Acid Fermentation Research Articles

Improvement of butanol production from sweet sorghum juice by Clostridium beijerinckii using an orthogonal array design

Optimization of three chemical supplements: CaCO3 (4–10g/L), (NH4)2SO4 (0.50–2.00g/L) and butyric acid (3–9g/L) for high levels butanol production by Clostridium beijerinckii TISTR 1461 from sweet sorghum juice was attempted using an L9 (34) orthogonal array design (OAD). The fermentation was carried out at 37°C in 1-L screw-capped bottles under strictly anaerobic conditions. The OAD results showed that the optimum concentrations of CaCO3, (NH4)2SO4 and butyric acid for butanol fermentation were 7, 1.25 and 6g/L, respectively. The butanol concentration (Pb) and productivity (Qb) values of the verification experiment under the optimum conditions in a 5-L fermenter were 15.46g/L and 0.43 g/L.h, respectively at 36h. The chemicals influencing the Pb and Qb values in descending order were butyric acid>CaCO3>(NH4)2SO4. In the control treatment (sweet sorghum juice without chemical supplementation), the Pb and Qb values were only 0.64g/L and 0.02g/L.h, respectively.

Isolating and evaluating lactic acid bacteria strains with or without sucrose for effectiveness of silage fermentation

AbstractThe aim of this study was to screen and evaluate lactic acid bacteria strains for their ability to ferment alfalfa, Leymus chinensis and native grass into silage. We isolated 186 lactic acid bacteria strains from alfalfa, native grass and selected eight strains by acid production test and growth rate test. The eight stains were identified using morphological observations, Gram staining, physiological and biochemical tests, an acid tolerance test and 16S rDNA sequencing. All eight strains (LP1, LP2, LC1, LC2, PP1, PP2, EF1 and EF2) grew at pH 4.0 and 6.5%NaCl. Strains LP1 and LP2 were identified as Lactobacillus plantarum, LC1 and LC2 as Lactobacillus casei, PP1 and PP2 as Pediococcus pentosaceus, EF1 as Enterococcus faecalis, and EF2 as Enterococcus faecium based on their 16S rDNA sequences. The eight strains and two commercial inoculants (PS and CL) were added with or without sucrose to native grass, L. chinensis, and alfalfa to produce silage. All eight screened strains decreased the pH and ammonia nitrogen (N) content and increased the lactic acid content of alfalfa silages. No butyric acid was detected in the L. chinensis and alfalfa silages. Addition of sucrose with the screened strains resulted in lower pH and ammonia N content, and higher lactic acid content and total fermentation acids content in all three silages. The eight strains improved the fermentation quality of alfalfa silage. All strains were more effective when supplemented with sucrose. No efficient lactic acid bacteria strain was found for ensiling the native grass, but the high fermentation quality native grass silage could be obtained using the combination of lactic acid bacteria strains and 2% sucrose.

Vliv kyselých siláží v krmné dávce dojnic na obsah parametrů bachorové fermentace

Twenty dairy cows were used in an experiment at which the influence of silages with different content of acids on the rumen fermentation was studied. Animals were divided into experimental and control group, each of them about 10 individuals. Feeding ratio consisted of maize silage (26 kg), alfalfa silage (13 kg), meadow hay (1 kg) and corn mixture (8.5 kg). The experimental group was fed an inoculated maize silage, with higher contents of fermentation acids. Intake of total acids per 1 kg live weigh was higher in the experimental group than control group (1.98 g/kg; 1.48 g/kg live weight, respectively). The rumen fluid was taken per orally 2-3 hours after feeding. Mean value of pH of rumen fluid was significantly (P<0.05) lower in the experimental group (5.8 ± 0.08) in comparison with control group (6.2 ± 0.06).The most significant increase (P<0.01) of VFA content (125 ± 5.2 mmol/l) and lactic acid content (4.8 ± 0.2 mmol/l) was observed in rumen fluid of experimental group. Significant differences (P<0.05) of propionic acid and butyric acid content were also found out between the groups. Nevertheless, acetic acid content was insignificant (P>0.05) lower in experimental group. A protozoa (infusoria) content was significantly (P<0.01) lower in the experimental group (175.76 ± 12.54 thousand/ml) as compared with the control group (288.1 ± 13.73 thousand/ml).

Screening the optimal ratio of symbiosis between isolated yeast and acetic acid bacteria strain from traditional kombucha for high-level production of glucuronic acid

Glucuronic acid-a human detoxifying drug can be found in traditional kombucha which is a sweetened-black tea fermented by symbiotic microflora between yeast and acetic acid bacteria embedded within a microbial cellulose membrane. The main purpose of the study is to obtain the new designed symbiosis from the isolated yeasts and bacterial strains which can produce the high-level glucuronic acid kombucha and avoid unexpected microbial contaminants. The isolation, selection and identification showed the best initial combination ratio between Dekkera bruxellensis KN89 and Gluconacetobacter intermedius KN89 is 4Y (yeast):6A (acetic acid -bacteria) in number of living cell per milliliter which produced 175.8 mg L−1 glucuronic acid in 7-day fermentation (P < 0.05). This study also provides a basic understanding about fermentation kinetics of this symbiosis in order to control and enhance the final product at the critical time point (after 54 hrs of process). The findings of this study are practically relevant in producing a safe and glucuronic acid enriched kombucha.

Cellulosic Fermentation Using Bacillus thermoamylovorans –Enabled Digested Sludge

AbstractThe effectiveness of the Bacillus thermoamylovorans-enabled digested sludge in catalyzing cellulosic fermentation was tested under batch, mesophilic (40 plus or minus 1°C), unacclimatized, and high-loading (1.6 g cellulose in 80 mL aqueous solution) conditions. B. thermoamylovorans isolated from a molasses-fed anaerobic bioreactor was capable of quickly converting cellulose to alcohols and volatile organic acids (VOAs) at an overall rate of 0.32 g CODS/g VSS-day [volatile suspended solids (VSS), soluble chemical oxygen demand (CODS)] without producing H2. The digested sludge grown on pig manure, after an initial lag of 6 days, was able to produce H2, alcohols, and VOAs from cellulose at the rates of 0.021 L H2/g VSS-day and 0.16 g CODS/g VSS-day, respectively. The experiment which used a mixture of 0.014 g B. thermoamylovorans and 0.172 g digested sludge yielded the best results, with about 11-fold and sevenfold rate increases in H2 production and acid fermentation, respectively, compared to th...

Vliv přídavku kyseliny benzoové na kvalitu fermentačního procesu v porovnání s neošetřenými silážemi

The influence of benzoic acid and formic acid (positive control) of ensilaged maize and pressed sugar beet pulp on quality fermentation processes was studied in a laboratory experiment. The effect of additive on the quality of fermentation process during maize ensiling was studied in a first model experiment. Preservatives such as formic acid and benzoic acid were added to ensiled maize at the concentration of 1L/t and 1 kg/t, respectively. When benzoic acid was used as a preservative, the pH and the N-NH3/ N total ratio decreased statistically (P&lt;0.05) significantly while the titration acidity increased (P&lt;0.05) in comparison with the control values. The addition of HCOOH to the maize silage reduced the level of acetic acid in dry matter by 11.3% while the overall level of acids decreased by 1.8%. The minimum loss of dry matter (2%) was found in the silage treated with formic acid in comparison with that of the control (11.0%).Sugar beet pulp silages with benzoic acid or formic acid after 32 days of storage had a better sensuous evaluation than the control silage. The most intensive decrease of pH value was observed after formic acid addition as compared with control silage. The statistically significantly (P&lt;0.05) highest lactic acid content (49.64 ± 0.28) as well as the highest ratio of LA/VFA were found in the sugar beet pulp silage with benzoic acid. Lactic acid constituted the highest percentage (P&lt;0.05) of all fermentation acids in the silage with benzoic acid additive (65.12 ± 0.80). Undesirable butyric acid (BA) was not found in any variant of silages. The positive correlation between the titration acidity and acids sum in dry matter of silage conserved with formic acid was found. The additive of organic acids reduced significantly TA and fermentation acids content. Between the pH value and lactic acid content, no correlation was found.

In vitro probiotic characteristics of Lactobacillus plantarum ZDY 2013 and its modulatory effect on gut microbiota of mice

Lactobacillus plantarum ZDY 2013, a novel strain isolated from Chinese traditional fermented acid beans, was systematically evaluated for its survival capacity under stress conditions (pH, bile salt, simulated gastrointestinal tract, and antibiotics), production of exopolysaccharide and antagonism against 8 pathogens. Its effect on mice gut microbiota was also investigated by quantitative PCR and PCR-denaturing gradient gel electrophoresis. The results showed that ZDY 2013 can grow at pH 3.5 and survive at pH 2.0 for 6 h and at 0.45% bile salt for 3 h. The exopolysaccharide yield was up to 204±7.68 mg/L. The survival rate of ZDY 2013 in a simulated gastrointestinal tract was as high as 65.84%. Antagonism test with a supernatant of ZDY 2013 showed maximum halo of 28 mm against Listeria monocytogenes. The inhibition order was as follows: Listeria monocytogenes, Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei, Enterobacter sakazakii, and Staphylococcus aureus. Lactobacillus plantarum ZDY 2013 was sensitive to some antibiotics (e.g., macrolide, sulfonamides, aminoglycoside, tetracyclines and β-lactams), whereas it was resistant to glycopeptides, quinolones, and cephalosporins antibiotics. Denaturing gradient gel electrophoresis profile demonstrated that ZDY 2013 administration altered the composition of the microbiota at various intestinal loci of the mice. Moreover, the quantitative PCR test showed that the administration of ZDY 2013 enhanced the populations of Bifidobacterium and Lactobacillus in either the colon or cecum, and reduced the potential enteropathogenic bacteria (e.g., Enterococcus, Enterobacterium, and Clostridium perfringens). Lactobacillus plantarum ZDY 2013 exhibited high resistance against low pH, bile salt, and gastrointestinal fluid, and possessed antibacterial and gut microbiota modulation properties with a potential application in the development of dairy food and nutraceuticals.

열적가용화공정을 이용한 하수슬러지의 가용화 특성 및 바이오가스 생산량 평가

본 연구는 하수처리장에서 발생되는 생슬러지와 잉여슬러지를 대상으로 열적가용화 공정의 적용성을 평가하였다. 열적가용화 효율 및 특성평가는 각 슬러지를 대상으로 <TEX>$100{\sim}220^{\circ}C$</TEX> 온도범위에서 30분간 전처리를 수행한 후 실시되었다. 그 결과, 가용화 온도가 상승함에 따라 <TEX>$SCOD_{Cr}$</TEX>, <TEX>$NH_4{^+}$</TEX>, VFAs 농도가 증가하는 경향을 확인할 수 있었다. 또한 COD 가용화효율 평가 결과, 온도 상승에 비례하는 경향이 나타나 열적가용화에 의해 가수분해 및 산발표 단계를 촉진시킨 것으로 판단된다. BMP (Biochemical Methane Potential) 실험을 통해 생슬러지의 경우 <TEX>$220^{\circ}C$</TEX>에서 가장 높은 biogas 생산량을 보여주었으나, 증가율은 5.6%로 열적가용화에 의한 효과가 미미한 것으로 나타났다. 반면 잉여슬러지의 경우 최대 38.8% ( <TEX>$180^{\circ}C$</TEX>) 증가하여, 열적가용화 공정은 잉여슬러지에 대한 적용성이 더욱 우수한 것으로 나타났다. In this study, an applicability of thermal pretreatment for primary and secondary sludge, which are generated in a sewage treatment plant, was evaluated. The efficiency and charateristics was investigated with each sludge after pretreatment under the condition of <TEX>$100{\sim}220^{\circ}C$</TEX> for 30 minutes. As the result, it was found that <TEX>$SCOD_{Cr}$</TEX>, <TEX>$NH_4{^+}$</TEX>, VFAs concentrations increased as the pre-treatment temperature increased. For COD solubilization, it was also highly dependent on an increase of temperature resulting in acceleration on hydrolysis and acid fermentation. In the BMP (Biochemical Methane Potential) experiment, for the primary sludge, it showed the higher biogas production rate at a temperature of <TEX>$220^{\circ}C$</TEX>, however, the effect was insignificant (5.6%). Whereas, for the secondary sludge, the increase on biogass production rate was 38.8% (<TEX>$180^{\circ}C$</TEX>) and this means that the secondary sludge is more suitable for an applicability of thermal pretreatment.

VLIV SMĚSI ORGANICKÝCH KYSELIN A MIKROBIÁLNÍHO INOKULANTU NA FERMENTAČNÍ PROCES LABORATORNÍCH SILÁŽÍ Z MAČKANÉHO VLHKÉHO ZRNA KUKUŘICE

In the experiment, the effect of chemical (A) and biological (B) additiva on the fermentation quality of climper high moisture maize grain corn was examined, compared with the untreated control (K). The chemical means contained propionic, formic and benzoic acids and ammonium formate as effective substances. As effective substances of bacterial water–soluble inoculants, selected were bacterial strains of Propionibacterium shermanii JS and Lactobacillus casei LC-705. Both conservative preservatives were added equally to the ensilaged material. The addition of chemical additivum under conditions of our experiment increased statistically significantly (P&lt;0.01) the contents of acetic acid (7.66±0.95 g/kg DM), ethanol (11.22±0.65 g/kg DM) and pH values (4.33±0.02) in experimental silages. Simultaneously, a statistically significant (P&lt;0.01) inhibition of lactic acid formation (15.17±2.75 g/kg DM) and of total content of all fermentation acids (22.33±2.38 g/kg DM) occurred. The bacterial inoculant increased significantly (P&lt;0.05) the content of lactic acid (26.78±2.63 g/kg DM) and the total acid content (32.87±2.88 g/kg DM) in inoculated silages. The inoculation positive effect was demonstrated highly significantly (P&lt;0.01) in reduction of ethanol amount (2.14±0.40 g/kg DM) and of totat acidification. The pH value (4.21±0.02) was significantly lower (P&lt;0.05) than that in the control silage (4.24±0.02). The fermentation characteristics in the inoculated silages by us were more favourable. The addition of organic acid mixture in the used concentration of 3.5 L/t did not confirm the positive effect on climper maize grain corn quality as expected.

Chemical composition and nutritive value of corn silage harvested in the northeastern United States after Tropical Storm Irene

In the fall of 2011, Hurricane (Tropical Storm) Irene caused significant damage to the forage corn crop in the northeastern United States. Compromised crops were subjected to various degrees of flooding, lodging, and contamination with sediment. The objective of this study was to determine if compromised plants harvested for silage fermented normally and if the nutritive value of these silages was adversely affected. The chemical and nutrient composition of compromised silages was compared with that from silages made from unaffected plants from the same region. The concentration of NEL and in vitro digestibility of NDF were lower in plants compromised by the hurricane. In addition, the ash content of compromised silages was higher than that of unaffected silages. Specifically, concentrations of Al, Co, Fe, and Mn were higher in compromised silages. Overall, silage fermentation appeared to be normal; the final silage pH, and concentrations of fermentation acids, alcohols, and esters were similar between compromised and unaffected silages. Numbers of yeasts (but not molds) tended to be higher in compromised silage than in unaffected silage. Pathogenic microorganisms were not detected in any silage. The incidences and concentrations of mycotoxins were similar between compromised and normal silage. Several farms that fed compromised silage reported subsequent health issues with their animals.

The Probiotical Potential of Lactobacilli from Therapeutic Preventive Beverage Kurunga.

IntroductionKurunga is a dairy drink made of a mix of lactic acid and alcoholic fermentation, characterized by high biological value based on protein composition, amino acid spectrum, fatty acid composition of lipids, vitamin and mineral substances, and physiological activity of microbiota containing lactobacilli, lactococci, bifidobacteria, and yeast. Among the probiotic correctors of normal microbiota isolated from national products, lactobacilli was of particular interest, with regards to a therapeutic – preventive effect. The aim of the study was to examine the probiotic properties of lactobacilli from kurunga.MethodsWe isolated lactic acid bacteria strains from kurunga. The isolated cultures were identified using common microbiological methods and phylogenetic analysis. The antibiotic activities of these strains were determined by measuring the growth inhibition zone of test cultures. The probiotic properties were measured as levels of resistance to bile and hydrochloric acids, in addition to the presence of superoxide dismutase (SOD) activity using the xanthine oxidase-cytochrome method. Proteolitic activity was determined at the various levels of pH (3.0, 4.2, 5.3, and 7.0).ResultsAccording to the morphological, cultural, physiological, biochemical properties and the genotypic analysis of the oligonucleotides sequence of specific genes, the most effective strain was identified as Lactobacillus diolivorans KL-2 (GenBank database KC438372). The isolated strain suppressed the growth of Gram-positive bacteria, such as Bacillus, Staphylococcus, and Listeria sp., as well as Gram-negative bacteria, such as E.coli, Proteus, Salmonella sp. They also possessed fungicidal action (based on Penicillum, Aspergillus sp, and Candida sp.). The strain was resistant to the action of the bile acids at concentrations of 0.8% to 1.0% and hydrochloric acid. The strain KL-2 possessed a relatively high SOD activity (25.74 U/mg of protein), a low proteolytic activity at a pH 3.0 (4.74·10-3 PU/ml), and high proteolytic activity at pH 4.2 (294.74·10-3 PU/ml), pH 5.3 (330.52·10-3 PU/ml) and pH 7.0 (713.68·10-3 PU/ml).ConclusionThe unique properties of this strain, such as stability in the gastrointestinal tract, the wide spectrum of bactericidal and fungicidal action to the pathogenic species, the relatively high superoxide dismutase and proteolytic activities, and the absence of toxicity, make it a prime candidate for probiotic culturing.

VLIV SILÁŽNÍCH ADITIV NA DYNAMIKU, KVALITU A AEROBNÍ STABILITU FERMENTAČNÍHO PROCESU KUKUŘIČNÝCH SILÁŽÍ

In the experiment, the effect of additives supplementation on the fermentation quality of corn silage was examined, compared with the untreated control (K). The aditive „A“ contained bacterial component of (Propionibactrium acidipropionici – MA126/4U 3*1010 and Lactobacillus plantarum – MA18/5U). The effective substances of bacterial inoculants „B“, selected were bacterial strains of (Lactobacillus casei ssp. rhamnosus LC – 705 DSM 7061 4*1011, Propionibacterium freudenreichii spp. shermanii JS DSM 6067 2-4*1011). There were used as effective substances of bacterial inoculants „C“ lactic bacteria and enzyme (Lactobacillus plantarum CCM 3769 1.67*1010, Lactococcus lactis CCM 4754 1.67*1010, Enterococcus faecium CCM 6226 1.67*1010, Pediococcus pentosaceus CCM 3770 1,67*1010, cellulase, hemicellulase, sodium benzoate). They were applied in the dose of prescript by producer. At conservations with all aditivum were statistically significant (P &lt; 0.01) increase of lactic acid formation from 55.31±9.72 g/kg DM of control silage to 59.60±10.84 g/kg DM aditivum „A“, 59.36±10.04 g/ kg DM aditivum „B“ rather to 60.74±9.90 g/kg DM aditivum „C“. Aditives „A“ and „B“ were statistically significant (P &lt; 0.01) increase propoinic acid and total fermentation acid content in silages occured. The fermentation characteristics in the microbial aditivum silages by us were more favourable. The date of fermentation was statistically significant (P &lt; 0.01) increase the contents of acetic acid from 45.49±2.83 g/kg DM of 4st day to 63.07±4.25 g/kg DM of 32ndday rather to 67.70±2.94 g/kg DM of 64st day. There were statistically significant (P &lt; 0.01) increase contents of acetic acid and total acid content. The date of fermentation was statistically significant (P &lt; 0.01) degressive of pH.

Nutritional value of ensiled grocery food waste for cattle.

Assessment of nutrient variability, feed value, ensiling capability, intake, and digestibility of grocery food waste recycled from large retail stores was conducted in 3 experiments. In Exp. 1, 115 proximate nutrient analyses of grocery byproduct feed (GBP) from stores in the southern United States from April 8, 2011, to November 18, 2012, were evaluated for variation in nutrient concentration. Grocery byproduct feed was characterized as being a readily fermentable, high-moisture energy feed with an average DM content of 17.5 ± 3.7% and TDN of 89.8 ± 7.1%. In Exp. 2 and 3, grocery food waste consisting of fruit, vegetables, and bakery items from large retail stores in the Atlanta, GA, area was used for ensiling and feeding studies. The GBP material for Exp. 2 was processed on farm into homogenous slurry and treated to reduce its moisture content and preserved in experimental silos. Drying treatments included 3 levels of citrus pulp substitution (8, 16, and 24% as-fed basis), or passively removing liquid as seepage after stacking for 24 h, or oven drying (24 h at 80°C). All GBP mixtures effectively ensiled after 28 d, as determined by changes in pH, soluble carbohydrates, and fermentation acids. Ensiled GBP was moderately stable during 72-h aerobic exposure. In Exp. 3, a feeding/digestibility trial, 8 yearling Holstein steers were used in a replicated 4 × 4 Latin Square and fed 4 incremental levels of ensiled GBP in total mixed rations (TMR). Steers were fed 0, 18, 36, and 54% ensiled GBP as part of a TMR containing 68% wheat silage and 32% concentrate on a DM basis. The rations averaged 35.9, 30.7, 26.8, and 23.8% DM with incremental levels of GBP. Steers increased DM intake and digestibility when fed increasing GBP (P < 0.5). Digestible energy and TDN were linearly related to the level of GBP fed (P < 0.01). The TDN content of GBP was 82.7% (DM basis) and similar to predicted TDN values from commercial feed analyses of GBP. The feeding and nutritive value of ensiled GBP indicates it can be priced to be used effectively as an energy supplement in TMR for cattle.

Optimisation of Poly(γ-Glutamic Acid) Production by Bacillus velezensis NRRL B – 23189 in Liquid Fermentation with Molasses as the Carbon Source without Addition of Glutamic Acid

Poly (γ-glutamic acid), also known as γ-PGA, is an extracellular polymer produced by microbial fermentation. It is water-soluble, edible, biodegradable, non-toxic towards humans and the environment, and it has many available sites for drug conjugation and a powerful ability to solubilise hydrophobic molecules. This work reports the application of molasses, citric acid and ammonium sulphate in the fermentation by Bacillus velezensis NRRL-23189 to produce γ-PGA and the detection of molasses consumption without the use of glutamic acid as a nutrient. Different concentrations of molasses, citric acid and ammonium sulphate were studied. The fermentation was agitated at 200 rpm at 27oC for 72 h, with an initial pH of 6.5 (NaOH 2N and HCl 2N). Spectrophotometric analyses were used to measure concentrations of γ-PGA and the residual sugar from molasses degradation. The maximum production of γ-PGA was 4.82 g/l, in a medium with molasses (200g/l), citric acid (12.5g/l) and ammonium sulphate (8g/l) in a fermentation that also resulted in the maximum sugar consumption.

Effects of ruminal doses of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells

The objective was to evaluate effects of a ruminal dose of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells. Six ruminally cannulated nonlactating nonpregnant Holstein cows (body weight=725±69.6kg) were assigned to treatments in a 3×3 Latin square design with 7-d periods; 1d for data and sample collection followed by a 6-d washout period. Cows were fed a diet containing whole-crop barley silage and dry ground corn, and dietary neutral detergent fiber and crude protein contents were 41.8 and 13.2% [dry matter (DM) basis], respectively. Treatment was a pulse-dose of sucrose, lactose, and corn starch (3.0, 3.0, and 2.85kg of DM, respectively; providing similar amounts of hexose across the treatments) through the ruminal cannulas. All treatments were given with alfalfa silage (1.75kg DM) to prevent acute rumen acidosis. Rumen pH was continuously monitored, and rumen fluid was sampled at 0, 30, 60, 90, 120, 150, and 180min after the dose. In addition, ruminal papillae were sampled from the ventral sac at 180min after the dose. Ruminal dosing with sucrose and lactose, compared with corn starch, increased ruminal total volatile fatty acid concentration and molar proportion of butyrate from 60 to 180min after the dose, and expression of genes for sodium hydrogen exchanger isoforms 1 and 2, and ATPase isoform 1 in ruminal epithelial cells. Ruminal dosing with sucrose, compared with lactose and corn starch, decreased rumen pH from 120 to 180min after the dose and molar proportion of acetate in ruminal fluid from 60 to 150min after the dose, and increased molar proportion of propionate in ruminal fluid from 60 to 150min, and expression of genes involved in butyrate metabolism (3-hydroxy-3-methylglutaryl-coenzyme A synthase isoform 1) and anion exchange across ruminal apical cell membrane (putative anion transporter isoform 1). These results suggest that replacing dietary starch with sugars may affect ruminal fermentation and metabolism regulating intracellular pH and fermentation acid absorption in ruminal epithelial cells, and that these effects can be greater for sucrose than lactose.

Effects of carbon dioxide on cell growth and propionic acid production from glycerol and glucose by Propionibacterium acidipropionici

The effects of CO2 on propionic acid production and cell growth in glycerol or glucose fermentation were investigated in this study. In glycerol fermentation, the volumetric productivity of propionic acid with CO2 supplementation reached 2.94g/L/day, compared to 1.56g/L/day without CO2. The cell growth using glycerol was also significantly enhanced with CO2. In addition, the yield and productivity of succinate, the main intermediate in Wood–Werkman cycle, increased 81% and 280%, respectively; consistent with the increased activities of pyruvate carboxylase and propionyl CoA transferase, two key enzymes in the Wood–Werkman cycle. However, in glucose fermentation CO2 had minimal effect on propionic acid production and cell growth. The carbon flux distributions using glycerol or glucose were also analyzed using a stoichiometric metabolic model. The calculated maintenance coefficient (mATP) increased 100%, which may explain the increase in the productivity of propionic acid in glycerol fermentation with CO2 supplement.

Comparison of anti-Campylobacter activity of free thymol and thymol-β-d-glucopyranoside in absence or presence of β-glycoside-hydrolysing gut bacteria

Thymol is a natural product that exhibits antimicrobial activity in vitro but in vivo results indicate that absorption within the proximal alimentary tract precludes its delivery to the distal gut. Presently, the anti-Campylobacter activity of thymol was compared against that of thymol-β-d-glucopyranoside, the latter being resistant to absorption. When treated with 1mM thymol, Campylobacter coli and jejuni were reduced during pure or co-culture with a β-glycoside-hydrolysing Parabacteroides distasonis. Thymol-β-d-glucopyranoside treatment (1mM) did not reduce C. coli and jejuni during pure culture but did during co-culture with P. distasonis or during mixed culture with porcine or bovine faecal microbes possessing β-glycoside-hydrolysing activity. Fermentation acid production was reduced by thymol-β-d-glucopyranoside treatment, indicating that fermentation was inhibited, which may limit its application to just before harvest. Results suggest that thymol-β-d-glucopyranoside or similar β-glycosides may be able to escape absorption within the proximal gut and become activated by bacterial β-glycosidases in the distal gut.

Novel bioconversion of sodium glutamate to γ-poly-glutamic acid and γ-amino butyric acid in a mixed fermentation using Bacillus subtilis HA and Lactobacillus plantarum K154

Both γ-poly-glutamic acid (γ-PGA) and γ-amino butyric acid (GABA) were produced from sodium glutamate in a mixed fermentation. A culture broth was obtained using a defined medium including 3% glutamate and Bacillus subtilis HA for 3 days at 42°C, with 1.20×108 CFU/mL viable cells, a 0.46 Pa·sn consistency index, and a 1.94% mucilage content. In a second fermentation using Lactobacillus plantarum K154 at 37°C for 3 days, 1.29% of the remaining glutamic acid in the viscous culture broth was converted to 0.86% GABA. Glutamic acid in the first culture broth fortified with 5% skim milk was completely converted to GABA. The final co-cultured broth had 0.48% GABA, a 0.294% tyrosine content, and viable cells of 1.06×109 CFU/mL (L. plantarum K154) and 5.42×105 CFU/mL (B. subtilis HA). Serial co-culturing of these two bacteria can provide novel ingredients fortified with γ-PGA, GABA, peptides, and probiotics.

Development of fermented and flavoured kefir milk

Kefir is a dairy beverage, obtained from lactic acid and alcoholic fermentation of its grains, which resembles yogurt in its flavour, aroma and consistency. It is composed of approximately 15-16 lactobacilli, approximately 7-9 streptococci/lactococci, 8 yeasts and 2 acetic bacteria (acetobacter). The fermenting action of Kefir bacteria and yeasts increases the biological value of milk, increasing synthesis of the B group vitamins, which help in the digestive process. The abundance in Calcium, Phosphor, and Magnesium is another of Kefir's characteristics, as for all other dairy products. It is an easily digested product that eliminates harmful bacteria and yeasts from the intestine, increases beneficial and protective bacterial population, and as a probiotic food has many therapeutic applications. This study had as its objective the production of fermented milk based on Kefir, when different flavours were tested, to have it sensorial tested to find the one with the highest acceptance. Firstly, an analysis of the total coliform content was performed, followed by a microbiological quantification analysis of the colony-forming-unit per gram (CFU/g), to ensure the quality of the product to be offered to tasters. Secondly, the Kefir milk was flavoured with 4 different flavours (passion fruit, strawberry, grape and mango), where juice from concentrate pulp and fruit bits were used, served to 60 tasters (students, professors and staff from UNISO), according to the model for rank-preference test (164/IV 'Testes Efetivos - Testes de preferencia' Effective Test - PreferenceTests) according to the Instituto Adolfo Lutz.

Lactobacillus plantarum Improves the Nutritional Quality of Italian Ryegrass with Alfalfa Mediated Silage

The present study was planned to analyze the nutritional quality, microbial counts and fermentative acids in Italian ryegrass (IRG) 80% and alfalfa 20% (IRG-HV) mediated silage inoculated with lactic acid bacteria (LAB) as a probiotic strain for 3 months. Crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF), total digestible nutrient (TDN) and In-vitro dry matter digestibility (IVDMD), lactic acid bacteria (LAB), yeast and fungi counts and fermentation metabolites such as lactic acid, acetic acid and butyric acids were analyzed. The result shows that the nutritional quality and metabolite profiles of silage were significantly improved with LAB. For microbial counts, LAB showed dominant followed by yeast as compared with control silage. The pH of the silage also reduced significantly when silage inoculated with LAB. The result confirmed that silage preparation using different crops with L. plantarum inoculation is most beneficial for the farmers.