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BackgroundBovine milk contains not only a variety of nutritional ingredients but also microRNAs (miRNAs) that are thought to be secreted by the bovine mammary epithelial cells (BMECs). The objective of this study was to elucidate the production of milk-related miRNAs in BMECs under the influence of lactogenic hormones.ResultsAccording to a microarray result of milk exosomal miRNAs prior to cellular analyses, a total of 257 miRNAs were detected in a Holstein cow milk. Of these, 18 major miRNAs of interest in the milk were selected for an expression analysis in BMEC culture that was treated with or without dexamethasone, insulin, and prolactin (DIP) to induce a lactogenic differentiation. Quantitative polymerase chain reaction (qPCR) results showed that the expressions of miR-21–5p (P = 0.005), miR-26a (P = 0.016), and miR-320a (P = 0.011) were lower in the DIP-treated cells than in the untreated cells. In contrast, the expression of miR-339a (P = 0.017) in the cell culture medium were lower in the DIP-treated culture than in the untreated culture. Intriguingly, the miR-148a expression in cell culture medium was elevated by DIP treatment of BMEC culture (P = 0.018). The medium-to-cell expression ratios of miR-103 (P = 0.025), miR-148a (P < 0.001), and miR-223 (P = 0.013) were elevated in the DIP-treated BMECs, suggesting that the lactogenic differentiation-induced secretion of these three miRNAs in BMECs. A bioinformatic analysis showed that the miRNAs down-regulated in the BMECs were associated with the suppression of genes related to transcriptional regulation, protein phosphorylation, and tube development.ConclusionThe results suggest that the miRNAs changed by lactogenic hormones are associated with milk protein synthesis, and mammary gland development and maturation. The elevated miR-148a level in DIP-treated BMECs may be associated with its increase in milk during the lactation period of cows.

Aims: To determine whether the carotenoid production improves stress tolerance of lactic acid bacteria, the cloned enterococcal carotenoid biosynthesis genes were expressed in Lactococcus lactis ssp. cremoris MG1363, and the survival rate of carotenoid-producing engineered MG1363 strain under stress condition was investigated. Methods and Results: We cloned carotenoid biosynthesis genes from yellowpigmented Enterococcus gilvus. The cloned genes consisted of crtN and crtM and its promoter region were inserted into the shuttle vector pRH100, and the resulting plasmid was named pRC. The cloned crtNM was expressed using pRC in noncarotenoid-producing L.

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Akkermansia muciniphila is a prominent member of the gut microbiota and the organism gets exposed to bile acids within this niche. Several gut bacteria have bile response genes to metabolize bile acids or an ability to change their membrane structure to prevent membrane damage from bile acids. To understand the response to bile acids and how A. muciniphila can persist in the gut, we studied the effect of bile acids and individual bile salts on growth. In addition, the change in gene expression under ox-bile condition was studied. The growth of A. muciniphila was inhibited by ox-bile and the bile salts mixture. Individual bile salts have differential effects on the growth. Although most bile salts inhibited the growth of A. muciniphila, an increased growth was observed under culture conditions with sodium deoxycholate. Zaragozic acid A, which is a squalene synthase inhibitor leading to changes in the membrane structure, increased the susceptibility of A. muciniphila to bile acids. Transcriptome analysis showed that gene clusters associated with an ABC transporter and RND transporter were upregulated in the presence of ox-bile. In contrast, a gene cluster containing a potassium transporter was downregulated. Membrane transporter inhibitors also decreased the tolerance to bile acids of A. muciniphila. Our results indicated that membrane transporters and the squalene-associated membrane structure could be major bile response systems required for bile tolerance in A. muciniphila. Key points • The growth of Akkermansia muciniphila was inhibited by most bile salts. • Sodium deoxycholate increased the growth of A. muciniphila. • The genes encoding transporters and hopanoid synthesis were upregulated by ox-bile. • The inhibitors of transporters and hopanoid synthesis reduced ox-bile tolerance.

Trillions of microbes inhabit the human gut and build extremely complex communities. Gut microbes contribute to host metabolisms for better or worse and are widely studied and associated with health and disease. Akkermansia muciniphila is a gut microbiota member, which uses mucin as both carbon and nitrogen sources. Many studies on A. muciniphila have been conducted since this unique bacterium was first described in 2004. A. muciniphila can play an important role in our health because of its beneficial effects, such as improving type II diabetes and obesity and anti-inflammation. A. muciniphila establishes its position as a next-generation probiotic. Besides the effect of A. muciniphila on host health, a technique for boosting has been investigated. In this review, we show what factors can modulate the abundance of A. muciniphila focusing on the interaction with host-derived substances, other bacteria and diets. This review also refers to the possibility of the interaction between medicine and A. muciniphila; this will open up future treatment strategies that can increase A. muciniphila abundance in the gut. Key points • Host-derived substances such as bile, microRNA and melatonin as well as mucin have beneficial effects on A. muciniphila. • Gut and probiotic bacteria and diet ingredients such as carbohydrates and phytochemicals could boost the abundance of A. muciniphila. • Several medicines could affect the growth of A. muciniphila.

γ-Aminobutyric acid (GABA) is one of the most important functional components in fermented foods because of its physiological functions, such as neurotransmission and antihypertensive activities. However, little is known about components other than GABA in GABA-rich fermented foods. A metabolomic approach offers an opportunity to discover bioactive and flavor components in fermented food. To find specific components in milk fermented with GABA-producing Lactococcus lactis 01-7, we compared the components found in GABA-rich fermented milk with those found in control milk fermented without GABA production using capillary electrophoresis time-of-flight mass spectrometry. A principal component analysis score plot showed a clear differentiation between the control milk fermented with L. lactis 01-1, which does not produce GABA, and GABA-rich milk fermented with a combination of L. lactis strains 01-1 and 01-7. As expected, the amount of GABA in GABA-rich fermented milk was much higher (1,216-fold) than that of the control milk. Interestingly, the amount of Orn was also much higher (27-fold) than that of the control milk. Peptide analysis showed that levels of 6 putative angiotensin-I-converting enzyme (ACE)-inhibitory peptides were also higher in the GABA-rich fermented milk. Furthermore, ACE-inhibitory activity of GABA-rich fermented milk tended to be higher than that of the control milk. These results indicate that the GABA-producing strain 01-7 provides fermented milk with other functional components in addition to GABA.

We measured the adhesion of candidate probiotic lactic acid bacteria (LAB) to carp intestinal mucus. The percentage of adherent bacteria varied among strains. Four strains, two with high adhesion and two with low adhesion in vitro, were tested for in vivo colonization ability. Carp were fed LAB-containing feed for 12 d, and then unsupplemented feed until day 33, and the numbers and compositions of intestinal LAB were analyzed during the entire period. LAB with lower in vitro adhesion disappeared quickly from the intestine after LAB feeding stopped. LAB with higher in vitro adhesion remained in the intestine 3 weeks after LAB feeding stopped, indicating a strong correlation between mucus adhesion in vitro and colonization ability in vivo. Next we isolated nine candidate probiotic LAB with high in vitro mucus-binding ability. Three of them were fed to carp, and all three were stably maintained in the intestine.