Biological activities of Saccharomyces cerevisiae and fermented rice bran as feed additives

In Vitro Antimicrobial Activity of Essential Oils Against Salmonella enterica Serotypes Enteritidis and Typhimurium Strains Isolated from Poultry

Salmonella enterica serotype Enteritidis and S. enterica serotype Typhimurium are frequently present among poultry and are associated with outbreaks of human salmonellosis. The study investigated the in vitro antimicrobial activity of essential oils (EOs) obtained from Aloysia triphylla, Cinnamomum zeylanicum, Cymbopogon citratus, Litsea cubeba, Mentha piperita, Syzygium aromaticum against S. Enteritidis and S. Thyphimurium strains previously isolated from poultry. A 1:1 mixture of C. zeylanicum and S. aromaticum was also tested. The activity of all compounds was evaluated against the yeast Saccharomyces cerevisiae, commonly used as probiotic. The highest antibacterial activity was observed for C. zeylanicum (minimum inhibitory concentrations (MICs) ranging from 1.26 mg/mL to 0.63 mg/mL), S. aromaticum (MICs from 2.637 mg/mL to 0.164 mg/mL) and the mixture (MICs from 1.289 mg/mL to 0.322 mg/mL). No activity was recorded against S. cerevisiae. The results suggest a possible use of C. zeylanicum and S. aromaticum, alone or in combination, in the farm environment for disinfection and in poultry diet, combined with S. cerevisiae administration, for an integrated approach to avoid Salmonella intestinal colonization.

Tissue lipid metabolism and hepatic metabolomic profiling in response to supplementation of fermented cottonseed meal in the diets of broiler chickens

This study investigated the effects of fermented cottonseed meal (FCSM) on lipid metabolites, lipid metabolism-related gene expression in liver tissues and abdominal adipose tissues, and hepatic metabolomic profiling in broiler chickens. One hundred and eighty 21-d-old broiler chickens were randomly divided into three diet groups with six replicates of 10 birds in each group. The three diets consisted of a control diet supplemented with unfermented cottonseed meal, an experimental diet of cottonseed meal fermented by Candida tropicalis, and a second experimental diet of cottonseed meal fermented by C. tropicalis plus Saccharomyces cerevisae. The results showed that FCSM intake significantly decreased the levels of abdominal fat and hepatic triglycerides (P<0.05 for both). Dietary FCSM supplementation down-regulated the mRNA expression of fatty acid synthase and acetyl CoA carboxylase in liver tissues and the lipoprotein lipase expression in abdominal fat tissues (P<0.05 for both). FCSM intake resulted in significant metabolic changes of multiple pathways in the liver involving the tricarboxylic acid cycle, synthesis of fatty acids, and the metabolism of glycerolipid and amino acids. These findings indicated that FCSM regulated lipid metabolism by increasing or decreasing the expression of the lipid-related gene and by altering multiple endogenous metabolites. Lipid metabolism regulation is a complex process, this discovery provided new essential information about the effects of FCSM diets in broiler chickens and demonstrated the great potential of nutrimetabolomics in researching complex nutrients added to animal diets.

Preparation of Yeast Hydrolysate Enriched in Cyclo-His-Pro (CHP) by Enzymatic Hydrolysis and Evaluation of Its Functionality

In this study, we attempted to enrich cyclo-His-Pro (CHP) using enzymatic hydrolysis of yeast and to evaluate the functionality of yeast hydrolysate (YH)-enriched CHP. Flavourzyme offered a better performance in enhancing CHP content than other proteases. The CHP enrichment conditions were optimized as follows: addition of 1% Flavourzyme, 48-h incubation at 60°C, and pH 6.0. The CHP content significantly increased by 20-fold after ultra-filtration (UF). Maximal CHP translation was obtained after heating for 8 h at 50°C and pH 7.0. YH showed poor foaming capacity between pH 3.0 to 9.0. The emulsifying activities of YHs were slightly higher at near acidic pH. Increase in heating temperature and time resulted in decreased CHP content. The results indicate that YH is more heat stable after UF. Therefore, the CHP in YH after UF can be used as a food additive with physiological CHP activity and high heat stability.

Thermal stability of yeast hydrolysate as a novel anti-obesity material

We examined the thermal stability of yeast hydrolysates before and after ultrafiltration (UF) in vitro, and the anti-obesity activity of yeast hydrolysates before and after heat treatment in vivo. Yeast hydrolysate after UF showed significantly higher thermal stability than before UF. Yeast hydrolysates before and after UF showed 3 and 4 thermal transition peaks in their thermograms, respectively, and the total thermal denaturation enthalpies of yeast hydrolysates before and after UF were 69.5 and 36.5 J/g, respectively. For the anti-obesity activity study, yeast hydrolysates before and after heating were administered ad libitum with water to 7-week-old male SD rats. The administration of yeast hydrolysate (YH-control; no heat treatment, YH-1; heat treatment at 140°C, and YH-2; heat treatment at 160°C) significantly increased mRNA expression of cocaine- and amphetamine-regulated transcript (CART) compared with control rats (saline administration). However, there was no significant difference between the heat-treated groups and YH-control and there was no significant difference in neuropeptide Y expression between the heat-treated groups and YH-control. These results suggest that yeast hydrolysate can be use an anti-obesity material after heat treatment.

Rice bran fermented with saccharomyces boulardii generates novel metabolite profiles with bioactivity

Emerging evidence supporting chronic disease fighting properties of rice bran has advanced the development of stabilized rice bran for human use as a functional food and dietary supplement. A global and targeted metabolomic investigation of stabilized rice bran fermented with Saccharomyces boulardii was performed in three rice varieties. Metabolites from S. boulardii-fermented rice bran were detected by gas chromatography-mass spectrometry (GC-MS) and assessed for bioactivity compared to nonfermented rice bran in normal and malignant lymphocytes. Global metabolite profiling revealed significant differences in the metabolome that led to discovery of candidate compounds modulated by S. boulardii fermentation. Fermented rice bran extracts from three rice varieties reduced growth of human B lymphomas compared to each variety's nonfermented control and revealed that fermentation differentially altered bioactive compounds. These data support that integration of global and targeted metabolite analysis can be utilized for assessing health properties of rice bran phytochemicals that are enhanced by yeast fermentation and that differ across rice varieties.

Acute and subacute toxicity of yeast hydrolysate from Saccharomyces cerevisiae

The objective of this study was to obtain data on the safety-in-use of yeast hydrolysate in 10-30 kDa molecular weight as a dietary supplement by assessing its acute and subacute oral toxicity in female and male Sprague-Dawley (SD) rats. The single oral dose of the hydrolysate at 5000 mg/kg did not produce mortality or significant changes in the general behavior and gross appearance of the internal organs of rats. In subacute toxicity study, the hydrolysate was administered orally at a dose of 1000 mg/kg/day for a period of 14 days. The satellite group was treated with the hydrolysate at the same dose and the same period and kept for another 14 days after treatment. There were no significant differences in organ weights between control and treated group of both sexes. Hematological analysis and blood chemistry revealed no toxicity effects of Saccharomyces cerevisiae hydrolysate. Pathologically, neither gross abnormalities nor histopathological changes were observed. These results show that the hydrolysate possesses very low toxicity as indicated in SD rat model.

Effects of Bacillus subtilis var. natto and Saccharomyces cerevisiae mixed fermented feed on the enhanced growth performance of broilers

Bacillus subtilis var. natto N21 (Bac; for greater proteolytic capacity) and Saccharomyces cerevisiae Y10 (Sac; for greater acidic capacity) were applied to produce a 2-stage combined fermentation feed. This study investigated whether the enhancement of Bac+Sac fermented feed on broiler growth performance was due to the probiotics per se or due to the fermentation process. Trial 1 included 1-d-old broiler chicks (n=144) randomly assigned to control, water added (same as in the fermentation feed, 23%), and Bac+Sac fermented feed (FBac+Sac) treatments with 4 replicates. Trial 2 included 21-d-old broiler chickens (n=12) assigned into control and FBac+Sac groups for a metabolic trial for nutrient availability. Trial 3 included 1-d-old male broiler chicks (n=216) randomly assigned into 6 treatments with 3 replicates. Treatments included a control, Sac fermented feed (FSac), FBac+Sac, Bac powder (PBac), Sac powder (PSac), and Bac+Sac powder (PBac+Sac). The results from trial 1 showed that FBac+Sac increased BW and feed intake (P<0.05) in 21- and 39-d-old chickens. The water-added group showed decreased BW, weight gain, and feed intake (P<0.05). Trial 2 showed that FBac+ Sac increased gross energy availability (P<0.05). Trial 3 showed that FBac+Sac increased 21- and 39-d-old BW and weight gain (P<0.05). Diets supplemented with probiotic powder or fermented with Sac did not improve broiler growth performance (P>0.05). The growth performance improvement of the FBac+Sac treatment was probably not due to the added water, probiotic powder inclusion, or through single-strain fermentation, but due to the 2-stage fermentation process using Bac and Sac strains.

Immunomodulating capacity of commercial fish protein hydrolysate for diet supplementation

Dietary proteins harbour bioactive peptides that can be released by a fermentation process. Fish proteins are a valuable and little-exploited source of potentially active biopeptides. The aim of this research was to evaluate the effects of a commercially available fermented fish protein concentrate (Seacure) (FPC) derived from a fermentation process, on the mucosal immune response in a murine model. BALB/c mice received the FPC or the non-fermented powder at different concentrations (0.20, 0.25 or 0.30mg/ml) for 2, 5 or 7 consecutive days. At the end of each feeding period, histological studies of the gut were carried out and the phagocytic activity of peritoneal macrophages, the number of IgA+ cells in the small intestine lamina propria and bronchial tissue and the number of IL-4+, IL-6+, IL-10+, IFNgamma+ and TNFalpha+ cells in the small intestine lamina propria were determined. Different accumulative doses of FPC did not induce any inflammatory immune response and the normal morphology of the small intestine was not affected. Phagocytic activity of peritoneal macrophages was enhanced following FPC administration at 0.3mg/ml for 7 consecutive days. The number of IgA+ cells increased in the small intestine lamina propria but not in the bronchial tissue. IL-4, IL-6 and IL-10 were all significantly increased in the lamina propria of the small intestine of animals that received FPC. At the same time, some pro-inflammatory cytokines such as IFNgamma and TNFalpha also increased, but the intestinal homoeostasis was maintained and no tissue damage was observed. We conclude that FPC is an immunomodulating food with a demonstrated capacity to enhance non-specific host defense mechanisms.

Characterization of the metabolic shift between oxidative and fermentative growth in Saccharomyces cerevisiae by comparative 13C flux analysis

Background

One of the most fascinating properties of the biotechnologically important organism Saccharomyces cerevisiae is its ability to perform simultaneous respiration and fermentation at high growth rate even under fully aerobic conditions. In the present work, this Crabtree effect called phenomenon was investigated in detail by comparative ¹³C metabolic flux analysis of S. cerevisiae growing under purely oxidative, respiro-fermentative and predominantly fermentative conditions.

Results

The metabolic shift from oxidative to fermentative growth was accompanied by complex changes of carbon flux throughout the whole central metabolism. This involved a flux redirection from the pentose phosphate pathway (PPP) towards glycolysis, an increased flux through pyruvate carboxylase, the fermentative pathways and malic enzyme, a flux decrease through the TCA cycle, and a partial relocation of alanine biosynthesis from the mitochondrion to the cytosol. S. cerevisiae exhibited a by-pass of pyruvate dehydrogenase in all physiological regimes. During oxidative growth this by-pass was mainly provided via pyruvate decarboxylase, acetaldehyde dehydrogenase, acetyl-CoA synthase and transport of acetyl-CoA into the mitochondrion. During fermentative growth this route, however, was saturated due to limited enzyme capacity. Under these conditions the cells exhibited high carbon flux through a chain of reactions involving pyruvate carboxylase, the oxaloacetate transporter and malic enzyme. During purely oxidative growth the PPP alone was sufficient to completely supply NADPH for anabolism. During fermentation, it provided only 60 % of the required NADPH.

Conclusion

We conclude that, in order to overcome the limited capacity of pyruvate dehydrogenase, S. cerevisiae possesses different metabolic by-passes to channel carbon into the mitochondrion. This involves the conversion of cytosolic pyruvate either into acetyl CoA or oxaloacetate followed by intercompartmental transport of these metabolites. During oxidative growth mainly the NAD specific isoforms of acetaldehyde dehydrogenase and isocitrate dehydrogenase catalyze the corresponding reactions in S. cerevisiae, whereas NADPH supply under fermentative conditions involves significant contribution of sources other than the PPP such as e. g. NADPH specific acetaldehyde dehydrogenase or isocitrate dehydrogenase.

A plate assay for simultaneous screening of polysaccharide- and protein-degrading micro-organisms

AIMS

To develop a plate assay for simultaneous screening of polysaccharide-degrading and protein-degrading micro-organisms.

METHODS AND RESULTS

A plate assay, based on the visible solubilization of small substrate particles and the formation of haloes on Petri dishes, containing a mixture of diversely coloured insoluble polysaccharides and dye-labelled collagen as chromogenic substrates, was developed. This method was successfully applied for isolating the diverse polysaccharide- and/or protein-degrading bacteria from soil and sludge samples. Selected strains were identified using 16S rDNA partial sequencing; most of them belong to the genera Bacillus, Cellulomonas and Cellulosimicrobium.

CONCLUSIONS

This novel approach provides unique and valuable information for direct primary screening when the target of selection is micro-organisms exhibiting protein-degrading activity, polysaccharide-degrading activity or a specific combination of them.

SIGNIFICANCE AND IMPACT OF THE STUDY

This plate assay is convenient and easy to perform, rapid, and more adaptable for screening of a large number of samples, compared with other existing methods in the literature.