The protective effect of Xanthoceras sorbifolia Bunge husks on cognitive disorder based on metabolomics and gut microbiota analysis.

AIM OF THE STUDY: The husks of Xanthoceras sorbifolia Bunge mainly used in north China as folk medicine were reported to have potential protective effect on cognitive impairment. However, the mechanism remains unclear. In order to fully understand the mechanism of the protection, a complementary study of the husks was conducted. MATERIALS AND METHODS: The urinary and fecal metabolomics were used to analyze the potential biomarkers by the liquid chromatography-tandem time of flight mass spectrometry, and the16S rDNA technology was applied to conduct the analysis of microbiota species in the fecal samples of the rats, which is a significant influencing factor for the development of cognitive impairment. RESULTS: In metabolomics study, ten potential metabolic biomarkers, which are hippuric acid, kynurenic acid, creatinine, phenylalanine, xanthurenic acid, phenylacetylglycine, succinyladenosine, cresol sulfate, tryptophan 2-C-mannoside and N4-Acetylcytidine in urine, along with two, including isoleucine and phenylalanine in feces, were preliminarily identified, involving multiple pathways such as tryptophan, purine, kynurenine, and phenylalanine metabolism. The perturbation of these metabolic pathways could be related with insulin resistance, oxidative stress, energy metabolism deficit and neuroinflammation, which were risk factors to cause cognitive impairment. In gut microbiota analysis, the relative abundance of c_Bacteroidia, c_Alphaproteobacteria, f_Prevotellaceae, f_Sphingomonadaceae, f_Burkholderiaceae, g_Prevotellaceae_NK3B31_group and p_Bacteroidetes was significantly changed in the rats with cognitive impairment. Spearman's analysis showed obvious correlation between the metabolites and the microbiota species. In the rats with pretreatment of the husks extract, metabolites maintained a relative normal level, and the husks extract could regulate the gut microbiota, especially f_Prevotellaceae and g_Prevotellaceae_NK3B31_group, indicating the effect of the husks on the metabolic pathways via GMs. Such amino acids as isoleucine and phenylalanine failed to show any significant correlation with the microbiota species, indicating that the husks exhibited the potential protective effect through gut microbiota and other pathways. CONCLUSIONS: The husks extract could improve the intestinal microenvironment, and the stability of intestinal microenvironment was associated with normality of tryptophan, purine, kynurenine and phenylalanine metabolic pathways etc, which probably had an effect on cognitive function. This complementary work suggested that gut microbiotas were potential targets of the husks to exert its effect on cognitive impairment.

Mode of action of a novel anti-Listeria bacteriocin (CAMT2) produced by Bacillus amyloliquefaciens ZJHD3-06 from Epinephelus areolatus.

Bacteriocin CAMT2, produced by Bacillus amyloliquefaciens ZJHD3-06, has been shown to exhibit protective activity against important food spoilage and food-borne bacterial pathogens. This study was conducted to investigate the mode of action of bacteriocin CAMT2 against highly pathogenic Listeria monocytogenes ATCC 19111. The addition of bacteriocin CAMT2 at 64 AU/ml inhibited L. monocytogenes ATCC 19111. An efflux of K+ ions, lactic acid dehydrogenase and an increase in extracellular electrical conductivity was observed in CAMT2-treated L. monocytogenes. Electron microscopy showed morphological alterations such as uneven cell surface, accumulation of cell debris and bacterial lysis. These results show that bacteriocin CAMT2 inhibit L. monocytogenes by increasing cell permeability and inducing membrane damage, hence it has the great application potentials in ensuring food safety.

[Diversity of antimicrobial bacteria associated with Siganus fuscescens from Naozhou island in Zhanjiang, China].

OBJECTIVE: Marine bacteria are a rich source of potentially useful antimicrobial molecules. The purpose of the study is to explore the diversity of bacteria with antimicrobial activity isolated from Siganus fuscescens gastrointestinal tract collected from Naozhou Island (20 degrees 52' N-20 degrees 56' N 110 degrees 33' E-110 degrees 38' E), Leizhou Bay, South China Sea. METHODS: We isolated bacteria from the gastrointestinal tract of fish sample using classical culturing technique, and determined antimicrobial activities of the isolates by Oxford cup method. We investigated diversity of antimicrobial isolates using phylogenetic comparative analysis of 16S rRNA gene sequences. RESULTS: According to the results of morphological observation and part of physiological and biochemical experiments, we isolated 68 strains from fish gastrointestinal tract. Among them, 19 strains with antimicrobial activities were acquired (27.9% of the isolates) and represented 19 different species, belonging to 12 genera (Rothia, Micrococcu, Brachybacterium, Brevibacterium, Psychrobacter, Paracoccus, Cobetia, Citrobacter, Pseudomonas, Bacillus, Lactobacillus and Staphylococcus) of 11 families (Microbacteriaceae, Dermabacteraceae, Brevibacteriaceae, Moraxellaceae, Rhodobacteraceae, Halomonadaceae, Enterobacteriaceae, Pseudomonadaceae, Bacillaceae, Lactobacillaceae and Staphylococcaceae) in three phyla (Actinobacteria, Proteobacteria and Firmicutes). Eight strains (42.1%), 7 strains (36.8%) and 4 strains (21.1%) were belonging to the phylum Firmicutes, Proteobacteria and Actinobacteria, respectively. The phylogenetic distance matrix results suggested that there were obvious genetic divergences between the majority of strains with antimicrobial activity and their phylogenetically most closely related typical strain, due to 16S rRNA gene sequences similarities ranging from 96.2 to 99.9%. In addition, 4 strains (ZJHD2-31, ZJHD5-23, ZJHD2-58 and M26) could represent potential new species, and identification of the novel strain M26 has been published in Antonie van Leeuwenhoek. CONCLUSION: There are abundant diversity for bacteria with antimicrobial activity and potentially more new species of microorganism in Siganus fuscescens gastrointestinal tract collected from Naozhou Island.

Brachybacterium huguangmaarense sp. nov., isolated from Lake sediment.

A Gram-stain positive strain, M1T, was isolated from the sediment of Maar Lake in Zhanjiang, Guangdong Province, China. The diagnostic cell-wall diamino acid was meso-diaminopimelic acid, and mycolic acids were not detected. The polar lipid profile of strain M1T consisted of diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unknown glycolipid. The predominant quinone was MK-7, with MK-6 as a minor component. The major fatty acids were anteiso-C15:0 and anteiso-C17:0, with iso-C18:0 as a minor component. The DNA G+C content of the genomic DNA was 71.0 mol%. 16S rRNA gene sequence analysis showed that strain M1T belongs to the family Dermabacteraceae, sharing highest sequence similarity with Brachybacterium nesterenkovii JCM 11648T (98.1%). Furthermore, a combination of DNA-DNA relatedness and physiological and biochemical properties indicated that the novel strain could be readily distinguished from its closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, strain M1T represents a novel species of the genus Brachybacterium, for which the name Brachybacterium huguangmaarense sp. nov. is proposed. The type strain is M1T (=CCTCC AB 2012866T=DSM 26370T).

Paracoccus siganidrum sp. nov., isolated from fish gastrointestinal tract.

A bacterial strain, designated M26(T), was isolated from a fish gastrointestinal tract, collected from Zhanjiang Port, South China. 16S rRNA gene sequence analysis indicated that strain M26(T) belongs to the subclass α-Proteobacteria, being related to the genus Paracoccus, and sharing highest sequence similarity with Paracoccus alcaliphilus JCM 7364(T) (98.1 %), Paracoccus huijuniae FLN-7(T) (97.3 %), Paracoccus stylophorae KTW-16(T) (97.1 %) and Paracoccus seriniphilus DSM 14827(T) (96.9 %). The major quinone was determined to be ubiquinone Q-10, with Q-9 and Q-8 as minor components. The major fatty acid was identified as C18:1ω7c, with smaller amounts of C18:0 and C16:0. The G+C content of the genomic DNA was determined to be 64.3 mol%. The DNA hybridization value between strain M26(T) and the most closely related type strain, P. alcaliphilus, was 29.0 ± 1.0 %. The results of physiological and biochemical tests and low DNA-DNA relatedness showed that the strain could be readily distinguished from closely related species. On the basis of these phenotypic and genotypic data, strain M26(T) is concluded to represent a novel species of the genus Paracoccus, for which the name Paracoccus siganidrum sp. nov. is proposed. The type strain is M26(T) (=CCTCC AB 2012865(T) = DSM 26381(T)).