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Objectives The cell wall of microalgae is a necessary barrier for its survival in aquatic environments. This barrier affects the recovery of lipids, representing one of the main difficulties in the development of microalgal biofuel production technology. In this context, this work aimed to test the effect of a new method based on melittin peptide as a pretreatment to cause cellular disruption in N. oleoabundans cultivated under different temperatures and nutrient concentrations. Results Neochloris oleoabundans cells were grown at 32°C in the presence of high concentration of nitrate-phosphate, cell disruption degree being recorded at 83.6%. Also, two-fold increase in lipid recovery following melittin treatment and solvent extraction was observed. Furthermore, it was possible to verify the effect of melittin, both before and after treatment on the morphology of the cells. Scanning electron microscopy (SEM) and confocal images of the melittin-treated microalgae revealed extensive cell damage with degradation of the cell wall and release of intracellular material. Conclusions Melittin peptide produced a selective cell wall rupture effect with the highest percentage of cell disruption degree when N. oleoabundans under culture condition with nitrate-phosphate repletion at 32 °C favors cell wall susceptibility to cell disruption by melittin peptide, representing the first report on lipid recovery from microalgae. Melittin is a promising option for the enhancement of the recovery of lipids from microalgae.

Recent research has shown that the use of biological extracts, which contain a wide variety of nutrients and phytohormones are potentially useful in the production of plants of agricultural importance. Seaweed extracts are particularly rich in minerals and micronutrients necessary for the growth of microalgae. The effect of three commercial extracts of Ascophyllum nodosum as plant growth inducers (Stimplex®, Acadian Soils® and Liquid Seaweed Concentrate®), provided by Acadian Sea Plants Ltd., were evaluated in relation to the growth and production of biomass and carotenoids in Haematococcus pluvialis. The results were evaluated by one-way ANOVA and post-hoc analysis utilizing Tukey's test with a significance level of 95% (α= 0.05). The reference medium used was the Bold basal medium, to which 250 ppm of each extract was added. The Stimplex® extract had an increase of 22.79% in cell density and 17% in dry matter, higher than the control culture. The content of carotenoids and antioxidant capacity, respectively, with Stimplex® was 30.05% and 141.76% higher than the control culture.

Street dust is widely recognized as one of the major non-point sources of heavy metal pollution and represents an important pathway for human exposure. Concentrations of heavy metals in 41 samples of street dust from six municipalities’ sampled zones on the Monterrey Metropolitan Area in Nuevo Leon, Mexico, were evaluated. The results of concentrations of metals from the downtown, eastern, southern and southeast zones follow the order of lead > zinc > cadmium with only at the downtown and east zones not detecting the presence of cadmium in the samples collected. For the other zones, the order was zinc > lead > cadmium. The downtown zone is characterized by its commercial activity and vehicular traffic, reaching values of 1590 mg kg−1 of lead per each 0.450 m2 sampled on the averaged collected sample representative of an area of 25 m2. The non-impacted area showed concentrations of lead at 7.36 mg kg−1, cadmium 0.25 mg kg−1 and zinc 70.5 mg kg−1. Based on these values, the ecological risk indexes are within the moderate to the extremely high range of pollution in all zones except for the southwest. The potential ecological index shows that lead is present as a pollutant in all sampled points and contributes greatly to a very high ecological risk index observed in the downtown zone of the Monterrey Metropolitan Area.

The aim of this study was to evaluate the production of blastospores and conidia of different native isolates and a strain of Isaria fumosorosea using different propagation techniques. Two liquid culture media of casamino acids and peptone as nitrogen sources and glucose as carbon source for both media cultures were respectively used in the production of blastospores, while for the production of conidia, the fungi were grown in potato dextrose agar; from these cultures, solutions of conidia to a concentration of 1×106 per milliliter were prepared to inoculate flasks with Sabouraud dextrose broth for the liquid phase of the biphasic culture, also known as preculture. Subsequently, rice grain bags were inoculated with the preculture and the conidia solutions, which were incubated for 14 days for solid fermentation and biphasic culture, respectively. The HIB-23 isolate recorded a concentration of 4.90×108 blastospores/ml in the casamino acid medium, while a concentration of 2.15×108 blastospores/ml was obtained in the peptone collagen medium. For the Pfr-612 strain, the conidia production in solid-state fermentation was 1.58×109 conidia/g, and for HIB-30 in the biphasic culture of 9.00×106 conidia/g. Solid-state fermentation proved to be the most effective method with an average of 1.09×109 conidia/g, whereas the biphasic culture was the least effective method with 2.76×106 conidia/g; no significant difference was reported for the submerged production media.

Beer is recognized as a safe beverage, owing to its excellent microbiological stability provided by its components, especially iso-α-acids from hop and ethanol which have antimicrobial activity. Despite these unfavourable conditions for bacteria, some lactic acid bacteria (LAB) can cause beer spoilage. Resistance to hop compounds is caused, in part, by the product of genes like horA. Understanding how LAB adapts to hop compounds as well as quick detection of these microorganisms is necessary to ensure high-quality beverages produced by the brewing industry. In this work, we searched for the presence of two main hop-resistance genes, horA and ORF5, and determined the capacity of four strains of Pediococcus damnosus isolated from a brewery environment to grow in the presence of increasing concentrations of iso-α-acids. All strains were able to grow in increasing concentrations of iso-α-acids up to 150 μg mL−1. This amount is 10 times greater than the concentration in average beer. Genetic amplification of genes associated with hop-resistance, demonstrated the presence of horA, but not ORF5 in all tested strains. This communication represents the first report of the presence of horA gene in bacteria isolated from breweries in our country. Copyright © 2017 The Institute of Brewing & Distilling

Se evaluo la mortalidad causada por 24 aislamientos nativos de Bacillus thuringiensis Berliner provenientes de suelo de Yucatan contra los lepidopteros Trichoplusia ni (Hubner), Spodoptera exigua (Hubner), y Helicoverpa zea (Boddie). Los bioensayos preliminares contra larvas neonatas comparados con las cepas HD-1, GM-7, IB-7, e IB-62 permitieron seleccionaron 8 cepas nativas para la determinacion de las CL50. En la comparacion de medias de las CL50 se encontro a la cepa GM-IB-92 significativamente mas toxica contra T. ni y de toxicidad similar contra S. exigua en comparacion con HD-1 y GM-7. Sin embargo, ninguna de las cepas nativas mostro toxicidad mayor a las cepas de referencia HD-1, GM-7, IB-7, e IB-62 contra H. zea. Dos formulaciones de la cepa GM-IB-92, preparadas con polimeros biodegradables y protectores de la luz ultra violeta fueron probadas y comparadas contra Dipel® 2X, donde presento mayor actividad toxica F2–5 contra T. ni. Las formulaciones preparadas mantuvieron su actividad toxica por al menos 90 dias de almacenamiento a 25–30°C. Los formulados preparados presentaron menor reduccion en la actividad insecticida, del 4–13% que el extracto sin formular que mostro 54–88% despues de la irradiacion con luz uv por 72 horas.

Resumen Anastrepha ludens es una de las plagas que afectan severamente la producción de frutas en México y otros países neotropicales. El objetivo de este estudio fue evaluar la virulencia y el efecto en la metamorfosis de cuatro aislados nativos y una cepa de colección de Isaria fumosorosea sobre A. ludens mediante bioensayos bajo condiciones de laboratorio [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)] al exponer larvas y pupas a una concentración de 1 × 108 blastosporas/ml mediante dos diferentes métodos, asperjado directo y asperjado de suelo. Los aislados HIB-23 e HIB-30 mostraron la más alta mortalidad sobre A. ludens mediante el método de asperjado directo sobre larvas (84 %) mientras que el aislado HIB-19 tuvo el más alto porcentaje de interrupción de la metamorfosis (43 %) sobre A. ludens por el método de aspersión directa sobre pupas. Estos resultados sugieren que A. ludens es susceptible al ataque por I. fumosorosea y esto puede influir en la terminación de su ciclo de vida. Abstract Anastrepha ludens is one of the pests that seriously affects fruit production in Mexico and other Neotropical countries. The aim of this study was to evaluate the virulence and effects of four native isolates and a collected strain of Isaria fumosorosea on the metamorphosis of A. ludens through the use of bioassays under laboratory conditions [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)]. Larvae and pupae were exposed to 1 × 108 blastospores/ ml using two different methods: direct spraying and spraying of soil. The isolates HIB-23 and HIB-30 showed the highest mortality on A. ludens when applied using the direct spraying method on larvae (84 %), while the isolate HIB-19 showed the highest percentage of interruption of the metamorphosis (43 %) of A. ludens when applied through the method of direct spraying on pupae. The results show that A. ludens is susceptible to the attack of I. fumosorosea, which causes the disruption of its life cycle.

The aim of this study was to evaluate pathogenicity and effect of four isolated native and a strain of Isaria fumosorosea on beet armyworm, Spodoptera exigua (Hubner), and corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). Bioassays in a laboratory used neonate larvae of beet armyworm and corn earworm reared on artificial diet, which were inoculated by spraying or immersing with suspensions of 1 × 108 ml-1 conidia of I. fumosorosea, and subsequently incubated at 26°C, 65 ± 5% relative humidity, and 14:10 light: dark hours. Isolated HIB-30 killed the most immersed corn earworms, but fewest beet armyworms. HIB-30 most disrupted metamorphosis, 40%, by immersing beet armyworms, while HIB-29 and Pfr-612 least interrupted metamorphosis (8%), by spraying and immersing, respectively.

A native strain of Heterorhabditis indica Poinar, Karunakar & David nematode from Guasave, Sinaloa, Mexico, was identified by sequencing internal transcribed spacer regions of ribosomal DNA (rDNA). Assays against immature sweetpotato whitefly, Bemisia tabaci (Gennadius), used four strains of nematodes: Heterorhabditis bacteriophora Poinar Guatemala strain, H. bacteriophora Chiapas strain, a commercial product Steinernema feltiae (Filipjev) (Koppert®), and the H. indica native strain from Sinaloa. All strains at concentrations of 1,000, 750, 500, and 250 infective juveniles per milliliter, without significant differences among them, killed 70 to 95% of B. tabaci biotype B nymphs on leaves of tomato, Solanum lycopersicum (Mill), under laboratory conditions. This study is the first report of a native H. indica strain in Mexico, which is proposed as a biological control agent against B. tabaci.

Three Metarhizium anisopliae and three Beauveria bassiana isolates were cultivated in media containing casamino acids, soybean flour or sunflower seed flour and were shaken for three days. M. anisopliae presented similar yields of around 106 submerged spores/ml without significant differences among them, whereas B. bassiana produced yields of around 108 spores/ml, of which GHA strain produced more submerged spores in the casamino acids medium. The other two strains showed no significant difference in the production of submerged spores in the three media used. Differences in mortality on Aedes aegypti larvae were observed with the submerged spores of Metarhizium depending on isolate and medium used. M. anisopliae 2157 caused significantly higher mortality (40%) when cultivated in casamino acids medium. It presented an LC50 of 8.93 × 105 submerged spores/ml water against mosquito larvae five days after application, whereas it caused 27% mortality in Ae. aegypti adults 10 days after application. In conclusio...

Blastospores of lsaria fumosorosea Wize grown in a bioreactor with casaminoacids or collagen peptone as the nitrogen source were evaluated for effectiveness against nymphs of silverleaf whitefly, Bemisia argentifolii Bellows & Perring, in cotton, Gossypium hirsutum L. The I. fumosorosea blastospores produced in the two liquid culture media were formulated with and without diatomaceous earth and sprayed onto terminal leaves of cotton in the field. The effectiveness of the materials was compared with Specifik®, a commercial formulation containing 1 × 1011 conidia per gram of I. fumosorosea formulated with Rhudo®, and a mixture of insecticides (Endosulfan® + Rescate® 20 PS). Blastospores produced in the medium containing casaminoacids as the main source of nitrogen and formulated with diatomaceous earth, as well as blastospores produced in the medium containing collagen peptone and not formulated with diatomaceous earth were most effective in reducing the number of nymphs. These experimental formul...

The aim of this study was to evaluate the production of blastospores and conidia of different native isolates and a strain of Isaria fumosorosea using different propagation techniques. Two liquid culture media of casamino acids and peptone as nitrogen sources and glucose as carbon source for both media cultures were respectively used in the production of blastospores, while for the production of conidia, the fungi were grown in potato dextrose agar; from these cultures, solutions of conidia to a concentration of 1×10

In this work, we examined the production of infective zoospores of Lagenidium giganteum in four culture media, and the larvicidal activity of the cultures was determined against Aedes aegypti larvae, as well as the effect of polymer encapsulation. Medium containing sunflower seed extract showed the greatest production of zoospores, 5.92 × 10 6 zoospores/ml after six days of fermentation at 25 ± 2 °C and 150 rpm shaking. This culture tested against A. aegypti 1st stage larvae caused different mortality rates at 24, 48 and 72 h posttreatment. The LC 50 obtained was 43.9, 41.1 and 42.9 μl of total culture/ml, at 24, 48 and 72 h posttreatment respectively, while the culture grown in medium with soybean meal showed 3–5 times higher LC 50 values. Finally, the total culture including mycelium, zoospores and presporangia formulated with 2.5% pectin showed significantly higher mortality rates, around 100% more than the unformulated culture, whose values were from 40 to 1% at 3, 6, 9, and 12 d posttreatment in the bioassays carried out in the laboratory to determine residual activity.

There are many advantages to using liquid cultures for the production of blastospores. These include mainly the processes of scale up which are relatively easy, as well as the control of parameters such as temperature, aeration and pH. In this work, we evaluated the production of Paecilomyces fumosoroseus blastospores using a low-cost liquid culture medium in a fermenter in comparison to a medium commonly used for this purpose, with regard to yield and viability of blastospores. The two media contained the same concentration of glucose but differed in N source (M1 containing casamino acids and M2 provided with collagen peptone and yeast extract). Starting with an inoculum of 1x106 blastospores/ml, M2 medium produced 2x1010 blastospores/ml after incubation for 72 h at 520 rev/min agitation and 1 v/v/m (volume air/volume liquid.min) aeration, while only 2.4 x 108/ml were produced with M1. In addition, the microorganisms in medium M1 grew more slowly during log phase and reached an earlier plateau at 36 h fermentation. The medium containing collagen peptone and yeast extract is an excellent alternative for the production of P. fumosoroseus blastospores, providing lower cost, higher yield and shorter propagation time, but formulation does need to be improved.

La comprensión de los aspectos básicos del desarrollo de los hongos entomopatógenos y el conocimiento detallado de los requerimientos nutricionales para su crecimiento y esporulación es esencial para la producción masiva y comercialización. El objetivo de este estudio fue evaluar la producción de blastoesporas en un medio de cultivo sumergido y de conidios en un cultivo bifásico, de cuatro aislados nativos y una cepa de B. bassiana con potencial para controlar Diaphorina citri (Hemiptera: Liviidae), pertenecientes a la colección del Instituto de Biotecnología, FCB-UANL, México. El diseño experimental fue completamente al azar y las medias se compararon con la prueba Tukey (p £ 0.05). En el medio de cultivo líquido formulado con glucosa y casaminoácidos, la producción de blastoesporas a las 72 h mostró para la cepa GHA la mayor (p £ 0.05) concentración (2.20×10 8 mL - 1 ) y una biomasa de 26 g L - 1 , y en el aislado HIB-4 ocurrió la producción menor (p £ 0.05) de blastoesporas (5.25×10 7 m L - 1 ) y biomasa de 7 g L - 1 . El aislado HIB-2 presentó 56 % de germinación en tie - rra de diatomeas como soporte y fue el valor mayor entre los hongos estudiados. En la fase sólida (grano de arroz), a los 14 d de incubación, el aislado HIB-4 presentó una producción de 1.82×10 9 conidios g - 1 y la cepa GHA produjo 2.35×10 8 conidios g - 1 . La viabilidad fue superior a 90 % para todos los hongos durante 4 semanas de almacenamiento a 4 °C. Así, es factible producir blastoesporas y conidios de aislados nativos de B. bassiana con potencial para el manejo de plagas que afectan las regiones citrícolas de México

The objective of the study was to isolate and characterize genetically native fungi that remain in the soil of the diverse citrus regions of Mexico. We collected 142 soil samples from different Mexican states: Campeche (13), Michoacan (15), Nuevo Leon (25), San Luis Potosi (25), Sinaloa (17), Sonora (17), Tabasco (5), Tamaulipas (20), and Yucatan (5). Larvae of Galleria mellonella were used as bait to detect, trap and multiply entomopathogenic fungi in vivo. 23% of the soil samples processed were positive for the presence of entomopathogenic fungi according to the macroscopic and microscopic characteristics: Beauveria was detected in 12% (17 isolates), Metarhizium in 1% (2 isolates) and Isaria in 10% (14 isolates). We analyzed the genetic variability of the fungi by using the sequences of internal transcribed ribosomal genes (ITS-5.8S-ITS2) and subsequently performed the digestion with the enzyme Hae III. The results of the PCR generated fragments of approximately 600 bp for Beauveria spp., and Metarhizium spp. In the case of Isaria spp., it amplified a fragment above of 600 bp. Both reference strains and field isolates produced similar restriction patterns. Genera of native entomopathogenic fungi were found on the diverse citrus areas of Mexico; this opens the field for the biological control of pests affecting citrus in each region.