PSX-A-20 Late-Breaking: Potential prebiotic effect of canola meal non-starch polysaccharide hydrolysis products in weaned piglets challenged with enterotoxigenic Escherichia coli F4

Enzymatically derived non-starch polysaccharide hydrolysis products (HP) may modulate enteric health outcomes in piglets. Thus, responses of weaned piglets to an oral challenge with enterotoxigenic Escherichia coli F4 (ETEC) when fed diets containing canola meal (CM) HP were investigated. The HP were obtained by incubating CM with a multi-carbohydrase (MC) blend. Thirty-five weaned piglets (8.08 ± 0.34 Kg BW) were individually assigned in a completely randomized design to 1 of 5 treatments: UCC (unchallenged control), NC (negative control challenged with ETEC), PC (NC + 0.1% AGP), HP1 (NC + 0.25% HP), HP2 (NC + 0.5% HP). After a seven-day adaptation period, piglets in the UCC group received 5 ml of PBS, whereas those in all other groups were orally challenged with 5 ml (5 × 106 CFU/mL) of ETEC F4. On d 14 all piglets were euthanized for tissue sampling. Data were analyzed using the PROC MIXED procedure of SAS 9.4, with the individual pig as the experimental unit. During the post-challenge period, piglets fed NC diet had lower (P < 0.05) G: F than those fed the PC, whereas the G: F was higher (P < 0.05) for piglets fed the HP-containing diets than that of piglets fed the NC diet. Piglets fed diets containing HP showed lower (P < 0.05) jejunum pH and fecal scores than piglets fed the NC diet. For gene expressions, the HP groups showed a greater level of toll like receptor 2 (TLR2) compared with NC group (P < 0.05). For the HP groups, HP1 had a higher (P < 0.05) level of TLR2 than HP2 treatment. Feeding HP resulted in lower relative abundance of Bifidobacterium in the colon of piglets compared with feeding with NC (P < 0.05). In conclusion, piglets fed diets with CM HP exhibited less severe ETEC-enteritis and had similar effects with AGP.

Antibodies to the Cryptococcus neoformans Capsule have Innate Glycosidase Activity

Classical antibody functions include opsonization, complement activation and enhancement of cellular antimicrobial function. Antibodies can also have catalytic activity, although the contribution of catalysis to their biological functions has been more difficult to establish. In this study, we mapped the epitopes of several monoclonal antibodies (mAbs) against the capsule of <i>Cryptococcus neoformans</i> using a synthetic glycan array. From this, we designed and synthesized two glycan based Förster Resonance Energy Transfer (FRET) probes, which allowed the discovery of antibodies with innate glycosidase activity, and analysis of their enzyme kinetics. We confirmed that the mAbs mediate glycosidase activity on intact cryptococcal capsules, by reacting antibody-treated capsules with a hydroxylamine-armed fluorescent probe, which revealed the appearance of reducing ends from polysaccharide hydrolysis in the capsule. Our results raise questions over the ubiquity of antibodies with catalytic activity against glycans and establish the utility of glycan-based FRET and hydroxylamine-armed fluorescent probes as tools for investigating this activity.

Polysaccharide hydrolysis in the presence of oil and dispersants: Insights into potential degradation pathways of exopolymeric substances (EPS) from oil-degrading bacteria

Oceanic oil-degrading bacteria produce copious amounts of exopolymeric substances (EPS) that facilitate their access to oil. The fate of EPS in the water column is in part determined by activities of heterotrophic microbes capable of utilizing EPS compounds as carbon and energy sources. To evaluate the potential of natural microbial communities to degrade EPS produced during oil degradation, we measured potential hydrolysis rates of six structurally distinct polysaccharides in two roller bottle experiments, using water from a natural oil seep in the northern Gulf of Mexico. The suite of polysaccharides used to measure the initial step in carbon degradation is indicative of polymers within microbial EPS. The treatments included (i) unamended surface or deep waters (whole water), and water amended with (ii) a water-accommodated fraction of oil (WAF), (iii) oil dispersant Corexit 9500, and (iv) WAF chemically-enhanced with Corexit (CEWAF). The oil and Corexit treatments were employed to simulate conditions during the Deepwater Horizon oil spill. Polysaccharide hydrolysis rates in the surface-water treatments were lowest in the WAF treatment, despite elevated levels of EPS in the form of transparent exopolymer particles (TEP). In contrast, the three deep-water treatments (WAF, Corexit, CEWAF) showed enhanced hydrolysis rates and TEP levels (WAF) compared to the whole water. We also observed variations in the spectrum of polysaccharide-hydrolyzing enzyme activities among the treatments. These substrate specificities were likely driven by activities of oil-degrading bacteria, shaping the pool of EPS and TEP as well as degradation products of hydrocarbons and Corexit compounds. A model calculation of potential turnover rates of organic carbon within the TEP pool suggests extended residence times of TEP in oil-contaminated waters, making them prone to serve as the sticky matrix for oily aggregates known as marine oil snow.