Bacillus subtilis ANSB168 Producing d-alanyl-d-alanine Carboxypeptidase Could Alleviate the Immune Injury and Inflammation Induced by Ochratoxin A

Antibacterial characteristics and mechanistic insights of combined tea polyphenols, Nisin, and epsilon-polylysine against feline oral pathogens: a comprehensive transcriptomic and metabolomic analysis

AIMS

This study evaluates the antibacterial characteristics and mechanisms of combined tea polyphenols (TPs), Nisin, and ε-polylysine (PL) against Streptococcus canis, Streptococcus minor, Streptococcus mutans, and Actinomyces oris, common zoonotic pathogens in companion animals.

METHODS AND RESULTS

Pathogenic strains were isolated from feline oral cavities and assessed using minimum inhibitory concentration (MIC) tests, inhibition zone assays, growth kinetics, and biofilm inhibition studies. Among single agents, PL exhibited the lowest MIC values against all four pathogens. TP showed significant resistance against S. minor, and Nisin against S. mutans. The combination treatment (Comb) of TP, Nisin, and PL in a ratio of 13:5:1 demonstrated broad-spectrum antibacterial activity, maintaining low MIC values, forming large inhibition zones, prolonging the bacterial lag phase, reducing growth rates, and inhibiting biofilm formation. RNA sequencing and metabolomic analysis indicated that TP, Nisin, and PL inhibited various membrane-bound carbohydrate-specific transferases through the phosphoenolpyruvate-dependent phosphotransferase system in S. canis, disrupting carbohydrate uptake. They also downregulated glycolysis and the citric acid cycle, inhibiting cellular energy metabolism. Additionally, they modulated the activities of peptidoglycan glycosyltransferases and d-alanyl-d-alanine carboxypeptidase, interfering with peptidoglycan cross-linking and bacterial cell wall stability.

CONCLUSIONS

The Comb therapy significantly enhances antibacterial efficacy by targeting multiple bacterial pathways, offering potential applications in food and pharmaceutical antimicrobials.

The Toxicokinetics, Excretion Patterns, and Milk Transmission of Ochratoxin A in Lactating Sows

Ochratoxin A (OTA), a mycotoxin commonly found in feedstuffs, is known for its detrimental effects on the kidneys and liver, posing significant health risks to animals and humans. This study investigated the toxicokinetics, excretion patterns, and milk transmission of Ochratoxin A (OTA) in lactating sows. The sows were administered a single oral dose of 500 μg/kg BW (body weight), followed by the systematic sampling of plasma, feces, urine, and milk. Plasma samples were collected at 0, 5, 15, and 30 min, and 1, 2, 3, 6, 9, 12, 24, 48, 72, 88, 96, and 120 h post administration. Feces samples were collected at 6 h intervals for the first 12 h, then at 12 h intervals until 120 h, while urine samples were collected at 6 h intervals up to 120 h. Milk samples were collected at 0, 6, 12, 24, 36, 48, 72, 96, and 120 h. The concentration of OTA and its primary metabolite OTα were quantitatively analyzed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The results revealed that the peak plasma concentrations of OTA (920.25 ± 88.46 μg/L) were observed at 9 h following administration. The terminal elimination half-life was recorded at 78.47 ± 7.68 h, with a volume of distribution of 0.16 ± 0.003 L/kg. Moreover, this study documented the excretion of OTA and OTα across a span of 120 h, revealing that feces and urine accounted for 18.70 ± 0.04% and 8.40 ± 0.002% of the total intake amounts, respectively (calculated based on substance amounts). Furthermore, this experiment detected OTA residues in the milk of lactating sows, with the milk-to-plasma (M/P) ratio initially increasing from 0.06 to 0.46 within the first 24 h following OTA ingestion. These findings offer an exhaustive temporal analysis of OTA's toxicokinetics in lactating sows, emphasizing its pervasive distribution and elimination through various bodily excreta.

Metagenomic association analysis of cognitive impairment in community-dwelling older adults

The gut microbiota is reportedly involved in neurodegenerative disorders, and exploration of differences in the gut microbiota in different cognitive status could provide clues for early detection and intervention in cognitive impairment. Here, we used data from the Taizhou Imaging Study (N = 516), a community-based cohort, to compare the overall structure of the gut microbiota at the species level through metagenomic sequencing, and to explore associations with cognition. Interestingly, bacteria capable of producing short-chain fatty acids (SCFAs), such as Bacteroides massiliensis, Bifidobacterium pseudocatenulatum, Fusicatenibacter saccharivorans and Eggerthella lenta, that can biotransform polyphenols, were positively associated with better cognitive performance (p < 0.05). Although Diallister invisus and Streptococcus gordonii were not obviously related to cognition, the former was dominant in individuals with mild cognitive impairment (MCI), while the later was more abundant in cognitively normal (CN) than MCI groups, and positively associated with cognitive performance (p < 0.05). Functional analysis further supported a potential role of SCFAs and lactic acid in the association between the gut microbiota and cognition. The significant associations persisted after accounting for dietary patterns. Collectively, our results demonstrate an association between the gut microbiota and cognition in the general population, indicating a potential role in cognitive impairment. The findings provide clues for microbiome biomarkers of dementia, and insight for the prevention and treatment of dementia.

Molecular Docking and In Vitro Studies of Ochratoxin A (OTA) Biodetoxification Testing Three Endopeptidases

Ochratoxin A (OTA) is considered one of the main mycotoxins responsible for health problems and considerable economic losses in the feed industry. The aim was to study OTA's detoxifying potential of commercial protease enzymes: (i) Ananas comosus bromelain cysteine-protease, (ii) bovine trypsin serine-protease and (iii) Bacillus subtilis neutral metalloendopeptidase. In silico studies were performed with reference ligands and T-2 toxin as control, and in vitro experiments. In silico study results showed that tested toxins interacted near the catalytic triad, similar to how the reference ligands behave in all tested proteases. Likewise, based on the proximity of the amino acids in the most stable poses, the chemical reaction mechanisms for the transformation of OTA were proposed. In vitro experiments showed that while bromelain reduced OTA's concentration in 7.64% at pH 4.6; trypsin at 10.69% and the neutral metalloendopeptidase in 8.2%, 14.44%, 45.26% at pH 4.6, 5 and 7, respectively (p < 0.05). The less harmful α-ochratoxin was confirmed with trypsin and the metalloendopeptidase. This study is the first attempt to demonstrate that: (i) bromelain and trypsin can hydrolyse OTA in acidic pH conditions with low efficiency and (ii) the metalloendopeptidase was an effective OTA bio-detoxifier. This study confirmed α-ochratoxin as a final product of the enzymatic reactions in real-time practical information on OTA degradation rate, since in vitro experiments simulated the time that food spends in poultry intestines, as well as their natural pH and temperature conditions.

Mycotoxins and cellular senescence: the impact of oxidative stress, hypoxia, and immunosuppression

Mycotoxins induce oxidative stress, hypoxia, and cause immunosuppressive effects. Moreover, emerging evidence show that mycotoxins have a potential of inducing cellular senescence, which are involved in their immunomodulatory effects. Mycotoxins upregulate the expression of senescence markers γ-H2AX, senescence-associated β-galactosidase, p53, p16, and senescence-associated secretory phenotype (SASP) inflammatory factors. Moreover, mycotoxins cause senescence-associated cell cycle arrest by diminishing cyclin D₁ and Cdk4 pathways, as well as increasing the expression of p53, p21, and CDK6. Mycotoxins may induce cellular senescence by activating reactive oxygen species (ROS)-induced oxidative stress. In addition, hypoxia acts as a double-edged sword on cell senescence; it could both act as the stress-induced senescence and also hinder the onset of cellular senescence. The SASP inflammatory factors have the ability to induce an immunosuppressive environment, while mycotoxins directly cause immunosuppression. Therefore, there is a potential relationship between mycotoxins and cellular senescence that synergistically cause immunosuppression. However, most of the current studies have involved the effect of mycotoxins on cell cycle arrest, but only limited in-depth research has been carried out to link the occurrence of this condition (cell cycle arrest) with cellular senescence.

Enzymatic degradation of ochratoxin A in the gastrointestinal tract of piglets

Animal feeds are often contaminated with ochratoxin A (OTA), a potent natural mycotoxin hazardous to animal and human health that accumulates in blood and tissues. To the best of our knowledge, this study is the first to investigate the in vivo application of an enzyme (OTA amidohydrolase; OAH) that degrades OTA into the nontoxic molecules phenylalanine and ochratoxin α (OTα) in the gastrointestinal tract (GIT) of pigs. Piglets were fed six experimental diets over 14 days, varying in OTA contamination level (50 or 500 μg/kg; OTA50 and OTA500) and presence of OAH; a negative control diet (no OTA added) and a diet containing OTα at 318 µg/kg (OTα318). The absorption of OTA and OTα into the systemic circulation (plasma and dried blood spots, DBS), their accumulation in kidney, liver, and muscle tissues, and excretion through feces and urine were assessed. The efficiency of OTA degradation in the digesta content of the GIT was also estimated. At the end of the trial, accumulation of OTA in blood was significantly higher in OTA groups (OTA50 and OTA500) in comparison to enzyme groups (OAH50 and OAH500, respectively). The supplementation of OAH explicitly reduced the absorption of OTA (P < 0.005) into plasma by 54% and 59% (from 40.53 ± 3.53 to 18.66 ± 2.28 ng/mL in piglets fed the 50 μg OTA/kg diets and from 413.50 ± 71.88 to 168.35 ± 41.02 ng/mL in piglets fed the 500 μg OTA/kg diets, respectively) and in DBS by 50% and 53% (from 22.79 ± 2.63 to 10.67 ± 1.93 ng/mL in piglets fed the 50 μg OTA/kg diets and from 232.85 ± 35.16 to 105.71 ± 24.18 ng/mL in piglets fed the 500 μg OTA/kg diets, respectively). The OTA concentrations in plasma were positively associated with the OTA levels detected in all tissues analyzed; adding OAH reduced OTA levels in the kidney, liver, and muscle (P < 0.005) by 52%, 67%, and 59%, respectively. The analysis of GIT digesta content showed that OAH supplementation led to OTA degradation in the proximal GIT where natural hydrolysis is inefficient. Overall, the data of present in vivo study demonstrated that supplementation of swine feeds with OAH successfully reduced OTA levels in blood (plasma and DBS) as well as in kidney, liver, and muscle tissues. Therefore, an approach to use enzymes as feed additives might be most promising to mitigate the harmful effects of OTA on the productivity and welfare of pigs and at the same time improving the safety of pig-derived food products.

Unveiling ochratoxin a controlling and biodetoxification molecular mechanisms: Opportunities to secure foodstuffs from OTA contamination

Anarchic growth of ochratoxin A (OTA) producing fungi during crop production, prolonged storage, and processing results in OTA contamination in foodstuffs. OTA in food exacerbates the risk of health and economic problems for consumers and farmers worldwide. Although the toxic effects of OTA on human health have not been well established, comprehensive preventive and remedial measures will be essential to eliminate OTA from foodstuffs. Strict regulations, controlling OTA at pre- or post-harvest stage, and decontamination of OTA have been adopted to prevent human and animal OTA exposure. Biological control of OTA and bio-decontamination are the most promising strategies due to their safety, specificity and nutritional value. This review addresses the current understanding of OTA biodegradation mechanisms and recent developments in OTA control and bio-decontamination strategies. Additionally, this review analyses the strength and weaknesses of different OTA control methods and the contemporary approaches to enhance the efficiency of biocontrol agents. Overall, this review will support the implementation of new strategies to effectively control OTA in food sectors. Further studies on efficacy-related issues, production issues and cost-effectiveness of OTA biocontrol are to be carried out to improve the knowledge, develop improved delivery technologies and safeguard the durability of OTA biocontrol approaches.

A Newly Isolated Alcaligenes faecalis ANSA176 with the Capability of Alleviating Immune Injury and Inflammation through Efficiently Degrading Ochratoxin A

Ochratoxin A (OTA) is one of the most prevalent mycotoxins that threatens food and feed safety. Biodegradation of OTA has gained much attention. In this study, an Alcaligenes faecalis strain named ANSA176, with a strong OTA-detoxifying ability, was isolated from donkey intestinal chyme and characterized. The strain ANSA176 could degrade 97.43% of 1 mg/mL OTA into OTα within 12 h, at 37 °C. The optimal levels for bacterial growth were 22–37 °C and pH 6.0–9.0. The effects of ANSA176 on laying hens with an OTA-contaminated diet were further investigated. A total of 36 laying hens were assigned to three dietary treatments: control group, OTA (250 µg/kg) group, and OTA + ANSA176 (6.2 × 10⁸ CFU/kg diet) group. The results showed that OTA decreased the average daily feed intake (ADFI) and egg weight (EW); meanwhile, it increased serum alanine aminopeptidase (AAP), leucine aminopeptidase (LAP), β2-microglobulin (β2-MG), immunoglobulin G (IgG), tumor necrosis factor-α (TNF-α), and glutathione reductase (GR). However, the ANSA176 supplementation inhibited or attenuated the OTA-induced damages. Taken together, OTA-degrading strain A. faecalis ANSA176 was able to alleviate the immune injury and inflammation induced by OTA.

Combined Toxicity Evaluation of Ochratoxin A and Aflatoxin B1 on Kidney and Liver Injury, Immune Inflammation, and Gut Microbiota Alteration Through Pair-Feeding Pullet Model

Ochratoxin A (OTA) and aflatoxin B1 (AFB1) are often co-contaminated, but their synergistic toxicity in poultry is limitedly described. Furthermore, the traditional ad libitum feeding model may fail to distinguish the specific impact of mycotoxins on the biomarkers and the indirect effect of mildew on the palatability of feed. A pair-feeding model was introduced to investigate the specific effect and the indirect effect of the combined toxicity of OTA and AFB1, which were independent and dependent on feed intake, respectively. A total of 180 one-day-old pullets were randomly divided into 3 groups with 6 replicates, and each replicate contained 10 chicks. The control group (Group A) and the pair-feeding group (Group B) received the basal diet without mycotoxin contamination. Group C was administrated with OTA- and AFB1-contaminated feed (101.41 μg/kg of OTA + 20.10 μg/kg of AFB1). The scale of feeding in Group B matched with the feed intake of Group C. The trial lasted 42 days. Compared with the control group, co-contamination of OTA and AFB1 in feed could adversely affect the growth performance (average daily feed intake (ADFI), body weight (BW), average daily weight gain (ADG), feed conversion ratio (FCR), and shank length (SL)), decrease the relative weight of the spleen (p < 0.01), and increase the relative weight of the kidney (p < 0.01). Moreover, the reduction of feed intake could also adversely affect the growth performance (BW, ADG, and SL), but not as severely as mycotoxins do. Apart from that, OTA and AFB1 also activated the antioxidative and inflammation reactions of chicks, increasing the level of catalase (CAT), reactive oxygen species (ROS), and interleukin-8 (IL-8) while decreasing the level of IL-10 (p < 0.01), which was weakly influenced by the feed intake reduction. In addition, OTA and AFB1 induced histopathological changes and apoptosis in the kidney and liver as well as stimulated the growth of pernicious bacteria to cause toxic effects. There were no histopathological changes and apoptosis in the kidney and liver of the pair-feeding group. The combined toxicity of OTA and AFB1 had more severe effects on pullets than merely reducing feed supply. However, the proper reduction of the feed intake could improve pullets’ physical health by enriching the bacteria Lactobacillus, Phascolarctobacterium, Bacteroides, Parabacteroides, and Barnesiella.