The use of probiotics for farm animals has increased considerably over the last 15 years. Probiotics are defined as live microorganisms which can confer a health benefit for the host when ...administered in appropriate and regular quantities. Once ingested, the probiotic microorganisms can modulate the balance and activities of the gastrointestinal microbiota, whose role is fundamental to gut homeostasis. It has been demonstrated that numerous factors, such as dietary and management constraints, can strongly affect the structure and activities of the gut microbial communities, leading to impaired health and performance in livestock animals. In this review, the most important benefits of yeast and bacterial probiotics upon the gastrointestinal microbial ecosystem in ruminants and monogastric animals (equines, pigs, poultry, fish) reported in the recent scientific literature are described, as well as their implications in terms of animal nutrition and health. Additional knowledge on the possible mechanisms of action is also provided.
The bovine gastrointestinal tract is the main reservoir for enterohaemorrhagic Escherichia coli (EHEC) responsible for food-borne infections. Characterization of nutrients that promote the carriage ...of these pathogens by the ruminant would help to develop ecological strategies to reduce their survival in the bovine gastrointestinal tract. In this study, we show for the first time that free ethanolamine (EA) constitutes a nitrogen source for the O157:H7 EHEC strain EDL933 in the bovine intestinal content because of induction of the eut (ethanolamine utilization) gene cluster. In contrast, the eut gene cluster is absent in the genome of most species constituting the mammalian gut microbiota. Furthermore, the eutB gene (encoding a subunit of the enzyme that catalyses the release of ammonia from EA) is poorly expressed in non-pathogenic E. coli. Accordingly, EA is consumed by EHEC but is poorly metabolized by endogenous microbiota of the bovine small intestine, including commensal E. coli. Interestingly, the capacity to utilize EA as a nitrogen source confers a growth advantage to E. coli O157:H7 when the bacteria enter the stationary growth phase. These data demonstrate that EHEC strains take advantage of a nitrogen source that is not consumed by the resident microbiota, and suggest that EA represents an ecological niche favouring EHEC persistence in the bovine intestine.
The monitoring of wetland extent is a global imperative, considering loss of ecosystem services and conservation value. To date, the understanding of the variation in the extent of lacustrine ...(inundated) wetlands has been limited, based on intermittently available, coarse-scale imagery. The aim of this study was to assess the capabilities of the freely available Sentinel-2 sensor in monitoring inundated wetlands. In particular, to demonstrate the ability to determine the maximum extent of inundation for reporting on the Sustainable Development Goal (SDG) 6.6 (Clean Water and Sanitation) and SDG 15.1 (i.e., halting biodiversity loss), the functional diversity and the hydrological regime of depressions were explored in the Mpumalanga Lake District (MLD) of South Africa. Using the monthly inundation data derived from Sentinel-2 images between January 2016 and May 2018, the results showed that the maximum extent of open water can be successfully reported for SDG 6.6. Lacustrine wetlands constituted about 47 of the 416 (but 66% of the total areal extent of) depressions in the MLD, while others were predominantly palustrine (vegetated). The functional diversity varied from predominantly (61% of the extent of) inundated depressions to seasonally (3%) inundated depressions. The Sentinel-2 sensor was able to detect intra- and inter-annual variation of the extent of inundation, making it suitable to monitor these wetlands for global and climate change impacts. TEST
AIMS: To monitor the effect of a live yeast additive on feedstuff colonization by targeted fibrolytic micro‐organisms and fibre degradation in the cow rumen. METHODS AND RESULTS: Abundance of ...adhering fibrolytic bacteria and fungi on feedstuffs incubated in sacco in the cow rumen was quantified by qPCR and neutral detergent fibre (NDF) degradation was measured. Saccharomyces cerevisiae I‐1077 (SC) increased the abundance of fibre‐associated Fibrobacter succinogenes on wheat bran (WB) and that of Ruminococcus flavefaciens on alfalfa hay (AH) and wheat silage (WS). The greatest effect was observed on the abundance of Butyrivibrio fibrisolvens on AH and soya hulls (SH) (P < 0·001). Fungal biomass increased on AH, SH, WS and WB in the presence of SC. NDF degradation of AH and SH was improved (P < 0·05) with SC supplementation. CONCLUSIONS: Live yeasts enhanced microbial colonization of fibrous materials, the degree of enhancement depended on their nature and composition. As an effect on rumen pH was not likely to be solely involved, the underlying mechanisms could involve nutrient supply or oxygen scavenging by the live yeast cells. SIGNIFICANCE AND IMPACT OF THE STUDY: Distribution of this microbial additive could be an interesting tool to increase fibre digestion in the rumen and thereby improve cow feed efficiency.
Year-round access to good quality forage is a physiological priority for ruminants and an economic priority for farmers. Ensiling is a method for preserving moist crops based on organic acid ...production by lactic acid bacteria under anaerobic conditions. However, silage can be a vector for undesirable microorganisms, impairing crop preservation, animal performance or the health of both animals and humans.
Major problems in silage processing are due to failure to apply good manufacturing practice (GMP). To improve silage preservation and guarantee the quality of this animal feed, silage additives such as chemicals, enzymes and bacterial agents can be employed.
The purpose of the present paper is to review existing information on the desirable and undesirable microorganisms involved in silage processing, and possible methods, using GMP or silage additives, of limiting silage degradation and its economic effects and health impact on animals and humans.
Active dry yeasts (ADYs) are increasingly used in ruminant nutrition as feed additives to improve feed efficiency and performance and, at the same time, to prevent health disorders. They are ...particularly useful in high-producing ruminants whose digestive microbial balance can be altered by high-dietary energy input. As ADYs can survive and remain metabolically active in the gut, they can exert probiotic effects by interacting with the autochthonous microbial species responsible for feed digestion. Up to now, the most consistent positive effects of ADYs have been reported on rumen microbial activity in young ruminants, stabilisation of rumen pH and prevention of acidosis, as well as stimulation of growth and activity of fibre-degrading bacteria. Effects of ADYs vary depending on biotic factors such as the strain of yeast and its viability, but also on abiotic factors, such as the nature of the diet or animal management. It is important to better understand the way by which yeasts can act on rumen microorganisms in order to direct selection of new generation ADYs. The objectives of this paper are to review the most important findings on effects of ADYs in the rumen, to describe identified modes of action, and to provide thoughts for further strain selection and applications in ruminant nutrition.
We use a newly processed altimeter data set to present a hitherto unprecedented description of the spatiotemporal structure of the East India Coastal Current (EICC): the data set resolves timescales ...ranging from a few months to a few years, and the high along‐track resolution yields the first description of the cross‐shore structure of the current. The seasonal cycle dominates the variability, but the nonannual timescales have similar energy levels all along the EICC path. There are short‐lived, intense intraseasonal bursts. In contrast to the seasonal cycle, the interannual and intraseasonal components are decorrelated along the coast, and possible mechanisms for the decorrelation (discontinuity in the flow) are discussed. In the cross‐shore direction, the current is highly correlated at all timescales: the EICC is trapped against the shelf with the current offshore flowing in the opposite direction at most locations. The EICC appears as an inherently discontinuous flow, taking the form of a few recirculating loops along the EICC path, with a typical cross‐shore spatial scale of 150–200 km. The loops are highly variable in direction at all timescales from intraseasonal to interannual. This discontinuity of the EICC in space and time implies that the basic pathways and advective timescales for the interbasin exchange of water masses between the Bay of Bengal and the Arabian Sea are not robust when the full spatiotemporal variability of the EICC is considered.
The first objective of this study was to evaluate the dynamics and their potential association with animal performance of the microbiota in both the rumen and colon of dairy cows as they move from a ...nonlactation to a lactation ration. The second objective was to assess the potential effects on the microbiota of live yeast supplementation. Twenty-one Holstein cows were split in 2 treatments consisting of 1 × 1010 cfu/d of live yeast (LY; n = 10) or no supplementation (control; n = 11) starting 21 d before until 21 d after calving. At 14 d before and 7 and 21 d after calving, samples of rumen and colon digesta were obtained from each cow using an endoscope. Total DNA was extracted and submitted to high-throughput sequencing. Shannon diversity index, in both the rumen and colon, was unaffected by LY; however, in the rumen it was lowest 7 d after calving and returned to precalving values at 21 d in milk, whereas in the colon it was greatest 14 d before calving but decreased after calving. In the rumen, LY supplementation increased the relative abundance (RA) of Bacteroidales (group UCG-001), Lachnospiracea (groups UCG-002 and UCG-006), and Flexilinea 14 d before calving, and increased RA of Streptococcus 21 d after calving compared with control cows. However, changes in the ruminal microbiota were more drastic across days relative to calving than as influenced by the dietary treatment, and the effect of LY in the colon was milder than in the rumen. The ruminal RA of several genera was associated with postcalving DMI, and that of Gastranaerophilales was the only order positively associated with milk yield. Several genera were positively correlated with feed efficiency, with Clostridiales (unclassified) being the only genus negatively associated with feed efficiency. In the colon, Prevotellaceae (group Ga6A1) was the only genus positively associated with feed efficiency. The ruminal RA of Prevotella 7 and Ruminobacter 14 d precalving was negatively correlated with dry matter intake and milk yield postcalving. The RA of Parabacteroides in the colon 14 d before calving was negatively correlated with milk yield, whereas the RA of Eggerthellaceae (unclassified) and Erysipelotrichaceae (groups c and unclassified) were positively correlated with feed efficiency. Interestingly, LY supplementation doubled the RA of Eggerthellaceae (unclassified) in the colon. It is concluded that microbial diversity in the rumen experiences a transient reduction after calving, whereas in the colon, the reduction is maintained at least until 21 d in milk. Most of the effects of LY on rumen microbiota were observed before calving, whereas in the colon, LY effects were more moderate but consistent and independent of the stage of production. The microbial community of the rumen after calving is more associated with feed intake, milk yield, and feed efficiency than that of the colon. However, the colon microbiota before calving is more associated with feed efficiency after calving than that of the rumen.
Multidrug resistant Gram-negative bacterial infections are an increasing public health threat due to rapidly rising resistance toward β-lactam antibiotics. The hydrolytic enzymes called β-lactamases ...are responsible for a large proportion of the resistance phenotype. β-Lactamase inhibitors (BLIs) can be administered in combination with β-lactam antibiotics to negate the action of the β-lactamases, thereby restoring activity of the β-lactam. Newly developed BLIs offer some advantage over older BLIs in terms of enzymatic spectrum but are limited to the intravenous route of administration. Reported here is a novel, orally bioavailable diazabicyclooctane (DBO) β-lactamase inhibitor. This new DBO, ETX1317, contains an endocyclic carbon–carbon double bond and a fluoroacetate activating group and exhibits broad spectrum activity against class A, C, and D serine β-lactamases. The ester prodrug of ETX1317, ETX0282, is orally bioavailable and, in combination with cefpodoxime proxetil, is currently in development as an oral therapy for multidrug resistant and carbapenem-resistant Enterobacterales infections.
The development of new antibiotics to treat infections caused by drug-resistant Gram-negative pathogens is of paramount importance as antibiotic resistance continues to increase worldwide
. Here we ...describe a strategy for the rational design of diazabicyclooctane inhibitors of penicillin-binding proteins from Gram-negative bacteria to overcome multiple mechanisms of resistance, including β-lactamase enzymes, stringent response and outer membrane permeation. Diazabicyclooctane inhibitors retain activity in the presence of β-lactamases, the primary resistance mechanism associated with β-lactam therapy in Gram-negative bacteria
. Although the target spectrum of an initial lead was successfully re-engineered to gain in vivo efficacy, its ability to permeate across bacterial outer membranes was insufficient for further development. Notably, the features that enhanced target potency were found to preclude compound uptake. An improved optimization strategy leveraged porin permeation properties concomitant with biochemical potency in the lead-optimization stage. This resulted in ETX0462, which has potent in vitro and in vivo activity against Pseudomonas aeruginosa plus all other Gram-negative ESKAPE pathogens, Stenotrophomonas maltophilia and biothreat pathogens. These attributes, along with a favourable preclinical safety profile, hold promise for the successful clinical development of the first novel Gram-negative chemotype to treat life-threatening antibiotic-resistant infections in more than 25 years.
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