Selection of useful probiotic lactic acid bacteria from the Lactobacillus acidophilus group and their applications to functional foods

In the present review, a new mass screening system for selecting probiotic strains from Lactobacillus (L) acidophilus group lactic acid bacteria (LAB) with strong adhesion to the human intestinal tract is described. Characteristics of antimicrobial peptides (bacteriocin), lactose‐hydrolyzing enzymes and immunostimulative oligo DNA motifs in L. gasseri strains are also described. Finally, the use of L. acidophilus LAB, selected by our screening method, that have strong adhesion to the human colonic mucosa in functional yogurt products is described. Adhesiveness to the human intestine is one of the most important characteristics of probiotic LAB. A new screening system that involves a combination of three methods is proposed: rat colonic mucin (RCM)‐micro plate assay, Carnoy's histochemical staining method and carbohydrate probe binding assay. By using an RCM‐coated poly‐vinylidene‐diflouride membrane that mimics the human colonic mucous layer, a new lectin was isolated and its structure was clarified by gene cloning. Furthermore, the structures and functions of a new cyclic bacteriocin (gassericin A), new lactose‐hydrolyzing enzymes, and new immunostimulating oligo DNA motifs from Lactobacillus gasseri (B₁ subgroup) were clarified. A new functional yogurt ‘Fit down’ is proposed, that is fermented by an adhesive strain of L. acidophilus LA67 selected by our screening and contains antihypertensive peptides derived from whey proteins by protease digestion. In the future, superior functional foods containing more effective probiotic LAB are expected to be developed by the use of the proposed mass screening system.     

Oral administration of Lactobacillus plantarum Lq80 and Megasphaera elsdenii iNP‐001 induces efficient recovery from mucosal atrophy in the small and the large intestines of weaning piglets

Weaning causes atrophy of intestinal mucosa and a drop of IgA protection in piglets which increases vulnerability to pathogenic infections. Probiotic lactobacilli may support recovery from such weaning stresses. Butyrate‐produce bacteria may support the growth of colonic mucosa. Megasphaera elsdenii, a lactate‐utilizing butyrate producer, may help butyrate production particularly when combined with lactobacilli. Weaned piglets (Experiment 1: 20 days old, Experiment 2: 28 days old) were orally dosed once a day with either (L) 10¹⁰ (cell/dose) L. plantarum Lq80, or (LM) 10¹⁰ (cell/dose) Lq80 with 10⁹ (cell/dose) M. elsdenii iNP‐001. Lq80 was contained in capsules resistant to gastric digestion. M. elsdenii was contained in capsules resistant to gastric and intestinal digestion. An untreated control (C) was also prepared. After 2 weeks of administration, L. plantarum enhanced the recovery from the villous atrophy in both experiments. The rectal and colonic IgA tended to be higher in L and LM than in C in Experiment 1. Colonic butyrate was higher in LM than in the others in Experiment 1. The thickness of the colonic mucosa was greater in LM than in the others in Experiment 1. In early weaned piglets, the effects of L. plantarum and M. elsdenii were clear.     

The investigation of probiotic potential of lactic acid bacteria isolated from traditional Mongolian dairy products

The aims of this study were to investigate the diversity of lactic acid bacteria (LAB) isolated from traditional Mongolian dairy products, and to estimate the probiotic potential of the isolated strains. We collected 66 samples of the traditional Mongolian dairy products tarag (n = 45), airag (n = 7), aaruul (n = 8), byasulag (n = 1) and eezgii (n = 5), from which 543 LAB strains were isolated and identified based on 16S ribosomal DNA sequence. The predominant species of those products were Lactobacillus (L.) delbrueckii ssp. bulgaricus, L. helveticus, L. fermentum, L. delbrueckii ssp. lactis and Lactococcus lactis ssp. lactis. However, we could not detect any LAB strains from eezgii. All LAB isolates were screened for tolerance to low pH and to bile acid, gas production from glucose, and adherence to Caco‐2 cells. In vitro, we found 10 strains possess probiotic properties, and almost identified them as L. plantarum or L. paracasei subspecies, based on 16S ribosomal DNA and carbohydrate fermentation pattern. These strains were differentiated from each other individually by randomly amplified polymorphic DNA analysis. Additionally, it was notable that 6/10 strains were isolated from camel milk tarag from the Dornogovi province.     

Effect of lactic acid bacteria,molasses, and their combination on the fermentation quality and bacterial community of cassava foliage silage

This study investigated the effects of LAB inoculants (L) and molasses (M) on the microbial community and fermentation quality of cassava foliage (CF). The small segments (about 2–3 cm) CF were ensiled in plastic bags and incubated at normal temperature (25°C). Four treatments were carried out as follows: control (no additives, CK), LAB inoculants (Lactobacillus plantarum, L), molasses (M), and LAB in combination with molasses (LM). The LAB and molasses obviously altered the bacterial community structure of the CF silage and enhanced the fermentation quality. The combination addition could increase the abundance of Lactobacillus and reduce the Pseudomonas. The LAB and molasses also significantly elevated the lactic acid concentration (P < 0.001) and decreased the pH (P < 0.001), as well as the concentrations of acetic acid, propionic acid, butyric acid, and ammonia-N (P < 0.05). In addition, the combination treatment displayed more effective results on silage fermentation. The LAB and molasses improved the fermentation quality of the CF silage by altering the bacterial community structure. Furthermore, the bacterial community was significantly correlated with fermentation indexes.     

Identification of lactic acid bacteria isolated from corn stovers

One hundred and twenty‐six strains were isolated from corn stover in Henan Province, China, of which 105 isolates were considered to be lactic acid bacteria (LAB) according to Gram‐positive, catalase‐negative and mainly metabolic lactic acid product. Analysis of the 16S ribosomal DNA sequence of 21 representative strains was used to confirm the presence of the predominant groups and to determine the phylogenetic affiliation of isolates. The sequences from the various LAB isolates showed high degrees of similarity to those of the GenBank type strains between 99.4% and 100%. The prevalent LAB, predominantly Lactobacillus (85.6%), consisted of L. plantarum (33.3%), L. pentosus (28.6%) and L. brevis (23.7%). Other LAB species as Leuconostoc lactis (4.8%), Weissella cibaria (4.8%) and Enterococcus mundtii (4.8%) also presented in corn stover. The present study is the first to fully document corn stover‐associated LAB involved in the silage fermentation. The identification results revealed LAB composition inhabiting corn stover and enabling the future design of appropriate inoculants aimed at improving the fermentation quality of silage.     

Effects of probiotic lactic acid bacteria on growth performance,carcass characteristics,hematological indices,humoral immunity,and IGF-I gene expression in broiler chicken

The effects of screened lactic acid bacteria strains were evaluated on growth performance, humoral immunity, and IGF-1 gene expression in broiler chickens. The three dietary groups of negative control fed basal diet, the native LAB probiotic group (NP), and PrimaLac commercial LAB probiotic (PC) were studied. The results revealed that NP and PC diets significantly improved feed conversion ratio and increased body weight, as well as relative weight of carcass compared with group fed NC diet (P?<?0.05). Lymphocyte level was significantly increased in birds fed NP and PC (P?<?0.01), while serum triglycerides and total cholesterol levels were significantly decreased compared with the NC (P?<?0.05). Significant increases were observed in antibody titers against Newcastle disease virus of vaccinated birds (P?<?0.03), and morphological analysis of ileum revealed significant increases (P?<?0.05) in the villus height and villus height/crypt depth in birds fed NP and PC compared with the NC. The dietary significantly increased Lactobacillus spp. (P?<?0.05), while Escherichia coli (P?<?0.04) populations were significantly decreased, and also, the expression of IGF-1 gene in liver tissue of broilers fed NP and PC was significantly increased compared with the NC (P?<?0.05). These results indicated that the identified native LAB strains can be used commercially as a low-cost probiotic in poultry industry of Iran.

     

Silage fermentation and ruminal degradation of stylo prepared with lactic acid bacteria and cellulase

In order to improve the silage fermentation of stylo (Stylosanthes guianensis ) in tropical areas, stylo silages were prepared with commercial additives Lactobacillus plantarum Chikuso‐1 (CH 1), L. rhamnasus Snow Lact L (SN ), Acremonium cellulase (CE ) and their combination as SN +CE or CH 1 + CE , and the fermentation quality, chemical composition and ruminal degradation of these silages were studied. Stylo silages treated with lactic acid bacteria (LAB ) or cellulase, the pH value and NH ₃‐N ? total‐N were significantly (P  <  0.05) decreased while the ruminal degradability of dry matter (DM ), crude protein (CP ), neutral detergent fiber (aNDF om) and acid detergent fiber (ADF om) were significantly (P  <  0.05) increased compared to control. Compared to LAB or cellulase‐treated silages, the DM , CP contents and relative feed value (RFV ), and the ruminal degradability in LAB plus cellulase‐treated silages were significantly (P  <  0.05) higher, but the aNDF om content was significantly (P  <  0.05) lower. CH 1 + CE treatment was more effective in silage fermentation and ruminal degradation than SN +CE treatment. The results confirmed that LAB or LAB plus cellulase treatment could improve the fermentation quality, chemical composition and ruminal degradation of stylo silage. Moreover, the combined treatment with LAB and cellulase may have beneficial synergistic effects on ruminal degradation.     

The bio‐surfactant mannosylerythritol lipid acts as a selective antibacterial agent to modulate rumen fermentation

Methyl‐mannosylerythritol lipid (MEL), a new sugar esterified lipid synthesized by Pseudozyma aphidis, was assessed for its functionality in modulating rumen fermentation and microbiota toward more propionate and less methane production. A pure culture study using rumen representatives showed that MEL selectively inhibited the growth of most Gram‐positive bacteria including Streptococcus bovis, ruminococci, and Fibrobacter succinogenes, but not Gram‐negative bacteria such as Megasphaera elsdenii, Succinivibrio dextrinosolvens, and Selenomonas ruminantium. A batch culture study revealed that MEL significantly decreased methane production in a dose‐dependent manner with accumulation of hydrogen, while propionate production was enhanced. A continuous culture (Rusitec) study confirmed all of these changes. A feeding study revealed that sheep fed a MEL diet showed an increased proportion of propionate, while proportions of acetate and butyrate were decreased without affecting total VFA level. These changes disappeared after cessation of MEL feeding. Based on these results, dietary application of MEL can favorably modify rumen fermentation in terms of the efficiency of dietary energy utilization.     

Characterization and application of lactic acid bacteria for tropical silage preparation

Strains TH 14, TH 21 and TH 64 were isolated from tropical silages, namely corn stover, sugar cane top and rice straw, respectively, prepared in Thailand. These strains were selected by low pH growth range and high lactic acid‐producing ability, similar to some commercial inoculants. Based on the analysis of 16S ribosomal RNA gene sequence and DNA‐DNA relatedness, strain TH 14 was identified as Lactobacillus casei, and strains TH 21 and TH 64 were identified as L. plantarum. Strains TH 14, TH 21, TH 64 and two commercial inoculants, CH (L. plantarum) and SN (L. rhamnosus), were used as additives to fresh and wilted purple Guinea and sorghum silages prepared using a small‐scale fermentation method. The number of epiphytic lactic acid bacteria (LAB) in the forages before ensilage was relatively low but the numbers of coliform and aerobic bacteria were higher. Sorghum silages at 30 days of fermentation were all well preserved with low pH (3.56) and high lactic acid production (72.86 g/kg dry matter). Purple Guinea silage inoculated with LAB exhibited reduced count levels of aerobic and coliform bacteria, lower pH, butyric acid and ammonia nitrogen and increased lactic acid concentration, compared with the control. Strain TH 14 more effectively improved lactic acid production compared with inoculants and other strains. © 2016 Japanese Society of Animal Science     

Effects of the acid-tolerant engineered bacterial strain Megasphaera elsdenii H6F32 on ruminal pH and the lactic acid concentration of simulated rumen acidosis in vitro

The aim of this study was to examine the effects of the acid-tolerant engineered bacterial strain Megasphaera elsdenii H6F32 (M. elsdenii H6F32) on ruminal pH and the lactic acid concentrations in simulated rumen acidosis conditions in vitro. A mixed culture of ruminal bacteria, buffer, and primarily degradable substrates was inoculated with equal numbers of M. elsdenii H6 or M. elsdenii H6F32. The pH and lactic acid concentrations in the mixed culture were determined at 0, 2, 4, 6, 8, 10, 12, 14, 16, and 18 h of incubation. Acid-tolerant M. elsdenii H6F32 reduced the accumulation of lactic acid and increased the pH value. These results indicate that acid-tolerant M. elsdenii H6F32 could be a potential candidate for preventing rumen acidosis.     

Interaction between lactic acid bacteria and yeasts in airag,an alcoholic fermented milk

The interaction between nine lactic acid bacteria (LAB) and five yeast strains isolated from airag of Inner Mongolia Autonomic Region, China was investigated. Three representative LAB and two yeasts showed symbioses were selected and incubated in 10% (w/v) reconstituted skim milk as single and mixed cultures to measure viable count, titratable acidity, ethanol and sugar content every 24 h for 1 week. LAB and yeasts showed high viable counts in the mixed cultures compared to the single cultures. Titratable acidity of the mixed cultures was obviously enhanced compared with that of the single cultures, except for the combinations of Lactobacillus reuteri 940B3 with Saccharomyces cerevisiae 4C and Lactobacillus helveticus 130B4 with Candida kefyr 2Y305. C. kefyr 2Y305 produced large amounts of ethanol (maximum 1.35 g/L), whereas non‐lactose‐fermenting S. cerevisiae 4C produced large amounts of ethanol only in the mixed cultures. Total glucose and galactose content increased while lactose content decreased in the single cultures of Leuconostoc mesenteroides 6B2081 and Lb. helveticus 130B4. However, both glucose and galactose were completely consumed and lactose was markedly reduced in the mixed cultures with yeasts. The result suggests that yeasts utilize glucose and galactose produced by LAB lactase to promote cell growth.     

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.     

Cultivable microbiota of Lithobates catesbeianus and advances in the selection of lactic acid bacteria as biological control agents in raniculture

The cultivable microbiota of skin and cloaca of captive Lithobates catesbeianus includes microorganisms generally accepted as beneficial and potentially pathogenic bacteria. In order to select a group of potentially probiotic bacteria, 136 isolates were evaluated for their surface properties and production of antagonistic metabolites. Then, 11 lactic acid bacteria (LAB) strains were selected and identified as Lactobacillus plantarum, Lb. brevis, Pediococcus pentosaceus, Lactococcus lactis, L. garvieae and Enterococcus gallinarum. Studies of compatibility indicate that all the strains could be included in a multi-strain probiotic, with the exception of Ent. gallinarum CRL 1826 which inhibited LAB species through a bacteriocin-like metabolite. These results contribute to the design of a probiotic product to improve the sanitary status of bullfrogs in intensive culture systems, to avoid the use of antibiotics and thus to reduce production costs. It could also be an alternative to prevent infectious diseases during the ex situ breeding of amphibian species under threat of extinction.     

Effect of Megasphaera elsdenii NCIMB 41125 dosing on rumen development,volatile fatty acid production and blood β‐hydroxybutyrate in neonatal dairy calves

Thirty calves were randomly assigned to two treatments and fed until weaning [42 days (d) of age]. Treatments were a control group (n = 15), which did not receive Megasphaera elsdenii (Me0) and a M. elsdenii group, which received a 50‐ml oral dose of M. elsdenii NCIMB 41125 (10⁸ CFU/ml) at day 14 day of age (Me14). Calves were given colostrum for the first 3 day followed by limited whole milk feeding. A commercial calf starter was offered ad libitum starting at day 4 until the end of the study. Fresh water was available throughout the study. Feed intake and growth were measured. Blood samples were collected via jugular venipuncture to determine β‐hydroxybutyrate (BHBA) concentrations. Fourteen male calves (seven per group) were euthanised on day 42 and digestive tracts harvested. Reticulo‐rumen weight was determined and rumen tissue samples collected from the cranial and caudal sacs of the ventral and dorsal portions of the rumen for measurements of papillae length, papillae width and rumen wall thickness. Dosing with M. elsdenii NCIMB 41125 improved starter dry matter intake (DMI), weaning body weight (BW) and tended to improve average daily gain. Calves in Me14 group had greater plasma BHBA concentration than Me0‐calves during the last 3 weeks of the trial and had at day 42 greater reticulo‐rumen weight, papillae width and papillae density compared to Me0. No differences in rumen wall thickness or papillae length were observed between the two groups. Total volatile fatty acids, acetate and propionate production did not differ between treatments, but butyrate production was greater in Me14 than Me0. Dosing M. elsdenii NCIMB 41125 showed benefit for calves with improved feed intake and rumen development suggesting increased epithelium metabolism and improved absorption of digestive end products.     

Fermentation quality and aerobic stability of mulberry silage prepared with lactic acid bacteria and propionic acid

The objective of this study was to examine the fermentation quality and aerobic stability of mulberry (Morus alba L.) silage prepared with lactic acid bacteria (LAB) and propionic acid (PA). The selected LAB strains Lactobacillus (L.) plantarum LC365281 (L1) and L. brevis LC365282 (L2), and commercial inoculant strains L. plantarum Gaofuji (GF) and L. buchneri Fresh (FR), and PA were used as additives for silage preparation. Silage treatments were designed as control, L1, L2, GF, FR, PA, PA + L1, PA + L2, PA + GF, or PA + FR. After 30 days of ensiling, the fermentation quality of silages treated with PA + L1 was improved, with a lower (p < 0.05) pH and NH₃‐N content than those of other treatments. During the aerobic exposure, the PA + LAB‐treated silages displayed an aerobic stability with stable pH value and lactic acid content. The results confirm that L. plantarum L1 and PA were the best additive combination for ensiling mulberry.     

Identification of lactic acid bacteria in the feces of dairy cows fed whole crop maize silage to assess the survival of silage bacteria in the gut

In order to assess the survival of lactic acid bacteria (LAB) in whole crop maize silage in the gut of dairy cows, one representative silage sample and three different feces samples were collected from dairy cows on three dairy farms in Hua Bei, China and three dairy farms in Kyushu, Japan. The composition of the bacterial community was examined by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction. Lactobacillus acetotolerans was detected in all bunker‐made maize silage samples, regardless of the dairy farm or sampling region from which they were sourced. A total of eight LAB species were detected in the maize silage samples, of which three (L. acetotolerans, L. pontis and L. casei) appeared to survive digestion. The populations of L. acetotolerans in silage and feces were 10^6–7 and 10^3–4 copies/g, respectively, indicating that, even for the LAB species showing potential survival in the gut, competition in this niche may be harsh and the population may substantially decrease during the digestion process. It may be difficult for silage LAB to survive in the gut of silage‐fed dairy cows, because marked decrease in population can take place during the digestion process, even for surviving species.     

Isolating and evaluating lactic acid bacteria strains for effectiveness on silage quality at low temperatures on the Tibetan Plateau

Four lactic acid bacteria (LAB) strains isolated from straw silages on the Tibetan Plateau were characterized, and their effects on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) at different temperatures (10°C, 15°C and 25°C) were studied. These LAB isolates were evaluated using the acids production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. All the isolates (M1, LM8, LO7 and LOG9) could grow at 5‐20°C, pH 3.5‐7.0 and NaCl (3.0%, 6.5%). Strains M1, LM8, LO7 and LOG9 were identified as Lactobacillus plantarum, L. coryniformis, Pediococcus pentosaceus and P. acidilactici, respectively, by sequencing 16S ribosomal DNA. The four isolates were added to Italian ryegrass for ensiling for 30 days at various temperatures. Compared with the corresponding control, inoculating with isolates M1, LM8 and LO7 could improve the silage quality of Italian ryegrass at low temperatures, indicated by significantly (P < 0.05) higher lactic acid (LA) contents and ratios of lactic acid/acetic acid (LA/AA), and significantly (P < 0.05) lower pH and ammonia nitrogen/total nitrogen (AN/TN). Compared with other isolates, LM8 performed better at 10°C and 15°C, indicated by the higher (P < 0.05) LA content and ratio of LA/AA, and the lower (P < 0.05) pH and AN/TN.     

Fermentation quality and chemical composition of shrub silage treated with lactic acid bacteria inoculants and cellulase additives

Effects of lactic acid bacteria (LAB) inoculants and cellulase additives on fermentation quality and chemical compositions of shrub silages were studied by using a small‐scale fermentation system. Two LAB inoculants of Qingbao (Lactobacillus plantarum, Pediococcus acidilacticii, Lactobacillus casei and Clostridium phage) and Caihe (Lactobacillus plantarum, Lactobacillus brevis and Pediococcus acidilactici) and a commercial cellulase made from Trichoderma reesei were used as additives for intermediate pea‐shrub, rush bushclover, arborescent ceratoides and shrubby silage preparation. The crude protein, neutral detergent fiber and water‐soluble carbohydrate contents of the four shrub materials were 10.1–14.2, 62.6–67.2 and 1.9–3.5% on a dry matter basis, respectively. All shrub silages had pH 3.40–4.43, ammonia‐N 0.1–0.2% g/kg and lactic acid 1.3–2.9% on a fresh matter basis. The silage quality of LAB‐inoculated silages did not have a greater effect than control silages, except shrubby silage preparation. Silages treated with the cellulase, the pH of rush bushclover and shrubby sweetvetch silage were significantly (P < 0.05) lower and the lactic acid content were significantly (P < 0.05) higher than the control silages. The results confirmed that shrub contained a relatively high content of crude protein; its silages can be preserved in good quality, and they are new potential resources for livestock feed.     

Production of a bacteriocin‐like inhibitory substance by Leuconostoc mesenteroides subsp. dextranicum 213M0 isolated from Mongolian fermented mare milk,airag

Strain 213M0 was selected with productivity of a bacteriocin‐like inhibitory substance (BLIS) among 235 strains of lactic acid bacteria (LAB) isolated from Mongolian fermented milk ‘airag’. Strain 213M0 was species‐identified as Leuconostoc mesenteroides subsp. dextranicum by morphological observation, carbohydrate fermentation profiling and sequencing the 16S rRNA gene. Incubation temperature proper to produce the BLIS was 25°C rather than 30 and 37°C, and the production actively proceeded during the exponential growth phase of the producer cells. Antibacterial effect of BLIS 213M0 was limited to all nine strains of Listeria sp. bacteria and seven strains of LAB cocci among 53 tested strains, which corresponds to a typical feature of the class IIa pediocin‐like bacteriocins. BLIS 213M0 was not inactivated in every broad pH range solution (pH 2.0‐11.0), and was stable against storage at 25°C for 1 week and heating at 121°C for 15 min under pH 4.5. Peptide frame of BLIS 213M0 was confirmed by inactivation with some peptidases, and then its molecular weight was estimated to be 2.6‐3.0 kDa using an in situ activity assay following sodium dodecyl sulfate polyacrylamide gel electrophoresis. The estimated size was different from the other Leuconostoc bacteriocins already reported. These results suggest that BLIS 213M0 would be a novel listericidal bacteriocin.     

Performance, intestinal microflora, and wall morphology of weanling pigs fed sodium butyrate

Adding organic acids to piglet diets is known to be helpful in overcoming postweaning syndrome, and butyric acid is known to be the main energy source for the epithelial cells of the large intestine and the terminal ileum. This study investigated the effect of sodium butyrate (SB) on in vitro and in vivo swine microflora, piglet growth performance, and intestinal wall morphology. During a 24-h in vitro cecal fermentation, total gas production and maximal rate of gas production were reduced linearly by SB (P < 0.001). Ammonia in cecal liquor was increased linearly by SB after 4, 8, and 24 h of fermentation (P < 0.001). In the in vivo study, 48 piglets housed in individual crates were allotted to 4 treatment groups (12 animals per treatment) for 6 wk. Piglets received a basal diet with a) no addition (control), or with SB at b) 1,000 ppm, c) 2,000 ppm, or d) 4,000 ppm. After 6 wk, 6 animals per treatment were killed, and samples of intestinal content and mucosa were collected. Sodium butyrate did not improve the animal growth performance. In the cecum, SB increased pH and isobutyric acid concentration (linear, P < 0.05) and tended to increase ammonia concentration (P = 0.056). Intestinal counts of clostridia, enterobacteriaceae, and lactic acid bacteria as well as intestinal mucosal morphology were not affected by feeding SB. This study showed that SB influenced the cecal microflora in an in vitro system, reducing the total gas production but increasing ammonia concentrations. When fed to piglets, SB did not improve the animal growth performance, increased cecal pH, and tended to increase cecal ammonia concentrations. Further studies will be needed to better understand the mechanisms underlying the effects observed when SB is fed to piglets.