Folate-producing bifidobacteria: metabolism, genetics, and relevance.

Folate (the general term for all bioactive forms of vitamin B9) plays a crucial role in the evolutionary highly conserved one-carbon (1C) metabolism, a network including central reactions such as DNA and protein synthesis and methylation of macromolecules. Folate delivers 1C units, such as methyl and formyl, between reactants. Plants, algae, fungi, and many bacteria can naturally produce folate, whereas animals, including humans, must obtain folate from external sources. For humans, folate deficiency is, however, a widespread problem. Bifidobacteria constitute an important component of human and many animal microbiomes, providing various health advantages to the host, such as producing folate. This review focuses on bifidobacteria and folate metabolism and the current knowledge of the distribution of genes needed for complete folate biosynthesis across different bifidobacterial species. Biotechnologies based on folate-trophic probiotics aim to create fermented products enriched with folate or design probiotic supplements that can synthesize folate in the colon, improving overall health. Therefore, bifidobacteria (alone or in association with other microorganisms) may, in the future, contribute to reducing widespread folate deficiencies prevalent among vulnerable human population groups, such as older people, women at child-birth age, and people in low-income countries.

Host-Diet Effect on the Metabolism of Bifidobacterium.

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.

Bifidobacteria in two-toed sloths (Choloepus didactylus): phylogenetic characterization of the novel taxon Bifidobacterium choloepi sp. nov.

Seven bifidobacterial strains were isolated from the faeces of two adult males of the two-toed sloth (Choloepus didactylus) housed in Parco Natura Viva, in Italy. Comparative sequence analysis of 16S rRNA and of five housekeeping (hsp60, rpoB, clpC, dnaJ, dnaG) genes revealed that these strains were classified into two clusters. On the basis of 16S rRNA gene sequence similarity, the type strain of Bifidobacterium catenulatum subsp. kashiwanohense DSM 21854T (95.4 %) was the closest neighbour to strain in Cluster I (BRDM 6T), whereas the type strain of Bifidobacterium dentium DSM 20436T (values were in the range of 98‒99.8 %) was the closest neighbour to the other six strains in Cluster II. The average nucleotide identity (ANI) values of BRDM 6T and of strains in Cluster II with the closely related type strains were 76.0 and 98.9 % (mean value) respectively. Therefore, genotyping based on the genome sequence of the strain BRDM 6T combined with phenotypic analyses clearly revealed that the strain BRDM 6T represents a novel species for which the names Bifidobacterium choloepi sp. nov. (BRDM 6T=NBRC 114053T=BCRC 81222T) is proposed.

Convalescent plasma as a treatment modality for coronavirus disease 2019 in Sudan.

Coronavirus disease 2019 (COVID-19) is a disease spreading rapidly in Sudan, the rest of the African continent and the world with no known definitive treatment or vaccines. However, among many treatment interventions being tested globally, beneficial effects and clinical improvements have been reported when convalescent plasma is used for treating COVID-19 patients. We prepared a guiding protocol for treating early to moderate COVID-19 patients with plasma transfusion from convalescent COVID-19 patients. This protocol was deduced based on previously published reports and studies that evaluated and tested convalescent plasma as a prospective therapy for COVID-19 patients. The protocol covers instructions on patient and donor selection criteria, plasma harvesting, plasma product specifications, dosage and precautions for convalescent plasma collection and transfusion process. Altogether, we prepared a treatment protocol that is tailored to the context of Sudan to be adopted by Sudan's health authority. Moreover, it will also provide reference for researchers to design open label clinical trials for convalescent plasma transfusion.

Phylogenetic characterization of two novel species of the genus Bifidobacterium: Bifidobacterium saimiriisciurei sp. nov. and Bifidobacterium platyrrhinorum sp. nov.

Three bifidobacterial Gram-stain-positive, non-spore forming and fructose-6-phosphate phosphoketolase-positive strains, SMA1T, SMB2 and SMA15T were isolated from the faeces of two adult males of the squirrel monkey (Saimiri sciureus). On the basis of 16S rRNA gene sequence similarities, the type strain of Bifidobacterium primatium DSM 100687T (99.3%; similarity) was the closest neighbour to strains SMA1T and SMB2, whereas the type strain of Bifidobacterium stellenboschense DSM 23968T (96.5%) was the closest neighbour to strain SMA15T. The average nucleotide identity (ANI) values of SMA1T and SAM15T with the closely related type strains were 93.7% and 88.1%, respectively. The in silico DNA‒DNA hybridization values with the closest neighbours were 53.1% and 36.9%, respectively. GC contents of strains SMA1T and SMA15T were 63.6 and 66.4 mol%, respectively. Based on the phylogenetic, genotypic and phenotypic data obtained, the strains SMA1T and SMA15T clearly represent two novel taxa within the genus Bifidobacterium for which the names Bifidobacterium saimiriisciurei sp. nov. (type strain SMA1T = BCRC 81223T = NBRC 114049T = DSM 106020T) and Bifidobacterium platyrrhinorum sp. nov. (type strain SMA15T = BCRC 81224T = NBRC 114051T = DSM 106029T) are proposed.

Characterization of Bifidobacterium species in feaces of the Egyptian fruit bat: Description of B. vespertilionis sp. nov. and B. rousetti sp. nov.

Fifteen bifidobacterial strains were obtained from faeces of Rousettus aegyptiacus; after grouping them by RAPD PCR only eight were selected and characterized. Analysis of 16S rRNA and of five housekeeping (hsp60, rpoB, clpC, dnaJ, dna G) genes revealed that these eight strains were classified into five clusters: Cluster I (RST 8 and RST 16T), Cluster II (RST 9T and RST 27), Cluster III (RST 7 and RST 11), Cluster IV (RST 19), Cluster V (RST 17) were closest to Bifidobacterium avesanii DSM 100685T (96.3%), Bifidobacterium callitrichos DSM 23973T (99.2% and 99.7%), Bifidobacterium tissieri DSM 100201T (99.7 and 99.2%), Bifidobacterium reuteri DSM 23975 T (98.9%) and Bifidobacterium myosotis DSM 100196T (99.3%), respectively. Strains in Cluster I and strain RST 9 in Cluster II could not be placed within any recognized species while the other ones were identified as known species. The average nucleotide identity values between two novel strains, RST 16T and RST 9T and their closest relatives were lower than 79% and 89%, respectively. In silico DNA-DNA hybridization values for those closest relatives were 32.5 and 42.1%, respectively. Phenotypic and genotypic tests demonstrated that strains in Cluster I and RST 9T in Cluster II represent two novel species for which the names Bifidobacterium vespertilionis sp. nov. (RST 16T=BCRC 81138T=NBRC 113380T=DSM 106025T ; RST 8=BCRC 81135=NBRC 113377) and Bifidobacterium rousetti sp. nov. (RST 9T=BCRC 81136T=NBRC 113378T=DSM 106027T) are proposed.

Alloscardovia theropitheci sp. nov., isolated from the faeces of gelada baboon, the 'bleeding heart' monkey (Theropithecus gelada).

A novel irregularly shaped and slightly curved rod bacterial strain, GLDI4/2T, showing activity of fructose 6-phosphate phosphoketolase was isolated from a faecal sample of an adult gelada baboon (Theropithecus gelada). Phylogenetic analyses based on 16S rRNA genes as well as multilocus sequences (representing fusA, gyrB and xfp genes) and the core genome revealed that GLDI4/2T exhibited phylogenetic relatedness to Alloscardovia omnicolens DSM 21503T and to Alloscardovia macacae DSM 24762T. Comparative analysis of 16S rRNA gene sequences confirmed the phylogenetic results showing the highest gene sequence identity with strain A. omnicolens DSM 21503T (96.0 %). Activities of α- and ß-gluco(galacto)sidases were detected in strain GLDI4/2T, which is characteristic for almost all members of the family Bifidobacteriaceae. Compared to other Alloscardovia species its DNA G+C content (43.8 mol%) was very low. Phylogenetic studies and the evaluation of phenotypic characteristics, including the results of biochemical, physiological and chemotaxonomic analyses, confirmed the novel species status for strain GLDI4/2T, for which the name Alloscardoviatheropitheci sp. nov. is proposed. The type strain is GLDI4/2T (=DSM 106019T=JCM 32430T).

Bifidobacterium jacchi sp. nov., isolated from the faeces of a baby common marmoset (Callithrix jacchus).

A novel Bifidobacterium strain, MRM 9.3T, was isolated from a faecal sample of a baby common marmoset (Callithrixjacchus). Cells were Gram-stain-positive, non-motile, non-sporulating, non-haemolytic, facultatively anaerobic and fructose 6-phosphate phosphoketolase-positive. Phylogenetic analyses based on 16S rRNA genes as well as multilocus sequences (representing hsp60, rpoB, clpC, dnaJ and dnaG genes) and the core genomes revealed that strain MRM 9.3T exhibited phylogenetic relatedness to Bifidobacterium myosotis DSM 100196T. Comparative analysis of 16S rRNA gene sequences confirmed the phylogenetic results showing the highest gene sequence identity with strain B.ifidobacterium myosotis DSM 100196T (95.6 %). The average nucleotide identity, amino acid average identity and in silico DNA-DNA hybridization values between MRM 9.3T and DSM 100196T were 79.9, 72.1 and 28.5 %, respectively. Phenotypic and genotypic features clearly showed that the strain MRM 9.3T represents a novel species, for which the name Bifidobacterium jacchi sp. nov. is proposed. The type strain is MRM 9.3T (=DSM 103362T =JCM 31788T).

Comparative analysis of probiotic bacteria based on a new definition of core genome.

The commensal genus Bifidobacterium has probiotic properties. We prepared a public library of the gene functions of the genus Bifidobacterium for its online annotation. Orthologous gene cluster analysis showed that the pan genomes of Bifidobacterium and Lactobacillus exhibit striking similarities when mapped to the Clusters of Orthologous Group (COG) database of proteins. When the core genes in each genus were selected based on our statistical definition of "core genome", core genes were present in at least 92% of 52 Bifidobacterium and in 97% of 178 Lactobacillus genomes. Functional comparison of the core genes of the two genera revealed a significant difference in the categories "amino acid transport and metabolism" representing their difference in niche specificity. Over-represented Bifidobacterium protein families were primarily involved in host interactions, the complex compound metabolism, and in stress responses. These findings coincide with the published information and validate our bias-resilient definition of the core genome.