fruit juice, among which microbial fermentation is a promising approach due to its simplicity and cost-effectiveness. In this study, we investigated the reduction of free sugars in apple and orange juices through fermentation using fructophilic lactic acid bacteria (FLAB) which possess a unique ability to preferentially utilize fructose over glucose as a carbon source. Methods Ten FLAB strains and five lactic acid bacteria (LAB) strains were used. Apple and orange juices were fermented by each strain at 37 °C for 18 h. The concentrations of glucose, fructose, sucrose, and mannitol in the fermented juices were measured using high-performance liquid chromatography. Based on the sugar reduction performance, Apilactobacillus kunkeei was selected for further evaluation under high osmotic pressure and low pH conditions. Results FLAB strains reduced glucose and fructose levels more effectively than the other LAB strains. Notably, A. kunkeei and Apilactobacillus zhangqiuensis markedly reduced not only glucose and fructose but also sucrose levels compared with other Apilactobacillus species. The total free sugar reduction rate by these two strains exceeded 40% in apple juice and 50% in orange juice. Furthermore, A. kunkeei retained its sugar-reducing ability under low pH (pH 4.0) and high osmotic pressure (40° Brix) conditions. Conclusion This study demonstrates that FLAB, especially A. kunkeei , are capable of efficiently reducing free sugars, i.e. glucose, fructose, and sucrose, in apple and orange juices. The sugar-reducing activity of A. kunkeei remains effective even under acidic conditions and high osmotic pressure. These characteristics suggest that fermentation with A. kunkeei is a promising approach for reducing the free sugar content in fruit juices.

Abstract Faecalibacterium prausnitzii has been suggested as a biomarker of a healthy microbiota in human adults. Here, we report a taxonomic study of F. prausnitzii using genomic information and evaluation of the quantitative real-time PCR (qPCR) assay by focusing on specific primers to quantify its population. Average nucleotide identity values revealed that strains deposited as F. prausnitzii in a public database were separated into eight genomogroups with significant differences at the species level. A total of six of the 10 primer pairs used in the previous studies for qPCR of F. prausnitzii contained sequence mismatches to 16S rRNA gene sequences of the tested strains with markedly different levels by in silico analysis. In vitro primer evaluation by qPCR generally agreed with the in silico analysis, and markedly reduced amount of DNA was recorded by qPCR in combination with the primer pairs containing sequence mismatches. The present study demonstrated that a part of the accumulated knowledge on F. prausnitzii is maybe based on biased results. 16S rRNA gene sequence is not a suitable gene marker for classification and quantification of F. prausnitzii.

Background Fructophilic lactic acid bacteria (FLAB) found in D-fructose rich niches prefer D-fructose over D-glucose as a growth substrate. They need electron acceptors for growth on D-glucose. The organisms share carbohydrate metabolic properties. Fructobacillus spp., Apilactobacillus kunkeei, and Apilactobacillus apinorum are members of this unique group. Here we studied the fructophilic characteristics of recently described species Apilactobacillus micheneri , Apilactobacillus quenuiae, and Apilactobacillus timberlakei . Results The three species prefer D-fructose over D-glucose and only metabolize D-glucose in the presence of electron acceptors. The genomic characteristics of the three species, i.e. small genomes and thus a low number of coding DNA sequences, few genes involved in carbohydrate transport and metabolism, and partial deletion of adhE gene, are characteristic of FLAB. The three species thus are novel members of FLAB. Reduction of genes involved in carbohydrate transport and metabolism in accordance with reduction of genome size were the common characteristics of the family Lactobacillaceae, but FLAB markedly reduced the gene numbers more than other species in the family. Pan-genome analysis of genes involved in metabolism displayed a lack of specific carbohydrate metabolic pathways in FLAB, leading to a unique cluster separation. Conclusions The present study expanded FLAB group. Fructose-rich environments have induced similar evolution in phylogenetically distant FLAB species. These are examples of convergent evolution of LAB.

Functional food ingredients, including prebiotics, have been ardently developed for improving the intestinal environment. Fructooligosaccarides (FOS), including fructans, are the well researched and commercialized prebiotics. However, to our knowledge, few studies have been conducted on the physiological effects of each component of FOS as prebiotics. 1-Kestose, a component of FOS, is composed of one glucose and two fructose molecules, and is considered as a key prebiotic component in short-chain FOS. In the present study, we examined the effects of dietary 1-kestose using 0.5-5% 1-kestose diets on cecal microbiota composition and cecal contents of short-chain fatty acids and lactate in rats. The findings indicate that dietary 1-kestose induced cecal hypertrophy and alterations in the cecal microbiota composition, including a marked increase in the cell number of Bifidobacterium spp. These alterations were associated with significant increases in acetate and lactate, and a marked increase in butyrate in cecal contents. Furthermore, dietary 1-kestose induced a significant decrease in serum insulin concentration in rats fed 2.5-5% 1-kestose diet. These findings suggest a potential of 1-kestose to be a prebiotic for improving the metabolism of the host.

The fructooligosaccharide 1-kestose cannot be hydrolyzed by gastrointestinal enzymes, and is instead fermented by the gut microbiota. Previous studies suggest that 1-kestose promotes increases in butyrate concentrations in vitro and in the ceca of rats. Low levels of butyrate-producing microbiota are frequently observed in the gut of patients and experimental animals with type 2 diabetes (T2D). However, little is known about the role of 1-kestose in increasing the butyrate-producing microbiota and improving the metabolic conditions in type 2 diabetic animals. Here, we demonstrate that supplementation with 1-kestose suppressed the development of diabetes in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, possibly through improved glucose tolerance. We showed that the cecal contents of rats fed 1-kestose were high in butyrate and harbored a higher proportion of the butyrate-producing genus Anaerostipes compared to rats fed a control diet. These findings illustrate how 1-kestose modifications to the gut microbiota impact glucose metabolism of T2D, and provide a potential preventative strategy to control glucose metabolism associated with dysregulated insulin secretion.

Our aim was to establish whether there is an interconnection between the compositional development of the gut microbiota and the amount of fussing and crying in early infancy. Behavioral patterns of 89 infants during the 7(th) and 12(th) week of life were recorded in parental diaries. Total distress was defined as the sum of daily amounts of crying and fussing. Infants' gut microbiota profiles were investigated by several molecular assays during the first six months of life. The median (range) duration of total distress among the infants was 106 (0-478) minutes a day during the 7(th) and 58 (0-448) minutes a day during the 12(th) week. The proportion of Bifidobacterium counts to total bacterial counts was inversely associated with the amount of crying and fussing during the first 3 months of life (p = 0.03), although the number of Bifidobacterium breve was positively associated with total distress (p = 0.02). The frequency of Lactobacillus spp. at the age of 3 weeks was inversely associated with total infant distress during the 7(th) week of life (p = 0.02). Bifidobacterium and Lactobacillus appear to protect against crying and fussing. Identification of specific strains with optimal protective properties would benefit at-risk infants.

Bifidobacterium has a diverse host range and shows several beneficial properties to the hosts. Many species should have co-evolved with their hosts, but the phylogeny of Bifidobacterium is dissimilar to that of host animals. The discrepancy could be linked to the niche-specific evolution due to hosts’ dietary carbohydrates. We investigated the relationship between bifidobacteria and their host diet using a comparative genomics approach. Since carbohydrates are the main class of nutrients for bifidobacterial growth, we examined the distribution of carbohydrate-active enzymes, in particular glycoside hydrolases (GHs) that metabolize unique oligosaccharides. When bifidobacterial species are classified by their distribution of GH genes, five groups arose according to their hosts’ feeding behavior. The distribution of GH genes was only weakly associated with the phylogeny of the host animals or with genomic features such as genome size. Thus, the hosts’ dietary pattern is the key determinant of the distribution and evolution of GH genes.