Author: MARIA MARCELA GAMBOA ANGULO
MARIA MARCELA GAMBOA ANGULO (2010)
Microorganisms are recognized worldwide
as the major source of secondary metabolites
with mega diverse structures and promissory biological
activities. However, as yet many of them remain
little or under-explored like the microbiota from
freshwater aquatic ecosystems. In the present review,
we undertook a recompilation of metabolites reported
with pesticidal properties from microalgae (cyanobacteria
and green algae) and fungi, speciﬁcally from
freshwater aquatic habitats.
MARIA MARCELA GAMBOA ANGULO (2014)
A total of 24 extracts (aqueous and ethanolic)
from nine plant species were evaluated against Alternaria
chrysanthemi, the causal agent of leaf spot of
chrysanthemum. The highest antifungal activity was shown
by ethanolic and aqueous extracts of Acalypha gaumeri root
(Growth inhibition, GI = 75 and 69%, respectively), and by
the aqueous extracts of Bonellia flammea stem and leaf (GI
= 63 and 50%, respectively). These active extracts were
subsequently assessed by agar dilution assay, where
ethanolic extract (EE) of A. gaumeri root caused the highest
inhibition of mycelial growth and sporulation, with a
median Inhibitory Concentration (IC ) of 0.53 mg/mL 50
against A. chrysanthemi GI. This extract was partitioned and
the highest activity was observed in the medium polarity
fraction (ACR-1E), where an IC of 0.13 mg/mL was 50
recorded. This fraction completely inhibited A.
chrysanthemi infection in chrysanthemum leaf, at
concentrations of 85μg/cm2. Also, A. gaumeri extract was
able to inhibit the fungal strains Alternaria sp. (ITC02),
Colletotrichum capsici, Colletotrichum gloeosporioides,
Corynespora cassiicola, Curvularia sp. (ITC10), and
Helminthosporium sp. (ITC04). The EE of A. gaumeri root
may be a potential source of botanical fungicide to control
Los hongos Beltraniella japonica, B. portoricensis, Beltraniopsis sp., Gliomastix murorum y MR45 asociados a hojarasca, se cultivaron en dos medios líquidos, Czapeck–Dox–extracto de levadura (CDL) y caldo de papa dextrosa (CPD). En cada caso, el micelio se separó del filtrado y ambas fases se sometieron a maceración con AcOEt obteniendo los correspondientes extractos fúngicos de filtrado (EFF) y micelio (EFM). Éstos se evaluaron en los ensayos de reducción del radical 2,2–difenil–1 –picrilhidrazilo (DPPH) y el antimicrobiano por microdilución contra cuatro patógenos. Los resultados mostraron una alta capacidad antioxidante en los EFF de B. japonica, G. murorum y MR45, en los medios CPD y CDL. La actividad antimicrobiana más alta se detectó contra S. aureus, producido por las dos cepas de Beltraniella (200 µg) en CPD y contra E. carotovora en el EFM de B. japonica en CDL. En ambos medios, B. japonica produce meleína, no obstante, para las demás cepas activas no se identificaron los componentes. El perfil biológico y las exploraciones preliminares por cromatografía de gases – espectrometría de masas (CG–EM) de los extractos activos confirman la versatilidad metabólica de los hongos del trópico mexicano, los cuales pueden ser susceptibles de manipulación para la producción de metabolitos útiles en farmacia y agricultura.
The whitefly (Bemisia tabaci Genn.) is a widely distributed and highly harmful plant pest species. The management of B. tabaci has been typically carried out by chemical pesticides. In the last decade however, there has been an increasing interest in natural products, particularly those of plant origin, to control this pest species. In the present work, aqueous and ethanolic extracts of native plants from the flora of the Yucatán peninsula (Acalypha gaumeri,Annona squamosa, Carlowrightia myriantha, Petiveria alliaceae and Trichilia arborea) and the introduced plant Azadirachta indica were collected and evaluated for insecticidal activity against eggs and nymphs Bemisia tabaci.
A total of 258 bacterial strains were isolated from the water and sediment of two cenotes in the Yucatan peninsula, all of which were screened against six pathogenic micro‐organisms. Antimicrobial activity was detected in 46 of the isolated strains against at least one of the target strains tested. Antimicrobially active isolates were identified as: Aeromonas, Bacillus, Burkholderia, Photobacterium, Pseudomonas, Serratia, Shewanella, Stenotrophomonas genera, and 13 remained unidentified. All antimicrobially active strains were able to grow in salt medium at a concentration of 75 g l−1, thus classifying as moderately halotolerant bacteria. Most of the antimicrobially active strains exhibited a broad action spectrum, where 61% was because of uncharacterized antimicrobial substances, 25% because of bacteriocins and 13% because of siderophores. Ten strains were able to biosynthesize biosurfactant metabolites.
Water extracts of Calea urticifolia Mill. for the control of Meloidogyne incognita. Nematropica 39:289-296. Water extracts of roots and leaves of Calea urticifolia Mill. were evaluated for the control of Meloidogyne incognita on tomato cv Rio Grande grown in pots. The number of galls per plant and the number of eggs per g of macerated roots were evaluated for application times of 0, 24, 48 and 72 hours after transplant and extract concentrations of 0, 50 and 100% as measured by number of galls per plant, both root and leaf extracts gave the same control (Tukey, P = 0.05). This was also true with extract concentrations where 50 and 56% galling reduction were obtained with both 50 and 100% concentrations respectively, compared to untreated plants. Root extract concentrations inhibited egg numbers per plant by 20% more than those treated with leaf extracts. For this parameter, the full concentration inhibited egg production by 72% compared to the untreated control, and the half concentration inhibited egg production by 31%, regardless of the origin of the extract. The lowest egg numbers per plant was obtained when extracts were applied at planting (45% reduction) and 72 h after planting (48% reduction).
The Central American Locust Schistocerca piceifrons piceifrons is one of the most damaging plant pest in Mexico and Central America. The present work was carried out to evaluate the seasonal population fluctuation of S. p. piceifrons and vegetation diversity and their association with weather factors and edaphic conditions in the gregarious zone of the Yucatán Península. The study was performed in seven sites during three seasons: North-wind (December 2013), rainy (June 2014) and dry (April 2014). The locust density was sampled in transect of 100 m2, as well as the vegetation in 16 m2: plant species richness (PSR) and relative species density (RSD), and analyzed by generalized linear models. Additionally, soil samples were obtained at 10 cm depth into a 4 × 6 m quadrat, land use in the sites was classified and temperature, precipitation and evaporation of each site were obtained from the database and they were analyzed with multiple factor analysis. The population density of S. p. piceifrons was higher in the sites Panaba, Tizimin, Tunkas and Cenotillo (F= 74.3, P < 0.0001). Characterization of vegetation showed that PSR and RSD were higher during the rainy season relative to those in the dry season (F= 50.4, P < 0.0001). RSD was identified as the most important group associated with locust density (0.86), followed by isotherm/isohyets (0.63), maximum precipitation and temperature (0.60), as well as the land use (0.65); no correlation between locust density and soil characteristics was found. Locust density was positively correlated with the abundance of the grass Panicum maximum (Sr2= 0.85, PC5= 0.87). This work shows that the population of S. p. piceifrons is high in the rainy season and influenced primarily by the abundance of the grass P. maximum and the precipitation. The results indicate that surveys for early detection and control of the locust on the Yucatán Península can focus on areas with the grass P. maximum to predict risk areas and target survey efforts. Rev. Biol. Trop. 66(1): 403-414. Epub 2018 March 01.
The development of plant-derived products to control Bemisia tabaci Genn. (Hemiptera: Aleyrodidae) is an urgent need for production of horticultural crops. Plant extracts and essential oils of several species of the genus Eugenia (Myrtaceae) have shown insecticidal activity. In southern Mexico, leaf extracts from Eugenia winzerlingii showed nematicidal effect but its insecticidal properties have not been explored. Therefore, the objective of this study was to evaluate the insecticidal effect of aqueous and organic extracts from E. winzerlingii leaves on B. tabaci egg, nymph and adult stages, and else to explore its nursery propagation. Then, extracts of this species were obtained by maceration with different polarity solvents. Bioassays were carried out on Capsicum chinense leaves. Mortality assays showed that aqueous and total crude ethanol (TCE) extracts necrosed the eggs (LC50 = 0.21% w/v and 4.68 mg/mL, respectively), whereas hexane, ethyl acetate (ETA), residual ethanol and TCE extracts affected the nymphs (LC50 = 0.25 - 4.85 mg/mL). In adults, oviposition inhibition by free choice assay indicated that TCE and ETA extracts had major activity (EC50 = 14.62 and 27.86 µg/cm2 , respectively). On other hand, the sexual and vegetative propagation of E. winzerlingii showed that this species can be easily cultivated by seeds. In conclusion, extracts of E. winzerlingii leaves are highly effective in controlling B. tabaci. TCE extract, in particular, was toxic to three stages of B. tabaci. This plant could be a potential alternative to develop a novel botanical insecticide to manage this destructive pest.
BIOASSAYS EUGENIA WINZERLINGII OVIPOSITION INHIBITION PLANT PROPAGATION BEMISIA TABACI BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA MOLECULAR BIOLOGÍA MOLECULAR DE PLANTAS BIOLOGÍA MOLECULAR DE PLANTAS
MARIA MANUELA DE JESUS REYES ESTEBANEZ ELIZABETH DE LOS ANGELES HERRERA PARRA JARIO CRISTOBAL ALEJO GABRIELA PATRICIA HEREDIA ABARCA BLONDY BEATRIZ CANTO CANCHE Irma Leticia Medina Baizabal MARIA MARCELA GAMBOA ANGULO (2011)
Forty seven fungal strains were isolated from plant debris in the tropical regions of Mexico, where fifteen of them were identified to species and twenty two to genus level. All isolates were grown in fermented rice and their EtOAc extracts screened against ten targets, four bacteria (Bacillus subtilis, Erwinia carotovora, Staphylococcus aureus and Xanthomonas campestris), the yeast Candida albicans, three phytopathogenic fungi (Alternaria tagetica, Colletotrichum gloeosporioides and Fusarium oxysporum), the Oomycete Pythium aphanidermatum and the nematode Meloidogyne incognita. Antimicrobial activity was detected in 18 isolates against at least one of the target strains tested. Seven of these isolates with broad spectrum activity, which were defatted and their minimum inhibitory concentrations (MICs) were determined by microdilution assay. The greatest antagonistic action was produced by Cylindrium elongatum with broad spectrum activity while Corynespora cassiicola and Memnoniella sp. MR33 showed moderate antimicrobial properties. On other hand, in vitro nematotoxic activity was clearly detected only in Selenosporella sp. GH26 with 91 (LD 50) and 147 µg/ml (LD 90). This is the first report on the isolation and biological evaluation of anamorphic fungi from some Mexican tropical regions, demonstrating their potential as a source of biologically active natural metabolites for use in future applications in agriculture or pharmacy. Antimicrobial and nematicidal screening of anamorphic fungi isolated from plant debris of tropical areas in Mexico
The increasing incidence of Candida albicans infections and resistance to current antifungal therapies has led to the search for new and more effective antifungal compounds. Actinobacterial species from the Streptomyces genus are recognized as some of the major producers of antimicrobial compounds. Therefore, the aims of this study were: (1) the identification of Streptomyces strains isolated from Mexican tropical acidic soils, (2) the evaluation of their antifungal activity on C. albicans, and (3) the exploration of the presence of polyketide synthase genes in their genome and antifungal secondary metabolites in their extracts. Four actinobacterial strains, isolated from previously unexplored soils with antibacterial antecedents, were selected. These strains were identified as Streptomyces angustmyceticus S6A-03, Streptomyces manipurensis S3A-05 and S3A-09, and Streptomyces parvisporogenes S2A-04, according to their molecular analyses. The ethanol extract of the lyophilized supernatant of S. parvisporogenes displayed the most interesting antifungal activity against C. albicans, with a minimum inhibitory concentration (MIC) of 0.5 mg/mL. Type I polyketide synthase (PKS-I) and non-ribosomal peptide synthase (NRPS) genes were detected in all strains. In addition, type II PKS genes (PKS-II) were also found in S. manipurensis S3A-05 and S. parvisporogenes. LC-UV-HRMS analysis of the active organic extract of S. parvisporogenes indicated the presence of the known antifungal compound carbazomycin G as the major component.