Misidentification of Phocaeicola (Bacteroides) dorei in two patients with bacteremia

Genome plasticity shapes the ecology and evolution of Phocaeicola dorei and Phocaeicola vulgatus

Phocaeicola dorei and Phocaeicola vulgatus are very common and abundant members of the human gut microbiome and play an important role in the infant gut microbiome. These species are closely related and often confused for one another; yet, their genome comparison, interspecific diversity, and evolutionary relationships have not been studied in detail so far. Here, we perform phylogenetic analysis and comparative genomic analyses of these two Phocaeicola species. We report that P. dorei has a larger genome yet a smaller pan-genome than P. vulgatus. We found that this is likely because P. vulgatus is more plastic than P. dorei, with a larger repertoire of genetic mobile elements and fewer anti-phage defense systems. We also found that P. dorei directly descends from a clade of P. vulgatus¸ and experienced genome expansion through genetic drift and horizontal gene transfer. Overall, P. dorei and P. vulgatus have very different functional and carbohydrate utilisation profiles, hinting at different ecological strategies, yet they present similar antimicrobial resistance profiles.

Genomes of Bacteroides ovatus, B. cellulosilyticus, B. uniformis, Phocaeicola vulgatus, and P. dorei isolated from gut cavernous fistulous tract micropathologies in Crohn's disease

Surgically removed bowels from Crohn's disease patients exhibit a novel form of micropathologies known as cavernous fistulous tract microlesions (CavFT), resembling fissures. We announce the genomes/plasmids and antimicrobial resistance genes of six CavFT bacterial isolates representing the Bacteroidota genera Bacteroides and Phocaeicola. Plasmids were identified in Bacteroides cellulosilyticus and Phocaeicola vulgatus.

Excess fermentation and lactic acidosis as detrimental functions of the gut microbes in treatment-naive TB patients

Introduction

The link between gut microbiota and host immunity motivated numerous studies of the gut microbiome in tuberculosis (TB) patients. However, these studies did not explore the metabolic capacity of the gut community, which is a key axis of impact on the host's immunity.

Methods

We used deep sequencing of fecal samples from 23 treatment-naive TB patients and 48 healthy donors to reconstruct the gut microbiome's metabolic capacity and strain/species-level content.

Results

We show that the systematic depletion of the commensal flora of the large intestine, Bacteroidetes, and an increase in Actinobacteria, Firmicutes, and Proteobacteria such as Streptococcaceae, Erysipelotrichaceae, Lachnospiraceae, and Enterobacteriaceae explains the strong taxonomic divergence of the gut community in TB patients. The cumulative expansion of diverse disease-associated pathobionts in patients reached 1/4 of the total gut microbiota, suggesting a heavy toll on host immunity along with MTB infection. Reconstruction of metabolic pathways showed that the microbial community in patients shifted toward rapid growth using glycolysis and excess fermentation to produce acetate and lactate. Higher glucose availability in the intestine likely drives fermentation to lactate and growth, causing acidosis and endotoxemia.

Discussion

Excessive fermentation and lactic acidosis likely characterize TB patients' disturbed gut microbiomes. Since lactic acidosis strongly suppresses the normal gut flora, directly interferes with macrophage function, and is linked to mortality in TB patients, our findings highlight gut lactate acidosis as a novel research focus. If confirmed, gut acidosis may be a novel potential host-directed treatment target to augment traditional TB treatment.

Bacterial Profile and Fatty Acid Composition of Anatolian Bee Bread Samples by Metataxonomic and Metabolomic Approach

This study investigated the bacterial and postbiotic potential of three Anatolian bee bread samples obtained from different regions of Turkey (Marmara, Aegean, and Mediterranean) and offered for human consumption. The families most commonly found in Anatolian bee bread were Lactobacillaceae, Oscillospiraceae, Bacteroidaceae, Prevotellaceae, and Lachnospiraceae. Lactobacillus delbruckeii was highly abundant, but also other beneficial bacteria, known to be next-generation probiotics, were revealed in bee bread, such as Prevotalla copri, Faecalibacterium prausnitzii, and Akkermansia muciniphila. Apart from these beneficial bacteria, bee bread samples also harbored undesired bacteria such as Phocaeicola vulgatus, Phocaeicola dorei, and Clostridium perfringens. Fatty acid composition showed that bee bread samples had butyric acid, a short-chain fatty acid, as a postbiotic. Additionally, polyunsaturated fatty acids were also found such as alfa-linolenic acid and eicosadienoic acid. The fatty acids with the highest amounts were palmitic acid (~ 30%), stearic acid (~ 17%), and alpha-linolenic acid (~ 12%). One of the samples exhibited antimicrobial activity against Staphylococcus aureus.

Functional Fermented Milk with Fruit Pulp Modulates the In Vitro Intestinal Microbiota

The effect of putative probiotic fermented milk (FM) with buriti pulp (FMB) or passion fruit pulp (FMPF) or without fruit pulp (FMC) on the microbiota of healthy humans was evaluated. FM formulations were administered into a simulator of the human intestinal microbial ecosystem (SHIME^®) to evaluate the viability of lactic acid bacteria (LAB), microbiota composition, presence of short-chain fatty acids (SCFA), and ammonium ions. The probiotic LAB viability in FM was affected by the addition of the fruit pulp. Phocaeicola was dominant in the FMPF and FMB samples; Bifidobacterium was related to FM formulations, while Alistipes was associated with FMPF and FMB, and Lactobacillus and Lacticaseibacillus were predominant in FMC. Trabulsiella was the central element in the FMC, while Mediterraneibacter was the central one in the FMPF and FMB networks. The FM formulations increased the acetic acid, and a remarkably high amount of propionic and butyric acids were detected in the FMB treatment. All FM formulations decreased the ammonium ions compared to the control; FMPF samples stood out for having lower amounts of ammonia. The probiotic FM with fruit pulp boosted the beneficial effects on the intestinal microbiota of healthy humans in addition to increasing SCFA in SHIME^® and decreasing ammonium ions, which could be related to the presence of bioactive compounds.