Elizabeth Ortiz-Vázquez

Antioxidant compounds, antioxidant activity and phenolic content in peel from three tropical fruits from Yucatan, Mexico.

The aim of this study was to determine the antioxidant compounds, antioxidant activity and content of individual phenolic compounds of freeze-dried peel from three tropical fruits grown in Yucatan, México: purple star apple (Chrysophyllum cainito L.), yellow cashew and red cashew (Anacardium occidentale). The freeze-dried peels were good source of antioxidant compounds. ABTS and DPPH values in the peel from each fruit were 3050.95-3322.31 μM Trolox/100g dry weight (DW) or 890.19-970.01 mg of vitamin C/100 g DW, and 1579.04-1680.90 μM Trolox/100 g DW or 340.18-362.18 mg of vitamin C/100 g DW, respectively. Six phenolic compounds were identified in the peel from the tropical fruits studied: ferulic, caffeic, sinapic, gallic, ellagic and myricetin. This study demonstrated that freeze-dried peels from purple star apple, yellow cashew and red cashew, could serve as potential sources of antioxidants for use in food and pharmaceutical industries.

Determination of some physicochemical characteristics, bioactive compounds and antioxidant activity of tropical fruits from Yucatan, Mexico.

The aim to the study was to determine the physicochemical composition, bioactive compounds and antioxidant activity of fruits from Yucatan, Mexico such as star apple, cashew, mombin, mamey sapote, white sapote, sugar apple, sapodilla, dragon fruit, nance, ilama, custard apple, mamoncillo and black sapote. The physicochemical characteristics were different between fruits and were good sources of bioactive compounds. The edible part with the highest values of antioxidant activity were mamoncillo, star apple, mombin, cashew, white sapote, ilama, custard apple, sugar apple, and nance. Total soluble phenols content showed a correlation with antioxidant activity by ABTS (R=0.52, P⩽0.05) and DPPH (R=0.43, P⩽0.05). A high correlation was obtained between the two assays (ABTS and DPPH) used to measure antioxidant activity in the tropical fruit species under study (R=0.82, P⩽0.05). The results show promising perspectives for the exploitation and use of tropical fruits studied with significant levels of nutrients and antioxidant activity.

A novel and highly efficient method for genetic transformation of fungi employing shock waves.

Genetic transformation of filamentous fungi is an essential tool in many areas such as biotechnology, medicine, phytopathology and genetics. However, available protocols to transform fungi are inefficient, laborious and have low reproducibility. We report the use of underwater shock waves as a novel method to transform filamentous fungi. An experimental piezoelectric shock wave generator was designed to expose fungal conidia to heterologous DNA. The device was successfully tested in Aspergillus niger, Fusarium oxysporum, Trichoderma reesei and Phanerochaete chrysosporium. The transformation frequency per number of conidia was between two and four orders of magnitude higher in comparison to previously published methods. For example, the frequency of transformation in A. niger was improved up to 5400-fold as compared with Agrobacterium protocols. Transformation was verified by expression of the green fluorescent protein, PCR and Southern blot. Our method offers new possibilities for fast, easy and efficient genetic manipulation of diverse fungal species.

Electrophoresis characterisation of protein as a method to establish the entomological origin of stingless bee honeys.

Increasing production of stingless-bee honey and the prospect of broader marker for natural and organic products indicate the need to establish parameters to determinate the entomological origin and authenticity of honey. In this research, honeys of Apis mellifera, Melipona beecheii and Trigona spp. were collected in Yucatan, Mexico. Stingless-bee honeys contained more water and less total sugars and reducing sugars. SDS-PAGE patterns show distinctive bands for each kind of honey. The SDS-PAGE pattern of A. mellifera proteins honey showed three bands with molecular weights between 10.2 and 74.8kDa, there were five proteins bands in M. beecheii honey with molecular weights between 6.1 and 97.0kDa and nine for Trigona spp. proteins between 9.3 and 86.7kDa. Conventional physicochemical parameters along with electrophoresis profiles of stingless-bee honeys proteins could be an alternative for determination of entomological origin.

Recombinant expression of four oxidoreductases in Phanerochaete chrysosporium improves degradation of phenolic and non-phenolic substrates.

Phanerochaete chrysosporium belongs to a group of lignin-degrading fungi that secretes various oxidoreductive enzymes, including lignin peroxidase (LiP) and manganese peroxidase (MnP). Previously, we demonstrated that the heterologous expression of a versatile peroxidase (VP) in P. chrysosporium recombinant strains is possible. However, the production of laccases (Lac) in this fungus has not been completely demonstrated and remains controversial. In order to investigate if the co-expression of Lac and VP in P. chrysosporium would improve the degradation of phenolic and non-phenolic substrates, we tested the constitutive co-expression of the lacIIIb gene from Trametes versicolor and the vpl2 gene from Pleurotus eryngii, and also the endogenous genes mnp1 and lipH8 by shock wave mediated transformation. The co-overexpression of peroxidases and laccases was improved up to five-fold as compared with wild type species. Transformant strains showed a broad spectrum in phenolic/non-phenolic biotransformation and a high percentage in synthetic dye decolorization in comparison with the parental strain. Our results show that the four enzymes can be constitutively expressed in a single transformant of P. chrysosporium in minimal medium. These data offer new possibilities for an easy and efficient co-expression of laccases and peroxidases in suitable basidiomycete species.

Tandem shock waves to enhance genetic transformation of Aspergillus niger.

Filamentous fungi are used in several industries and in academia to produce antibiotics, metabolites, proteins and pharmaceutical compounds. The development of valuable strains usually requires the insertion of recombinant deoxyribonucleic acid; however, the protocols to transfer DNA to fungal cells are highly inefficient. Recently, underwater shock waves were successfully used to genetically transform filamentous fungi. The purpose of this research was to demonstrate that the efficiency of transformation can be improved significantly by enhancing acoustic cavitation using tandem (dual-pulse) shock waves. Results revealed that tandem pressure pulses, generated at a delay of 300 μs, increased the transformation efficiency of Aspergillus niger up to 84% in comparison with conventional (single-pulse) shock waves. This methodology may also be useful to obtain new strains required in basic research and biotechnology.

Antibacterial properties of honey produced by Melipona beecheii and Apis mellifera against foodborn microorganisms

The aim of this study was to determine the antibacterial activity in vitro of Melipona and Apis honey against various foodborne microorganisms. The results of qualitative test showed that Melipona honey inhibited both Staphylococcus aureus ATCC25923 and H08M06 strains and both Escherichia coli ATCC35922 and H12K06 strains. Apis honey inhibited both E. coli ATCC35922 and H12K06 strains and S. aureus ATCC25923 strain. Minimum inhibitory concentrations of Melipona honey (5–16%, w/v) were lower than those of Apis honey (15–31%, w/v). This study demonstrated that the antibacterial potency of Melipona honey could be a new alternative for controlling foodborne illness.

Which bee honey components contribute to its antimicrobial activity? A review

The antimicrobial activity of bee honey is one of its most studied biological properties, with an extensive spectrum of activity against medically important microorganisms. The specificity of this activity depends on the components of the honey, which vary according to its floral and entomological origin. The action mechanisms of the most transcendental compounds for honey antimicrobial activity; acidity, osmolarity and hydrogen peroxide, are reported. Recent studies have demonstrated the existence of other compounds contributing to the antimicrobial activity of honey such as, enzymes, antimicrobial peptides, phenolic compounds and Methylglyoxal. This article describes both the most important therapeutic properties and the components attributing antimicrobial activity to bee honey, as well as the microorganisms which this effect has been evaluated and their respective minimum inhibitory concentration (MIC). In conclusion, it has been demonstrated that the antimicrobial activity and other biological activities of bee honey such as antitumor, anti-inflammatory, antioxidant and antiviral properties are conferred by a group of components intrinsic to honey and it depends of the botanical, geographical and entomological origin of the honey.

Efficient transformation of Mycosphaerella fijiensis by underwater shock waves.

Black leaf streak disease, also known as black Sigatoka, causes dramatic losses in production of banana and plantains fruits. The disease is caused by the pathogenic fungus Mycosphaerella fijiensis (anamorph Pseudocercospora fijiensis; Mycosphaerellaceae). Genetic transformation of M. fijiensis would allow a better understanding of molecular basis of pathogenicity and design novel approaches to control the infection caused by this pathogen. However, transformation of this fungus has not been easy. We report here a protocol for genetic transformation of M. fijiensis employing underwater shock waves and intact conidia. The recombinant strains recovered showed genetic stability over >10 generations. The frequency of transformation obtained was between 75 and 150 times higher than the efficiency reported in the only article published on transformation of M. fijiensis using spheroplasts. This improvement allowed the use of a thousand times less cells than the amount employed before, avoiding the need for cumbersome successive batch cultures. Our protocol is simple, highly efficient, fast and reproducible and together with the available genomes of M. fijiensis and Musa acuminata, it offers new possibilities to study the diverse mechanisms of pathogenesis of the fungus.

Antibacterial Activity of Proteins Extracted from the Pulp of Wild Edible Fruit of Bromelia Pinguin L.

ABSTRACT Bromelia pinguin L. is a natural source of bioactive compounds. The main purpose of this research was to isolate and characterize bioactive proteins from its fruit. B. pinguin proteins were fractionated by gel filtration chromatography, and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antibacterial activity of the proteins was analyzed against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923, and the enzymatic activity was evaluated by protease activity and trypsin inhibitions assays. Protein fraction obtained by gel filtration chromatography exhibited antibacterial activity against E. coli (minimum inhibitory concentration [MIC] 0.3492 mg/mL) and S. aureus (MIC 0.6845 mg/mL). The proteolytic activity of the fraction was 0.985 Ucas/mL. The substrate-sodium dodecyl sulfate-polyacrylamide gel electrophoresis assay detected protease inhibitors with molecular weights of 43 and 74 kDa. Antibacterial studies of E.coli and S. aureus were determined by comparing the protein fraction with different antibiotics. The antibacterial activity of proteins extracted from the pulp of the fruit of Bromelia pinguin L. could be related to the presence of enzymes, protease inhibitors and peptides.