Purification and characterization of the enzymes from Brevundimonas naejangsanensis that degrade ochratoxin A and B.

Ochratoxin A (OTA) and Ochratoxin B (OTB) co-contaminate many types of agricultural products. Screening enzymes that degrade both OTA and OTB has significance in food safety. In this study, four novel OTA and OTB degrading enzymes, namely BnOTase1, BnOTase2, BnOTase3, and BnOTase4, were purified from the metabolites of the Brevundimonas naejangsanensis ML17 strain. These four enzymes hydrolyzed OTA into OTα and hydrolyzed OTB into OTß. BnOTase1, BnOTase2, BnOTase3, and BnOTase4 have the apparent Km values for hydrolyzing OTA of 19.38, 0.92, 12.11, 1.09 µmol/L and for hydrolyzing OTB of 0.76, 2.43, 0.60, 0.64 µmol/L respectively. OTα and OTß showed no significant cytotoxicity to HEK293 cells, suggesting that these enzymes mitigate the toxicity of OTA and OTB. The discovery of the novel OTA and OTB degrading enzymes enriches the research on ochratoxin control and provides objects for protein rational design.

Both Saccharomyces boulardii and Its Postbiotics Alleviate Dextran Sulfate Sodium-Induced Colitis in Mice, Association with Modulating Inflammation and Intestinal Microbiota.

OBJECTIVE: To investigate the effect of Saccharomyces boulardii and its freeze-dried and spray-dried postbiotics on the intervention and potential mechanism of dextran sulfate sodium (DSS)-induced ulcerative colitis in mice. [Methods] After the acclimation period of C67BL/6J mice, a colitis model was constructed by applying 2% DSS for 7 d, followed by 7 d of intervention. Subsequently, the disease activity index (DAI), organ index, colon length, colon HE staining of pathological sections, ELISA for blood inflammatory factors (Interleukin (IL)-1ß, IL-6, IL-10, Tumor necrosis factor (TNF)-α), Real time quantitative polymerase chain reaction (RT-qPCR) to determine the levels of colonic inflammatory factors (IL-1ß, IL-6, IL-10, TNF-α), Occludin gene expression, and intestinal flora were assessed to evaluate the protective effects of S. boulardii and its postbiotics on colitis in mice. RESULTS: Compared with the DSS group, S. boulardii and the postbiotics interventions effectively improved colonic shortening and tissue damage, increased the expression of intestinal tight junction protein, reduced the secretion of pro-inflammatory factors, increased the secretion of anti-inflammatory factors, and maintained the homeostasis of intestinal microorganisms. Postbiotics intervention is better than probiotics. CONCLUSIONS: S. boulardii and its postbiotics can effectively alleviate DSS-induced colitis in mice through modulating host immunity and maintaining intestinal homeostasis. Postbiotics are promising next-generation biotherapeutics for ulcerative colitis treatment.

Warfarin Adherence Among Patients with Atrial Fibrillation in Rural Area of Dongyang, China: A Questionnaire-Based Study.

Introduction: Adherence to warfarin is associated with improved outcome in patients with atrial fibrillation (AF), but the adherence status of patients in rural areas of China is not known. Methods: A questionnaire-based study evaluating warfarin adherence of rural residents with AF was carried out in Dongyang, China. Potentially eligible patients were screened and contacted by telephone, and their demographic characteristics were collected. Illness perception was assessed using the Brief Illness Perception Questionnaire (BIPQ), and warfarin adherence was assessed using a Chinese-version adherence scale. Univariate and multivariate analyses were conducted to identify factors associated with unsatisfactory adherence. Results: A total of 201 patients (male, n=99; mean age, 70.3±8.12 years) were included, among whom 95 (47.3%) patients showed good adherence and 63 (31.3%) poor adherence. Number of co-dispensed drugs (multivariate analysis: odds ratio [OR]=3.64, 95% confidence interval [CI] 1.35-9.81, p=0.011) and BIPQ score (OR=1.25, 95% CI 1.17-1.33, p<0.001) were identified as factors associated with good adherence. Conclusion: Medical adherence to warfarin needs to improve in rural patients with AF. Efforts that can reduce the number of co-dispensed drugs and increase illness perception may improve warfarin adherence. This study may benefit future management of warfarin administration to rural patients with AF.

Genome mining reveals the genes of carboxypeptidase for OTA-detoxification in Bacillus subtilis CW14.

Bacillus subtilis CW14, isolated from fresh elk droppings in Beijing Zoo, is a Gram-positive, conferred Generally Recognized as Safe (GRAS) bacterium with the capacity of ochratoxin A (OTA) detoxification. The genome sequence of the CW14 strain showed a size of 4,287,522 bp with 44.06% GC content. It was predicted many putative enzymes involved in degrading mycotoxin by analyzing the signal peptides and the transmembrane regions. Nine extracellular enzymes were predicted relating to OTA detoxification, including four D-Ala-D-Ala carboxypeptidases, two hydrolases, two amidases, and one lactamase. Indeed, two of the carboxypeptidase genes dacA and dacB, expressed in Escherichia coli, were verified contributing to OTA detoxification. DacA and OTA were mixed incubated for 24 h, and the degradation rate reached 71.3%. After purification, the concentration of recombinant DacA protein was 0.5 mg/mL. Bacillus subtilis CW14 and its carboxypeptidases may be used as OTA detoxification agents in food and feed industry production.

Fungal G-Protein-Coupled Receptors: A Promising Mediator of the Impact of Extracellular Signals on Biosynthesis of Ochratoxin A.

G-protein-coupled receptors (GPCRs) are transmembrane receptors involved in transducing signals from the external environment inside the cell, which enables fungi to coordinate cell transport, metabolism, and growth to promote their survival, reproduction, and virulence. There are 14 classes of GPCRs in fungi involved in sensing various ligands. In this paper, the synthesis of mycotoxins that are GPCR-mediated is discussed with respect to ligands, environmental stimuli, and intra-/interspecific communication. Despite their apparent importance in fungal biology, very little is known about the role of ochratoxin A (OTA) biosynthesis by Aspergillus ochraceus and the ligands that are involved. Fortunately, increasing evidence shows that the GPCR that involves the AF/ST (sterigmatocystin) pathway in fungi belongs to the same genus. Therefore, we speculate that GPCRs play an important role in a variety of environmental signals and downstream pathways in OTA biosynthesis. The verification of this inference will result in a more controllable GPCR target for control of fungal contamination in the future.