Propionibacterium Acidipropionici Research Articles

Flavor formation by amino acid catabolism in low-salt sufu paste, a Chinese fermented soybean food

In this study, the low-salt sufu paste was fermented enhanced by a mixed starter (Pichia fermentans, Kodamaea ohmeri and Lactococcus lactis subsp.) and α-ketoglutarate. Multispecies microbial community is crucial for the flavor formation of sufu paste during post-ripening. Consequently, the primary biochemical pathways of the flavor formation were analyzed using a metagenomic approach in conjunction with gas chromatography mass spectrometry (GC-MS). After post-ripening for 15 d, a total of 86 volatile flavor compounds (VFCs) were tentatively identified, in which 6 compounds were recognized as the main characteristic VFCs. The metagenomics revealed that Actinomucor elegans, Lactobacillus fermentum, Lactococcus lactis subsp., Pichia fermentans, Lactobacillus delbrueckii and Propionibacterium acidipropionici were the dominant species. According to the functional annotation, amino acid metabolisms were identified as the predominant pathways for flavor formation. Among them, aromatic amino acids metabolisms accounted for the highest proportion, up to 41.3%. The VFCs formation pathways mainly involved transamination, decarboxylation, dehydrogenation and oxidation reaction. The amino acid transamination was proposed as a crucial step in VFCs formation, and the corresponding aminotransferases were the key rate-limiting enzymes. These findings have implications for enhancing the flavor quality of sufu paste and elucidating the mechanism of flavor formation in traditional soybean fermented food.

Propionic acid production by Propionibacterium acidipropionici CDBB‐B‐1981 from enzymatic hydrolysates of Agave bagasse pretreated by steam explosion

AbstractThe biochemical pathway for propionic acid (PA) production is an interesting alternative that can include the utilization of biomass as feedstock. This study evaluated the utilization of Agave bagasse (AB), a lignocellulosic residue, to produce PA by Propionibacterium acidipropinici in batch systems (125 mL‐hermetic bottles and 1000 mL‐bioreactor). The process included a steam explosion pretreatment at 142°C for 15 min and enzymatic hydrolysis, where solid loading (2.75% and 5% in pretreatment and 2.5%, 3.75%, and 5% in enzymatic hydrolysis) was evaluated. Furthermore, the enzymatic concentrations of 18.3 filter paper unit (FPU)/gAB (1×) of Cellic® CTec2 and 1.5× and 3× were tested. The yields of total carbohydrates (TC) obtained at the two solid loadings tested in the pretreatment were statistically similar, but the 3x enzymatic concentration enhanced the yields of TC, glucose, and xylose (0.23 ± 0.01, 0.15 ± 0.01 and 0.03 ± 0.01 g/gAB, respectively). The hydrolysates obtained under these conditions were evaluated as carbon sources for PA production, obtaining a productivity of 0.069 ± 0.006 g/L h and a yield product/substrate of 0.44 gPA/gTC. The control of pH in the culture reduced the fermentation time in the bioreactor by 52% compared with the hermetic bottles without pH control. The potential of hydrolysates as carbon sources for PA production was evidenced, as approximately 50% of the initial carbon was converted to this product. The observed yield product/substrate was similar to those reported from hydrolysates of diverse biomass types, pretreatments, or enzymatic cocktails and the same or related microorganisms. However, the system studied has advantages, such as not requiring the addition of chemical or detoxification stage, and lower temperature and time compared to other pretreatments.

Using bifidobacterium and propionibacterium strains in probiotic consortia to normalize the gastrointestinal tract.

The gastrointestinal microflora regulates the body's functions and plays an important role in its health. Dysbiosis leads to a number of chronic diseases such as diabetes, obesity, inflammation, atherosclerosis, etc. However, these diseases can be prevented by using probiotics - living microorganisms that benefit the microflora and, therefore, improve the host organism's health. The most common probiotics include lactic acid bacteria of the Bifidobacterium and Propionibacterium genera. We studied the probiotic properties of the following strains: Bifidobacterium adolescentis АС-1909, Bifidobacterium longum infantis АС-1912, Propionibacterium jensenii В-6085, Propionibacterium freudenreichii В-11921, Propionibacterium thoenii В-6082, and Propionibacterium acidipropionici В-5723. Antimicrobial activity was determined by the 'agar blocks' method against the following test cultures: Escherichia coli ATCC 25922, Salmonella enterica ATCC 14028, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa B6643, Proteus vulgaris ATCC 63, and Listeria monocytogenes ATCC 7644. Moderate antimicrobial activity against all the test cultures was registered in Bifidobacterium adolescentis АС-1909, Propionibacterium jensenii В-6085, and Propionibacterium thoenii В-6082. Antioxidant activity was determined by the DPPH inhibition method in all the lactic acid strains. Our study indicated that some Propionibacterium and Bifidobacterium strains or, theoretically, their consortia could be used as probiotic cultures in dietary supplements or functional foods to prevent a number of chronic diseases.

Evolutionary engineering and chemical mutagenesis of Propionibacterium acidipropionici for improved propionic acid production from sugarcane-derived saccharides

Propionic acid (PA) is a 3-carbon carboxylic acid widely used in the chemical, food and pharmaceutical industries. Current production of PA is primarily via petrochemical routes and alternative sources using renewable feedstocks are desirable. The goal of the present study was to develop bacterial strains for efficient PA production by fermentation of sugarcane-derived saccharides in inverted sugarcane syrup. Adaptive evolution and random chemical mutagenesis of Propionibacterium acidipropionici were individually evaluated. Although evolutionary engineering proved to be a suitable strategy for producing strains tolerant to acid stress, chemical mutagenesis coupled with a novel screening methodology proved to be a superior strategy for strain improvement. The selected strain presented high PA productivity (0.55 g L−1 h−1) and titer (40 g L−1) in relation to the parental strain (0.38 g L−1 h−1 and 27 g L−1, respectively), in fermentations using inverted sugarcane syrup.

Acid-tolerant bacteria and prospects in industrial and environmental applications

Acid-tolerant bacteria such as Streptococcus mutans, Acidobacterium capsulatum, Escherichia coli, and Propionibacterium acidipropionici have developed several survival mechanisms to sustain themselves in various acid stress conditions. Some bacteria survive by minor changes in the environmental pH. In contrast, few others adapt different acid tolerance mechanisms, including amino acid decarboxylase acid resistance systems, mainly glutamate-dependent acid resistance (GDAR) and arginine-dependent acid resistance (ADAR) systems. The cellular mechanisms of acid tolerance include cell membrane alteration in Acidithiobacillus thioxidans, proton elimination by F1-F0-ATPase in Streptococcus pyogenes, biofilm formation in Pseudomonas aeruginosa, cytoplasmic urease activity in Streptococcus mutans, synthesis of the protective cloud of ammonia, and protection or repair of macromolecules in Bacillus caldontenax. Apart from cellular mechanisms, there are several acid-tolerant genes such as gadA, gadB, adiA, adiC, cadA, cadB, cadC, speF, and potE that help the bacteria to tolerate the acidic environment. This acid tolerance behavior provides new and broad prospects for different industrial applications and the bioremediation of environmental pollutants. The development of engineered strains with acid-tolerant genes may improve the efficiency of the transgenic bacteria in the treatment of acidic industrial effluents. KEY POINTS: • Bacteria tolerate the acidic stress by methylating unsaturated phospholipid tail • The activity of decarboxylase systems for acid tolerance depends on pH • Genetic manipulation of acid-tolerant genes improves acid tolerance by the bacteria.

Evaluation of the type of silo associated or not with additives on the nutritional value, aerobic stability, and microbiology of pearl millet silage.

The objective of this study was to evaluate the effect of the silo type with the use or not of additives on chemical composition, in vitro gas production, fermentative losses, aerobic stability, fermentative profile, and microbial population of the pearl millet silage. We used a randomized block design in a 2 × 3 factorial scheme, with two types of silos (plastic bags and PVC silos) and three additives ([CON] without additive; 50 g of ground corn [GC], and Lactobacillus plantarum and Propionibacterium acidipropionici, with five replicates per treatment. We evaluated the chemical analyses, in vitro gas production, losses, aerobic stability, pH, ammoniacal nitrogen, and microbial population of the silages. The use of GC in the ensiling process improved the chemical composition of the silages. The additives and the type of silo did not affect (p > 0.05) the gas production kinetics, ammoniacal nitrogen, and population of lactic acid bacteria and fungi. Thus, the use of ground corn improved the nutritional value of the pearl millet silage. In turn, the inoculant provided better aerobic stability for the pearl millet silage. The plastic bag silos without vacuum were not efficient in the ensiling process like the PVC silos, which resulted in low-quality silage.

Propionibacteriaium acidipropionici CP 88 Dose Alters In Vivo and In Vitro Ruminal Fermentation Characteristics

Twelve 5-year-old beef steers, with an average weight of 2000 lbs., fitted with rumen canulae were used in a 4 × 4 incomplete Latin square design to examine the impact of the direct fed microbial Propionibacterium acidipropionici CP 88 (PA) on rumen fermentation characteristics, in vitro CH4, CO2, and N2 production, and in vivo CH4 and CO2 production. All steers were housed in the same pen equipped with eight GrowSafe feeding stations to monitor individual animal feed intake and one GreenFeed System to estimate individual animal CH4 and CO2 production. Steers were fed a corn-silage-based diet throughout the experiment. Treatments consisted of PA administered at: (1) control (0.0); (2) 1.0 × 108; (3) 1.0 × 109; and (4) 1.0 × 1010 cfu∙animal−1∙day (d)−1. Treatments were administered directly into the rumen as a single bolus dose daily. On day 7 and 14 of each period, rumen fluid was collected from each steer 2 h post treatment administration for VFA analysis and in vitro DM digestibility determination. Following a 14 d washout period, animal treatments were switched and the experiment repeated until the 4 × 4 Latin square was complete. In vivo propionic acid molar proportions and total VFA concentrations were greater (p < 0.05) in steers receiving PA when compared with controls. All other in vivo rumen fermentation characteristics were similar across treatments. In vitro DM disappearance (p < 0.05) and total VFA (p < 0.05) were greater and CH4 lesser (p < 0.04) in fermentation vessels incubated with rumen fluid from animals receiving PA when compared with controls. Dry matter disappearance (p < 0.03) and propionic acid molar proportions increased (p < 0.04) linearly as the dose of PA increased. In vitro total VFA tended (p < 0.08) to increase linearly and CH4 production per unit of DM digested tended (p < 0.09) to decrease quadratically in response to PA dose. All other in vitro rumen fermentation characteristics were similar across treatments. These data indicate that PA impacts in vivo and in vitro rumen fermentation characteristics.

Microbiome of rehydrated corn and sorghum grain silages treated with microbial inoculants in different fermentation periods

Due to the co-evolved intricate relationships and mutual influence between changes in the microbiome and silage fermentation quality, we explored the effects of Lactobacillus plantarum and Propionibacterium acidipropionici (Inoc1) or Lactobacillus buchneri (Inoc2) inoculants on the diversity and bacterial and fungal community succession of rehydrated corn (CG) and sorghum (SG) grains and their silages using Illumina Miseq sequencing after 0, 3, 7, 21, 90, and 360 days of fermentation. The effects of inoculants on bacterial and fungal succession differed among the grains. Lactobacillus and Weissella species were the main bacteria involved in the fermentation of rehydrated corn and sorghum grain silage. Aspergillus spp. mold was predominant in rehydrated CG fermentation, while the yeast Wickerhamomyces anomalus was the major fungus in rehydrated SG silages. The Inoc1 was more efficient than CTRL and Inoc2 in promoting the sharp growth of Lactobacillus spp. and maintaining the stability of the bacterial community during long periods of storage in both grain silages. However, the bacterial and fungal communities of rehydrated corn and sorghum grain silages did not remain stable after 360 days of storage.

Metagenomics insight into bioaugmentation mechanism of Propionibacterium acidipropionici during anaerobic acidification of kitchen waste

In the present study, a biochemical strategy for improving propionic acid production from kitchen waste acidification by bioaugmentation with Propionibacterium acidipropionici (P. acidipropionici) was investigated. When the inoculum of P. acidipropionici was 30% (w/w) of the seeding sludge, the propionic acid production increased by 79.57%. Further, bioaugmentation improved the relative abundance of Firmicute and Actinobacteria. The results of metagenomic analysis further reveal that the ATP-binding cassette (ABC) transporters and all related pathways of Propanoate metabolism (ko00640) were enriched when P. acidipropionici was added. For Propanoate metabolism, most functional genes involved in the conversion from Glycolysis / Gluconeogenesis (ko00010) to Propanoyl-CoA and conversion from Propanoyl-CoA to propionic acid were enhanced after bioaugmentation with P. acidipropionici, thereby promoting propionic acid production. As such, bioaugmentation with P. acidipropionici was effective in the anaerobic acidification of kitchen waste for propionic acid production.

Snaplage with microbial inoculant or organic acids has altered fermentative losses, microorganism counts, starch content and improves feed intake, digestibility and modulates ruminal fermentation in lambs

ABSTRACT Two experiments were performed to evaluate snaplage ensiling additives and determine the effects of feeding snaplage to lambs. In Exp. 1, grains, ears and husk from maize harvested at the R4 phenological stage were ensiled (65.3% DM content) in 30 min-silos in a completely randomised design with the following treatments: control (CON); microbial inoculant (INO), (Lactobacillus plantarum and Propionibacterium acidipropionici) at 4 g/ton of ensiled material; and organic acids (OA), a blend of organic acids at 2 g/kg of ensiled material. In Exp. 2, nine lambs were used in a 3 × 3 Latin square design. Lambs were randomly assigned to the following diets: control (CON); rehydrated maize silage (RHC), diet containing 380 g/kg RHC; or snaplage (SNAP), diet containing 770 g/kg of SNAP. Snaplage with OA exhibited greater DM recovery, lactic acid bacteria count and DM content than other treatments. Snaplage with INO had the lowest counts of aerobic bacteria and mould. Lambs-fed SNAP had greater nutrient intake and digestibility, ruminal short-chain fatty acid concentrations, and N retention compared to other groups. Incorporating OA to snaplage decreased DM losses and improved microbiological quality and chemical composition. Feeding snaplage to lambs may improve DM intake and apparent digestibility.

Re-ensiling and microbial inoculant use effects on the quality of maize silages exposed to air

Re-ensiling has increased worldwide due to the increase in marketing of silage between farms. However, litlle is known about the aerobic deterioration and microbial inoculants effect in this process. The aim of this study was to determine the re-ensiling and microbial inoculant use effects on the maize silage quality. Experimental treatments included maize silage exposed to air for zero or 18 h, with or without microbial inoculant use containing a mixture of Lactobacillus plantarum and Propionibacterium acidipropionici. The forage was ensiled in 20 plastic buckets (20 liters capacity) with five repetitions per treatment. The silos were opened after 116 days and the chemical composition, in vitro dry matter digestibility (IVDMD), fermentative parameters, microorganism counts, total dry matter (DM) losses and aerobic stability of silage were evaluated. Re-ensiling reduced the non-fibrous carbohydrates content by 14.8%, whereas it increased the neutral detergent fiber content by 6%. The IVDMD was reduced by 6.1% in re-ensiled silages. In addition, re-ensiling increased the losses due to gases, effluents, and total DM. Lower lactic acid content and higher acetic acid content in re-ensiled maize silages were also observed. However, IVDMD increased by 4.6% in inoculated silages. Re-ensiling reduced the nutritive value and IVDMD of maize silages and should be avoided in production systems. The microbial inoculant use was not effective in improving the re-ensiled silage quality, which does not justify its use in these conditions. Farms should avoid purchasing maize silage due to reduction in nutritional value in the re-ensiling process. However, in some cases where farms need to purchase silage for feeding planning, the time between silo opening and re-ensiling should be as short as possible to reduce nutrient loss. Furthermore, in this situation the inoculant use does not improve silage conservation, which makes its use unnecessary.

Exploring the Effects of Different Bacteria Additives on Fermentation Quality, Microbial Community and In Vitro Gas Production of Forage Oat Silage.

Simple SummaryForage oat is an important feed resource in the world. Few studies on the application of different bacterial additives in forage oat silage have been found, which limits the utilization and promotion of oat silage in animal husbandry. In this study, we compared the fermentation quality and in vitro gas production of oat silage treated with four additives (Lactiplantibacillus plantarum F1,LP; Lacticaseibacillus rhamnosus XJJ01, LR; Lacticaseibacillus paracasei XJJ02, LC; and Propionibacterium acidipropionici 1.1161, PP). The results show that compared to the CK group (without additives), the LR group had a higher dry matter content, while the LP group showed an improvement in fermentation quality. At the same time, the bacterial community in the LR group was also different from that in other groups. The treatments of PP and LC had no significant effects on fermentation quality, but the in vitro gas production was significantly reduced in the treated oat silage. These results could help us to optimize the utilization of forage oat silage in balanced ruminant diets.Bacterial inoculants are considered as a good choice for successful ensiling, playing a key role in improving the silage quality. However, the potential of different bacteria, especially the propionic acid bacteria, in forage oat ensiling is yet to be explored. Therefore, the purpose of this study was to investigate the regulation effects of different bacterial additives on the fermentation quality of forage oat silage. Four additives (Lactiplantibacillus plantarum F1, LP; Lacticaseibacillus 0rhamnosus XJJ01, LR; Lacticaseibacillus paracasei XJJ02, LC; and Propionibacterium acidipropionici 1.1161, PP; without additives, CK) were inoculated in forage oat silage, and the fermentation quality and organic compounds were determined after 60 days of ensiling. Notably, LR showed higher dry matter preservation compared to other additives and CK. In addition, LP and LR showed strong lactic acid synthesis capacity, resulting in lower pH compared to other additives and CK. The treatments of PP and LC increased the bacterial diversity in silage, while the bacterial community in the LR group was different from that in other groups. In addition, the PP- and LC-treated oat silage showed significantly lower total in vitro gas production and a lower methane content. These results suggest that LP is more favorable for producing high-quality oat silage than LR, LC, or PP. Both the PP- and LC- treated oat silage may reduce rumen greenhouse gas emissions.

212 The Effects of Propionibacterium Acidipropionici P169 in an in Vitro Ruminal Acidosis Model

Abstract The objective was to evaluate the effect of Propionibacterium acidipropionici P169 (PA) concentration on fermentation characteristics in a ruminal acidosis in vitro model. Ruminal acidosis is a common metabolic disorder in feedlot cattle characterized by a low rumen pH. The experiment included 5 treatments in a completely randomized design. Treatments included a negative control (NCON), 5 × 105 colony forming units (CFU) PA (PA5), 5 × 106 CFU PA (PA6), 5 × 107 CFU PA (PA7), and a positive control with greater forage inclusion (PCON). Flasks for NCON, PA5, PA6, and PA7 contained 8.75 g of substrate (70% corn, 15% DDG, 15% silage) while substrate for PCON flasks contain additional silage (40% corn, 15% DDG, 45% silage). Treatments were run in duplicate and the experiment was replicated 3 times. All flasks included 175 mL of inoculum (4 McDougall’s buffer:1 rumen fluid). Flasks were incubated at 39◦C for 36 hours and sample aliquots were collected every 4 hours. The MIXED procedure of SAS 9.4 was used for statistical analysis with a repeated measures analysis. A treatment by hour interaction (P < 0.01) was observed for pH; at hour 8, PCON was the least and PA5 was the greatest. From 20 to 36 h, PCON had the greatest pH. There was no treatment by hour interaction (P = 0.99) observed for redox potential. However, treatment affected (P < 0.01) redox potential with PCON being greater than PA6, PA7, and NCON, with PA5 being intermediate. In vitro dry matter disappearance (IVDMD) tended (P = 0.09) to be affected by treatment; PA5, PA6, and PA7 were greater than PCON. In conclusion, Propionibacterium acidipropionici P169 concentrations affected IVDMD, pH, and redox in a ruminal acidosis in vitro model.

Effect of microbial inoculant on the fermentation profile, nutritional value and microbial population on corn, sorghum, and pearl millet silages

The objective of the present study was to evaluate the use of microbial inoculant on the chemical composition, in vitro gas production, pH, dry matter losses, aerobic stability and microbial population on silages of corn, sorghum and pearl millet in plastic bags silos (without vacuum). The experiment was carried out in a randomized block design, in a 2 × 3 factorial scheme, with and without (control) inoculant consisting of Lactobacillus plantarum and Propionibacterium acidipropionici and on three crops, corn, sorghum and pearl millet, with four replicates. The use of the inoculant did not affect the chemical composition of the silages, except the crude protein (P = 0.0062) and lignin (P = 0.0567) contents. Gas production was neither affected (P > 0.05) by the inoculant nor by the crop. Regarding aerobic stability, we observed that the inoculant affected the temperature of the sorghum silage (P = 0.0123). The inoculant decreased the N-NH3 (P =0.0095) content and increased (P = 0.0441) the lactic acid bacteria population in the silages. Thus, the microbial inoculant did not improve the fermentation profile or nutritional value of corn, pearl millet and sorghum silages in plastic bag silos (without vacuum).

Applicability of Neural Networks for the Fermentation of Propionic Acid by Propionibacterium acidipropionici

According to our best knowledge, this is the first report applying Artificial neural networks (ANN) for simulation of batch propionic acid (PA) fermentation. Therefore, the main focus of this research was to investigate the applicability of ANN on PA fermentations. To demonstrate this, we used the results of 40 Propionibacterium acidipropionici fermentations (ca 2,000 data points) to build up the ANN, and additional two independent fermentations to demonstrate the prediction capability of the observed ANN. Analyzing the predicted output parameters we observed, that ratio of propionic acid to acetic acid (PA/AA) variables can only be used for ANN after normalization. Finally, the fit of the ANN model to the measured data was fine (average correlation coefficients over 0.9). A special feature was also tested: fermentation time was also used as an input parameter, thus making the ANN suitable to predict time course of PA fermentations as well which was also satisfying.

Efficient Production of Propionic Acid in the Fed-Batch Fermentation of Propionibacterium acidipropionici and Its Metabolic Flux Analysis

To improve the fermentation efficiency of Propionibacterium acidipropionici, a simplified metabolic network was established to provide theoretical guidance for medium optimization and process regulation. The effect of glucose and glycerol on propionic acid production and metabolic flux distribution was investigated and the combination of glucose and glycerol was optimized. The results showed that the productivity of propionic acid could be improved by enhancing the synthesis of pyruvate and its flux distribution to the oxaloacetate branch. Finally, the scaled-up fed-batch fermentation of P. acidipropionici was conducted. The concentration of propionic acid reached 51.75 ± 3.62g/L with a glucose/glycerol ratio of 4:1, an improvement of 79.25% relative to the use of glucose alone, and the corresponding productivity and yield were 0.39g/(L· h) and 0.52g/g, respectively. Therefore, the combination of glucose and glycerol significantly improved the productivity of propionic acid and provides a new strategy for industrial production.

Propionic acid production from glycerol in immobilized cell bioreactor using an acid-tolerant strain of Propionibacterium acidipropionici obtained by adaptive evolution

Propionic acid (PA) production from agro-industrial residues using propionibacteria has gained interest as an alternative to fossil-based process. Microbial production is however characterized by product inhibition, lowering the product titers and productivity. In this study, Propionibacterium acidipropionici DSMZ4900 was subjected to adaptive evolution to tolerate higher acid concentrations. The strain adapted to growth in medium spiked with 20 g/L PA exhibited improved product titer (16.8 vs 8.72 g/L) and productivity (0.52 vs 0.17 g/L·h) with glycerol as carbon source in batch fermentations. It was immobilized on polyethyleneimine coated recycled glass beads Poraver® and used for fermentations in recycle batch mode with increasing glycerol concentration and decreasing pH, respectively. Doubling yeast extract concentration raised PA yield and productivity by >1.5 fold. Glycerol at 100 g/L was completely consumed to give ∼58 g/L PA at yield of 0.64 mol/mol and productivity of 0.28 g/L·h at pH 6.5. Decreasing fermentation pH to 5.0 increased PA productivity to 0.23 g/L·h from 0.14 g/L·h at pH 6.0 with 20 g/L glycerol, while immobilized cells exhibited no growth. The study shows combination of adaptive evolution and immobilization of cells to result in a robust system for PA fermentation at high glycerol concentration and lower pH.

Fermentative losses and chemical composition and in vitro digestibility of corn grain silage rehydrated with water or acid whey combined with bacterial-enzymatic inoculant

This study aimed to evaluate the effects of rehydration with water or acid whey, as well as the effects of bacterial-enzymatic inoculant on fermentation losses, aerobic stability, and chemical composition and in vitro digestibility of corn grain silages. The treatments consisted of corn kernels (Zea mays) ground through a 3-mm sieve and rehydrated with chlorine-free water or unsalted whey (NaCl) combined or not with bacterial-enzymatic inoculant. This was a 2 x 2 factorial completely randomized design with sources of rehydration (water or whey) and absence and presence of bacterial-enzymatic inoculant with eight replications. Water and acid whey were added to ground corn with 12% moisture in order to increase it to 35%. Rehydrated corn was ensiled in Polyvinyl chloride (PVC) minisilos and stored for 60 d. The bacterial-enzymatic inoculant used was composed of Lactobacillus curvatus, L. acidophilus, L. plantarum, L. buchneri, L. lactis, Pediococcus acidilactici, Propionibacterium acidipropionici and Enterococcus faecium, in concentrations of 1010 CFU g-1 and 5% cellulose-based enzyme complex. The aerobic exposure of silages was evaluated for 120 hours. There was interaction (P = 0.02) between the sources of rehydration and the use or not of the inoculant on the values of silage temperature during aerobic exposure. There was a difference for dry matter (DM) losses (P=0.38) between rehydrated corn silages with and without inoculant. DM losses were 37.51% higher in silage without inoculant compared to silage with inoculant (3.84% DM). There was no difference between the sources of rehydration on DM losses (P = 0.39), with a mean value of 4.99%. Corn rehydration using acid whey (P < 0.01) increased 2.19% and 31.36% DM and ash content compared to water, an average of 66.14% and 1.28%, respectively. There was no interaction (P = 0.30) between the sources of rehydration and the use of inoculants on the in vitro digestibility of DM (mean of 79.26%). The use of the bacterial-enzymatic inoculant improved the fermentation characteristics, aerobic stability and nutritional value of corn grain silage rehydrated with water or whey.

Bioaugmentation as a strategy for tailor-made volatile fatty acid production

This study aimed to develop a novel strategy for tailor-made volatile fatty acid (VFA) composition. For this purpose, the mixed microbial culture was bioaugmented by Propionibacterium acidipropionici. Anaerobic sequencing batch reactors were operated with cheese wastewater under alkali pH. While the maximum propionic acid production almost four times increased (3779 ± 201 mgCODeq propionic acid/L in the bioaugmented reactor and 942 ± 172 mgCODeq propionic acid/L in the control reactor), there was no significant difference in VFA composition. The gene copy number of P.acidipropionici increased 20 times after the bioaugmentation. Furthermore, the gene copy number of P.acidipropionici was positively correlated with total VFA and isovaleric acid concentration. The relative abundance of family Flavobacteriaceae increased in the bioaugmented reactor, which might be caused by the syntrophic relation between Flavobacteriaceae and P. acidipropionici. The cycle analysis results showed that the shorter cycle (6h) could ensure the same efficiency.

FERMENTATION AND MICROBIAL DYNAMICS OF PERENNIAL GRASSES SILAGE PREPARED WITH BIOLOGICAL INOCULANT

Ensilage provides an effective means of conserving green forage to supply as feed to ruminants. The fermentation process presented in the ensilage process depend on lactic acid bacteria (LAB). Silage quality is variable and the only way to effectively control the fermentation process, to improve the ensiling process and the quality of the resulting silage is to use an additive, mostly biological inoculants with LAB. The aim of this study was to evaluate the fermentation and microbial dynamics of perennial grasses silage with biological inoculant. Alfalfa and Poaceae mixed grasses were ensiled. Into grass silage was added biological additive, consisted of mixture of homofermentative and heterofermentative LAB and enzymes. Inoculant included strains Lactobacillus plantarum, Pediococcus acidilactici, Pediococcus pentosaceus, Propionibacterium acidipropionici, α-amylase, β-glucanase, cellulase and hemicellulase. The fermentative quality, chemical composition parameters and microbiological counts of silages at 7, 14, 21 and 60 days after ensilage were evaluated. Fermentation dynamics were examined using chemical analysis. The study showed higher values of dry matter, crude fat and NDF after supplementation of biological additive in all analyzed samples. Conversely, there was a reduction of the pH and water soluble carbohydrates concentration. Ensiling caused an increase of acetic acid concentrations as well (p0.001). There were found significant differences (p0.05) in contents of NEL between 21 and 60 days of ensiling after treatment and between the control group of fresh grass and 7 and 21 days after treatment as well. At the 7 day of fermentation process there was a significant increase in Lactobacillus spp. abundance (p0.001) and on 60 day there was a decrease in Clostridium spp. abundance (p0.001).