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Minimal standards represent a collection of criteria that can be practically utilized for the description of new cultivable strains that represent novel genera and species in accordance with Recommendation 30b of the Bacteriological Code (1990 Revision). Due to the extraordinary importance of LAB and bifidobacteria in food fermentations, and their technological benefits for human and animal health, the publication of the Minimal Standards for the accurate taxonomic description and identification of species belonging to Bifidobacterium, Lactobacillus and related genera is a very important issue. These guidelines should be utilized consistently among all the researchers in order to minimize the risk of false allocation or duplications of new taxa. Modern taxonomic approach comprises phenotypic and genotypic characterization (polyphasic approach). Concerning genotypic characterization, in addition to DNA G+C content (mol%) data, the description should be based on DNA–DNA hybridization (DDH), 16S rRNA gene sequence similarities and at least two housekeeping gene (e.g. hsp60 and recA) sequence similarities. DDH might not be needed if the 16S rRNA gene sequence similarity to the closest known species is lower than 97 %. These guidelines are consistent with the most recently revisited standards of the microbial systematic community. The application of the above‐mentioned general criteria can provide a firm basis for the descriptions of novel genera and species. A general consideration could be that the minimal standards can provide a firm basis for the descriptions of novel genera and species, but due to rapid development of molecular techniques in taxonomy, updates should be envisaged from time to time.

Here we analyze the first complete genome sequence of Pyrococcus chitonophagus. The archaeon was previously suggested to belong to the Thermococcus rather than the Pyrococcus genus. Whole genome phylogeny as well as whole proteome comparisons using all available complete genomes in Thermococcales clearly showed that the species belongs to the Pyrococcus genus. P. chitonophagus was originally isolated from a hydrothermal vent site and it has been described to effectively degrade chitin debris, and therefore is considered to play a major role in the sea water ecology and metabolic activity of microbial consortia within hot sea water ecosystems. Indeed, an obvious feature of the P. chitonophagus genome is that it carries proteins showing complementary activities for chitin degradation, i.e. endo- and exo-chitinase, diacetylchitobiose deacetylase and exo-β-d glucosaminidase activities. This finding supports the hypothesis that compared to other Thermococcales species P. chitonophagus is adapted to chitin degradation. © 2016, Springer Japan.

Background: Streptococcus macedonicus is an intriguing streptococcal species whose most frequent source of isolation is fermented foods similarly to Streptococcus thermophilus. However, S. macedonicus is closely related to commensal opportunistic pathogens of the Streptococcus bovis/Streptococcus equinus complex. Methodology/Principal Findings: We analyzed the pSMA198 plasmid isolated from the dairy strain Streptococcus macedonicus ACA-DC 198 in order to provide novel clues about the main ecological niche of this bacterium. pSMA198 belongs to the narrow host range pCI305/pWV02 family found primarily in lactococci and to the best of our knowledge it is the first such plasmid to be reported in streptococci. Comparative analysis of the pSMA198 sequence revealed a high degree of similarity with plasmids isolated from Lactococcus lactis strains deriving from milk or its products. Phylogenetic analysis of the pSMA198 Rep showed that the vast majority of closely related proteins derive from lactococcal dairy isolates. Additionally, cloning of the pSMA198 ori in L. lactis revealed a 100% stability of replication over 100 generations. Both pSMA198 and the chromosome of S. macedonicus exhibit a high percentage of potential pseudogenes, indicating that they have co-evolved under the same gene decay processes. We identified chromosomal regions in S. macedonicus that may have originated from pSMA198, also supporting a long co-existence of the two replicons. pSMA198 was also found in divergent biotypes of S. macedonicus and in strains isolated from dispersed geographic locations (e.g. Greece and Switzerland) showing that pSMA198's acquisition is not a recent event. Conclusions/Significance: Here we propose that S. macedonicus acquired plasmid pSMA198 from L. lactis via an ancestral genetic exchange event that took place most probably in milk or dairy products. We provide important evidence that point towards the dairy origin of this species. © 2015 Papadimitriou et al.

An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics. It is now 13 years since the definition of probiotics and 12 years after guidelines were published for regulators, scientists and industry by the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO). The FAO/WHO definition of a probiotic--"live microorganisms which when administered in adequate amounts confer a health benefit on the host"--was reinforced as relevant and sufficiently accommodating for current and anticipated applications. However, inconsistencies between the FAO/WHO Expert Consultation Report and the FAO/WHO Guidelines were clarified to take into account advances in science and applications. A more precise use of the term 'probiotic' will be useful to guide clinicians and consumers in differentiating the diverse products on the market. This document represents the conclusions of the ISAPP consensus meeting onthe appropriate use and scope of the term probiotic.

Background: Within the genus Streptococcus, only Streptococcus thermophilus is used as a starter culture in food fermentations. Streptococcus macedonicus though, which belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC), is also frequently isolated from fermented foods mainly of dairy origin. Members of the SBSEC have been implicated in human endocarditis and colon cancer. Here we compare the genome sequence of the dairy isolate S. macedonicus ACA-DC 198 to the other SBSEC genomes in order to assess in silico its potential adaptation to milk and its pathogenicity status.Results: Despite the fact that the SBSEC species were found tightly related based on whole genome phylogeny of streptococci, two distinct patterns of evolution were identified among them. Streptococcus macedonicus, Streptococcus infantarius CJ18 and Streptococcus pasteurianus ATCC 43144 seem to have undergone reductive evolution resulting in significantly diminished genome sizes and increased percentages of potential pseudogenes when compared to Streptococcus gallolyticus subsp. gallolyticus. In addition, the three species seem to have lost genes for catabolizing complex plant carbohydrates and for detoxifying toxic substances previously linked to the ability of S. gallolyticus to survive in the rumen. Analysis of the S. macedonicus genome revealed features that could support adaptation to milk, including an extra gene cluster for lactose and galactose metabolism, a proteolytic system for casein hydrolysis, auxotrophy for several vitamins, an increased ability to resist bacteriophages and horizontal gene transfer events with the dairy Lactococcus lactis and S. thermophilus as potential donors. In addition, S. macedonicus lacks several pathogenicity-related genes found in S. gallolyticus. For example, S. macedonicus has retained only one (i.e. the pil3) of the three pilus gene clusters which may mediate the binding of S. gallolyticus to the extracellular matrix. Unexpectedly, similar findings were obtained not only for the dairy S. infantarius CJ18, but also for the blood isolate S. pasteurianus ATCC 43144.Conclusions: Our whole genome analyses suggest traits of adaptation of S. macedonicus to the nutrient-rich dairy environment. During this process the bacterium gained genes presumably important for this new ecological niche. Finally, S. macedonicus carries a reduced number of putative SBSEC virulence factors, which suggests a diminished pathogenic potential. © 2014 Papadimitriou et al.; licensee BioMed Central Ltd.

In the year 2002 Bifidobacterium longum, B. infantis and B. suis were unified into a single species, B. longum, preserving the former species names through the creation of the three biotypes ‘longum’, ‘infantis’ and ‘suis’. Consequently the use of the species name B. infantis and B. suis was to be discontinued. The above taxonomic rearrangement of B. longum was based on DNA-DNA hybridizations, 16S rRNA and HSP60 sequence analysis. However a variety of other genotypic techniques including ribotyping, ARDRA, RAPD-PCR, BOX-PCR, PCR-DGGE, comparison of the Rec A, tuf and ldh gene sequences, plasmid profiling and considerable variation in carbohydrate fermentation patterns as well as results of starch and PAGE electrophoresis experiments, clearly discriminate former ‘B. longum’, ‘B. infantis’, and ‘B. suis’ strains. In the present paper we compile this published information and propose the description of Bifidobacterium longum subsp. longum subsp. nov., Bifidobacterium longum subsp. infantis comb. nov. and Bifidobacterium longum subsp. suis comb. nov. The “International Committee on Systematic Bacteriology Subcommittee on Bifidobacterium, Lactobacillus and related organisms” is in favour of this proposal.

The species Streptococcus macedonicus is associated with the food environment, especially with fermented dairy products. Here we present the complete 2.1-Mb genome sequence of strain ACA-DC 198, which was isolated from naturally fermented Greek kasseri cheese.

Here, we describe plasmid pREN of Lactobacillus rennini ACA-DC 1534, isolated from traditional Kopanisti cheese. pREN is a circular molecule of 4371bp. Orf calling revealed a novel repA-orf2 operon with the deduced product of orf2 showing no similarity to other known proteins. Downstream of this operon, a gene cluster encoding different mobilization proteins, namely mobC, mobA1, mobA2 and mobB, was detected. Based on the sequence of the origin of replication (ori) and the similarity pattern of RepA, pREN was placed in the pUCL287 family of theta-replicating plasmids. Multiple sequence alignment demonstrated for the first time the degree of conservation in the pUCL287 oris. Our analysis supported that the identified conserved repeats could drive similar secondary structures in the oris of all plasmids. Furthermore, comparative mapping of pREN with its related plasmids (i.e. pLB925A03 and pLJ42) showed that they retain a unique combination in the architecture of their replication and mobilization elements within the pUCL287 family. Phylogenetic analysis also established that these plasmids have undergone a modular evolutionary process in order to acquire their mob genes. Research on plasmids from uncommon lactic acid bacteria will expand our appreciation for their divergence and will aid their rational selection for biotechnological applications. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.

gsiB, coding for glucose starvation-inducible protein B, is a characteristic member of the σB stress regulon of Bacillus subtilis and several other Gram-positive bacteria. Here we provide in silico evidence for the horizontal transfer of gsiB in lactic acid bacteria that are devoid of the σB factor. © 2011, American Society for Microbiology. All Rights Reserved.

Selected immunomodulatory probiotic bacteria can counteract inflammation of the intestine through multiple regulatory activities and may be either complementary or an alternative to conventional treatments toward inflammatory bowel disease (IBD), a growing health concern in developed countries. Probiotic strains such as lactobacilli and bifidobacteria are able to induce anti-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs) in vitro and were shown to exert efficient anti-inflammatory effects on colitis in vivo (9, 26). However, little is known about the immunomodulatory potential of highly consumed starter bacteria such as dairy propionibacteria. Consumption of fermented products has an impact on immune system function (25), and the bacterial content of these products is responsible for immunomodulation (6, 10). Dairy propionibacteria display various probiotic properties either similar to or distinct from those reported for probiotic bifidobacteria and lactic acid bacteria (3). Although an anti-inflammatory potential of a few dairy propionibacterium strains was occasionally suggested in vitro (15) or in animals (22, 24, 31), no reliable observation was established in terms of strain variability and of specific mechanisms involved. In addition, supplementation with dairy propionibacteria in human randomized, placebo-controlled, double-blind trials has mainly concerned mixtures comprising probiotic bacteria assigned to genera other than Propionibacterium but rarely with propionibacteria alone (16). Thus, because of synergistic effects, it is not possible to attribute observed health benefits to a specific bacterium per se within the mixtures.

The pLAC1 plasmid of Lactobacillus acidipiscis ACA-DC 1533, a strain isolated from traditional Kopanisti cheese, was characterised. Nucleotide sequence analysis revealed a circular molecule of 3478. bp with a G. +. C content of 37.2%. Ab initio annotation indicated four putative open reading frames (orfs). orf1 and orf4 were found to encode a replication initiation protein (Rep) and a mobilization protein (Mob), respectively. The deduced products of orf2 and orf3 revealed no significant homology to other known proteins. However, in silico examination of the plasmid sequence supported the existence of a novel operon that includes rep, orf2 and orf3 in pLAC1 and that this operon is highly conserved also in plasmids pLB925A02, pSMA23, pLC88 and pC7. RT-PCR experiments allowed us to verify that these three genes are co-transcribed as a single polycistronic mRNA species. Furthermore, phylogenetic analysis of pLAC1 Rep and Mob proteins demonstrated that they may have derived from different plasmid origins, suggesting that pLAC1 is a product of a modular evolution process. Comparative analysis of full length nucleotide sequences of pLAC1 and related Lactobacillus plasmids showed that pLAC1 shares a very similar replication backbone with pLB925A02, pSMA23 and pLC88. In contrast, mob of pLAC1 was almost identical with the respective gene of plasmids pLAB1000, pLB4 and pPB1. These findings lead to the conclusion that pLAC1 acquired mob probably via an ancestral recombination event. Our overall work highlights the importance of characterizing plasmids deriving from non-starter 'wild' isolates in order to better appreciate plasmid divergence and evolution of lactic acid bacteria. © 2010 Elsevier B.V.

On August 29–31, 2004, 84 academic and industry scientists from 16 countries gathered in Copper Mountain, Colorado USA to discuss certain issues at the forefront of the science of probiotics and prebiotics. The format for this invitation only meeting included six featured lectures: engineering human vaginal lactobacilli to express HIV-inhibitory molecules (Peter Lee, Stanford University), programming the gut for health (Thaddeus Stappenbeck, Washington University School of Medicine), immune modulation by intestinal helminthes (Joel Weinstock, University of Iowa Hospitals and Clinics), hygiene as a cause of autoimmune disorders (G. A. Rook, University College London), prebiotics and bone health (Connie Weaver, Purdue University) and prebiotics and colorectal cancer risk (Ian Rowland, Northern Ireland Centre for Food and Health). In addition, all participants were included in one of eight discussion groups on the topics of engineered probiotics, host-commensal bacteria communication, ‘omics’ technologies, hygiene and immune regulation, biomarkers for healthy people, prebiotic and probiotic applications to companion animals, development of a probiotic dossier, and physiological relevance of prebiotic activity. Brief conclusions from these discussion groups are summarized in this paper.