Mycotoxin production from fungi isolated from grapes

AIMS: In order to assess the potential for producing mycotoxins, fungi were isolated from wine producing grapes. METHODS AND RESULTS: The isolates were identified and Penicillium expansum, the most well recognized mycotoxin producer, was analysed for mycotoxin production by TLC. Many of the strains produced patulin and/or citrinin, often depending on whether they were grown on a grape or yeast extract sucrose media. CONCLUSION: Citrinin was produced by all strains grown in the yeast extract sucrose medium, but only one strain (from 51) was able to produce this compound in grape juice medium. Patulin was produced in the yeast extract medium by 20 strains and in grape juice medium by 33 strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of mycotoxins in wine producing grapes is discussed. Grapes contamination with patulin seems not to contribute to wine contamination, and no ochratoxin producing fungi was identified.     

Diterpenes derived from clerodanes from Pulicaria angustifolia

The investigation of Pulicaria angustifolia afforded, in addition to known triterpenes and caryophyllene epoxide, four methyl esters of diterpenes, all derived from clerodane. Three of them are derivatives of seco-nidoresedic acid. The structures were elucidated by spectroscopic methods.     

Genotyping Echinococcus granulosus from dogs from Western Iran

Cystic echinococcosis is a zoonotic infection caused by the dog tapeworm, Echinococcus granulosus. In the present study, adults of E. granulosus (n = 20) were collected from 71 dogs from Western Iran and were genetically characterized using DNA sequencing of the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase 1 (nad1). Consensus sequences were obtained for cox1 (366) and nad1 (471) genes. Phylogenetic analysis of concatenated nad1 and cox1 nucleotide sequence data was performed using Bayesian Inference approach. Overall, the dog isolates indicated nine different sequences in cox1 and seven in nad1 genes. Three genotypes (G1 [75%], G2 [10%] and G3 [15%]) were identified from the isolates. The G2 sequences indicated 100% homology with reference G2 sequence in both cox1 (Genbank accession number M84662) and nad1 (AJ237633) genes. G3 sequences showed 100% homology with G3 reference sequence in nad1 (AJ237633), but displayed two different cox1 profiles, each having 99% homology with reference G3 sequence (M84663). In the phylogenetic tree all of the isolates were grouped into a distinct cluster corresponding to the G1–G3 complex with relevant reference sequences. The presence of G1 genotype (sheep strain) of E. granulosus sensu stricto as dominant genotype in dogs is emphasized. To the best of our knowledge, this study established the first record of E. granulosus sensu stricto, G2 genotype in Iran.     

Chemiluminescence from an erythrocyte folic acid oxidase from normal individuals and from cancer patients

Folic acid oxidase from erythrocytes oxidatively cleaves folic acid at the C-9-N-10 bond to yield pterin-6-aldehyde and p-aminobenzoyl glutamic acid, with the concomitant generation of singlet oxygen. The emission from singlet oxygen is proportional to the enzyme activity. DABCO was used as a singlet oxygen emission enhancer to increase the sensitivity of the measurement. In general, pregnant women show high enzymatic activity, but the emission is strongly quenched by DABCO. This is contrary to normal and cancer cases in which an increase in the emission was observed. This effect is larger in cancer cases. These results are presented as a potential method for detecting physiological and pathological human conditions.     

Isolation of Toxoplasma gondii from goats from Brazil

Goats are economically important in many countries, and little is known of caprine toxoplasmosis in Brazil. Antibodies to Toxoplasma gondii were assayed in the sera of 143 goats from 3 Brazilian states, using modified agglutination test (MAT titer > or = 1:25); 46 (32.2%) tested positive. Samples of brain, heart, diaphragm, and masseter of seropositive animals were pooled, digested in pepsin, and bioassayed in mice. Viable T. gondii specimens were isolated from tissue homogenates of 12 goats; the isolates were designated TgGtBr1-12. Ten of the 12 isolates killed 100% of infected mice, indicating that goats can harbor mouse-virulent T. gondii and, hence, can serve as a source of infection for humans.     

Phytoalexins from Brassicaceae: News from the front

The chemical structures, syntheses, metabolism and biological activities of the cruciferous phytoalexins discovered to date, with particular focus on the latest results dealing with their biosynthesis and detoxification are reviewed.     

Plant regeneration from protoplasts isolated from callus ofGentiana crassicaulis

Fast growing calli induced from hypocotyl segments ofGentiana crassicaulis were used for preparation of protoplasts. High yields of viable protoplasts were produced in an enzyme solution containing 1–2% cellulase, I% pecfinase, and 0.5% Hemicellulase. Protoplasts were cultured in KM8P medium containing 1 mg/l 2,4-D, 0.5 mg/l 6BA, 500 mg/l LH, 0.5 M glucose and 0.1 M mannitol by the solid-liquid dual layer culture method. First division occurred within 4–5 days of culture at a frequency of 17.8%. Sustained divisions led to callus formation. Periodically diluting the cultures with freshly prepared liquid medium containing 1% glucose was critical for colony formation. Protocolonies about 2 mm in size were transferred onto MS medium supplemented with 3 mg/l ZT, 2 mg/l 6BA, 1 mg/l GA₃, 1 mg/l NAA and 6% sucrose to obtain embryogenic calli. Plantlets were regenerated via somatic embryogenesis at high frequency on hormone-free MS Medium.Abbreviations 6BA 6-benzylaminopurine - NAA naphthaleneacetic acid - 2,4-D 2,4 - dichlorophenoxyacetic acid - ZT zeatin - GA₃ gibberellic acid - LH lactalbumin hydrolysate - MES 2-(N-morpholino)-ethane sulfonic acid - MS Murashige & Skoog's medium(1962)     

Novel transaminases from thermophiles: from discovery to application

Transaminases (TAs) are promising biocatalysts for chiral amine synthesis; however, only few thermophilic TAs have been described to date. In this work, a genome mining approach was taken to seek novel TAs from nine thermophilic microorganisms. TA sequences were identified from their respective genome sequences and their Pfam were predicted confirming that TAs class I–II are the most abundant (50%), followed by class III (26%), V (16%), IV (8%) and VI (1%). The percentage of open reading frames (ORFs) that are TAs ranges from 0.689% in Thermococcus litoralis to 0.424% in Sulfolobus solfataricus. A total of 94 putative TAs were successfully cloned and expressed into E. coli, showing mostly good expression levels when using a chemical chaperone media containing d -sorbitol. Kinetic and end-point colorimetric assays with different amino donors–acceptors confirmed TAs activity allowing for initial exploration of the substrate scope. Stereoselective and non-stereoselective serine-TAs were selected for the synthesis of hydroxypyruvate (HPA). Low HPA reaction yields were observed with four non-stereoselective serine-TAs, whilst two stereoselective serine-TAs showed significantly higher yields. Coupling serine-TA reactions to a transketolase to yield l -erythrulose (Ery) substantially increased serine conversion into HPA. Combining both stereoselective serine-TAs and transketolase using the inexpensive racemic D/L-serine led to high Ery yield (82%). Thermal characterization of stereoselective serine-TAs confirmed they have excellent thermostability up to 60°C and high optimum temperatures.