Associations between bacterial and fungal communities in the human gut microbiota and their implications for nutritional status and body weight.

This study examined the interplay between bacterial and fungal communities in the human gut microbiota, impacting on nutritional status and body weight. Cohorts of 10 participants of healthy weight, 10 overweight, and 10 obese individuals, underwent comprehensive analysis, including dietary, anthropometric, and biochemical evaluations. Microbial composition was studied via gene sequencing of 16S and ITS rDNA regions, revealing bacterial (bacteriota) and fungal (mycobiota) profiles. Bacterial diversity exceeded fungal diversity. Statistically significant differences in bacterial communities were found within healthy-weight, overweight, and obese groups. The Bacillota/Bacteroidota ratio (previously known as the Firmicutes/Bacteroidetes ratio) correlated positively with body mass index. The predominant fungal phyla were Ascomycota and Basidiomycota, with the genera Nakaseomyces, Kazachstania, Kluyveromyces, and Hanseniaspora, inversely correlating with weight gain; while Saccharomyces, Debaryomyces, and Pichia correlated positively with body mass index. Overweight and obese individuals who harbored a higher abundance of Akkermansia muciniphila, demonstrated a favorable lipid and glucose profiles in contrast to those with lower abundance. The overweight group had elevated Candida, positively linked to simple carbohydrate consumption. The study underscores the role of microbial taxa in body mass index and metabolic health. An imbalanced gut bacteriota/mycobiota may contribute to obesity/metabolic disorders, highlighting the significance of investigating both communities.

Accelerometer-based sleep metrics and gut microbiota during adolescence: Association findings from a Brazilian population-based birth cohort.

BACKGROUND: Sleep and gut microbiota are emerging putative risk factors for several physical, mental, and cognitive conditions. Sleep deprivation has been shown to be linked with unhealthy microbiome environments in animal studies. However, in humans, the results are mixed. Epidemiological studies evaluating the effect of accelerometer-based sleep measures on gut microbiome are scarce. This study aims to explore the relationship between sleep duration and efficiency with the gut microbiota in adolescence. METHODS: A subsample of 352 participants from the 2004 Pelotas (Brazil) Birth Cohort Study with sleep and fecal microbiota data available were included in the study. Sleep duration and sleep efficiency were obtained from actigraphy information at 11 years old whereas microbiota information from fecal samples was collected at 12 years. The fecal microbiota was analyzed via Illumina MiSeq (16S rRNA V3-V4 region) and the UNOISE pipeline. Alpha was assessed in QIIME2. Association measures for sleep variables and microbial α-diversity, and bacterial relative abundance were assessed through generalized models (linear and logistic regression), adjusting for maternal and child variables confounders. RESULTS: Adjusted models showed that sleep duration was positively associated with Simpson index of α-diversity (ß = 0.003; CI95 %: 0.00004; 0.01). Both sleep duration (OR = 0.43; CI95 % 0.25; 0.74) and efficiency (OR = 0.55; CI95 % 0.38; 0.78) were associated with lower Bacteroidetes abundance. CONCLUSION: Our results suggest that sleep duration and efficiency are linked to gut microbiota diversity and composition even with 1-2 years gap from exposure to outcome. The findings support the role of sleep in the gut-brain axis as well as provide insights on how to improve microbiota health.

Effect of whole oilseeds in the diet on bacterial diversity in the solid fraction of the ruminal content of steers.

Our hypothesis was that different whole oilseeds included in the diet for steers confined could alter the diversity of rumen bacteria compared to a diet without oilseeds or an exclusively forage diet. It was aimed to evaluate the effects of oilseeds inclusion in the diet on bacterial diversity in the solid fraction of the ruminal content of steers, by gene sequences of the conserved 16S rDNA region. Six crossbred steers castrated males, fitted with ruminal cannula were used in a 6 × 6 Latin square design, using 21-day period. At the start of the experiment, the live weight of the animals averaged 416 ± 9.7 kg (mean ± SD). A total of 2,180,562 16S rDNA sequences were generated for the Bacteria domain by MiSeq sequencing. The bacterial diversity was composed of 24 bacterial phyla, with the most abundant being Firmicutes, Bacteroidetes, and Proteobacteria. Other phyla with less diversity were also identified including Eurychaeota, Tenericutes, SR1 Absconditalbacteria, Synergistetes, Actinobacteria, Saccharibacteria, Elusimicrobia, Cyanobacteria, Verrucomicrobia, Fusobacteria, Lentisphaerae. The similarity in the bacterial community averaged 50% for all the experimental diets. Steers-fed corn silage exhibited a great diversity of bacteria of the Firmicutes phylum. The steers-fed oilseeds in the diet had a great diversity of bacteria from the phylum Bacteroidetes and Proteobacteria. The inclusion of whole oilseeds in the steer diets can alter the rumen bacteria population by up to 50% of total diversity.

Alteración de la microbiota intestinal y su relación con enfermedades gastrointestinales y hepatobiliares / Disruption of the intestinal microbiota and its relationship with gastrointestinal and hepatobiliary diseases

La interrupción de la simbiosis que existe entre el cuerpo humano y su microbioma puede resultar en una disbiosis, un desequilibrio en la interacción huésped-microbiota, que puede asociarse al desarrollo de diversas enfermedades como el síndrome de intestino irritable, hígado graso no alco-hólico, enfermedad hepática alcohólica y cirrosis, entre otras. En ciertas condiciones patológicas y por múltiples factores de riesgo, la capacidad de autorregulación del intestino se puede alterar, contribuyendo al incremento de la permeabilidad con inflamación intestinal crónica. El diagnóstico y el tratamiento, así como la relación entre la permeabilidad intestinal, la disbiosis y las patologías gastrointestinales y hepatobiliares, todavía no tienen estudios clínicos validados o con el soporte científico adecuado, por lo que se realiza una revisión de la literatura con la finalidad de aportar conceptos que puedan orientar con respecto a la importancia del estudio del microbioma humano en estas enfermedades.

Disruption of the symbiosis that exists between the human body and its microbiome can result in dys-biosis, an imbalance in the host-microbiota interaction, which may be associated with the develop-ment of various diseases such as irritable bowel syndrome, non-alcoholic fatty liver disease, alcoholic liver disease and cirrhosis, among others. In certain pathological conditions and due to multiple risk factors, the self-regulating capacity of the intestine may be lost, contributing to increased permeability with chronic intestinal inflammation. Its diagnosis and treatment as well as the relationship between intestinal permeability, dysbiosis and gastrointestinal and hepatobiliary pathologies have not been validated in clinical studies or have adequate scientific support, so a review of the literature is carried out in order to provide concepts that can guide with respect to the importance of the study of the human microbiome in these diseases

MliR, a novel MerR-like regulator of iron homeostasis, impacts metabolism, membrane remodeling, and cell adhesion in the marine Bacteroidetes Bizionia argentinensis.

The MerR family is a group of transcriptional activators with conserved N-terminal helix-turn-helix DNA binding domains and variable C-terminal effector binding regions. In most MerR proteins the effector binding domain (EBD) contains a cysteine center suited for metal binding and mediates the response to environmental stimuli, such as oxidative stress, heavy metals or antibiotics. We here present a novel transcriptional regulator classified in the MerR superfamily that lacks an EBD domain and has neither conserved metal binding sites nor cysteine residues. This regulator from the psychrotolerant bacteria Bizionia argentinensis JUB59 is involved in iron homeostasis and was named MliR (MerR-like iron responsive Regulator). In silico analysis revealed that homologs of the MliR protein are widely distributed among different bacterial species. Deletion of the mliR gene led to decreased cell growth, increased cell adhesion and filamentation. Genome-wide transcriptomic analysis showed that genes associated with iron homeostasis were downregulated in mliR-deletion mutant. Through nuclear magnetic resonance-based metabolomics, ICP-MS, fluorescence microscopy and biochemical analysis we evaluated metabolic and phenotypic changes associated with mliR deletion. This work provides the first evidence of a MerR-family regulator involved in iron homeostasis and contributes to expanding our current knowledge on relevant metabolic pathways and cell remodeling mechanisms underlying in the adaptive response to iron availability in bacteria.

Chronic-Antibiotics Induced Gut Microbiota Dysbiosis Rescues Memory Impairment and Reduces ß-Amyloid Aggregation in a Preclinical Alzheimer's Disease Model.

Alzheimer's disease (AD) is a multifactorial pathology characterized by ß-amyloid (Aß) deposits, Tau hyperphosphorylation, neuroinflammatory response, and cognitive deficit. Changes in the bacterial gut microbiota (BGM) have been reported as a possible etiological factor of AD. We assessed in offspring (F1) 3xTg, the effect of BGM dysbiosisdysbiosis in mothers (F0) at gestation and F1 from lactation up to the age of 5 months on Aß and Tau levels in the hippocampus, as well as on spatial memory at the early symptomatic stage of AD. We found that BGM dysbiosisdysbiosis with antibiotics (Abx) treatment in F0 was vertically transferred to their F1 3xTg mice, as observed on postnatal day (PD) 30 and 150. On PD150, we observed a delay in spatial memory impairment and Aß deposits, but not in Tau and pTau protein in the hippocampus at the early symptomatic stage of AD. These effects are correlated with relative abundance of bacteria and alpha diversity, and are specific to bacterial consortia. Our results suggest that this specific BGM could reduce neuroinflammatory responses related to cerebral amyloidosis and cognitive deficit and activate metabolic pathways associated with the biosynthesis of triggering or protective molecules for AD.

Firmicutes, Bacteroidetes and Actinobacteria in Human Milk and Maternal Adiposity.

The main objective was to explore the relationship between the microbiota of human milk and adiposity in Mexican mothers during the first lactation stage. METHODS: Seventy lactating women were included. Adiposity by anthropometric measurements and by bioelectric impedance was obtained. The donation of human milk was requested, from which bacterial DNA was extracted and qPCR of the 16S region was performed. The Mann-Whitney U test, Spearman and Pearson correlations, and multiple linear regressions models were also calculated. RESULTS: The median percentage of Bacteroidetes had a direct and significant correlation with normal adiposity, current BMI, waist circumference, and body fat percentage. The correlation with current BMI became significantly inverse in women with BMI ≥ 25. In women with normal BMI, the percentage of Actinobacteria showed a direct and significant correlation with current BMI, waist circumference, and percentage of body fat. Multiple linear regressions showed that pre-pregnancy BMI was the variable with the highest predictive value with the Bacteroidetes phyla in normal BMI and in BMI ≥ 25. CONCLUSIONS: the adiposity of the woman before pregnancy and during lactation would have an important effect on the abundance of Bacteroidetes and Actinobacteria in human milk.

Mucilaginibacter sp. Strain Metal(loid) and Antibiotic Resistance Isolated from Estuarine Soil Contaminated Mine Tailing from the Fundão Dam.

In 2015 a mine dam with Mn-Fe-rich tailings collapsed releasing million tons of sediments over an estuary, in the Southwest of Brazil. The tailings have a high concentration of metals that contaminated soil until the present day. The high contaminant concentrations possibly caused a selection for microorganisms able to strive in such harsh conditions. Here, we isolated metal(loid) and anti-biotic resistance bacteria from the contaminated estuarine soil. After 16S rDNA sequencing to identify the strains, we selected the Mucilaginibacter sp. strain for a whole-genome sequence due to the bioprospective potential of the genus and the high resistance profile. We obtained a complete genome and a genome-guided characterization. Our finding suggests that the 21p strain is possibly a new species of the genus. The species presented genes for resistance for metals (i.e., As, Zn, Co, Cd, and Mn) beyond resistance and cross-resistance for antibiotics (i.e., quinolone, aminoglycoside, ß-lactamase, sulphonamide, tetracycline). The Mucilaginibacter sp. 21p description as new species should be further explored, as their extracellular polymeric substances and the potential of this strain as bioremediation and as a growth promoter in high met-al(loid) contaminated soil.

Characterization of the Cafeteria Diet as Simulation of the Human Western Diet and Its Impact on the Lipidomic Profile and Gut Microbiota in Obese Rats.

The obesity pandemic has been strongly associated with the Western diet, characterized by the consumption of ultra-processed foods. The Western lifestyle causes gut dysbiosis leading to impaired fatty acid metabolism. Therefore, this study aimed to evaluate shifts in gut microbiota and correlate these with serum fatty acid profiles in male Wistar rats fed a cafeteria diet. Ten male rats were fed with standard diet (CTL, n = 5) and cafeteria diet (CAF, n = 5) for fifteen weeks. Body weight and food intake were recorded once and three times per week, respectively. At the end of the study, fresh fecal samples were collected, tissues were removed, and serum samples were obtained for further analyses. Gut microbiota was analyzed by sequencing the V3-V4 region of 16S rRNA gene. Serum fatty acid profiles were fractioned and quantified via gas chromatography. The CAF diet induced an obese phenotype accompanied by impaired serum fatty acids, finding significantly higher proportions of total saturated fatty acids (SFAs) and C20:3 n-6, and lower C18:1 n-7 and C18:3 n-3 in the phospholipid (PL) fraction. Furthermore, circulating C10:0, total n-3 and n-7 decreased and total monounsaturated fatty acids (MUFAs), including oleic acid C18:1 n-9, increased in the cholesterol ester (CE) fraction. The obesity metabotype may be mediated by gut dysbiosis caused by a cafeteria diet rich in C16:0, C18:0, C18:1 n-9 and C18:2 n-6 fatty acids resulting in a 34:1 omega-6/omega-3 ratio. Therefore, circulating C10:0 was associated with several genera bacteria such as Prevotella (positive) and Anaerotruncus (negative). Two classes of Firmicutes, Bacilli and Erysipelotrichi, were positively correlated with PL- C20:3 n-6 and CE- 18:1 n-9, respectively. TM7 and Bacteroidetes were inversely correlated with PL-SFAs and CE- 18:2 n-6, respectively.

Prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in clinically healthy and metabolically ill subjects.

BACKGROUND: Blastocystis is a typical anaerobic colon protist in humans with controversial pathogenicity and has relation with alterations in the intestinal microbiota composition (dysbiosis), whose eventual indicator is the Firmicutes/Bacteroidetes ratio (F/B ratio); this indicator is also linked to complications such as diabetes, obesity, or inflammatory bowel disease. The present study investigated the prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in healthy and metabolic diseased subjects. METHODS: Fecal and blood samples were collected consecutively from 200 healthy subjects and 84 subjects with metabolic disease; Blastocystis and its most frequent subtypes were identified by end-point PCR and the two most representative phyla of the intestinal microbiota Firmicutes and Bacteroidetes by real-time PCR. RESULTS: The prevalence of Blastocystis in healthy subjects was 47.0, and 65.48% in subjects with metabolic disease; the most prevalent subtype in the total population was ST3 (28.38%), followed by ST1 (14.86%), ST4, ST5, and ST7 (each one of them with 14.19% respectively), and finally ST2 (8.78%). The low F/B ratio was associated with the prevalence of Blastocystis in the two cohorts FACSA (OR = 3.78 p < 0.05) and UNEME (OR = 4.29 p < 0.05). Regarding the subtype level, an association between the FACSA cohort ST1 and ST7 with low Firmicutes/Bacteroidetes ratio was found (OR = 3.99 and 5.44 p < 0.05, respectively). CONCLUSIONS: The evident predatory role of Blastocystis over Firmicutes phylum was observed in both cohorts since the abundance of bacterial group's Bacteroidetes increases in the groups colonized by this eukaryote and, therefore, may have a beneficial effect.

Frigoriflavimonas asaccharolytica gen. nov., sp. nov., a novel psychrophilic esterase and protease producing bacterium isolated from Antarctica.

The rod-shaped and Gram-stain-negative bacterial strain 16FT, isolated from an air sample collected at King George Island, maritime Antarctica, was investigated to determine its taxonomic status. Strain 16FT is strictly aerobic, catalase positive, oxidase positive and non-motile. Strain 16FT hydrolyses casein, lecithin, Tween 20, 60 and 80, but not aesculin, gelatin and starch. Growth of strain 16FT is observed at 0-20 °C (optimum 10 °C), pH 5.0-8.0 (optimum pH 6.0), and in the presence of 0-2.0% NaCl (optimum 0.5%). The predominant menaquinone is MK-6, and the major fatty acids comprise anteiso-C15:0 and iso-C15:0. The major polar lipids are phosphatidylethanolamine, ornithine lipid OL2, unidentified phospholipid PL1 and the unidentified lipids L3 and L6 lacking functional groups. The DNA G + C content based on the draft genome sequence is 32.3 mol%. Sequence analysis of the 16S rRNA gene indicates the highest similarity to Kaistella palustris 3A10T (95.4%), Kaistella chaponensis Sa 1147-06 T (95.2%), Kaistella antarctica AT1013T (95.1%), Kaistella carnis NCTC 13525 T (95.1%) and below 95.0% to other species with validly published names. Phylogenetic analysis based on 16S rRNA gene and whole-genome sequences places strain 16FT in a distinct branch, indicating a separate lineage within the family Weeksellaceae. Based on the data from our polyphasic approach, 16FT represents a novel species of a new genus, for which the name Frigoriflavimonas asaccharolytica gen. nov, sp. nov. is proposed. The type strain is 16FT (= CCM 8975 T = CGMCC No.1.16844 T).

Altered milk yield and rumen microbial abundance in response to concentrate supplementation during the cold season in Tibetan sheep

BACKGROUND Weight loss and decline of milk yield in Tibetan sheep was a challenge for the dairy industry in Qinghai-Tibet Plateau, which were considered to be caused by underfeeding of the sheep during the harsh winter. The objective of this study was to assess the role of feed supplementation in the milk performance and rumen microbiome of ewes under forage-based diets. Based on parity, milking period, milk yield, and body weight, ten 1.5-yr-old ewes were allocated randomly into two groups. One group of ewes was fed no supplement Control group (CON) and the other group was fed with concentrate feed supplement (Treatment group, T). Individual milk yield was determined daily; both the milk composition and rumen bacterial characteristics were analyzed after the end of feeding trials. RESULTS Results showed that lactose in the milk of the CON group was significantly lower (P < 0.05) than that of the T group at days 30 and 60. Milk yield in the T group was greater than in the CON group at day 30 (P < 0.05). Additionally, the dominant ruminal bacteria (phyla Bacteroidetes, Firmicutes, and Verrucomicrobia) were shared by both groups through 16S rRNA gene pyrosequencing. Greater relative abundance of Bacteroidales RF16 group in family level, Victivallales in order level, Lentisphaeria in class level, and Lachnospiraceae bacterium in species level were observed in the T group than in the CON group (P < 0.05). CONCLUSIONS These results demonstrated that supplementation of concentrate in the cold season improved milk lactose yield and milk production, and the rumen microbial abundance of Tibetan sheep.

Firmicutes Levels in the Mouth Reflect the Gut Condition With Respect to Obesity and Early Childhood Caries.

The present cross-sectional study investigated whether Firmicutes (F) and Bacteroidetes (B) levels in the mouth reflected the gut condition in obesity and early childhood caries (ECC). Eighty preschoolers (3-5 years) were equally assigned into four groups: 1. obese + ECC, 2. obese + caries-free (CF), 3. eutrophic + ECC, and 4. eutrophic + CF. Nutritional status and ECC were assessed based on the WHO criteria. Dental biofilm and fecal samples were collected for F and B quantification using RT-PCR analysis. Data were evaluated using three-way-ANOVA and Pearson's correlation (α = 0.05). Regardless of the anatomical location effect (p = 0.22), there were higher values for F in the obese children + ECC compared with those in obese + caries-free (CF) in both mouth and gut (p < 0.05). The correlation for F at these sites was negative in obese children + ECC (r = -0.48; p = 0.03) and positive in obese children + CF (r=0.50; p = 0.03). Bacteroidetes were influenced by ECC (p = 0.03) and the anatomical location (p = 0.00), and the levels tended to be higher in the mouth of the obese children + ECC (p = 0.04). The F/B ratio was higher in the gut and was affected by the anatomical location (p = 0.00). This preliminary study suggested that modulated by ECC, counts of oral Firmicutes reflected corresponding condition in the gut of obese preschoolers. In addition, we first evidenced that the Firmicutes phylum behave differently according to the nutritional status and caries experience and that supragingival biofilm and gut could share levels of similarity.

Green banana flour supplementation improves obesity-associated systemic inflammation and regulates gut microbiota profile in mice fed high-fat diets.

This study evaluated the effect of green banana flour (GBF) consumption on obesity-related conditions in mice fed high-fat diets. GBF was prepared using stage 1 green banana pulp, which was dehydrated and milled. Mice were fed a control diet (n = 20; 10% of energy from lipids) or a high-fat diet (n = 20; 50% of energy from lipids). After 10 weeks, mice were divided into 4 groups based on feed: standard chow (SC; n = 10), standard with 15% GBF (SB; n = 10), high-fat diet (HF; n = 10) and high-fat diet with 15% GBF (HFB; n = 10) for 4 weeks. HFB exhibited lower gains in body weight (-21%; p < 0.01) and in all fat pads (p < 0.01) compared with the HF group. SC, SB, and HFB showed smaller retroperitoneal white adipose tissue diameters (p < 0.001). SB and HFB-treated mice showed lower levels of leptin, IL-6, and TNF-α compared with the SC and HF groups (p < 0.01). In the GBF-fed groups, there was a reduction in the abundance of Firmicutes (SB: -22%; HFB: -23%) and an increase in Bacteroidetes (SB: +25%; HFB: +29%) compared with their counterparts. We demonstrated that GBF consumption attenuated inflammation and improved metabolic status, adipose tissue remodeling, and the gut microbiota profile of obese mice. Novelty: Green banana flour (GBF) consumption, rich in resistant starch, regulates body weight in mice fed high-fat diets. GBF consumption improves fat pad distribution in mice fed high-fat diets. GBF improves obesity-associated systemic inflammation and regulates gut microbiota profile in mice fed high-fat diets.

Metagenomics approach to identify lignocellulose-degrading enzymes in the gut microbiota of the Chinese bamboo rat cecum

BACKGROUND: Lignocellulose is considered a renewable organic material, but the industrial production of biofuel from lignocellulose is challenging because of the lack of highly active hydrolytic enzymes. The guts of herbivores contain many symbiotic microorganisms that have evolved to hydrolyze plant lignocellulose. Chinese bamboo rats mainly consume high-fiber foods, indicating that some members of the intestinal tract microbiota digest lignocellulose, providing these rats with the energy required for growth. RESULTS: Here, we used metagenomics to analyze the diversity and functions of the gut microbiota in Chinese bamboo rats. We identified abundant populations of lignocellulose-degrading bacteria, whose main functions involved carbohydrate, amino acid, and nucleic acid metabolism. We also found 587 carbohydrate-active enzyme genes belonging to different families, including 7 carbohydrate esterase families and 21 glycoside hydrolase families. The glycoside hydrolase 3, glycoside hydrolase 1, glycoside hydrolase 43, carbohydrate esterase 4, carbohydrate esterase 1, and carbohydrate esterase 3 families demonstrated outstanding performance. CONCLUSIONS: The microbes and enzymes identified in our study expand the existing arsenal of proficient degraders and enzymes for lignocellulosic biofuel production. This study also describes a powerful approach for targeting gut microbes and enzymes in numerous industries.

The Bacterial Community of the Foliose Macro-lichen Peltigera frigida Is More than a Mere Extension of the Microbiota of the Subjacent Substrate.

Lichens host highly diverse microbial communities, with bacteria being one of the most explored groups in terms of their diversity and functioning. These bacteria could partly originate from symbiotic propagules developed by many lichens and, perhaps more commonly and depending on environmental conditions, from different sources of the surroundings. Using the narrowly distributed species Peltigera frigida as an object of study, we propose that bacterial communities in these lichens are different from those in their subjacent substrates, even if some taxa might be shared. Ten terricolous P. frigida lichens and their substrates were sampled from forested sites in the Coyhaique National Reserve, located in an understudied region in Chile. The mycobiont identity was confirmed using partial 28S and ITS sequences. Besides, 16S fragments revealed that mycobionts were associated with the same cyanobacterial haplotype. From both lichens and substrates, Illumina 16S amplicon sequencing was performed using primers that exclude cyanobacteria. In lichens, Proteobacteria was the most abundant phylum (37%), whereas soil substrates were dominated by Acidobacteriota (39%). At lower taxonomic levels, several bacterial groups differed in relative abundance among P. frigida lichens and their substrates, some of them being highly abundant in lichens but almost absent in substrates, like Sphingomonas (8% vs 0.2%), and others enriched in lichens, as an unassigned genus of Chitinophagaceae (10% vs 2%). These results reinforce the idea that lichens would carry some components of their microbiome when propagating, but they also could acquire part of their bacterial community from the substrates.

The Firmicutes/Bacteroidetes Ratio: A Relevant Marker of Gut Dysbiosis in Obese Patients?

The gut microbiota is emerging as a promising target for the management or prevention of inflammatory and metabolic disorders in humans. Many of the current research efforts are focused on the identification of specific microbial signatures, more particularly for those associated with obesity, type 2 diabetes, and cardiovascular diseases. Some studies have described that the gut microbiota of obese animals and humans exhibits a higher Firmicutes/Bacteroidetes ratio compared with normal-weight individuals, proposing this ratio as an eventual biomarker. Accordingly, the Firmicutes/Bacteroidetes ratio is frequently cited in the scientific literature as a hallmark of obesity. The aim of the present review was to discuss the validity of this potential marker, based on the great amount of contradictory results reported in the literature. Such discrepancies might be explained by the existence of interpretative bias generated by methodological differences in sample processing and DNA sequence analysis, or by the generally poor characterization of the recruited subjects and, more particularly, the lack of consideration of lifestyle-associated factors known to affect microbiota composition and/or diversity. For these reasons, it is currently difficult to associate the Firmicutes/Bacteroidetes ratio with a determined health status and more specifically to consider it as a hallmark of obesity.

Fulvivirga aurantia sp. nov. and Xanthovirga aplysinae gen. nov., sp. nov., marine bacteria isolated from the sponge Aplysina fistularis, and emended description of the genus Fulvivirga.

Two Gram-stain-negative, strictly aerobic, marine bacteria, designated as strains RKSG066T and RKSG123T, were isolated from a sponge Aplysina fistularis collected at a depth of 15 m off the west coast of San Salvador, The Bahamas. Investigation of nearly full-length 16S rRNA gene and whole genome-based phylogenies revealed that both strains belong to the order Cytophagales within the class Cytophagia and phylum Bacteroidetes. Strain RKSG066T formed a monophyletic clade with described members of the genus Fulvivirga, while strain RKSG123T formed a well-supported paraphyletic branch apart from this and other related genera within the family Flammeovirgaceae. For both RKSG066T and RKSG123T, optimal growth parameters were 30-37 °C, pH 7-8 and 2-3 % (w/v) NaCl; cells were catalase- and oxidase-positive, and flexirubin-type pigments were absent. The predominant fatty acids were iso-C15 : 0, C16 : 0, C18 : 0, iso-C17 : 0 3-OH, C16 : 1 ω5c, iso-C15 : 0 3-OH, C18 : 1 ω9c and iso-C15 : 1 G for RKSG066T, and iso-C17 : 0 3-OH, C16 : 1 ω5c, iso-C15 : 0, C16 : 0 3-OH and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) for RKSG123T. Menaquinone-7 was the major respiratory quinone for both strains. The DNA G+C contents of RKSG066T and RKSG123T were 39.5 and 36.7 mol%, respectively. On the basis of phylogenetic distinctiveness and polyphasic analysis, the type strain RKSG066T (=TSD-73T=LMG 29870T) is proposed to represent a novel species of the genus Fulvivirga, for which the name Fulvivirga aurantia sp. nov. is proposed. The type strain RKSG123T (=TSD-75T=LMG 30075T) is proposed to represent the type species of a novel genus and species with the proposed name Xanthovirga aplysinae gen. nov., sp. nov. Additionally, the genus Fulvivirga is emended to include strains of orange-pigmented colonies that contain the predominant cellular fatty acids C16 : 0, C18 : 0, C16  :  1 ω5c and C18  :  1 ω9c.

Interaction between high-fat diet and ethanol intake leads to changes on the fecal microbiome.

It is known that high-fat diet and alcohol intake can modulate the gut microbiota and consequently affect physiological processes such as fat storage and conditional behavior. However, the effects of the interaction between high-fat diet, its withdrawal and ethanol intake in gut microbiota remain unclear. To address this question, we used an animal model in which C57BL/6 mice were fed on standard (AIN93G) or high-sugar and -butter (HSB) diet for 8 weeks. Then, a protocol of free choice between water and a 10% alcohol solution was introduced, and the HSB diet was replaced with AIN93G in two experimental groups. This model allowed us to distinguish the individual effects of HSB diet and ethanol, and the effects of its interaction on the microbiome. The interaction of those factors was the main driver in the structure changes of the fecal microbial community. HSB diet and ethanol consumption directly affected the abundance of Firmicutes and Actinobacteria phylum, and Clostridiaceae and Coriobacteriaceae family. On the other hand, we also showed that abundance of Bacteroidales_S24-7 family and the Firmicutes/Bacteroidetes ratio were affected only by HSB diet consumption and that ethanol consumption was uniquely responsible for the bacterial translocation to the liver, indicating a breaking of the gut barrier. Finally, we also pointed out that the withdrawal of the HSB diet affects the preference for alcohol and shows a structural resilience in the fecal microbiome. These results highlight the importance of the gut microbiome modulation and its possible role on the phenotype developed by animals.

Novel bacteriocyte-associated pleomorphic symbiont of the grain pest beetle Rhyzopertha dominica (Coleoptera: Bostrichidae).

BACKGROUND: The lesser grain borer Rhyzopertha dominica (Coleoptera: Bostrichidae) is a stored-product pest beetle. Early histological studies dating back to 1930s have reported that R. dominica and other bostrichid species possess a pair of oval symbiotic organs, called the bacteriomes, in which the cytoplasm is densely populated by pleomorphic symbiotic bacteria of peculiar rosette-like shape. However, the microbiological nature of the symbiont has remained elusive. RESULTS: Here we investigated the bacterial symbiont of R. dominica using modern molecular, histological, and microscopic techniques. Whole-mount fluorescence in situ hybridization specifically targeting symbiotic bacteria consistently detected paired bacteriomes, in which the cytoplasm was full of pleomorphic bacterial cells, in the abdomen of adults, pupae and larvae, confirming previous histological descriptions. Molecular phylogenetic analysis identified the symbiont as a member of the Bacteroidetes, in which the symbiont constituted a distinct bacterial lineage allied to a variety of insect-associated endosymbiont clades, including Uzinura of diaspidid scales, Walczuchella of giant scales, Brownia of root mealybugs, Sulcia of diverse hemipterans, and Blattabacterium of roaches. The symbiont gene exhibited markedly AT-biased nucleotide composition and significantly accelerated molecular evolution, suggesting degenerative evolution of the symbiont genome. The symbiotic bacteria were detected in oocytes and embryos, confirming continuous host-symbiont association and vertical symbiont transmission in the host life cycle. CONCLUSIONS: We demonstrate that the symbiont of R. dominica constitutes a novel bacterial lineage in the Bacteroidetes. We propose that reductive evolution of the symbiont genome may be relevant to the amorphous morphology of the bacterial cells via disruption of genes involved in cell wall synthesis and cell division. Genomic and functional aspects of the host-symbiont relationship deserve future studies.