Lilia H. Morales-Ramos

Novel toxicity of native and HD Bacillus thuringiensis strains against to the sugarcane borer Diatraea saccharalis

Diatraea saccharalis (F.) (Lepidoptera: Pyralidae) is a pest that causes great economic losses to sugarcane producers in Mexico. In order to obtain alternatives for control of this pest, several Bacillus thuringiensis strains (native and from the Howard Dulmage collection) were tested. In bioassays, strains HD-133, HD-551, GM-7, GM-10, and GM-34 caused more than 50% mortality with a 50 μg/ml spore-crystal complex concentration, and were selected as toxic strains. The lowest LC50 value corresponded to GM-34 (33.21 μg/ml). Cry1B and cry1C genes were detected by PCR analysis in the toxic strains. HD-133 and GM-10 habored cry1C gene, HD-551 and GM-7 strains harbored cry1B gene, while GM34 strain did not contain cry1B nor cry1C. An additional PCR analysis was performed to detect cry1A-type genes. All the toxic strains habor at least one cry1A-type gene. Immunoblotting revealed that all strains cross-reacted with an antiCry1A, and only the HD-551 gave a positive signal with antiCry1B polyclonal antisera. GM-7 crystal protein showed no cross-reaction with polyclonal Cry1B antiserum. The toxicity of these strains may be related to some member of the Cry1A toxin class.

Effect of Native Mexican Isolates of Isaria fumosorosea (Wize) Brown & Smith1 on Spodoptera exigua (Hübner) and Helicoverpa zea (Boddie)2

Abstract. 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 (Hübner), 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.

Cadmium(II) and Lead(II) removal by Chlorella sp. Immobilized and E. coli genetically engineered with mice Metallothionein I

The pollution caused by heavy metals is one of the major environmental problems that is imperative to be solved. New technologies, easy to implement and to adapt to any system, deserve special attention and are a focus of this work the ability of Chlorella sp. and E. coli genetically engineered with mice metallothionein I, both immobilized in alginate of calcium to remove Cd(II) and Pb(II) from aqueous solutions was investigated in batch assays for the treatment of diluted aqueous solutions. The kinetics, sorption capacities and sorption percentage were determined. The influence of metal concentration in solution is discussed in the terms of Langmuir isotherm and constants. Sorption capacities increased with increasing metal concentration in solution. For solution containing 300 mg/L of metal, the observed uptake capacities were 94.941±1.094 mgCd/g Chlorella. , 24.076±2.292 mgCd/g E.coli and 239.17±2.478 mgPb/g Chlorella , 37.952±4.245 mgPb/g E.coli . The Langmuir constants to Chlorella sp. were q max =285.72(mg Pb /g), b=0.0276(l/mg Pb ), q max =103.65(mg Cd /g) and b=0.0005(l/mg Cd ) while to E. coli were q max =28.141(mg Pb /g), b=0.113(l/mg Pb ), q max =24.272(mg Cd /g) and b =0.019(1/mg Cd ). The biomass of the algae showed to have better capacity of metallic sorption that the biomass of the bacteria genetically engineering. The study proved that microorganisms biomass is a suitable material for the removal of the studied heavy metals ions from aqueous solutions, achieving removal efficiencies higher than 90%, and could be considered as a potential material for treating effluent polluted with Cd(II) and Pb(II) ions.