The intestinal microbiota affect various physiological traits of host animals such as brain development, obesity, age, and the immune system. In the swine industry, understanding the relationship between intestinal microbiota and growth stage is essential because growth stage is directly related to the feeding system of pigs, thus we studied the intestinal microbiota of 32 healthy pigs across five sows at 10, 21, 63, 93, and 147 d of ages. The intestinal microbiota were altered with growth of pigs and were separated into three distinct clusters. The relative abundance of several phyla and genera were significantly different between growth stages. We observed co-occurrence pattern of the intestinal microbiota at each growth stage. In addition, we predicted the functions of the intestinal microbiota and confirmed that several KEGG pathways were significantly different between growth stages. We also explored the relationship between the intestinal microbiota and innate factors such as the maternal effect and gender. When pigs were young, innate factors affected on construction of intestinal microbiota, however this tendency was disappeared with growth. Our findings broaden the understanding of microbial ecology, and the results will be used as a reference for investigating host-microbe interactions in the swine industry.

In the poultry industry, many efforts have been undertaken to further improve the growth performance of broilers and identification and modulation of body weight (BW)-related bacteria could be one of the strategies to improve productivity. However, studies regarding the relationship between microbiota and BW are scarce. The objective of the present study was to investigate the relationship between microbiota and BW in different sections of the gastrointestinal tract (GIT). A total of twenty 18-day-old birds were selected based on the BW, and samples were collected from the three different sections of the GIT, which included the crop, ileum and cecum. Bacterial genomic DNA was extracted from the samples, and the V4 region of 16S rRNA gene were amplified. Amplicons were sequenced on Illumina MiSeq, and microbial communities were analyzed by using QIIME. In principal coordinate analysis, bacterial communities were clustered into three groups, based on the sections of GIT. Several BW-related bacterial groups were identified from linear regression analysis. At the genus level, Streptococcus from the ileum as well as Akkermansia in both ileum and cecum, were negatively related to BW, whereas Bifidobacterium in the ileum and Lactococcus in the cecum showed a positive correlation. The results from the present study showed that particular bacterial communities in the GIT were related to BW, and the study has broadened the understanding of the intestinal microbial ecosystem in broiler chickens.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2604-8) contains supplementary material, which is available to authorized users.

Due to the ban on the use of antimicrobial growth promoters in livestock feeds, understanding the relationship between intestinal microbiota and the physiology of the host has become very important for improving livestock performance. In this study, we investigated the relationship between intestinal microbiota and body weights of weaned piglets. Lighter (n = 9) and heavier (n = 9) 9-week-old weaned piglets were selected from approximately one hundred individuals based on their body weights. Their fecal microbial communities were analyzed by sequencing the V4 region of the 16S rRNA gene. The microbial richness estimators of the heavier piglets were significantly higher than those of the lighter piglets. At the phylum level, the microbiota of the heavier group had significantly higher levels of Firmicutes and a higher Firmicutes-to-Bacteroidetes ratio than that of the lighter group. At the genus level, the levels of several genera, such as Anaerococcus and Lactococcus, were significantly different in the two groups. In particular, the lighter group had significantly higher levels of opportunistic pathogenic bacteria, such as Anaerotruncus and Bacteroides, compared with those of the heavier group. Moreover, the levels of bacteria expressing the components of several metabolic pathways were significantly different in the two groups. The microbiota of the heavier group had a significantly higher involvement in three KEGG pathways concerned with xenobiotic degradation than that of the lighter group. These results may provide insights into host-microbe interactions occurring in the piglet intestine and will be useful in establishing a strategy for improving growth performance in the swine industry.

Lactobacillus salivarius is an important member of the animal gut microflora and is a promising probiotic bacterium. However, there is a lack of research on the genomic diversity of L. salivarius species. In this study, we generated 21 L. salivarius draft genomes, and investigated the pan-genome of L. salivarius strains isolated from humans, pigs and chickens using all available genomes, focusing on host adaptation. Phylogenetic clustering showed a distinct categorization of L. salivarius strains depending on their hosts. In the pan-genome, 15 host-specific genes and 16 dual-host-shared genes that only one host isolate did not possess were identified. Comparison of 56 extracellular protein encoding genes and 124 orthologs related to exopolysaccharide production in the pan-genome revealed that extracellular components of the assayed bacteria have been globally acquired and mutated under the selection pressure for host adaptation. We also found the three host-specific genes that are responsible for energy production in L. salivarius. These results showed that L. salivarius has evolved to adapt to host habitats in two ways, by gaining the abilities for niche adhesion and efficient utilization of nutrients. Our study offers a deeper understanding of the probiotic species L. salivarius, and provides a basis for future studies on L. salivarius and other mutualistic bacteria.

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As alternatives to antibiotics in livestocks, probiotics have been used, although most of them in the form of liquid or semisolid formulations, which show low cell viability after oral administration. Therefore, suitable dry dosage forms should be developed for livestocks to protect probiotics against the low pH in the stomach such that the products have higher probiotics survivability. Here, in order to develop a dry dosage forms of probiotics for poultry, we used hydroxypropyl methylcellulose phthalate 55 (HPMCP 55) as a tablet-forming matrix to develop probiotics in a tablet form for poultry. Here, we made three different kinds of probiotics-loaded tablet under different compression forces and investigated their characteristics based on their survivability, morphology, disintegration time, and kinetics in simulated gastrointestinal fluid. The results indicated that the probiotics formulated in the tablets displayed higher survival rates in acidic gastric conditions than probiotics in solution. Rapid release of the probiotics from the tablets occurred in simulated intestinal fluid because of fast swelling of the tablets in neutral pH. As a matrix of tablet, HPMCP 55 provided good viability of probiotics after 6 months under refrigeration. Moreover, after oral administration of probiotics-loaded tablets to chicken, more viable probiotics were observed, than with solution type, through several digestive areas of chicken by the tablets.

After the introduction of a ban on the use of antibiotic growth promoters (AGPs) for livestock, reuterin-producing Lactobacillus reuteri is getting attention as an alternative to AGPs. In this study, we investigated genetic features of L. reuteri associated with host specificity and antipathogenic effect. We isolated 104 L. reuteri strains from porcine feces, and 16 strains, composed of eight strains exhibiting the higher antipathogenic effect (group HS) and eight strains exhibiting the lower effect (group LS), were selected for genomic comparison. We generated draft genomes of the 16 isolates and investigated their pan-genome together with the 26 National Center for Biotechnology Information-registered genomes. L. reuteri genomes organized six clades with multi-locus sequence analysis, and the clade IV includes the 16 isolates. First, we identified six L. reuteri clade IV-specific genes including three hypothetical protein-coding genes. The three annotated genes encode transposases and cell surface proteins, indicating that these genes are the result of adaptation to the host gastrointestinal epithelia and that these host-specific traits were acquired by horizontal gene transfer. We also identified differences between groups HS and LS in the pdu-cbi-cob-hem gene cluster, which is essential for reuterin and cobalamin synthesis, and six genes specific to group HS are revealed. While the strains of group HS possessed all genes of this cluster, LS strains have lost many genes of the cluster. This study provides a deeper understanding of the relationship between probiotic properties and genomic features of L. reuteri.

Probiotics show low cell viability after oral administration because they have difficulty surviving in the stomach due to low pH and enzymes. For the oral delivery of probiotics, developing a formula that protects the probiotic bacteria from gastric acidity while providing living cells is mandatory. In this study, we developed tablets using a new pH-sensitive phthalyl inulin (PI) to protect probiotics from gastric conditions and investigated the effects of different compression forces on cell survival. We made three different tablets under different compression forces and measured survivability, disintegration time, and kinetics in simulated gastric-intestinal fluid. During tableting, there were no significant differences in probiotic viability among the different compression forces although disintegration time was affected by the compression force. A higher compression force resulted in higher viability in simulated gastric fluid. The swelling degree of the PI tablets in simulated intestinal fluid was higher than that of the tablets in simulated gastric fluid due to the pH sensitivity of the PI. The probiotic viability formulated in the tablets was also higher in acidic gastric conditions than that for probiotics in solution. Rapid release of the probiotics from the tablet occurred in the simulated intestinal fluid due to the pH sensitivity. After 6 months of refrigeration, the viability of the PI probiotics was kept. Overall, this is the first study to show the pH-sensitive properties of PI and one that may be useful for oral delivery of the probiotics.