Baker's yeast (Saccharomyces cerevisiae) antigen in obese and normal weight subjects

Gut mycobiome in metabolic diseases: Mechanisms and clinical implication

Obesity, type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are three common metabolic diseases with high prevalence worldwide. Emerging evidence suggests that gut dysbiosis may influence the development of metabolic diseases, in which gut fungal microbiome (mycobiome) is actively involved. In this review, we summarize the studies exploring the composition changes of gut mycobiome in metabolic diseases and mechanisms by which fungi affect the development of metabolic diseases. The current mycobiome-based therapies, including probiotic fungi, fungal products, anti-fungal agents and fecal microbiota transplantation (FMT), and their implication in treating metabolic diseases are discussed. We highlight the unique role of gut mycobiome in metabolic diseases, providing perspectives for future research on gut mycobiome in metabolic diseases.

From ASCA breakthrough in Crohn's disease and Candida albicans research to thirty years of investigations about their meaning in human health

Anti-Saccharomyces cerevisiae antibodies (ASCA) are human antibodies that can be detected using an enzyme-linked immunosorbent assay involving a mannose polymer (mannan) extracted from the cell wall of the yeast S. cerevisiae. The ASCA test was developed in 1993 with the aim of differentiating the serological response in two forms of inflammatory bowel disease (IBD), Crohn's disease and ulcerative colitis. The test, which is based on the detection of anti-oligomannosidic antibodies, has been extensively performed worldwide and there have been hundreds of publications on ASCA. The earlier studies concerned the initial diagnostic indications of ASCA and investigations then extended to many human diseases, generally in association with studies on intestinal microorganisms and the interaction of the micro-mycobiome with the immune system. The more information accumulates, the more the mystery of the meaning of ASCA deepens. Many fundamental questions remain unanswered. These questions concern the heterogeneity of ASCA, the mechanisms of their generation and persistence, the existence of self-antigens, and the relationship between ASCA and inflammation and autoimmunity. This review aims to discuss the gray areas concerning the origin of ASCA from an analysis of the literature. Structured around glycobiology and the mannosylated antigens of S. cerevisiae and Candida albicans, this review will address these questions and will try to clarify some lines of thought. The importance of the questions relating to the pathophysiological significance of ASCA goes far beyond IBD, even though these diseases remain the preferred models for their understanding.

Characterization of Two Zymomonas mobilis Wild Strains and Analysis of Populations Dynamics during Their Leavening of Bread-like Doughs

Two Zymomonas mobilis wild strains (UMB478 and 479) isolated from water kefir were characterized for their biomass production levels and leavening performance when used as the inoculum of a real bread-like dough formulation. The obtained baked product would be consumable by people with adverse responses to Saccharomyces cerevisiae. In liquid cultures, the two strains reached similar biomass concentration (0.7 g CDW/L). UMB479 showed an interesting resistance to NaCl (MBC 30 g/L), that may be useful in the bakery sector. When inoculated in doughs, UMB479 produced the maximum dough volume (650 mL) after 5 h, glucose was almost consumed and 1 g/100 g of ethanol produced, +200% respective to UMB478. Using S. cerevisiae for comparison purposes, the dough doubled its volume fast, in only 2 h, but reached a final level of 575 mL, lower than that achieved by Z. mobilis. The analysis of bacterial and fungal population dynamics during dough leavening was performed through the Automated Ribosomal Intergenic Spacer Analysis (ARISA); doughs leavened by UMB479 showed an interesting decrease in fungal richness after leavening. S. cerevisiae, instead, created a more complex fungal community, similar before and after leavening. Results will pave the way for the use of Z. mobilis UMB479 in commercial yeast-free leavened products.

Gastrointestinal manifestations after Roux-en-Y gastric bypass surgery in individuals with and without type 2 diabetes

BACKGROUND

Roux-en-Y gastric bypass (RYGB) surgery is an effective treatment for obesity, which improves cardiovascular health and reduces the risk of premature mortality. However, some reports have suggested that RYGB may predispose patients to adverse health outcomes, such as inflammatory bowel disease (IBD) and colorectal cancer.

OBJECTIVES

The present prospective study aimed to evaluate the impact of RYGB surgery on cardiovascular risk factors and gastrointestinal inflammation in individuals with and without type 2 diabetes (T2D).

SETTING

University hospital setting in Finland.

METHODS

Blood and fecal samples were collected at baseline and 6 months after surgery from 30 individuals, of which 16 had T2D and 14 were nondiabetics. There were also single study visits for 6 healthy reference patients. Changes in cardiovascular risk factors, serum cholesterol, and triglycerides were investigated before and after surgery. Fecal samples were analyzed for calprotectin, anti-Saccharomyces cerevisiae immunoglobulin A antibodies (ASCA), active lipopolysaccharide (LPS) concentration, short-chain fatty acids (SCFAs), intestinal alkaline phosphatase activity, and methylglyoxal-hydro-imidazolone (MG-H1) protein adducts formation.

RESULTS

After RYGB, weight decreased on average -21.6% (-27.2 ± 7.8 kg), excess weight loss averaged 51%, and there were improvements in cardiovascular risk factors. Fecal calprotectin levels (P < .001), active LPS concentration (P < .002), ASCA (P < .02), and MG-H1 (P < .02) values increased significantly, whereas fecal SCFAs, especially acetate (P < .002) and butyrate (P < .03) levels, were significantly lowered.

CONCLUSION

The intestinal homeostasis is altered after RYGB, with several fecal markers suggesting increased inflammation; however, clinical significance of the detected changes is currently uncertain. As chronic inflammation may predispose patients to adverse health effects, our findings may have relevance for the suggested association between RYGB and increased risks of incident IBD and colorectal cancer.

Zymomonas mobilis in Bread Dough: Characterization of Dough Leavening Performance in Presence of Sucrose

Zymomonas mobilis, because of its fermentative metabolism, has potential food applications in the development of leavened baked goods consumable by people with adverse responses to Saccharomyces cerevisiae. Since Z. mobilis is not able to utilize maltose present in flour, the effect of sucrose addition (2.5 g/100 g flour) on bread dough leavening properties was studied. For comparison purposes, leavening performances of S. cerevisiae with and without sucrose were also investigated. Doughs leavened by Z. mobilis without sucrose addition showed the lowest height development (14.95 ± 0.21 mm) and CO2 production (855 ± 136 mL). When sucrose was added, fermentative performances of Z. mobilis significantly (p < 0.05) improved (+80% and +85% of gas production and retention, respectively), with a dough maximum height 2.6 times higher, results indicating that Z. mobilis with sucrose can be leavened in shorter time with respect to the sample without addition. S. cerevisiae did not benefit the sucrose addition in terms of CO2 production and retention, even if lag leavening time was significantly (p < 0.05) shorter (about the half) and time of porosity appearance significantly (p < 0.05) longer (about 26%) with respect to S. cerevisiae alone. Results demonstrate that in the presence of sucrose, Z. mobilis can efficiently leaven a bread dough, thus providing innovation possibilities in the area of yeast-free leavened products.

Use of a Selected Leuconostoc Citreum Strain as a Starter for Making a "Yeast-Free" Bread

The aim of this study was the characterization and selection of bacterial strains suitable for the production of a “yeast-free” bread. The strains Leuconostoc citreum C2.27 and Weissella confusa C5.7 were selected for their leavening and acidification capabilities and individually used as starters in bread-making tests. Liquid type-II sourdoughs, singly inoculated with the two selected strains, were characterized and employed for bread-making, through the set-up of a biotechnological protocol without the use of baker’s yeast as a leavening agent. Aiming to verify the ability of the selected strains to dominate the fermentation process, bacteria and yeasts were isolated from liquid sourdoughs and doughs, genetically characterized and identified. Both the selected strains were suitable for the production of bread, even if L. citreum C2.27 showed the highest leavening capacity and was able to dominate the dough microbiota. The effects of different salt concentrations on the selected strain performances were also investigated. The applicability of the developed protocol, adapted for the production of the typical Apulian bread, “puccia”, and the suitability of the strain L. citreum C2.27 were confirmed at pilot scale in an industrial bakery. The puccia bread, which was produced with the liquid sourdough fermented with L. citreum C2.27, without baker’s yeast and salt, was similar in appearance to the conventional product containing baker’s yeast and was judged positively by a sensory analysis.

Can Zymomonas mobilis Substitute Saccharomyces cerevisiae in Cereal Dough Leavening?

Baker&rsquo;s yeast intolerance is rising among Western populations, where Saccharomyces cerevisiae is spread in fermented food and food components. Zymomonas mobilis is a bacterium commonly used in tropical areas to produce alcoholic beverages, and it has only rarely been considered for dough leavening probably because it only ferments glucose, fructose and sucrose, which are scarcely present in flour. However, through alcoholic fermentation, similarly to S. cerevisiae, it provides an equimolar mixture of ethanol and CO₂ that can rise a dough. Here, we propose Z. mobilis as a new leavening agent, as an alternative to S. cerevisiae, overcoming its technological limit with different strategies: (1) adding glucose to the dough formulation; and (2) exploiting the maltose hydrolytic activity of Lactobacillus sanfranciscensis associated with Z. mobilis. CO₂ production, dough volume increase, pH value, microbial counts, sugars consumption and ethanol production were monitored. Results suggest that glucose addition to the dough lets Z. mobilis efficiently leaven a dough, while glucose released by L. sanfranciscensis is not so well fermented by Z. mobilis, probably due to the strong acidification. Nevertheless, the use of Z. mobilis as a leavening agent could contribute to increasing the variety of baked goods alternative to those leavened by S. cerevisiae.

Early gut mycobiota and mother-offspring transfer

BACKGROUND

The fungi in the gastrointestinal tract, the gut mycobiota, are now recognised as a significant part of the gut microbiota, and they may be important to human health. In contrast to the adult gut mycobiota, the establishment of the early gut mycobiota has never been described, and there is little knowledge about the fungal transfer from mother to offspring.

METHODS

In a prospective cohort, we followed 298 pairs of healthy mothers and offspring from 36 weeks of gestation until 2 years of age (1516 samples) and explored the gut mycobiota in maternal and offspring samples. Half of the pregnant mothers were randomised into drinking probiotic milk during and after pregnancy. The probiotic bacteria included Lactobacillus rhamnosus GG (LGG), Bifidobacterium animalis subsp. lactis Bb-12 and Lactobacillus acidophilus La-5. We quantified the fungal abundance of all the samples using qPCR of the fungal internal transcribed spacer (ITS)1 segment, and we sequenced the 18S rRNA gene ITS1 region of 90 high-quantity samples using the MiSeq platform (Illumina).

RESULTS

The gut mycobiota was detected in most of the mothers and the majority of the offspring. The offspring showed increased odds of having detectable faecal fungal DNA if the mother had detectable fungal DNA as well (OR = 1.54, p = 0.04). The fungal alpha diversity in the offspring gut increased from its lowest at 10 days after birth, which was the earliest sampling point. The fungal diversity and fungal species showed a succession towards the maternal mycobiota as the child aged, with Debaryomyces hansenii being the most abundant species during breast-feeding and Saccharomyces cerevisiae as the most abundant after weaning. Probiotic consumption increased the gut mycobiota abundance in pregnant mothers (p = 0.01).

CONCLUSION

This study provides the first insight into the early fungal establishment and the succession of fungal species in the gut mycobiota. The results support the idea that the fungal host phenotype is transferred from mother to offspring.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00159523.

Anti-Saccharomyces cerevisiae antibodies (ASCA) are associated with body fat mass and systemic inflammation, but not with dietary yeast consumption: a cross-sectional study

BACKGROUND

Baker's/brewer's yeast, Saccharomyces cerevisiae, has been used as an alternative to antibiotic growth promoters to improve growth performance in animals. In humans, Saccharomyces cerevisiae is among the most commonly detected fungi in fecal samples and likely originates from food. Recently, an association between anti-Saccharomyces cerevisiae antibodies (ASCA) and obesity in humans was suggested, but the cause of the elevated ASCA levels is not clear. Our aim was to study ASCA in morbidly obese subjects and explore potential associations with anthropometrics, diet, co-morbidities and biomarkers of inflammation and gut permeability.

METHODS

Subjects with morbid obesity referred to a specialized hospital unit were included. Diet and clinical data were recorded with self-administered questionnaires. Main dietary sources of baker's/brewer's yeast (e.g. bread and beer) were used as a proxy for the intake of yeast. Laboratory analyses included ASCA, serum zonulin (reflecting gut permeability), C-reactive protein and a routine haematological and biochemical screening.

RESULTS

One-hundred-and-forty subjects; 109 (78%) female, 98 with dietary records, mean age 43 years and BMI 42 kg/m2 were included. The number of ASCA positive subjects was 31 (22%) for IgG, 4 (2.9%) for IgA and 3 (2.1%) for IgM. Age, body fat mass and C-reactive protein were significantly higher in IgG-positive compared to IgG-negative subjects (P < 0.05). A borderline significant association was found between elevated zonulin and ASCA IgG-positivity (P = 0.06). No association was found between yeast-containing food and ASCA IgG-positivity, or between yeast-containing food and fat mass.

CONCLUSIONS

The findings indicate that ASCA IgG-positivity may be linked to the generalized inflammation commonly seen with increased adiposity, but not to dietary yeast intake. Other potential causes for the raised ASCA IgG concentrations, such as genetic predisposition, deviations in the gut microbiota and cross-reactivity of ASCA with other antigens, were not explored.

Unconventional bacterial association for dough leavening

The purpose of the research was to obtain innovative yeast-free doughs leavened by Zymomonas mobilis and Lactobacillus sanfranciscensis. Z. mobilis, as well as Saccharomyces cerevisiae, produces an equimolar mixture of ethanol and CO₂ through glucose, fructose or sucrose fermentation. In the present work, the inability of Z. mobilis to metabolize maltose has been circumvented by the addition of L. sanfranciscensis in the formulation. Indeed, L. sanfranciscensis, a heterofermentative lactic acid bacterium (LAB) typical of sourdough environment, hydrolyzes maltose releasing glucose which can be used by Z. mobilis for its metabolism. Biomass samples of Z. mobilis subs. mobilis DSM 424 and L. sanfranciscensis DSM 20663 were grown separately in liquid media and then associated in a model dough. Leavening trials set up by using three different microbial combinations (Lactobacillus:Zymomonas 80+80mg, 15+145mg and 145+15mg biomass, i.e. 1:1, 1:10 and 10:1 respectively on cell dry weight basis) evidenced CO₂ production levels (mL) higher than the mathematical sum of CO₂ produced by the single bacteria. In particular, when the biomass combination of L. sanfranciscensis and Z. mobilis was 1:1 (80+80mg cdw) and 10:1 (145+15mg cdw) a CO₂ production of 46.3-41.4mL versus 26.7-28.5mL was achieved. The calculated productivity gain showed positive performances of the microbial combination up to 180-240min leavening. The subsequent efficiency loss may be due several factors, above all glucose shortage for Z. mobilis, as well as decrease of dough pH that can negatively affect both Lactobacillus and Zymomonas metabolism. As in traditional sourdoughs, L. sanfranciscensis was responsible for the souring activity with positive effects on both dough tasting and reduction of spoilage microbiota; Z. mobilis was instead responsible for most of the CO₂ production. A bakery product leavened with the unconventional association Z. mobilis - L. sanfranciscensis will be addressed to people having adverse responses to the ingestion of bakery goods, thus providing innovation in the area of yeast-free leavened food.