Honghui Zhu

Isolation of deoxynivalenol-transforming bacteria from the chicken intestines using the approach of PCR-DGGE guided microbial selection.

BackgroundContamination of grains with trichothecene mycotoxins, especially deoxynivalenol (DON), has been an ongoing problem for Canada and many other countries. Mycotoxin contamination creates food safety risks, reduces grain market values, threatens livestock industries, and limits agricultural produce exports. DON is a secondary metabolite produced by some Fusarium species of fungi. To date, there is a lack of effective and economical methods to significantly reduce the levels of trichothecene mycotoxins in food and feed, including the efforts to breed Fusarium pathogen-resistant crops and chemical/physical treatments to remove the mycotoxins. Biological approaches, such as the use of microorganisms to convert the toxins to non- or less toxic compounds, have become a preferred choice recently due to their high specificity, efficacy, and environmental soundness. However, such approaches are often limited by the availability of microbial agents with the ability to detoxify the mycotoxins. In the present study, an approach with PCR-DGGE guided microbial selection was developed and used to isolate DON -transforming bacteria from chicken intestines, which resulted in the successful isolation of several bacterial isolates that demonstrated the function to transform DON to its de-epoxy form, deepoxy-4-deoxynivalenol (DOM-1), a product much less toxic than DON.ResultsThe use of conventional microbiological selection strategies guided by PCR-DGGE (denaturing gradient gel electrophoresis) bacterial profiles for isolating DON-transforming bacteria has significantly increased the efficiency of the bacterial selection. Ten isolates were identified and isolated from chicken intestines. They were all able to transform DON to DOM-1. Most isolates were potent in transforming DON and the activity was stable during subculturing. Sequence data of partial 16S rRNA genes indicate that the ten isolates belong to four different bacterial groups, Clostridiales, Anaerofilum, Collinsella, and Bacillus.ConclusionsThe approach with PCR-DGGE guided microbial selection was effective in isolating DON-transforming bacteria and the obtained bacterial isolates were able to transform DON.

Characterization of phytochemicals and antioxidant activities of a purple tomato (Solanum lycopersicum L.).

A newly developed nongenetically modified purple tomato V118 was investigated for its phytochemical compositions and antioxidant activities. A highly efficient and sensitive UPLC method was developed for both the phenolics and carotenoids, which showed that in addition to the phytochemicals commonly known for tomatoes, V118 had a unique composition of anthocyanins. The total carotenoid content of V118 was 234.78 μg/g dry weight (DW), and the total phenolic content was 659.11 mg GAE/100 g DW. The antioxidant activities of the lipophilic extract as measured by the PCL and ORAC-L assays were 30.11 μmol TE/g DW and 11.97 μmol TE/g DW, respectively, while the hydrophilic extracts as determined by the ORAC-H and FRAP assays were 323.23 μmol TE/g DW and 54.95 μmol AAE/g DW, respectively. The LC-MS study showed three major anthocyanins, which were mainly acylglycosides of petunidin and malvidin. This study showed that purple tomatoes such as V118 possess additional phytochemicals like anthocyanins, which can potentially have added health benefits.

Evaluation of antioxidant activities and chemical characterisation of staghorn sumac fruit (Rhus hirta L.)

Staghorn sumac (Rhus hirta L.) is a native tree in Eastern Canada whose fruit has been used by aboriginal peoples to treat various illnesses, and has recently been found to be a good source of antioxidants. However, the phytochemical composition of R. hirta is not known. In this study, we used Four highly accepted assays and confirmed its FRAP, ORAC, β-CLAMS and PCL values to be 79.95 μmol AAE/g DW, 1544 μmol TE/g DW, RAA 129% and 4513 μmol TE/g DW, respectively. The antioxidant activities correlated positively to the total polyphenols content, which was higher in the ethanolic extract (81.6 mg GAE/ g DW) compared to the water extract (46.3mg GAE/g DW), suggesting polyphenols play an important role. Quantitative data from UHPLC and qualitative studies using HPLC-DAD-MS showed that in addition to commonly found phenolic acids, flavonoids and anthocyanins, R. hirta fruit contained a novel group of unique anthocyanins with aglycones (anthocyanidins) at 449, 419 and 433 Da. Further studies on the identification and their health beneficial effects are being conducted.

An efficient method for the determination of furan derivatives in apple cider and wine by solid phase extraction and high performance liquid chromatography—Diode array detector

A reliable SPE-HPLC/DAD method was developed for the simultaneous separation and quantitation of 10 furan derivatives in apple cider and wine matrices, including 5-hydroxymethyl-2-furaldehyde (5-HMFD), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDMF), 2-furoic acid (2-FA), 2-furaldehyde (2-F), 3-furaldehyde (3-F), 2-acetylfuran (2-AF), 5-methyl-2-furaldehyde (5-MFD), methyl 2-furoate (MFT), 2-propionylfuran (2-PF) and ethyl 2-furoate (EFT). All the compounds were satisfactorily separated on a C18 column in less than 30 min. The solid phase extraction parameters have been optimized, including the sorbent, sample volume, washing and elution solvent. The relative standard deviations (RSDs) (intra- and inter-day) of all analytes were less than 6.4% for apple cider at 5mg/L spiking level and less than 3.9% (except 2-FA) for wine at 0.5mg/L spiking level. The limits of detection (LOD) and limits of quantitation (LOQ) were low (LOD 0.002-0.093 mg/L, LOQ 0.01-0.31 mg/L) compared to the usual concentrations of these compounds in these food matrices. The absolute recoveries of all compounds were higher than 77.8% (most of them were 80.5-103%) at different spiking levels (apple cider 0.5-50mg/L). The results showed that the developed method was precise, sensitive, robust and of good selectivity.

Bioaccessibility, Cellular Uptake, and Transport of Astaxanthin Isomers and their Antioxidative Effects in Human Intestinal Epithelial Caco-2 Cells

The bioaccessibility, bioavailability, and antioxidative activities of three astaxanthin geometric isomers were investigated using an in vitro digestion model and human intestinal Caco-2 cells. This study demonstrated that the trans-cis isomerization of all-E-astaxanthin and the cis-trans isomerization of Z-astaxanthins could happen both during in vitro gastrointestinal digestion and cellular uptake processes. 13Z-Astaxanthin showed higher bioaccessibility than 9Z- and all-E-astaxanthins during in vitro digestion, and 9Z-astaxanthin exhibited higher transport efficiency than all-E- and 13Z-astaxanthins. These might explain why 13Z- and 9Z-astaxanthins are found at higher concentrations in human plasma than all-E-astaxanthin in reported studies. All three astaxanthin isomers were effective in maintaining cellular redox homeostasis as seen in the antioxidant enzyme (CAT, SOD) activities ; 9Z- and 13Z- astaxanthins exhibited a higher protective effect than all-E-astaxanthin against oxidative stress as demonstrated by the lower cellular uptake of Z-astaxanthins and lower secretion and gene expression of the pro-inflammatory cytokine IL-8 in Caco-2 cells treated with H2O2. We conclude, for the first time, that Z-astaxanthin isomers may play a more important role in preventing oxidative stress induced intestinal diseases.