Antioxidant and Antifungal Properties of Cinnamon, Cloves, Melia azedarach L. and Ocimum gratissimum L. Extracts against Fusarium oxysporum Isolated from Infected Vegetables in Mauritius.

BACKGROUND: Fusarium species, a group of economically destructive phytopathogens, are poorly studied in Mauritius where agriculture holds much significance. Furthermore, the increasing popularity of organic farming has prompted interest in alternatives to chemical fungicides. METHODS: After gaining an overview of Fusarium prevalence in Mauritius fields through a survey, the pathogen was isolated from infected crops and identified based on morphological and molecular characteristics. Methanol and water extracts were then prepared from Melia azedarach, Ocimum gratissimum, cinnamon and cloves before determining their phytochemical profiles. Additionally, the antioxidant and antifungal effects of different concentrations of aqueous extracts were assessed. RESULTS: The isolate was confirmed as Fusarium oxysporum, and cloves inhibited its growth by up to 100%, especially at 60 and 90 g/L, with the results being significantly higher than those of the synthetic fungicide mancozeb. Over 50% inhibition was also noted for cinnamon and Ocimum gratissimum, and these effects could be linked to the flavonoids, phenols and terpenoids in the extracts. CONCLUSION: This study presented the aqueous extracts of cloves, cinnamon and Ocimum gratissimum as potential alternatives to chemical fungicides. It also confirmed the prevalence of Fusarium infection in Mauritius fields, thereby highlighting the need for additional studies on the pathogen.

Prevalence, Genomic Characterization, and Risk Assessment of Human Pathogenic Vibrio Species in Seafood.

ABSTRACT: Pathogenic Vibrio species are largely responsible for human diseases associated with consumption of contaminated seafood. The aim of this study was to determine the prevalence, population densities, species diversity, and molecular characteristics of pathogenic Vibrio in various seafood commodities and the health risks associated with consumption of these contaminated commodities. Samples of finfish and shellfish (oysters and sea urchins) were collected from various regions and analyzed for Vibrio with the most-probable-number (MPN) technique. Genomic DNA of putative Vibrio isolates was analyzed by whole genome sequencing for taxonomic identification and identification of virulence and antimicrobial resistance genes. The risk of Vibrio-related illnesses due to the consumption of contaminated seafood was assessed with Risk Ranger. Populations of presumptive Vibrio were 2.6 to 4.4 log MPN/g and correlated with season; Vibrio levels were significantly higher (P < 0.05) in the summer. Fifteen Vibrio isolates were identified as Vibrio alginolyticus (five isolates), Vibrio parahaemolyticus (six isolates), Vibrio harveyi (two isolates), and Vibrio diabolicus (two isolates). Two of the six V. parahaemolyticus isolates (ST 2504 and ST 2505) from oysters harbored either the tdh gene for thermostable direct hemolysin or the trh gene for thermostable direct hemolysin-related hemolysin. In addition to virulence genes, the shellfish isolates also harbored genes encoding resistance to multiple antibiotics, including tetracycline, penicillin, quinolone, and ß-lactams, thus arousing concern. The risk assessment predicted that an estimated 21 cases of V. parahaemolyticus-associated gastroenteritis could occur in the general population annually due to consumption of contaminated oysters. This study highlights both the wide prevalence and diversity of Vibrio in seafood and the potential for certain strains to threaten public health.

Multigene Phylogenetics and Morphology Reveal Five Novel Lasiodiplodia Species Associated with Blueberries.

Botryosphaeriaceous fungi cause stem blight, canker and dieback in woody plants. During a survey on the fungal pathogens associated with blueberries in China, 135 blighted, cankered or dead blueberry branches were collected from Fujian and Shandong Provinces. Based on the morphological characterization and phylogenetic analyses of a concatenated ITS rDNA, tef1-α, TUB, and RPB2 loci, five new species of Lasiodiplodia, viz., L. clavispora, L. fujianensis, L. henanica, L. nanpingensis and L. paraphysoides were recognized. Detailed descriptions and illustrations, as well as multigene phylogenies, are provided in this paper. The diversity of plant pathogens on agriculturally and economically important plants is higher than anticipated.

Morpho-molecular characterization of Discosia ravennica sp. nov. and a new host record for Sporocadus rosigena.

Collections of fungal samples from two dead leaf specimens from Italy were subjected to morphological examination and phylogenetic analyses. Two coelomycetous taxa belonging to two different genera in Xylariomycetidae, Sordariomycetes, namely Discosia and Sporocadus, were identified. The Discosia taxon is revealed as a new species and is herein introduced as Discosia ravennica sp. nov. while the Sporocadus taxon is identified as Sporocadus rosigena. Multi-locus phylogeny based on DNA sequence data of the large subunit (LSU) and internal transcribed spacer (ITS) of nuclear ribosomal genes, ß-tubulin (ß-tub) and RNA polymerase II second largest subunit (rpb2) showed that D. ravennica is related to D. neofraxinea but it forms an independent lineage that supports its new species status. The new taxon also differs from other Discosia species by its unilocular to bilocular, superficial and applanate conidiomata with basal stroma composed of cells of textura angularis, elongate-ampulliform conidiogenous cells and conidia smaller in size. Sporocadus rosigena is here reported as a new host record from Quercus ilex from Italy. Descriptions, illustrations and molecular data for both species are provided in this paper.

Multigene phylogenetic analyses to establish new Valsaria species and taxonomic significance of spore ornamentation.

During our studies on fungal diversity from plant substrates, a new species of Valsaria was isolated from dead branches of Ostrya carpinifolia. The taxon is morphologically similar to other taxa in Valsariaceae and is characterized by pseudostromata, apically free pseudoparaphyses, bitunicate asci, and dark brown, 2-celled ascospores. However, it differs from extant species in number of guttules and ornamentation of spore. It is introduced herein as Valsaria ostryae sp. nov. within the family Valsariaceae. Multigene phylogenies based on combined LSU, ITS and RPB2 DNA sequence data generated from maximum likelihood, maximum parsimony and MrBayes analyses indicate that V. ostryae is basal to V. lopadostomoides and V. rudis and its establishment as a new species is strongly supported. No discordance was found between our morphological and phylogenetic species boundaries as postulated by other researchers and our molecular data strongly supports ornamentation of spore as useful for species delineation. Valsaria species do not appear to be host specific. Full morphological details are provided herein and phylogenetic relationships of Valsaria species are also discussed in light with host association.

Heavy metal bioaccumulation in commercial Lethrinidae fish species in Mauritius.

Concentrations of heavy metals arsenic, cadmium, lead and mercury and trace elements chromium, copper, nickel and zinc were tested in the muscle tissue of four commercial edible lethrinids fish species from different region of Mauritius. Sky emperor (Lethrinus mahsena) was collected from coastal regions as well as offshore regions (banks) for this study. Blackspot emperor (Lethrinus harak) and spangled emperor (Lethrinus nebulosus) were also studied for their popularity in the fish market. Condition factor was calculated for each fish and the highest value obtained was in Lethrinus mahsena collected from offshore regions (2.598 cm/g). Flame atomic absorption spectrometry was used to analyse copper, nickel and zinc while, graphite furnace technique was used for cadmium, chromium and lead. Mercury levels were evaluated with the cold vapour technique and arsenic with the thermal hydride cell. The level of lead, mercury, copper, nickel and zinc ranged from 0.0011-0.0024 mg/L, 0.0016-0.0036 mg/L, 0.080-0.389 mg/L, 0.566-1.192 mg/L and 0.219-0.422 respectively in wet weight. Interspecies variations in levels of heavy metals and trace elements were observed for nickel and no significant variations occurred for mercury, lead and zinc. Concentrations of heavy metals and trace elements were all within the permissible level except for nickel. As per this study, the Food Act 1998 of Mauritius must be reviewed in order to incorporate the Maximum Permissible Level for nickel.