Propionibacterium Acidipropionici Research Articles

Chemical composition and production of ethanol and other volatile organic compounds in sugarcane silage treated with chemical and microbial additives

Sugarcane silage can be used in animal production systems; however, it is important to apply additives to improve its chemical composition and fermentative quality. We evaluated the effect of chemical (urea and calcium oxide (CaO)) and microbial (Lactobacillus buchneri (LB), Lactobacillus plantarum, Pediococcus pentosaceus, and Propionibacterium acidipropionici) additives on chemical composition, fermentation profile, microorganism population, and production of ethanol and other volatile organic compounds in sugarcane silage. Treatments studied were silage without inoculant (SS), SS with LB, SS with Lactobacillus plantarum and Pediococcus pentosaceus, SS with Lactobacillus plantarum and Propionibacterium acidipropionici, SS with 5 g CaO/kg fresh material (FM) (5CaO), SS with 10 g CaO/kg FM (10CaO), SS with 5 g urea/kg FM (5urea), and SS with 10 g urea/kg FM (10urea). The highest crude protein content (P = 0.001) and the lowest N-linked to fibre content (P = 0.001) occurred when applying urea. None of the treatments reduced the presence of yeast (P = 0.054), but a trend was detected of treatments based on CaO as promising in this Control. The silages treated with CaO had lower ethyl ester and ethanol (average for CaO-based treatments of 0.012 g/kg dry matter and 0.695 g/kg dry matter, respectively), and silages treated with 10urea had less acetone (P = 0.001) and methanol (P = 0.001). The sugarcane silages treated with chemical additive CaO reduced ethanol production and ester formation. There was a high correlation (r = 0.984) between ethyl acetate + ethyl lactate and ethanol contents.

Effect of re-ensiling on the quality of sorghum silage

The commercialization of silage in many countries, including Brazil, has increased in recent years. Re-ensiling of previously ensiled forage occurs when silage is relocated from one farm to another, where it will be compacted and sealed again. During this process, silage is exposed to oxygen before being ensiled, which may affect its quality. We exposed sorghum silage to air during the anaerobic storage phase to simulate the transportation of silages between farms. Experimental treatments included silage exposed to air for 0 or 12 h, with or without the use of an inoculant containing a mixture of Lactobacillus plantarum and the propionic bacteria Propionibacterium acidipropionici (1 × 106 cfu/g of forage; Biomax corn, Lallemand, Saint-Simon, France), totaling 4 treatments: conventional silage, conventional silage with inoculant use, re-ensilage after exposure to air, and re-ensilage after exposure to air with use of an inoculant. The sorghum was stored in experimental silos containing about 9.0 kg of fresh forage per replicate. Treatments were tested in a factorial 2 × 2 design with 5 replicates each. Chemical composition, in vitro dry matter digestibility, fermentative characteristics, losses (due to gas, effluents, and total dry matter), microorganism counts, and aerobic stability of sorghum silage were evaluated. Dry matter content of sorghum before ensiling was 273.12 g/kg. The 12-h re-ensiling process increased the effluent loss of the silage when compared with conventional silage (456.42 vs. 201.19 g/kg of FM, respectively). In addition, re-ensiled silages presented lower concentrations of lactic acid and higher concentrations of propionic acid than the silages that had not been opened during storage. The aerobic stability of silage was not affected by the re-ensiling process and the use of inoculant. The use of inoculant increased the pH and loss of dry matter of the silages (4.23 vs. 3.98 and 14.05 vs. 7.82%, respectively) and therefore did not provide any benefits in this study.

Whey utilization in a two-stage fermentation process

Abstract Whey is a major by-product of the cheese and dairy industry and has valuable nutritional constituents, however poses a major environmental risk if disposed of without prior treatment. The main components of whey except of water are lactose, lactic acid, soluble proteins, lipids, vitamins and mineral salts which give a very high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) load (30,000 - 50,000 ppm and 60.000 - 80,000 ppm, respectively) to the whey. This composition provides adequate nitrogen and carbon source to be utilized by microorganisms. The aim of this study was to examine the whey utilization in a two-stage fermentation process using Lactobacillus species and Propionibacterium acidipropionici. In the first stage Lactobacillus species utilise the main part of the nitrogen source while covert lactose content to lactic acid. In the second stage Propionibacterium acidipropionici utilize lactic acid and produce propionic acid. This two-stage fermentation process can be a feasible option, both for bioremediation of whey and production of propionic acid from waste sources. High lactose conversion (>90%) to lactic acid was achieved at the first stage, but its conversion to propionic acid during the second stage was insufficient (~30%). The COD was successfully decreased during the fermentations.

Comparative genomics and transcriptomics analysis-guided metabolic engineering of Propionibacterium acidipropionici for improved propionic acid production.

Acid stress induced by the accumulation of organic acids during the fermentation of propionibacteria is a severe limitation in the microbial production of propionic acid (PA). To enhance the acid resistance of strains, the tolerance mechanisms of cells must first be understood. In this study, comparative genomic and transcriptomic analyses were conducted on wild-type and acid-tolerant Propionibacterium acidipropionici to reveal the microbial response of cells to acid stress during fermentation. Combined with the results of previous proteomic and metabolomic studies, several potential acid-resistance mechanisms of P. acidipropionici were analyzed. Energy metabolism and transporter activity of cells were regulated to maintain pH homeostasis by balancing transmembrane transport of protons and ions; redundant protons were eliminated by enhancing the metabolism of certain amino acids for a relatively stable intracellular microenvironment; and protective mechanism of macromolecules were also induced to repair damage to proteins and DNA by acids. Transcriptomic data indicated that the synthesis of acetate and lactate were undesirable in the acid-resistant mutant, the expression of which was 2.21-fold downregulated. In addition, metabolomic data suggested that the accumulation of lactic acid and acetic acid reduced the carbon flow to PA and led to a decrease in pH. On this basis, we propose a metabolic engineering strategy to regulate the synthesis of lactic acid and acetic acid that will reduce by-products significantly and increase the PA yield by 12.2% to 10.31 ± 0.84 g/g DCW. Results of this study provide valuable guidance to understand the response of bacteria to acid stress and to construct microbial cell factories to produce organic acids by combining systems biology technologies with synthetic biology tools.

Propionic acid production from soy molasses by Propionibacterium acidipropionici: Fermentation kinetics and economic analysis

Propionic acid (PA) is a specialty chemical; its calcium salt is widely used as food preservative. Soy molasses (SM), a low-value byproduct from soybean refinery, contains sucrose and raffinose-family oligosaccharides (RFO), which are difficult to digest for most animals and industrial microorganisms. The feasibility of using SM for PA production by P. acidipropionici, which has genes encoding enzymes necessary for RFO hydrolysis, was studied. With corn steep liquor as the nitrogen source, stable long-term PA production from SM was demonstrated in sequential batch fermentations, achieving PA productivity of >0.8 g/L h and yield of 0.42 g/g sugar at pH 6.5. Economic analysis showed that calcium propionate as the main component (63.5%) in the product could be produced at US $1.55/kg for a 3000-MT plant with a capital investment of US $10.82 million. At $3.0/kg for the product, the process offers attractive 40% return of investment and is promising for commercial application.

<b>Aerobic stability in corn silage (<i>Zea mays</i>L.) ensiled with different microbial additives

This study aimed to assess different microbial additives, regarding the efficiency of aerobic stability in corn silages. The corn hybrid used for silages production was the DKB 310. The treatments consisted of: 1) control treatment without any microbial additive; 2) Treatment with LPPA composed of: Lactobacillus plantarum CCT 0580 3.1 x 1010 CFU g-1 and Propionibacterium acidipropionici CCT 4843 3.1 x 1010 CFU g-1; 3) Treatment with Inoculum, composed of Bacillus subtilis CCT 0089 3.0 x 109 CFU g-1, Lactobacillus plantarum CCT 0580 1.2 x 1010 CFU g-1 and Propionibacterium acidipropionici CCT 4843 1.5 x 1010 CFU g-1 and 4) Treatment LB, composed only of Lactobacillus buchneri CCT 3746 2.6 x 1010 CFU g-1. The experimental design was completely randomized with five replicates for each treatment. For the parameters evaluated daily, we used the split plot design, in which the different silages were assigned to the plots and the time of exposure to air was assigned to the subplots. There was no difference of additives on silage pH in any of the evaluation days. The control silage reached higher temperatures indicating greater vulnerability. All additives had no aerobic instability. Silages made with the use of microbial additives were effective in maintaining the aerobic stability.

Conversion of an inactive xylose isomerase into a functional enzyme by co-expression of GroEL-GroES chaperonins in Saccharomyces cerevisiae

BackgroundSecond-generation ethanol production is a clean bioenergy source with potential to mitigate fossil fuel emissions. The engineering of Saccharomyces cerevisiae for xylose utilization is an essential step towards the production of this biofuel. Though xylose isomerase (XI) is the key enzyme for xylose conversion, almost half of the XI genes are not functional when expressed in S. cerevisiae. To date, protein misfolding is the most plausible hypothesis to explain this phenomenon.ResultsThis study demonstrated that XI from the bacterium Propionibacterium acidipropionici becomes functional in S. cerevisiae when co-expressed with GroEL-GroES chaperonin complex from Escherichia coli. The developed strain BTY34, harboring the chaperonin complex, is able to efficiently convert xylose to ethanol with a yield of 0.44 g ethanol/g xylose. Furthermore, the BTY34 strain presents a xylose consumption rate similar to those observed for strains carrying the widely used XI from the fungus Orpinomyces sp. In addition, the tetrameric XI structure from P. acidipropionici showed an elevated number of hydrophobic amino acid residues on the surface of protein when compared to XI commonly expressed in S. cerevisiae.ConclusionsBased on our results, we elaborate an extensive discussion concerning the uncertainties that surround heterologous expression of xylose isomerases in S. cerevisiae. Probably, a correct folding promoted by GroEL-GroES could solve some issues regarding a limited or absent XI activity in S. cerevisiae. The strains developed in this work have promising industrial characteristics, and the designed strategy could be an interesting approach to overcome the non-functionality of bacterial protein expression in yeasts.

Propionic acid production from corn stover hydrolysate by Propionibacterium acidipropionici

BackgroundThe production of value-added chemicals alongside biofuels from lignocellulosic hydrolysates is critical for developing economically viable biorefineries. Here, the production of propionic acid (PA), a potential building block for C3-based chemicals, from corn stover hydrolysate is investigated using the native PA-producing bacterium Propionibacterium acidipropionici.ResultsA wide range of culture conditions and process parameters were examined and experimentally optimized to maximize titer, rate, and yield of PA. The effect of gas sparging during fermentation was first examined, and N2 was found to exhibit improved performance over CO2. Subsequently, the effects of different hydrolysate concentrations, nitrogen sources, and neutralization agents were investigated. One of the best combinations found during batch experiments used yeast extract (YE) as the primary nitrogen source and NH4OH for pH control. This combination enabled PA titers of 30.8 g/L with a productivity of 0.40 g/L h from 76.8 g/L biomass sugars, while successfully minimizing lactic acid production. Due to the economic significance of downstream separations, increasing titers using fed-batch fermentation was examined by changing both feeding media and strategy. Continuous feeding of hydrolysate was found to be superior to pulsed feeding and combined with high YE concentrations increased PA titers to 62.7 g/L and improved the simultaneous utilization of different biomass sugars. Additionally, applying high YE supplementation maintains the lactic acid concentration below 4 g/L for the duration of the fermentation. Finally, with the aim of increasing productivity, high cell density fed-batch fermentations were conducted. PA titers increased to 64.7 g/L with a productivity of 2.35 g/L h for the batch stage and 0.77 g/L h for the overall process.ConclusionThese results highlight the importance of media and fermentation strategy to improve PA production. Overall, this work demonstrates the feasibility of producing PA from corn stover hydrolysate.

A field study investigating the effectiveness of vat milk controls by qPCR for the prevention of undesired propionic acid fermentation in Sbrinz PDO cheese

The accurate monitoring of propionic acid bacteria (PAB) in cheese milk is of high importance since they can provoke undesired propionic acid fermentation during the ripening of unpasteurised milk cheeses. In the present study, we analysed 560 vat milk samples and 40 corresponding Sbrinz cheeses to evaluate the effectiveness of qPCR based controls of vat milks for the prevention of undesired propionic acid fermentation in Sbrinz PDO cheese. Two qPCR assays were used: one for the thermoduric species Propionibacterium freudenreichii and the other for the combined detection of the thermosensitive species Propionibacterium thoenii, Propionibacterium jensenii, and Propionibacterium acidipropionici. Thermoduric and thermosensitive PAB were detected in 35% and 19%, respectively, of the vat milks. However, in defective Sbrinz cheeses with propionic acid fermentation P. freudenreichii was the predominant species, indicating that low contaminations of thermosensitive PAB in vat milk do not present a risk in the manufacture of hard cooked cheeses.

Awakening sleeping beauty: production of propionic acid in Escherichia coli through the sbm operon requires the activity of a methylmalonyl-CoA epimerase

BackgroundPropionic acid is used primarily as a food preservative with smaller applications as a chemical building block for the production of many products including fabrics, cosmetics, drugs, and plastics. Biological production using propionibacteria would be competitive against chemical production through hydrocarboxylation of ethylene if native producers could be engineered to reach near-theoretical yield and good productivity. Unfortunately, engineering propionibacteria has proven very challenging. It has been suggested that activation of the sleeping beauty operon in Escherichia coli is sufficient to achieve propionic acid production. Optimising E. coli production should be much easier than engineering propionibacteria if tolerance issues can be addressed.ResultsPropionic acid is produced in E. coli via the sleeping beauty mutase operon under anaerobic conditions in rich medium via amino acid degradation. We observed that the sbm operon enhances amino acids degradation to propionic acid and allows E. coli to degrade isoleucine. However, we show here that the operon lacks an epimerase reaction that enables propionic acid production in minimal medium containing glucose as the sole carbon source. Production from glucose can be restored by engineering the system with a methylmalonyl-CoA epimerase from Propionibacterium acidipropionici (0.23 ± 0.02 mM). 1-Propanol production was also detected from the promiscuous activity of the native alcohol dehydrogenase (AdhE). We also show that aerobic conditions are favourable for propionic acid production. Finally, we increase titre 65 times using a combination of promoter engineering and process optimisation.ConclusionsThe native sbm operon encodes an incomplete pathway. Production of propionic acid from glucose as sole carbon source is possible when the pathway is complemented with a methylmalonyl-CoA epimerase. Although propionic acid via the restored succinate dissimilation pathway is considered a fermentative process, the engineered pathway was shown to be functional under anaerobic and aerobic conditions.

An overview on the biotechnological production of propionic acid: From up to downstream processes

The increasing demand for propionic acid production and wide applications in several industries especially in food (as preservative and satiety-inducer) has led looking for biosynthesis of this acid with a low total cost. This paper gives an overview on biotechnological aspects of propionic acid production and moves on to the introducing of Propionibacterium as the most popular one. Also all process variables influencing on production yield, different simple and complex carbon sources, metabolic pathway of production, engineered mutants with increased productivity, and modified tolerance against high concentrations of acid have been described. Then possible methods of extraction and analysis of this organic acid as well as several applied bioreactors, the different culture systems and substrates have been introduced. It can be concluded maximum biomass and propionic acid production may be achieved by using metabolic engineering microorganisms, and study on the most significant factors influencing on yield. To date, the maximum reported yield for propionic acid (PA) production is 0.973 g.g -1 obtained from cultivation of Propionibacterium acidipropionici in a three-electrode amperometric culture system with medium containing 0.4 mM cobalt sepulchrate. Also, the best promising substrate for PA bioproduction may be achieved by glycerol as a carbon source in an extractive continuous fermentation. Simultaneous production of propionic acid and vitamin B 12 is suggested, and finally limitations and strategies for competitive microbial production with respect to chemical process from economical view of point are proposed and presented. Finally some future trends for bioproduction of propionic acid is suggested. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;}

Dairy Propionibacteria: Versatile Probiotics.

Dairy propionibacteria are used as cheese ripening starters, as biopreservative and as beneficial additives, in the food industry. The main species, Propionibacterium freudenreichii, is known as GRAS (Generally Recognized As Safe, USA, FDA). In addition to another dairy species, Propionibacterium acidipropionici, they are included in QPS (Qualified Presumption of Safety) list. Additional to their well-known technological application, dairy propionibacteria increasingly attract attention for their promising probiotic properties. The purpose of this review is to summarize the probiotic characteristics of dairy propionibacteria reported by the updated literature. Indeed, they meet the selection criteria for probiotic bacteria, such as the ability to endure digestive stressing conditions and to adhere to intestinal epithelial cells. This is a prerequisite to bacterial persistence within the gut. The reported beneficial effects are ranked according to property’s type: microbiota modulation, immunomodulation, and cancer modulation. The proposed molecular mechanisms are discussed. Dairy propionibacteria are described as producers of nutraceuticals and beneficial metabolites that are responsible for their versatile probiotic attributes include short chain fatty acids (SCFAs), conjugated fatty acids, surface proteins, and 1,4-dihydroxy-2-naphtoic acid (DHNA). These metabolites possess beneficial properties and their production depends on the strain and on the growth medium. The choice of the fermented food matrix may thus determine the probiotic properties of the ingested product. This review approaches dairy propionibacteria, with an interest in both technological abilities and probiotic attributes.

An overview of biotechnological production of propionic acid: From upstream to downstream processes

Abstract The increasing demand for propionic acid (PA) production and its wide applications in several industries, especially the food industry (as a preservative and satiety inducer), have led to studies on the low-cost biosynthesis of this acid. This paper gives an overview of the biotechnological aspects of PA production and introduces Propionibacterium as the most popular organism for PA production. Moreover, all process variables influencing the production yield, different simple and complex carbon sources, the metabolic pathway of production, engineered mutants with increased productivity, and modified tolerance against high concentrations of acid have been described. Furthermore, possible methods of extraction and analysis of this organic acid, several applied bioreactors, and different culture systems and substrates are introduced. It can be concluded that maximum biomass and PA production may be achieved using metabolically engineered microorganisms and analyzing the most significant factors influencing yield. To date, the maximum reported yield for PA production is 0.973 g·g-1, obtained from Propionibacterium acidipropionici in a three-electrode amperometric culture system in medium containing 0.4 mM cobalt sepulchrate. In addition, the best promising substrate for PA bioproduction may be achieved using glycerol as a carbon source in an extractive continuous fermentation. Simultaneous production of PA and vitamin B12 is suggested, and finally, the limitations of and strategies for competitive microbial production with respect to chemical process from an economical point of view are proposed and presented. Finally, some future trends for bioproduction of PA are suggested.

Dairy propionibacteria prevent the proliferative effect of plant lectins on SW480 cells and protect the metabolic activity of the intestinal microbiota in vitro

Plant lectins are specific carbohydrate-binding proteins that are widespread in legumes such as beans and pulses, seeds, cereals, and many plants used as farm feeds. They are highly resistant to cooking and digestion, reaching the intestinal lumen and/or blood circulation with biological activity. Since many legume lectins trigger harmful local and systemic reactions after their binding to the mucosal surface, these molecules are generally considered anti-nutritive and/or toxic substances. In the gut, specific cell receptors and bacteria may interact with these dietary components, leading to changes in intestinal physiology. It has been proposed that probiotic microorganisms with suitable surface glycosidic moieties could bind to dietary lectins, favoring their elimination from the intestinal lumen or inhibiting their interaction with epithelial cells. In this work, we assessed in vitro the effects of two representative plant lectins, concanavalin A (Con A) and jacalin (AIL) on the proliferation of SW480 colonic adenocarcinoma cells and metabolic activity of colonic microbiota in the absence or presence of Propionibacterium acidipropionici CRL 1198. Both lectins induced proliferation of colonic cells in a dose-dependent manner, whereas ConA inhibited fermentative activities of colonic microbiota. Pre-incubation of propionibacteria with lectins prevented these effects, which could be ascribed to the binding of lectins by bacterial cells since P. acidipropionici CRL 1198 was unable to metabolize these proteins, and its adhesion to colonic cells was reduced after reaction with Con A or AIL. The results suggest that consumption of propionibacteria at the same time as lectins could reduce the incidence of lectin-induced alterations in the gut and may be a tool to protect intestinal physiology.

РАЗРАБОТКА СУХОГО БАКТЕРИАЛЬНОГО ПРЕПАРАТА ДЛЯ СИЛОСОВАНИЯ С ОПТИМАЛЬНЫМ СООТНОШЕНИЕМ МОЛОЧНОКИСЛЫХ И ПРОПИОНОВОКИСЛЫХ КУЛЬТУР

<p>Silage represents the main forage for agricultural animals during a winter period and requires the use of preservatives providing the maintenance of its quality. The use of microbial biopreservatives improves the silage consumption and productivity of animals. Multicomponent biopreservatives containing lactic acid and propionic acid bacteria are able to significantly improve organoleptic qualities and preservation of silage, especially its aerobic staility. In this study, the technology of production of liophylized bacterial preparations of earlier developed <em>Lactobacillus plantarum</em> VKPM B-4173, <em>Lactococcus lactis</em> subsp. <em>lactis</em> VKPM В-2092, and <em>Propionibacterium acidipropionici</em> VKPM В-5723 strains, characterized by valuable traits, has been developed. The optimum modes of the culture broth concentration and freeze-drying have been developed, which provide the minimization of biomass losses and obtaining of dry preparations containing at least 1 · 10<sup>11</sup> CFU/mL of viable cells. The optimum flow rate for the streaming centrifuging was 130 L/h, and the optimum temperature and duration of a preliminary freezing before the freexe-drying were 8 h at –35-40°С or 12-14 h at –25°С. The analysis of the effect of different proportions of the used strains in the final preparation on some qualitative characteristics of silage made it possible to determine the optimal proportion of <em>L. plantarum</em> VKPM B-4173, <em>L. lactis</em> VKPM В-2092, and <em>P. acidipropionici</em> VKPM В-5723 strains equal to 2 : 2 : 1, respectively. The use of such biopreservative provides the maintenance of the maximum protein content (94% of the initial level) and the maximum concent of total organic acids (2.9%) in the corn silage at the 60<sup>th</sup> day of storage. In this case, the content of lactic and acetic acids was equal to 69.4 and 31.1% of the total organic acid content, respectively. In addition, this proportion provided the minimum ammonium content in the silage (125±5 ppm or 61.6% of the control). Based on the obtained results, authors recommend to use the developed biopreservative for the improvement of the silage quality.<strong></strong></p>

Productivity of lactating cows fed on a diet of haylage from a vetch pea-oat mixture with the introduction of new biological preservative

The effect of a new biological preservative representing a mix of lyophilized Lactobacillus plantarum VKPM V-4173, Lactococcus lactis subsp. lactis VKPM V-2092 and Propionibacterium acidipropionici VKPMV-5723 strains (40 : 40 : 20) on the quality of haylage prepared from a mix of vetch, oats, and pea has been studied. The total bacteria content in the preservative was 1·1011 CFU/g. Five different variants of conservation of alfalfa haylage prepared at the budding stage were evaluated under laboratory conditions. The variants included a self-conserved control and the preservative at two different dosages (3 and 6 g/ton) with and without the addition of cellulolytic enzymes. The best results were observed in the case of both the enzyme-free and the enzyme-containing preservative at the dosage equal to 6 g/ton. These variants provided the maximum protein content in the haylage (94.3% and 94.5% of the initial content, respectively) and a high content of lactic acid (62.9% and 65.4% of the total acid content, respectively) and also good organoleptic characteristics. The determined optimum biopreservative dosage was tested under industrial conditions using 750 tons of vetch-oats-pea haylage. The use of the biopreservative provided a high-quality haylage of high nutritive value. Industrial evaluation of the effect on the productivity of milk cattle (n = 15) of the addition of the biopreservative to the haylage showed that the maximum average daily yield of milk with basic fat content (3.4%) was obtained from cows of the experimental group whose ration included haylage prepared with the use of the studied preservative. This yield came to32.7 kg , which exceeded the yield for the control group (fed on self-conserved haylage) by 7.0%. Three months feeding of cows with the haylage prepared with the use of the new preservative brought a significant saving of money (4,862 rubles per a head at the prices of 2015–2016).

Feed supplementation with avian Propionibacterium acidipropionici contributes to mucosa development in early stages of rearing broiler chickens.

Different studies in animal rearing claim the probiotic potential of species of the genus Propionibacterium. The effects of strains of Propionibacterium acidipropionici isolated from poultry intestine on microbiota activity and intestinal mucosa development were investigated in the early stage of rearing chicks and the safety of the dose used was investigated. The strains P. acidipropionici LET105 and LET107, administered as monoculture to chicks from the 1st to 14th day of life in a daily dose of 106 cfu/ml administered in the drinking water resulted harmless. The animals arrived at the expected weight for age and no differences were observed with respect to the food intake and water consumption related to control without bacteria administration. The analysis of microbiota composition revealed the presence of propionibacteria at the middle and end of the trial only in treated groups. Normal development of lactic acid bacteria and bifidobacteria, and slow colonisation by Bacteroides at the 7th day of the study was observed in the same groups. Analysis of the organic acids concentrations in the caecal content of birds revealed higher lactic acid and lower butyric acid production. Lower short chain fatty acids total concentration than expected during treatment was related to a better development of the gut mucosa. Increase in length of villus-crypt units, goblet cells counts and neutral mucins production were evidenced. Higher mucus secretion produced by dietary supplementation with propionibacteria could provide increased protection against pathogens.

A new highly productive Propionibacterium acidipropionici FL-48 strain with increased resistance to propionic acid and the scaling up of its production for industrial bioreactors

Propionic acid bacteria, including Propionibacterium acidipropionici, are widely used in the chemical industry to produce propionic acid and also for food and feed preservation. However, the efficiency of the industrial production of these bacteria is limited by their sensitivity to high concentrations of propionic acid excreted into the cultivation medium. Therefore, the development of new biotechnological processes and strains able to overcome this limitation and to improve the profitability of the microbiological production remains a relevant problem. A new P. acidipropionici FL-48 strain characterized by an increased resistance to 10 g/L of propionic acid (the number of viable cells after 24-h cultivation reached 1.05 × 106) was developed by a two-step induced mutagenesis using UV and diethyl sulphate from the P. acidipropionici VKPM B-5723 strain. The mutant strain exceeded the parental strain in the biomass accumulation rate and the amount of produced propionic and acetic acids by 35%, 20%, and 16%, respectively. The stability of such important characteristics as the biomass accumulation rate and the viability on media containing heightened concentrations of propionic acid was confirmed by three sequential monoclonal subculturings on a medium supplemented with 10 g/L of propionic acid. The optimization of the cultivation technology made it possible to determine the optimum seed inoculum dose (10% of the fermentation medium volume) and the best pH level for the active growth stage (6.1 ± 0.1). The scaling up of the fermentation to a 100-L bioreactor under observance of optimum cultivation conditions demonstrated a high biomass growth rate with a sufficient reproducability; after 20 h of fermentation, the number of viable cells in the culture broth exceeded 1 × 1010 CFU/mL. The new strain could be interesting as the component of silage and haylage biopreservatives and also could be used as an efficient producer of propionic acid.

ПОВЫШЕНИЕ КАЧЕСТВА КОРМОВ И МОЛОЧНОЙ ПРОДУКТИВНОСТИ КОРОВ ПРИ ИСПОЛЬЗОВАНИИ НОВОГО БИОЛОГИЧЕСКОГО КОНСЕРВАНТА В ЛИОФИЛИЗИРОВАННОЙ ФОРМЕ

<p>The effect of new biological preservative representing the mix of liophylized lactobacteria strains <em>Lactobacillus plantarum</em> VKPM V-4173; <em>Lactococcus lactis </em>subsp.<em> lactis </em>VKPM V-2092, and <em>Propionibacterium acidipropionici</em> VKPMV-5723 (at a ratio of 40:40:20) on the quality of a maize silage has been studied. The total bacteria content in the preparation was 1´10<sup>11</sup> CFU/g. Different variants of a silage conservation have been accesses under laboratory conditions using laboratory vessels; the variants included a preservative-free (control) variant and the dosages of 1.0, 2.0, and 3.0 g per a ton of conserved maize green mass. The evaluation of the dynamical changes in the ammonia content, pH, organic acid content and their ratio, and the analysis of the chemical composition of a silage performed at the 7<sup>th</sup>, 21<sup>st</sup>, and 60<sup>th</sup> days after the filling showed the dosage of 3.0 g/ton provided the best results.</p><p>An industrial testing of the studied preservative (3.0 g/ton) showed that, comparing to the preservative-free silage, the use of the new preservative during the filling of a maize sillage provided the better preservation of nutrients and more optimal pH and ratio of organic acids in the silage mass. The industrial evaluation of the effect of the preservative addition to the silage on the productivity of milk cattle (<em>n </em>= 12) showed that the maximum average daily yield of milk of the basis fat content was obtained from cows of the experimental group, which ration included maize silage prepared with the use of the studied preservative. This yield made 28.86 kg that exceeds the same value of the control group by 4.0%. The feeding of cows with the silage prepared with the use of the new preservative provided an increase of the volatile fatty acid content and bacteria amount in the rumen contents and simultaneously decreased the ammonia content that evidenced the improvement of the digestion processes. The digestibility of nutrients of the whole ration of cows from the experimental group was higher than that in the control group.</p><br /><p><strong> </strong></p>

PROSPECTS FOR THE APPLICATION OF ULTRASONIC MEMBRANE EXTRACTORS IN THE SUBMERGED CULTIVATION OF LACTIC ACID AND PROPIONIC ACID BACTERIA

The industrial production of lactic acid and propionic acid bacteria , which produce lactic, acetic and propionic acids and used as the components of biological preservatives of feed and fodder, requires to maintain a total concentration of organic acids in fermentation broth at a level of one percent during the whole fermentation process. The higher concentration inhibits the growth and development of these microorganisms, so their cell concentration in fermentation broth does not exceed 0.6·10 9 ml -1 . Under laboratory conditions, pH of cultivation medium can be regulated by the neutralization of organic acids with alkaline, but under the large-scale production, the loss of produced lactic, acetic, and propionic acids is inexpedient, since they are widely used in various industrial segments including the conservation of rich fodder. One of the possible solutions is the use of a membrane extractor to remove organic acids, which represent valuable metabolites, from the cultural broth directly during the cultivation process. In this study, the efficiency of a specially designed membrane extractor equipped with additional ultrasonic transducers, which reduced diffusion limitations near the membrane surface, has been assessed in the process of submerged cultivation of three bacterial cultures: Lactococcus lactis VPKM B-2092 , Lactobacillus plantarum VPKM B-4173 , and Propionibacterium acidipropionici VPKM B-5723 . The extractor was connected to the fermenter as external device and consisted of a cartridge filter preventing the biomass uptake into the extractor and a membrane extractor of a “liquid-liquid”type equipped with pH-state and hydrodynamic ultrasonic transducers. Whereas classic pH-states feed a pH-correcting solution into a fermenter according to a signal from a pH sensor, the developed pH-state construction turned on the US membrane extractor to remove excess organic acids from the fermentation broth. Due to the maintenance of optimum pH, the final concentration of L. lactis, L. plantarum, and P. acidipropionici cells increased in 5.8, 3.6, and 3.2 times, respectively. The equipping of a membrane extractor with ultrasonic transducers accelerated the removal of organic acids from fermentation broth of L. lactis, L. plantarum, and P. acidipropionici in 5.25, 5, and 6.25 times, respectively, i.e., provided a more rapid and efficient fermentation. The proposed technology improves the economical efficiency of the process and provides the required diversity of technical solutions for its use in a microbiological production.