Virulence Genes Analysis of Vibrio parahaemolyticus and Anti-vibrio Activity of the Citrus Extracts.

Vibrio parahaemolyticus (VP) is a marine bacterium that opportunistically caused foodborne gastroenteritis in human and some diseases in marine animals. The isolated strain of V. parahaemolyticus WS001 from Samut Sakhon, Thailand has a presence of ldh (~ 450 bp) toxA (~ 333 bp) and toxB (~ 1269 bp) genes which showed pathogenicity in shrimp. This strain is suspected as low pathogenicity in human due to the lack of tdh and trh genes for encoding thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), respectively. The shrimp pathogenic strain was tested and revealed the multi-antibiotic resistances but was susceptible to norfloxacin (10 µg/ml). Citrus peel extracts were examined because they are rich in bioactive compounds such as saponins, tannins, flavonoids, steroids, and alkaloids that are effective in anti-VP activities. The ethanolic peel extracts of Citrus aurantifolia (Christm.) Swingle and Citrus hystrix DC. were found to be more anti-VP effect than other solvent extracts by Agar disc diffusion method at an optimum concentration of 50 mg/ml and Broth micro-dilution method (MICs of 50-100 mg/ml and MBCs of 100-200 mg/ml). Thus, C. aurantifolia (Christm.) Swingle peel extract was a distinctive candidate for the development of alternative natural agent to control the spreading of diseases in shrimp.

In vitro assessment of Enterococcus faecalis MTC 1032 as the potential probiotic in food supplements.

Probiotics become important bacteria in our daily life due to their benefit on human health. In this study, a subset of bacterial strains from children was isolated and evaluated for beneficial probiotic traits such as antimicrobial activity, bile and acid tolerance, and pathogenic cell adherence inhibition. The strain with the best antimicrobial activity was selected for further characterization on the basis of morphological, biochemical characteristics and gene sequence. This strain was Gram-positive, oxidase and catalase-negative, and it produced acids by fermenting sugar and starch as carbon sources. Additionally, it could only hydrolyze bile-esculin, but not red blood cells. The 16S rDNA gene sequence revealed that this strain was Enterococcus faecalis. Interestingly, this strain effectively inhibited a variety of pathogens by acid and bacteriocin production and was bile-tolerant, able to survive under acidic condition. In the safety assessments, E. faecalis MTC 1032 could adhere to host epithelial cells and evidently inhibited pathogenic cell adhesion as demonstrated by cell reduction over time of E. coli ATCC 25922 and S. typhimurium ATCC 13311 on Caco-2 cell line. In summary, it was clearly represented that E. faecalis MTC 1032 provided suitable properties and could be a candidate as a probiotic strain in food supplements.

Effects of types and amounts of stabilizers on physical and sensory characteristics of cloudy ready-to-drink mulberry fruit juice.

In this study, the pH of mulberry juice was optimized for high anthocyanin content and an attractive red color. Mulberry juice pH values of 2.5, 4.0, 6.0, and 8.0 were evaluated. A pH of 2.5 gave an anthocyanin content of 541.39 ± 106.43 mg of cyanidin-3-glucoside per liter, and the a* value was 14 ± 1.00. The effects of stabilizers (CMC and xanthan gum) on the physical characteristics of cloudy ready-to-drink mulberry fruit juice (via the addition of mulberry fruit pulp at a mass fraction of 5%) during storage (4°C for 1 week) were also determined using different mass fractions of the stabilizers (0.1%, 0.3%, and 0.5%). Increasing the stabilizer mass fraction increased the viscosity, turbidity, stability of turbidity, and h* value. Using xanthan gum as the stabilizer produced better results for these parameters than CMC. The type of stabilizer and its mass fraction had no effect on most sensory characteristics, including appearance, color, taste, texture, and overall acceptability (P ≥ 0.05), but did affect the odor (P ≥ 0.05). Xanthan gum stabilizer gave the juice a better odor than CMC. Cloudy mulberry juice containing 0.5% xanthan gum as the stabilizer had the highest acceptance rate among panelists (average acceptance was 6.90 ± 1.37 points) and produced no precipitate during storage.

Isolation and characterization of Lactobacillus salivarius MTC 1026 as a potential probiotic.

Researchers are becoming more interested in studying probiotics at present due to their benefit to human and animal health. In this study, newly isolated strains from human feces were evaluated for probiotic properties. A total of sixty isolated strains were collected from feces and six out of sixty isolated strains could inhibit the growth of Salmonella typhi and Salmonella typhimurium. The strain which gave the best inhibitory effect was selected for further characterization as a probiotic strain. The identification of this strain was analyzed on the basis of morphological and biochemical characteristics and 16S rDNA gene sequence. This strain was Gram-positive, rod shaped, and catalase and oxidase-negative, and produced acids from D-glucose, D-fructose, lactose, mannitol, sorbitol, inulin and starch. It could not hydrolyze esculin or red blood cells. Based on its 16S rDNA gene sequence, it was Lactobacillus salivarius, and so was called L. salivarius MTC 1026 in this study, and was closely related with L. salivarius DSPV 344T isolated from the calf gut. It was able to survive in gastric and small intestinal juices at pH 2.0 and 1.0% bile salt for several hours and also could grow at 45°C. Moreover, this strain showed inhibitory activity against a variety of food-borne pathogens. It was highly sensitive to piperacillin, chloramphenicl, ampicillin, erythromycin and ceftazidime. After plasmid curing, this strain was susceptible to gentamicin, amikacin, norfloxacin and ciprofloxacin. L. salivarius MTC 1026 could significantly inhibit the adhesion process of E. coli ATCC 25922 and S. typhimurium ATCC 13311 on Caco-2 monolayers in a competition assay and also reduced invasion of both pathogens (4-log cfu/ml) in an exclusion and displacement assay. Therefore, it was clearly demonstrated in this study that L. salivarius MTC 1026 has shown promising properties as a candidate for a potential probiotic for applications in humans and animals.