Vibrio parahaemolyticus is a leading seafood-borne pathogen that can cause acute gastroenteritis and even death in humans. In aquatic ecosystems, phages constantly transform bacterial communities by horizontal gene transfer. Nevertheless, biological functions of prophage-related genes in V. parahaemolyticus remain to be fully unveiled. Herein, for the first time, we studied one such gene VpaChn25_0724 encoding an unknown hypothetical protein in V. parahaemolyticus CHN25. This gene deletion mutant ΔVpaChn25_0724 was constructed by homologous recombination, and its complementary mutant ΔVpaChn25_0724-com was also obtained. The ΔVpaChn25_0724 mutant exhibited a sever defect in growth and swimming motility particularly at lower temperatures. Biofilm formation and cytotoxicity capacity of V. parahaemolyticus CHN25 was significantly lowered in the absence of VpaChn25_0724. Comparative secretomic analysis revealed an increase in extracellular proteins of ΔVpaChn25_0724, which likely resulted from its damaged cell membrane. Comparison of transcriptome data showed twelve significantly altered metabolic pathways in ΔVpaChn25_0724, suggesting inactive transport and utilization of carbon sources, repressed energy production and membrane biogenesis in ΔVpaChn25_0724. Comparative transcriptomic analysis also revealed several remarkably down-regulated key regulators in bacterial gene regulatory networks linked to the observed phenotypic variations. Overall, the results here facilitate better understanding of biological significance of prophage-related genes remaining in V. parahaemolyticus.

Outbreaks and prevalence of infectious diseases worldwide are some of the major contributors to morbidity and morbidity in humans. Pharmacophageous plants are the best source for searching antibacterial compounds with low toxicity to humans. In this study, we identified, for the first time, antibacterial components and action modes of methanol-phase extract from such one edible herbaceous plant Rumex madaio Makino. The bacteriostatic rate of the extract was 75% against 23 species of common pathogenic bacteria. The extract was further purified using the preparative high-performance liquid chromatography (Prep-HPLC) technique, and five separated componential complexes (CC) were obtained. Among these, the CC 1 significantly increased cell surface hydrophobicity and membrane permeability and decreased membrane fluidity, which damaged cell structure integrity of Gram-positive and -negative pathogens tested. A total of 58 different compounds in the extract were identified using ultra-HPLC and mass spectrometry (UHPLC-MS) techniques. Comparative transcriptomic analyses revealed a number of differentially expressed genes and various changed metabolic pathways mediated by the CC1 action, such as down-regulated carbohydrate transport and/or utilization and energy metabolism in four pathogenic strains tested. Overall, the results in this study demonstrated that the CC1 from R. madaio Makino are promising candidates for antibacterial medicine and human health care products.

Vibrio parahaemolyticus is a seafoodborne pathogen that can cause severe gastroenteritis and septicemia diseases in humans and even death. The emergence of multidrug-resistant V. parahaemolyticus leads to difficulties and rising costs of medical treatment. The bacterium of environmental origins containing no major virulence genes (tdh and trh) has been reported to be associated with infectious diarrhea disease as well. Identification of risk factors in V. parahaemolyticus is imperative for assuming food safety. In this study, we obtained secretomic and proteomic profiles of V. parahaemolyticus isolated from 12 species of commonly consumed aquatic products and identified candidate protein spots by using two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry techniques. A total of 11 common and 28 differential extracellular proteins were found from distinct secretomic profiles, including eight virulence-associated proteins: outer membrane channel TolC, maltoporin, elongation factor Tu, enolase, transaldolase, flagellin C, polar flagellin B/D, and superoxide dismutase, as well as five antimicrobial and/or heavy metal resistanceassociated ABC transporter proteins. Comparison of proteomic profiles derived from the 12 V. parahaemolyticus isolates also revealed five intracellular virulence-related proteins, including aldehyde-alcohol dehydrogenase, outer membrane protein A, alkyl hydroperoxide reductase C, phosphoenolpyruvate-protein phosphotransferase, and phosphoglycerate kinase. Additionally, our data indicated that aquatic product matrices significantly altered proteomic profiles of the V. parahaemolyticus isolates with a number of differentially expressed proteins identified. The results in this study meet the increasing need for novel diagnosis candidates of the leading seafoodborne pathogen worldwide.

Purpose: The aim of this study was to identify salt tolerance-related genes of Lactobacillus plantarum D31 and T9 strains, isolated from Chinese traditional fermented food, by genomic analysis. Methods: Tolerance of L. plantarum D31 and T9 strains was evaluated at different stress conditions (temperatures, acid, osmolality, and artificial gastrointestinal fluids). Draft genomes of the two strains were determined using the Illumina sequencing technique. Comparative genomic analysis and gene transcriptional analysis were performed to identify and validate the salt tolerance-related genes.Results: Both L. plantarum D31 and T9 strains were able to withstand high osmotic pressure caused by 5.0% NaCl, and L. plantarum D31 even to tolerate 8.0% NaCl. L. plantarum D31 genome contained 3,315,786 bp (44.5% GC content) with 3106 predicted protein-encoding genes, while L. plantarum T9 contained 3,388,070 bp (44.1% GC content) with 3223 genes. Comparative genomic analysis revealed a number of genes involved in the maintenance of intracellular ion balance, absorption or synthesis of compatible solutes, stress response, and modulation of membrane composition in L. plantarum D31 and or T9 genomes. Gene transcriptional analysis validated that most of these genes were coupled with the stress-resistance phenotypes of the two strains.Conclusions: L. plantarum D31 and T9 strains tolerated 5.0% NaCl, and D31 even tolerated 8.0% NaCl. The draft genomes of these two strains were determined, and comparative genomic analysis revealed multiple molecular coping strategies for the salt stress tolerance in L. plantarum D31 and T9 strains.

Slicing is an abiotic stress during fresh-cut lotus root slices (FLS) preparation. To evaluate the potential ability of slicing to induce antioxidant capacity (AC) in FLS, fresh lotus roots were sliced into 0.4 cm thick slices and stored at 7°C for 7 days using intact root segments as control. Results showed slicing induced 68.3% higher phenylalanine ammonia-lyase (PAL) activity and parallel 130.5% more total phenol (TP) accumulation after 7 days storage compared to control. AC values in FLS assayed by FRAP and ABTS •+ were 41.5% and 93.8% more than those in control samples at the end of storage, respectively. Such increases in AC values were mainly attributed to TP accumulation as a positive correlation existed between AC and TP. However, slicing significantly accelerated FLS browning by increasing the polyphenol oxidase (PPO) activity during storage. Nevertheless, FLS was still marketable with the maximum browning index of 1.9 after 7 days storage.

Vibrio parahaemolyticus is a waterborne pathogen that can cause acute gastroenteritis, wound infection, and septicemia in humans. The molecular basis of its pathogenicity is not yet fully understood. Phages are found most abundantly in aquatic environments and play a critical role in horizontal gene transfer. Nevertheless, current literature on biological roles of prophage-encoded genes remaining in V. parahaemolyticus is rare. In this study, we characterized one such gene VpaChn25_0734 (543-bp) in V. parahaemolyticus CHN25 genome. A deletion mutant ΔVpaChn25_0734 (543-bp) was obtained by homologous recombination, and a revertant ΔVpaChn25_0734-com (543-bp) was also constructed. The ΔVpaChn25_0734 (543-bp) mutant was defective in growth and swimming mobility particularly at lower temperatures and/or pH 7.0–8.5. Cell surface hydrophobicity and biofilm formation were significantly decreased in the ΔVpaChn25_0734 (543-bp) mutant (p < 0.05). Based on the in vitro Caco-2 cell model, the deletion of VpaChn25_0734 (543-bp) gene significantly reduced the cytotoxicity of V. parahaemolyticus CHN25 to human intestinal epithelial cells (p < 0.05). Comparative secretomic and transcriptomic analyses revealed a slightly increased extracellular proteins, and thirteen significantly changed metabolic pathways in the ΔVpaChn25_0734 (543-bp) mutant, showing down-regulated carbon source transport and utilization, biofilm formation, and type II secretion system (p < 0.05), consistent with the observed defective phenotypes. Taken, the prophage-encoded gene VpaChn25_0734 (543-bp) enhanced V. parahaemolyticus CHN25 fitness for survival in the environment and the host. The results in this study facilitate better understanding of pathogenesis and genome evolution of V. parahaemolyticus, the leading sea foodborne pathogen worldwide.

Background Anti-malarial drug resistance is still a major threat to malaria elimination in the Great Mekong Sub-region. Plasmodium vivax parasites resistant to anti-malarial drugs are now found in Myanmar. Molecular surveillance on drug resistance genes in P. vivax parasites from northeastern Myanmar was aimed at estimating the underlying drug resistance in this region. Methods Blood samples from patients with vivax malaria were collected from Laiza city in northeastern Myanmar in 2020. Drug resistance genes including Pvcrt-o, Pvmdr1, Pvdhfr and Pvdhps were amplified and sequenced. Genetic polymorphisms and haplotypes were analysed to evaluate the prevalence of mutant alleles associated with drug resistance. Results A total of 149 blood samples from P. vivax patients were collected. The prevalence of Pvmdr1 mutations at codons 958 and 1076 was 100.0% and 52.0%, respectively, whereas no single nucleotide polymorphism was present at codon 976. The proportions of single and double mutant types were 48.0% and 52.0%, respectively. A K10 “AAG” insertion in the Pvcrt-o gene was not detected. Mutations in Pvdhfr at codons 57, 58, 61, 99 and 117 were detected in 29.9%, 54.3%, 27.6%, 44.9% and 55.1% of the samples, respectively. Wild type was predominant (46.3%), followed by quadruple and double mutant haplotypes. Of three types of tandem repeat variations of Pvdhfr, Type B, with three copies of GGDN repeats, was the most common. Pvdhps mutations were only detected at codons 383 and 553 and the wild type Pvdhps was dominant (78.0%). Eleven haplotypes were identified when combining the mutations of Pvdhfr and Pvdhps, among which the predominant one was the wild type (33.9%), followed by double mutant alleles S58R/S117N /WT (24.6%). Conclusions This study demonstrated resistant P. vivax phenotypes exists in northeastern Myanmar. Continued surveillance of drug resistance markers is needed to update treatment guidelines in this region.

In this study, we investigated the antioxidant and antimicrobial activities of Isodon amethystoides (Benth.) CY Wu et Hsuan leaf extracts. Leaves were subjected to extraction with acetone, chloroform, ethanol and ethyl acetate. The extraction efficiency of these four solvents ranked as follows: acetone > chloroform > ethanol > ethyl acetate; highest extraction yield of 18.27% was obtained using acetone as the solvent. Total phenolic content and flavonoid content were determined using Folin-Ciocalteau and aluminium chloride (AlCl 3) methods, respectively. The acetone extract had the highest total phenolic content (146.77 mg GAE/g dry extract) and flavonoid content (81.57 mg RE/g dry extract) among the four types of extracts. Further, the antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the antimicrobial activity was evaluated using disc-diffusion and broth microdilution assay. The strongest antioxidant activity was observed in the acetone extract with a half minimal inhibitory concentration (IC 50) of 0.4024 mg/mL in the DPPH scavenging assay. The acetone and ethyl acetate extracts exhibited strong antimicrobial activity. The strongest antibacterial activity of the acetone extract was observed against Bacillus subtilis and Escherichia coli with a minimum inhibitory concentration (MIC) of 0.10 mg/mL and 0.05 mg/mL, respectively. The acetone extract had high antifungal activity against three of the six agriculturally important pathogenic fungi with MIC ranging from 0.5 mg/mL to 0.8 mg/mL. The antioxidant and antimicrobial activities may be attributed to the high total phenolic and flavonoid contents in the acetone extract. Our findings suggest I. amethystoides leaves as an important source of natural compounds with potential use in agriculture.