Propionic Acid Production Research Articles

Bioproduction of propionic acid using levulinic acid by engineered Pseudomonas putida.

The present study elaborates on the propionic acid (PA) production by the well-known microbial cell factory Pseudomonas putida EM42 and its capacity to utilize biomass-derived levulinic acid (LA). Primarily, the P. putida EM42 strain was engineered to produce PA by deleting the methylcitrate synthase (PrpC) and propionyl-CoA synthase (PrpE) genes. Subsequently, a LA-inducible expression system was employed to express yciA (encoding thioesterase) from Haemophilus influenzae and ygfH (encoding propionyl-CoA: succinate CoA transferase) from Escherichia coli to improve the PA production by up to 10-fold under flask scale cultivation. The engineered P. putida EM42:ΔCE:yciA:ygfH was used to optimize the bioprocess to further improve the PA production titer. Moreover, the fed-batch fermentation performed under optimized conditions in a 5 L bioreactor resulted in the titer, productivity, and molar yield for PA production of 26.8 g/L, 0.3 g/L/h, and 83%, respectively. This study, thus, successfully explored the LA catabolic pathway of P. putida as an alternative route for the sustainable and industrial production of PA from LA.

Effect of zero-valent iron on acidification and methane production using food waste under different food-to-microorganism ratios

During anaerobic fermentation of food waste (FW), acidification destabilizes the fermentation, and affects methane production. This study analyzed the anaerobic fermentation of FW to produce acid and gas under different food-to-microorganism (F/M) ratios after adding zero-valent iron (ZVI) to improve the performance of anaerobic fermentation. Results showed that when the F/M was 2, ZVI had a significant promoting effect on acetic acid, ethanol, and butyric acid production but significantly reduced propionic acid production. Moreover, optimal acid production was observed when 6 g L−1 ZVI powder was added. Furthermore, at ≥6 g L−1 ZVI, the biodegradation rate increased to >70%, and the cumulative methane production of the load increased to >440 mg L−1. Therefore, these results indicate that adding ZVI to FW digestion under different F/M ratios can increase methane production in an anaerobic fermentation system by promoting acetic acid production and reducing propionic acid production.

Use of apple pomace, glycerine, and potato wastewater for the production of propionic acid and vitamin B12

Propionic acid bacteria (PAB) are a source of valuable metabolites, including propionic acid and vitamin B12. Propionic acid, a food preservative, is synthesized from petroleum refining by-products, giving rise to ecological concerns. Due to changing food trends, the demand for vitamin B12 has been expected to increase in the future. Therefore, it is necessary to look for new, alternative methods of obtaining these compounds. This study was conducted with an aim of optimizing the production of PAB metabolites using only residues (apple pomace, waste glycerine, and potato wastewater), without any enzymatic or chemical pretreatment and enrichment. Media consisting of one, two, or three industrial side-streams were used for the production of PAB metabolites. The highest production of propionic acid was observed in the medium containing all three residues (8.15 g/L, yield: 0.48 g/g). In the same medium, the highest production of acetic acid was found — 2.31 g/L (0.13 g/g). The presence of waste glycerine in the media had a positive effect on the efficiency of propionic acid production and P/A ratio. The concentration of vitamin B12 obtained in the wet biomass of Propionibacterium freudenreichii DSM 20271 ranged from 90 to 290 µg/100 g. The highest production of cobalamin was achieved in potato wastewater and apple pomace, which may be a source of the precursors of vitamin B12 — cobalt and riboflavin. The results obtained show both propionic acid and vitamin B12 can be produced in a more sustainable manner through the fermentation of residues which are often not properly managed.Key points• The tested strain has been showed metabolic activity in the analyzed industrial side-streams (apple pomace, waste glycerine, potato wastewater).• All the side-streams were relevant for the production of propinic acid.• The addition of waste glycerine increases the propionic acid production efficiency and P/A ratio.• B12 was produced the most in the media containing potato wastewater and apple pomace as dominant ingredients.

A redox-based strategy to enhance propionic and butyric acid production during anaerobic fermentation

This study investigated the selective production of volatile fatty acids (VFAs) during anaerobic mixed‐culture fermentation. The experiment used chicken manure (CM) as a potential substrate to produce high added‐value propionic acid and butyric acid under an alkaline environment. The conversion of CM into selective VFAs depends highly on operational conditions such as pH and redox balance. Therefore, the current experiment is designed to employ amino acid addition and develop a redox balance control method to control the final VFA profile. This study showed that 0.2–5.0 % valine and threonine addition successfully enhanced propionic acid and butyric acid production during alkaline fermentation and hence decreased the proportion of acetic acid from 83 % to approximately 47 %. The oxidation–reduction potential (ORP) and redox cofactor ratio (NADH/NAD+) were measured to support the selective VFA production mechanism. The results obtained in this study bring extra value to the valorization of CM within the circular economy concept for selective value-added VFA production.

Effect of Fe3O4 on propionic acid production by anaerobic fermentation of waste cooking oil and aerobic sludge

In this study, Fe3O4 was added to the anaerobic fermentation process of waste cooking oil (WCO) and aerobic sludge (AS), and its effects on the production of volatile fatty acids (VFAs) were explored from the perspectives of propionic acid concentration, Fe2+ concentration, and microorganisms. The results showed that when the dosage of Fe3O4 was 5 g/L, it was conducive to the hydrolysis and acidification of WCO. And it had a significant effect on the concentration of VFAs and propionic acid. The maximum concentration of VFAs was 7142.84 ± 201.48 mg COD/L, and the maximum concentration of propionic acid was 4990.92 ± 124.76 mg COD/L, which increased by 20.65 % and 27.65 % respectively compared with the blank group. Meanwhile, microbial community analysis showed that Firmicutes, Proteobacteria, and Bacteroidetes are the main phylum for the production of VFA in the anaerobic fermentation of WCO and as. Veillonellaceae under Firmicutes was the main microorganism to produce propionic acid. It provides microbial support for the hydrolysis of WCO and the subsequent production of propionic acid. This study provides a new idea for Fe3O4 to promote the hydrolysis of WCO and produce propionic acid, and brings potential economic benefits to WCO treatment.

Limosilactobacillus reuteri Attenuates Atopic Dermatitis via Changes in Gut Bacteria and Indole Derivatives from Tryptophan Metabolism.

Gut bacteria are closely associated with the development of atopic dermatitis (AD) due to their immunoregulatory function. Indole derivatives, produced by gut bacteria metabolizing tryptophan, are ligands to activate the aryl hydrocarbon receptor (AHR), which plays a critical role in attenuating AD symptoms. Limosilactobacillus reuteri, a producer of indole derivatives, regulates mucosal immunity via activating the AHR signaling pathway. However, the effective substance and mechanism of L. reuteri in the amelioration of AD remain to be elucidated. In this research, we found that L. reuteri DYNDL22M62 significantly improved AD-like symptoms in mice by suppressing IgE levels and the expressions of thymic stromal lymphopoietin (TSLP), IL-4, and IL-5. L. reuteri DYNDL22M62 induced an increase in the production of indole lactic acid (ILA) and indole propionic acid (IPA) via targeted tryptophan metabolic analysis and the expression of AHR in mice. Furthermore, L. reuteri DYNDL22M62 increased the proportions of Romboutsia and Ruminococcaceae NK4A214 group, which were positively related to ILA, but decreased Dubosiella, which was negatively related to IPA. Collectively, L. reuteri DYNDL22M62 with the role of modulating gut bacteria and the production of indole derivatives may attenuate AD via activating AHR in mice.

Effect of Bergamot and Laoxianghuang Polysaccharides on Gut Microbiota Derived from Patients with Hyperlipidemia: An Integrative Analysis of Microbiome and Metabolome during In Vitro Fermentation.

The aim of this study was to investigate the effects of bergamot polysaccharide (BP) and Laoxianghuang polysaccharides (LPs, fermented bergamot) on the microbiome and metabolome during the in vitro fermentation of gut microbiota from patients with hyperlipidemia. Results indicated that both BP and LPs were able to increase the production of acetic acid, propionic acid, and butyric acid. However, only LPs could decrease the content of isobutyric acid and isovaleric acid, which are detrimental to gut health. A 16S rRNA analysis showed that both BP and LPs could reduce the proportion of Fusobacterium, whereas they increased the Bacteroides content in hyperlipidemia. Untargeted UPLC-MS/MS metabolomic profiling found six bio-markers that were significantly changed after BP and LPs intervention, and four of the down-regulated metabolites were long-chain fatty acids associated with vascular diseases. These findings provide new evidence that BP and LPs have the potential to regulate imbalances in the gut microbiota in patients with hyperlipidemia and ameliorate its metabolic abnormalities.

Effects of Zymosan on Short-Chain Fatty Acid and Gas Production in in vitro Fermentation Models of the Human Intestinal Microbiota.

In this study, the effects of zymosan (HG, hydrolyzed glucan) on the structure and metabolism of fecal microbiota in Chinese healthy people was investigated by an in vitro simulated intestinal microecology fermentation model. We found that HG significantly regulated fecal microbiota composition, including the increase of Bifidobacterium, Faecalibacterium, Prevotella and the decrease of Escherichia-Shigella. Moreover, HG significantly increased the total production of short chain fatty acids (SCFAs) and gases, in which the production of Acetic acid, Propionic acid, CO2, and H2 significantly increased while the production of Isovaleric acid and NH3 significantly decreased. Additionally, the supplement of HG showed certain differences in the regulation of microbiota from four groups. HG significantly increased the relative abundance of Bifidobacterium and significantly decreased the relative abundance of Escherichia-Shigella excluding the older men group. Meanwhile, and the relative abundance of Lactobacillus was significantly increased in young populations. And the relative abundance of Bacteroides was significantly decreased only in the young women. Furthermore, HG significantly increased H2 concentration only in older men. These findings suggest that HG, as a new generation of prebiotics, could regulate the structure of fecal microbiota and its metabolites in a better direction, but when HG participates in precision nutrition formula, it may be necessary to consider the differences in the utilization of different populations.

Experimental determination of the lower flammability limit and limiting oxygen concentration of propanal/air mixtures under elevated temperatures and pressures

Aside from being a critical intermediate species in the combustion of hydrocarbons, propanal, as an isomer of acetone and propylene oxide, is also an important chemical raw material widely used in propionic acid production under elevated temperatures and pressures. Unfortunately, propanal reacts readily with air or oxygen, resulting in severe flame or explosion accidents under those special conditions. To reduce the risk, the concentration of propanal and oxygen needs to be controlled strictly. Therefore, the lower flammability limit (LFL) and the limiting oxygen concentration (LOC) of propanal at elevated temperatures and pressures need to be known. To this end, experiments were carried out in a reinforced 20 L spherical explosive vessel at the temperatures of 75 ℃ and 95 ℃ and pressures varying from 0.5 MPa to 2.2 MPa. The influences of temperature and pressure on the LFL and LOC were analyzed. The results show that the oxidation of propanal proceeds slowly during the air injection at 95 ℃. It is worth noting that air can be substituted by a mixture of 79% N2 and 21% O2. During the gas distribution, mixing N2 with propanal first can effectively reduce the oxidation reaction, and the resultant LFLs of propanal/N2/O2 are slightly lower than that of propanal/air. In the presence of the throttling effect, gaseous propanal and its oxides will condense into droplets near the exhaust port. Then the droplets absorb heat and vaporize into gases again under elevated temperatures, increasing the concentration of combustible components in the confined space. Thus, there is still an explosion risk in the vessel after the unignited low concentration propanal has been rapidly discharged from elevated pressures to the atmospheric pressure. Also, propanal has a lower LOC than conventional hydrocarbon gases (e.g., methane and propane), and the LOC decreases with increasing initial pressure. Specifically, at 95 ℃, the LOCs of the propanal/N2/O2 mixtures were 4.3% and 3.3% for 1.0 and 2.2 MPa, respectively. In addition, the empirical formula in the existing literature is not suitable for estimating the LOC of propanal.

Dietary γ-Aminobutyric Acid Supplementation Inhibits High-Fat Diet-Induced Hepatic Steatosis via Modulating Gut Microbiota in Broilers.

The present study aims to investigate the effect of γ-aminobutyric acid (GABA) on liver lipid metabolism and on AA broilers. Broilers were divided into three groups and fed with low-fat diets, high-fat diets, and high-fat diets supplemented with GABA. Results showed that GABA supplementation decreased the level of triglyceride (TG) in the serum and liver of broilers fed high-fat diets, accompanied by up-regulated mRNA expression of genes related to lipolysis and β-oxidation in the liver (p < 0.05). Furthermore, GABA supplementation increased liver antioxidant capacity, accompanied by up-regulated mRNA expression of antioxidant genes (p < 0.05). 16S rRNA gene sequencing showed that GABA improved high-fat diet-induced dysbiosis of gut microbiota, increased the relative abundance of Bacteroidetes phylum and Barnesiella genus, and decreased the relative abundance of Firmicutes phylum and Ruminococcus_torques_group and Romboutsia genus (p < 0.05). Moreover, GABA supplementation promoted the production of propionic acid and butyric acid in cecal contents. Correlation analysis further suggested the ratio of Firmicutes/Bacteroidetes negatively correlated with hepatic TG content, and positively correlated with cecal short chain fatty acids content (r > 0.6, p < 0.01). Together, these data suggest that GABA supplementation can inhibit hepatic TG deposition and steatosis via regulating gut microbiota in broilers.

Effect of linear and branched fructans on growth and probiotic characteristics of seven Lactobacillus spp. isolated from an autochthonous beverage from Chiapas, Mexico.

The effect that the fructans of Cichorium intybus and Agave salmiana have on health, as well as on the growth of some Lactobacillus species, has been demonstrated. The aim of this work was to evaluate the effect of linear and branched fructans on the growth of seven strains and some probiotic characteristics. The molecular identification of seven strains was performed. Moreover, the growth, resistance to antibiotics and simulated gastrointestinal conditions were also evaluated when these microorganisms were grown in a culture medium containing agave and chicory fructans. The strains were identified as Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Lactiplantibacillus fabifermentans and Lactiplantibacillus paraplantarum. The results suggest that the seven Lactobacillus strains were able to grow using agave (branched) and chicory (linear) fructans. The linear and branched fructans statistically influenced the kinetic parameters. The specific growth rate varied between 0.270 and 0.573h-1 and the generation time between 1.21 and 2.45h for all strains and culture media. All strains showed a growth of 9 Log CFU/mL in all the culture media. Production of lactic, acetic, propionic, butyric, formic and succinic acid was influenced by linear and branched fructans (p < 0.05). All the strains survived simulated gastrointestinal conditions greater than 83%. The resistance of Lactobacillus against ciprofloxacin and rifaximin was significantly affected by linear and branched fructans, but survival to gastrointestinal conditions was not affected by the type of substrate. These results highlight the use of the seven strains, which have probiotic potential; therefore, these could be applied in several biotechnological products.

Rapid identification of new isolates of Acidipropionibacterium acidipropionici by fluorescence in situ hybridization (FISH)

Acidipropionibacterium acidipropionici is widely used for many applications, such as propionic acid production, cereal silage, and also as probiotic. Due to this plethora of applications, new isolates of A. acidipropionici with improved features are being searched for. These new isolates must be accurately identified, however, most approaches become expensive and time-consuming when the number of isolates is high. On the contrary, fluorescence in situ hybridization allows the affordable, reliable, and rapid identification of microorganisms in pure cultures and environmental and medical samples. Therefore, the aim of this work was to apply a fluorescent in situ hybridization probe for the reliable identification of new A. acidipropionici isolates. To this end, probe Pap446, specific for A. acidipropionici, was validated by hybridization assays with strains of this species from different origins, other species of the same genus or family, and unrelated genera. Eight isolates with propionibacterium characteristics were obtained from milk and feces of cows. Probe Pap446, hybridized only with isolates III and VI. The identity of these isolates was further confirmed by PCR using group and species-specific primers for propionibacteria and 16S rDNA sequencing.

FERMENTACIÓN RUMINAL Y PRODUCCIÓN DE METANO IN VITRO DE DIETAS PARA OVINOS CON INCLUSIÓN DE TANINOS CONDENSADOS Y NIVELES CRECIENTES DE ACEITE DE ORÉGANO (Lippia graveolens)

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Ruminants have been related to greenhouse gas production. Therefore, it has been necessary to find alternatives by using natural additives to reduce their production by modulation of rumen fermentation. &lt;strong&gt;Objective&lt;/strong&gt;. It was to evaluate the effect of the addition of condensed tannins (CT) and different levels of essential oregano oil (&lt;em&gt;Lippia graveolens&lt;/em&gt;) (EOO) in sheep's diets on &lt;em&gt;in vitro&lt;/em&gt; fermentation products such as total gas production, methane (CH&lt;sub&gt;4&lt;/sub&gt;), carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;), pH, ammoniacal nitrogen (N-NH&lt;sub&gt;3&lt;/sub&gt;), and volatile fatty acids (VFA). &lt;strong&gt;Methodology.&lt;/strong&gt; There were evaluated six experimental diets: the control diet with 4% of CT kg/DM, and 0.02, 0.04, 0.06, 0.08 or 1% de EOO kg/DM, respectively. Total gas production, CH&lt;sub&gt;4&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt;, pH, N-NH&lt;sub&gt;3&lt;/sub&gt;, and AGV were measured at different &lt;em&gt;in vitro&lt;/em&gt; incubation times. &lt;strong&gt;Results.&lt;/strong&gt; Total gas production was not affected (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05) due to treatment or the interaction treatment*time. An exponential increment was observed (&lt;em&gt;P&lt;/em&gt; &amp;lt; 0.05) according to incubation time. CH&lt;sub&gt;4&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; production increased at 48 h. The lowest emissions of these gases were recorded when 0.04, 0.06, 0.08, and 1% of EOO were added to the diet. Nevertheless, no differences were found (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05) due to treatment or the interaction treatment*time. Acetic and butyric acid concentrations were affected due to incubation time and the interaction treatment*time; however, there was no effect due to treatment (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05). Propionic acid production and pH were not affected (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05) due to treatment, time, or interaction treatment*time. N-NH&lt;sub&gt;3&lt;/sub&gt; production increased through incubation time (&lt;em&gt;P&lt;/em&gt; &amp;lt; 0.05), with the highest concentration at 48 h for all treatments, without differences (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05) due to treatment or interaction treatment*time. &lt;strong&gt;Implications.&lt;/strong&gt; These results suggest that the inclusion levels of TC and EOO in the diet were not enough to affect rumen fermentation or methane production. Therefore, it is necessary to evaluate higher levels of these compounds in sheep's diets. &lt;strong&gt;Conclusion.&lt;/strong&gt; The addition of CT or the different levels of EOO included in sheep's diets evaluated in this study did not affect total gas production, CH&lt;sub&gt;4&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt;, pH, concentration of N-NH&lt;sub&gt;3&lt;/sub&gt;, AGV, and pH.&lt;/p&gt;

Assessment on the Fermentation Quality and Bacterial Community of Mixed Silage of Faba Bean With Forage Wheat or Oat.

Faba bean (Vicia faba L.), although a kind of high-quality and high-yield forage, could hardly achieve a great quality of silage because of its high buffering capacity. Mixed silage of faba bean with forage wheat (Triticum aestivum L.) or oat (Avena sativa L.) at different ratios could improve the fermentation quality and bacterial community. Compared with 100% faba bean silage (BS), mixed silage improved the fermentation quality, not only increased lactic acid production and reduced pH, but reduced the production of propionic acid and ammonia nitrogen. The chemical compositions of faba bean with forage wheat (BT) mixed silage were better than that of faba bean with oat (BO) mixed silage, and that of 3:7, 5:5 (fresh matter basis) mixing ratios were better than 1:9. However, the fermentation quality of BO mixed silage was better than that of BT, and that of 3:7 mixed silage (BO30) was the best overall. Analysis of the bacterial community showed that mixed silage increased the relative abundance of lactic acid bacteria after ensiling, and the relatively higher abundance of Lactobacillus showed the inhibitory effects on the proliferation of Serratia and Hafnia_Obesumbacterium, so that it alleviated their negative effects on silage and stabilized the fermentation quality. This present study exhibited that mixed silage of faba bean with forage wheat or oat not only had significant effects on chemical compositions and fermentation quality of materials but modified bacterial community so that improved the fermentation quality effectively. The mixed silage of 30% faba bean with 70% oat (BO30) is recommended in the faba bean mixed silage.

Pomegranate peel polyphenols interaction with intestinal flora and its metabolic transformation

1. Pomegranate peel polyphenols (PPPs) have anti-oxidation, anti-atherosclerosis, anti-obesity effect, and so on. However, few studies have been conducted on the absorption and transformation of pomegranate polyphenols in the gut and the biologically active forms that ultimately work in the body. 2. In this study, PPPs (300 mg/kg/day) were given to normal rats and relatively sterile rats by gavage respectively. The relatively sterile rats were obtained by neomycin sulfate (250 mg/kg/day) gavage to rats. The purpose of this study is to elaborate the relationship between intestinal flora and polyphenol metabolism of pomegranate peel, and to quantitatively analyze the transformation process of its metabolite urolithin in rats. 3. The results showed that decreased bacterial diversity could significantly reduce the abundance of PPPs metabolites in feces and urine in relatively sterile rats. PPPs can regulate intestinal flora structure, significantly enhance the content of Clostrida Firmicutes (P < 0.05), and effectively promote acetic acid, propionic acid, butyric acid, iso-butyric acid and valeric acid production in rat (P < 0.05 or P < 0.01 or P< 0.001). PPPs can significantly elevate the relative proportion of Ruminococcaceae (P < 0.05). Ruminococcaceae_NK4A214_group, Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-005 can promote the metabolic transformation of PPPs and make the utilization of Urolithin A more effective.

Hydroxy-selenomethionine supplementation promotes the in vitro rumen fermentation of dairy cows by altering the relative abundance of rumen microorganisms.

AimsThis study aims to investigate the effect of hydroxy‐selenomethionine supplementation on the in vitro rumen fermentation characteristics and microorganisms of Holstein cows.Methods and ResultsFive fermentation substrates, including control (without selenium supplementation, CON), sodium selenite supplementation (0.3 mg kg−1 DM, SS03), and hydroxy‐selenomethionine supplementation (0.3, 0.6 and 0.9 mg kg−1 DM, SM03, SM06 and SM09, respectively) were incubated with rumen fluid in vitro. The results showed that in vitro dry matter disappearance and gas production at 48 h was significantly higher in SM06 than SM03, SS03 and CON; propionate and total volatile fatty acid (VFA) production was higher in SM06 than CON. Moreover, higher species richness of rumen fluid was found in SM06 than others. Higher relative abundance of Prevotella and Prevotellaceae‐UCG‐003 and lower relative abundance of Ruminococcus‐1 were detected in SM06 than CON. Besides, higher relative abundance of Ruminococcaceae_UCG‐005 was found in CON than other treatments.ConclusionsIt is observed that 0.6 mg kg−1 DM hydroxy‐selenomethionine supplementation could increase cumulative gas production, propionate, and total VFAs production by altering the relative abundance of Prevotella, Prevotellaceae‐UCG‐003, Ruminococcaceae_UCG‐005 and Ruminococcus‐1, so that it can be used as a rumen fermentation regulator in Holstein cows.Significance and Impact of the StudyThis study provides an optimal addition ratio of hydroxy‐selenomethionine on rumen fermentation and bacterial composition via an in vitro test.

Broccoli microgreens have hypoglycemic effect by improving blood lipid and inflammatory factors while modulating gut microbiota in mice with type 2 diabetes.

This study aims to explore the hypoglycemic effect of lyophilized broccoli microgreens on type 2 diabetes (T2D) in mice. The experiment lasted 18weeks, including 1week of adaptation (normal diet) and 17-week experimental period (high-fat diet). After ingestion of broccoli microgreens, the body weight and glucose homeostasis were improved. Meanwhile, the blood lipid status, antioxidant indexes, and inflammatory factors level were improved. Moreover, the insulin resistance and the pathological changes in mice organs were reversed. In addition, the composition of gut microbiota and the production of propionic acid in intestinal content were improved. Our experiment proved that broccoli microgreens have the ability to regulate T2D and improve symptoms of mice T2D induced by high-fat diet and streptozotocin (STZ). PRACTICAL APPLICATIONS: For years, the functionality of broccoli microgreens has attracted much attention. This article will prove the therapeutic effect of broccoli microgreens on T2D and explain its principle of action in the management of T2D.

Metagenomics and network analysis elucidating the coordination between fermentative bacteria and microalgae in a novel bacterial-algal coupling reactor (BACR) for mariculture wastewater treatment

To achieve the goal of treating mariculture wastewater economically and efficiently, a novel bacterial-algal coupling reactor (BACR) integrating acidogenic fermentation and microalgae cultivation was firstly investigated for mariculture wastewater treatment. Volatile fatty acids (VFAs) generated in the dark chamber migrated into the photo chamber for microalgal utilization, which alleviated the pH drop and feedback inhibition of the acidogenic fermentation. The maximum dry cell weight (DCW) of microalgae was 1.46 g/L, and pollutants such as chemical oxygen demand (COD), ammonium (NH4+-N) and total phosphorus (TP) in the BACR were effectively removed under the mixotrophic culture condition. Furthermore, bacterial community profiles and functional genes in the BACR and single acidogenic fermentation reactor were identified. Compared with the single acidogenic fermentation reactor, most of the fermentative bacteria (e.g., Ruminococcus, Christensenellaceae R-7 group, Exiguobacterium, Pseudomonas and Levilinea) were enriched by the BACR. From the genetic perspective, the abundances of dominant genes (ackA, acs and atoD) associated with acetic, propionic and butyric acid production were greatly enhanced in the BACR. In the fatty acid biosynthesis pathway (ko00061), three kinds of high-abundance acetyl-CoA carboxylase genes and eight kinds of downstream functional genes were up-regulated in the BACR. Finally, based on co-occurrence network analysis, the coordination between fermentative bacteria and microalgae in the BACR was revealed. This study provided a deep insight into the advantage and potential of the BACR in mariculture wastewater treatment.

Growth characterization of Propionibacterium and propionic acid production capabilities at different temperatures and pH levels.

Bacteria from the Propionibacterium genus were cocktailed to investigate growth and production of propionic acid at different temperatures and pH levels. A gas chromatograph with a flame ionization detector was also used for instrumental analysis. The Propionibacterium cocktails did not produce propionic acid at 10 and 20°C for 10days, but produced propionic acid at concentrations of 3265.32, 3670.76, and 1926.04μg/mL at 25, 30, and 40°C for 18days, respectively. In pH tests, the cocktails did not produce propionic acid at pH 3 and 9 for 14 and 7days, respectively. However, they produced propionic acid at concentrations of 2596.66, 2952.66, 3321.35, and 3586.95μg/mL at pH 4, 5, 6, and 7 for 18days, respectively. Growth characteristics of Propionibacterium cocktails by temperature and pH were set so that they reached the extinction stage after four days in the logarithmic phase.

FERMENTATION OF MILK WHEY PERMEATE WITH DIFFERENT DAIRY PROPIONIBACTERIA STRAINS

This research was focused on whey ultrafiltration permeate (UF) fermentation by genetically unmodified (wild) organisms. We chose five classical Propionibacterium (Prb) strains which are attributed to the dairy subclass. The optimal temperature for Prb growth is around 28-30°C, however, for energy saving purposes the aim of this study was to observe the organic acid, especially propionic acid (PA) and biomass production of the chosen Prb (DSM 20273 Acidipropionibacterium acidipropionici = A, DSM 20272 Acidipropionibacterium acidipropionici = B; DSM 4902 Prb. freudenreichii = E; DSM 20535 Acidipropionibacterium jensenii = J; DSM 20276 Acidipropionibacterium thoenii = T) at the room temperature (22±0.5 °C). As expected, all the strains were able to convert lactose into acid, however, with different efficiency, thus the production of PA by Prb is strain-dependent. The higher productivity of PA was observed in samples with strains T, J, and B in a 26-day period, however, it should be noted that also the strain E showed high efficiency in a shorter (6-day) period. The highest concentration of PA was produced by strain T, and it reached 3.7±0.13 g L-1 within 26-day period. The concentration of the PA produced depends on the duration of fermentation, and on the proportions of other acids produced as well. An individual strain initially can produce PA more slowly than others, but over time can be effective, which may be related to adaptation to environmental conditions. We also observed the presence of background microflora in whey permeates – most likely lactic acid bacteria. Lactic acid was produced most rapidly and was the most abundant acid produced from whey UF.