Characterization of gut microbiome profile in children with confirmed wheat allergy

BACKGROUND

Food allergies pose serious health risks, including life-threatening anaphylactic reactions, increased morbidity, and reduced quality of life. Wheat allergy is a common concern in Asia. There is growing interest in understanding the potential association between dysregulation of the gut microbiome and the development of food allergies.

OBJECTIVE

This study aimed to explore the gut microbiome of Thai children with wheat allergy and its potential association with allergic responses.

METHODS

Microbial abundance was assessed using Quantitative Insights into Microbial Ecology 2 (QIIME2) microbiome analysis based on 16S rDNA data. The correlation between microbial richness and relevant parameters was evaluated using the Spearman correlation analysis. Additionally, the microbial community functions were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2).

RESULTS

The gut microbiome analysis revealed significant differences between the two groups at the phylum and genus levels. Firmicutes (p = 0.012) and Verrucomicrobia (p < 0.001) were enriched in wheat-allergic children, whereas specific gut microbes such as Megamonas (p = 0.04), Romboutsia (p < 0.001), Fusobacterium (p < 0.001), Clostridium senso stricto1 (p < 0.001), and Turicibacter (p < 0.001) were more abundant in healthy children. Anaerostripes (p = 0.011), Erysipelatoclostridium (p < 0.001), Prevotella 2 (p < 0.001), Ruminiclostridium 5 (p < 0.001), and Clostridium innnocuum (p < 0.001) were enriched in children with a confirmed wheat allergy. Functional analysis indicated disparities in the pathways related to arginine and polyamine biosynthesis.

CONCLUSION

These findings offer valuable insights into the gut microbiome of children with wheat allergy and its potential impact on symptom severity, laying the groundwork for further research and interventions aimed at addressing this health concern.

Comparative genotypic characterization related to antibiotic resistance phenotypes of clinical carbapenem-resistant Acinetobacter baumannii MTC1106 (ST2) and MTC0619 (ST25)

BACKGROUND

The prevalence of Acinetobacter baumannii in nosocomial infections and its remarkable ability to develop antimicrobial resistance have been a critical issue in hospital settings. Here, we examined the genomic features related to resistance phenotype displayed by carbapenem-resistant A. baumannii (CRAB) MTC1106 (ST2) and MTC0619 (ST25).

RESULTS

Resistome analysis of both strains revealed that MTC1106 possessed higher numbers of antimicrobial resistance genes compared to MTC0619. Some of those genetic determinants were present in accordance with the susceptibility profile of the isolates. The predicted ISAba1 region upstream of blaOXA-23 gene was related to carbapenem resistance since this IS element was well-characterized to mediate overexpression of carbapenemase genes and eventually provided capability to confer resistance. Unlike MTC0619 strain, which only carried class B and D β-lactamase genes, MTC1106 strain also possessed blaTEM-1D, a class A β-lactamase. Regarding to aminoglycosides resistance, MTC0619 contained 5 related genes in which all of them belonged to three groups of aminoglycosides modifying enzyme (AME), namely, N-acetyltransferase (AAC), O-nucleotidyltransferase (ANT), and O-phosphotransferase (APH). On the other hand, MTC1106 lacked only the AAC of which found in MTC0619, yet it also carried an armA gene encoding for 16S rRNA methyltransferase. Two macrolides resistance genes, mph(E) and msr(E), were identified next to the armA gene of MTC1106 isolate in which they encoded for macrolide 2'-phosphotransferase and ABC-type efflux pump, respectively. Besides acquired resistance genes, some chromosomal genes and SNPs associated with resistance to fluoroquinolones (i.e. gyrA and parC) and colistin (i.e. pmrCAB, eptA, and emrAB) were observed. However, gene expression analysis suggested that the genetic determinants significantly contributing to low-level colistin resistance remained unclear. In addition, similar number of efflux pumps genes were identified in both lineages with only the absence of adeC, a part of adeABC RND-type multidrug efflux pump in MTC0619 strain.

CONCLUSIONS

We found that MTC1106 strain harbored more antimicrobial resistance genes and showed higher resistance to antibiotics than MTC0619 strain. Regarding genomic characterization, this study was likely the first genome comparative analysis of CARB that specifically included isolates belonging to ST2 and ST25 which were widely spread in Thailand. Taken altogether, this study suggests the importance to monitor the resistance status of circulating A. baumannii clones and identify genes that may contribute to shifting the resistance trend among isolates.

Association between Gut Microbiota with Mild Cognitive Impairment and Alzheimer's Disease in a Thai Population

BACKGROUND

Mild cognitive impairment (MCI) and Alzheimer's disease (AD) are common in older adults. Much recent work has implicated the connection between the gut and the brain via bidirectional communication of the gastrointestinal tract and the central nervous system through biochemical signaling. Altered gut microbiota composition has shown controversial results based on geographic location, age, diet, physical activity, psychological status, underlying diseases, medication, and drug use.

OBJECTIVES

This study aimed to investigate the relationships of gut microbiota with MCI and AD.

METHODS

16S metagenome profiles from stool collection of participant groups (normal; n = 20, MCI; n = 12, AD; n = 20) were analyzed. The diagnosis of cognitive conditions was made by standard criteria consisting of clinical interviews, physical examinations, cognitive assessments, laboratory examinations, and neuroimaging by both structural neuroimaging and amyloid positron emission tomography scans. Correlations between medical factors with food frequency and the fecal microbiome were elucidated.

RESULTS

A significant difference at the operational taxonomic unit level was observed. The significantly higher abundance of bacteria in nondementia patients belonged to the Clostridiales order, including Clostridium sensu stricto 1 (p < 0.0001), Fusicatenibacter (p = 0.0007), Lachnospiraceae (p = 0.001), Agathobacter (p = 0.021), and Fecalibacterium (p < 0.0001). In contrast, Escherichia-Shigella (p = 0.0002), Bacteroides (p = 0.0014), Holdemanella (p < 0.0001), Romboutsia (p = 0.001), and Megamonas (p = 0.047) were the dominant genera in the AD group. Left and right hippocampus and right amygdala volumes were significantly decreased in the AD group (p < 0.001) and significantly correlated with the groups of bacteria that were significantly different between groups.

CONCLUSION

There was a relationship between the composition of the gut microbiome and neurodegenerative disorders, including MCI and AD. Reduction of Clostridiaceae and increases in Enterobacteriaceae and Bacteroides were associated with persons with MCI and AD, consistent with previous studies. The altered gut microbiome could be potentially targeted for the early diagnosis of dementia and the reduction of AD risk.

Biosurfactant-Producing Bacillus velezensis PW192 as an Anti-Fungal Biocontrol Agent against Colletotrichum gloeosporioides and Colletotrichum musae

In this study, plant-root-associated Bacillus species were evaluated as antifungal biocontrol agents by analyzing the production of surface bioactive molecules known as lipopeptide biosurfactants. This study aimed to isolate and characterize antifungal biosurfactant-producing Bacillus bacterium. Bacillusvelezensis PW192 was isolated from the rhizosphere of Lagerstroemia macrocarpa var macrocarpa and identified based on phylogenetic analysis of the 16S rRNA gene. The biosurfactant was excreted to cultured supernatant and exhibited emulsification power up to 60% and a decrease in surface tension from 72 in distilled water to 21 mN/m. The surface tension properties were stable in a broad range of pH from 6 to 10, in high temperatures up to 100 °C, and in salinities with a NaCl concentration up to 12% (w/v). Starting from 0.5 mg of acid, precipitated crude biosurfactant exhibited antifungal activity toward Anthracnose, caused by the phytopathogens Colletotrichum gloeosporioides and C. musae. The chemical structures of the biosurfactant were structurally characterized as lipopeptides fengycin A and fengycin B. The stability of the biosurfactant, as well as the antifungal properties of B. velezensis PW192, can potentially make them useful as agricultural biocontrol agents, as well as in other biotechnological applications.

Synergistic degradation of pyrene by five culturable bacteria in a mangrove sediment-derived bacterial consortium

A pyrene-degrading microbial consortium was obtained after enrichment with mangrove sediment collected from Thailand. Five cultivable bacteria (Mycobacterium spp. PO1 and PO2, Novosphingobium pentaromativorans PY1, Ochrobactrum sp. PW1, and Bacillus sp. FW1) were successfully isolated from the consortium. Draft genomes of them showed that two different morphotypes of Mycobacterium (PO1 and PO2), possessed a complete gene set for pyrene degradation. PY1 contained genes for phthalate assimilation via protocatechuate, a central intermediate, by meta-cleavage pathway, and PW1 possessed genes for protocatechuate degradation via ortho-cleavage pathway. The occurrence of biosurfactant-producing genes in FW1 suggests the involvement in enhancing the pyrene bioavailability. Biotransformation experiments revealed that Mycobacterium completely degraded 100mgL^-1 pyrene within six days, whereas no significant degradation was observed with the others. Notably, PY1 and PW1 exhibited higher activity for protocatechuate degradation than the others. The artificially reconstructed consortia containing Mycobacterium with the other three strains (PY1, PW1 and FW1) showed three-fold higher degradation rate for pyrene than the individual Mycobacterium. The enhanced pyrene biodegradation achieved in the consortium was due to the cooperative interaction of bacterial mixture. Our findings showing that synergistic degradation of pyrene in the consortium will facilitate the application of the defined bacterial consortium in bioremediation.

Enhanced Cry1Da production in Bacillus thuringiensis by driving expression from the σ(E) -dependent BtI promoter

AIMS

To increase the Cry1Da production in Bacillus thuringiensis by enhancing BtI promoter activity and fusion with upstream sequence from cry1Ab.

METHODS AND RESULTS

The effects of joining the upstream sequence of cry1Ab that contains E2 subunit pyruvate dehydrogenase (PDH) recognition site to the cry1Da promoter as well as the effects of substitution mutation of conserved sequences of its BtI promoter on cry1Da expression was monitored by constructing cry1Da promoter-lacZ fusions. Changing the -35 region of the cry1Da BtI promoter to that of cry1Ab enhanced β-galactosidase activity about three fold as comparing to that of the wild-type promoter with its own upstream sequence. In contrast, the same cry1Da mutated promoter linked to the above upstream sequence of cry1Ab enhanced enzyme activity up to seven fold, but was five fold lower than that of the full-length cry1Ab promoter. The cry1Ab-cry1Da hybrid promoter with the -35 BtI mutation efficiently increased Cry1Da synthesis by 133% and resulted in a 2·3-fold increase in insect larval toxicity when comparing to the wild type.

CONCLUSIONS

The cry1Ab promoter as well as mutation of -35 region of BtI promoter together with fusion with E2 subunit PDH recognition site efficiently enhanced Cry1Da production in B. thuringiensis.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results provide useful information to construct an efficient cry1Da gene expression in B. thuringiensis.

PlcRa, a new quorum-sensing regulator from Bacillus cereus, plays a role in oxidative stress responses and cysteine metabolism in stationary phase

We characterized a new quorum-sensing regulator, PlcRa, which is present in various members of the B. cereus group and identified a signaling heptapeptide for PlcRa activity: PapRa₇. We demonstrated that PlcRa is a 3D structural paralog of PlcR using sequence analysis and homology modeling. A comparison of the transcriptomes at the onset of stationary phase of a ΔplcRa mutant and the wild-type B. cereus ATCC 14579 strain showed that 68 genes were upregulated and 49 genes were downregulated in the ΔplcRa mutant strain (>3-fold change). Genes involved in the cysteine metabolism (putative CymR regulon) were downregulated in the ΔplcRa mutant strain. We focused on the gene with the largest difference in expression level between the two conditions, which encoded -AbrB2- a new regulator of the AbrB family. We demonstrated that purified PlcRa bound specifically to the abrB2 promoter in the presence of synthetic PapRa₇, in an electrophoretic mobility shift assay. We further showed that the AbrB2 regulator controlled the expression of the yrrT operon involved in methionine to cysteine conversion. We found that the ΔplcRa mutant strain was more sensitive to hydrogen peroxide- and disulfide-induced stresses than the wild type. When cystine was added to the culture of the ΔplcRa mutant, challenged with hydrogen peroxide, growth inhibition was abolished. In conclusion, we identified a new RNPP transcriptional regulator in B. cereus that activated the oxidative stress response and cysteine metabolism in transition state cells.