Restrictions on the use of antimicrobial compounds have led to a surge of interest in alternative solutions, such as natural, plant-based compounds. In our study, we investigated the efficacy of three feed supplements containing different additives, namely, probiotics (Lactobacillus spp., “Test substance A”), turmeric (Curcuma longa L., “Test substance B”), and fenugreek (Trigonella foenum graecum, “Test substance C”). In the experiment, we tested 180 birds of the Bábolna Tetra-SL laying hybrid breed that were infected with Salmonella enteritidis strains. The birds were randomly divided into six groups: three groups treated with the different additives, a negative control group, a positive control group, and an antibiotic-treated group using enrofloxacin. We examined the maturation and the time course of shedding of Salmonella; at the end of rearing, pathological and histopathological examinations were performed. When Salmonella was isolated from the cloacal swab samples, the enrofloxacin-treated group had a high number of animals shedding Salmonella by day 9, which was like the group treated with test material C. The greatest reduction in Salmonella shedding was observed in the groups treated with test materials A and B. In terms of pathological parameters, villus length and crypt depth were significantly better in the group treated with test material C compared to the positive and negative controls, and when comparing the body weight of the tested animals, the group treated with test material B had a significantly larger absorption surface area compared to the positive control group. Overall, the supplement with test material C proved to be the most effective. In the future, it is worthwhile to investigate the combination of the tested active substances for their possible synergistic effects and to perform a dose-response study to select the optimal dosage.

The purpose of this study was to determine the effectiveness of a phytobiotic-prebiotic feed additive (PPFA, which contains a combination of chicory and extracts of carob pulp and fenugreek) in the diets of fattening pigs on growth indicators, carcass characteristics, and fecal microbiota. A total of 329 crossbred pigs were randomly divided into two dietary treatments, including a basal diet without additives as the control group and a basal diet supplemented with 1 kg/T PPFA as the trial group. The PPFA supplementation led to a significant increase in the body weight gain and average daily gain of the trial group compared to those of the control group after 70 days of feeding. Through the S-EUROP evaluation system, we also found that the fattening pigs fed PPFA significantly improved their carcass indicators. Furthermore, it was shown that PPFA regulated porcine intestinal microbiota, including promoting the growth of the beneficial commensal bacteria (i.e., Bifidobacterium and Lactobacillus) while inhibiting some potential pathogen bacteria (i.e., Bacteroidaceae and Campylobacteraceae). Our work revealed that the phytobiotic-prebiotic feed additive containing carob pulp, chicory, and fenugreek positively influences the intestinal microbiota, growth performance, and carcass traits in fattening swine.

Fumonisins are sphingolipid-like mycotoxins that cause serious damage by contaminating food and feed. The tricarballylic acid (TCA) units of fumonisin B₁ (FB₁; accounting for 70 % of fumonisin contamination) can be removed by fumonisin B₁ esterase (FE, EC 3.1.1.87) providing a biotechnological FB₁ detoxification possibility. Here, we report the regioselective cleavage of the TCA ester at C6 in the first step of FB₁ hydrolysis and kinetic characterization for two FEs. The low K_M values (4.76-44.3 μM) are comparable to concentrations of environmental contaminations, and the high catalytic efficiencies are promising for practical applications. The X-ray structure of one of the FEs enabled the understanding of the FB₁ hydrolysis at molecular level and revealed an arginine pocket key for substrate binding, and the catalytic role of the glutamate preceding the catalytic serine. Computations showed that this FE is likely capable of detoxifying any fumonisin indicating its potential applicability in food and feed products.

This study compared the minimal inhibition concentrations (MICs) and their effects on the growth kinetics of seven different types of zinc (Zn) compounds and Na₂EDTA in the case of three typical commensal beneficial microorganisms (Bacillus subtilis, Lactococcus lactis, and Saccharomyces cerevisiae). The seven Zn compounds included ZnSO₄, four Zn–amino acid chelates, and two Zn–EDTA complexes. Both MICs and growth kinetic parameters indicated that different microorganisms show different sensitivities; for example, B. subtilis, L. lactis, and S. cerevisiae were most sensitive to ZnSO₄, Na₂EDTA, and Zn(NH₃)₂(Gly)₂, respectively. Both ZnEDTA and Zn(NH₃)₂(Lys)₂ improved the growth rate of all beneficial commensal intestinal microorganisms at low concentrations (5–10 mg/L) and showed low toxicity towards all tested strains. At higher concentrations (100–500 mg/L), all compounds decreased the growth rate and increased the lag phase. In conclusion, both growth kinetic parameters and MICs tested effectively measured the inhibitory effects of the test materials; however, growth kinetics provides a more detailed picture of the concentration-dependent effects and those on the mechanisms of microbial growth inhibition.

This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Kangiella koreensis (KkPAL) into pET19b expression vector. Optimization of protein expression and purification conditions yielded 15 mg pure soluble protein from one liter of E. coli culture. Enzymatic activity measurements of the ammonia elimination reaction from different natural aromatic amino acids proved the protein to be a phenylalanine ammonia-lyase. The isolated protein showed remarkably high, 81.7 °C melting temperature, making it especially suitable for biocatalytic applications.

Nowadays, protein purification by the aid of affinity tags can be carried out with high speed and efficiency. However, in several cases, affinity tags can significantly alter the key properties of enzymes, especially activity and/or thermostability. This study focused on the purification of the non-tagged phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL), as well as on the purification of the TEV (Tobacco Etch Virus) protease, the molecular scissors used to remove the affinity tag from the recombinantly expressed PcPAL. Removal of the 6xHis-tag led to a 1.5-fold increase in the specific activity of PcPAL, while the absence of the affinity tag did not significantly alter the thermostability of the protein. The purity and oligomerization state of the proteins of interest were also analyzed by size exclusion chromatography, both before and after the removal of the affinity tag, confirming the stability of the tetrameric fold of PcPAL.