Hugo Alberto Luna-Olvera

Removal of chromium and lead by a sulfate-reducing consortium using peat moss as carbon source

The effect of pre-treated peat moss on the ability of a sulfate-reducing microbial consortium to remove chromium and lead in solution was evaluated. The most active bacterial community (235.7 mmol H2S/g VSS) was selected from among eight consortia. The peat moss was pre-treated with different HCl concentrations and contact times. The best combination of treatments was 20% HCl for 10 min. The constant substrate affinity Ks was 740 mg COD/L and the ratio COD/SO4(2-) was 0.71. At pH 5, higher production of biogenic sulfide was observed. The up-flowpacked bed bioreactor operated at a flow of 8.3 mL/min for 180 h to obtain removal efficiency (by sulfate-reducing activity) of 90% lead and 65% chromium. It is important to consider that peat moss is a natural adsorbent that further influences the removal efficiency of metal ions.

Paecilomyces fumosoroseus blastospore production using liquid culture in a bioreactor

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.

Evaluation of Heterorhabditis indica (Rhabditida: Heterorhabditidae) Nematode Strain from Sinaloa, Mexico, Against Bemisia tabaci Immatures Under Laboratory Conditions

Abstract. 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.

Detection of group I and group II introns in a Mexican Bacillus thuringiensis collection

Group I and II introns are non-coding sequences able to excise themselves from precursor mRNA by self-splicing. Both groups are ribozymes and may also code Open Reading Frames (ORF) for enzymes involved in the homing process; the Homing Endonuclease (HEase) in group I introns and maturase for group II. In this study, Mexican Bacillus thuringiensis strains belong to the Universidad Autonoma de Nuevo Leon collection were evaluated for the presence of these introns. For this propose, specific primers were designed for group I introns inserted in the ribonucleotide reductase operon and group II introns B.th.I, Bth.I2and B.th.I3. The PCR results obtained with primers for group I, was a DNA band of 600 bp for most strains (fifty four) and one of 200 bp for six one. The nucleotide sequence of 600 pb DNA band revealed more than 95% homology with the amplicons and group I introns reported before. Concern to group II introns, we can not see PCR products correspond to expect DNA band size.

Identification and characterization of a Cry7-like protein of Bacillus thuringiensis GM-33 strain holotype for subsp. monterrey

V.E. Aguirre-Arzola, A. G, Alcazar-Pizana, L. J. Galan-Wong, H. A. Luna-Olvera, B.E. Rivera Chavira and B. Pereyra-Alferez 1 Instituto de Biotecnologia. Facultad de Ciencias Biologicas. Universidad Autonoma de Nuevo Leon. Pedro de Alba y Manuel L. Barragan S/N. Cd. Universitaria. San Nicolas de los Garza, NL. 66450. Mexico 2 Facultad de Ciencias Quimicas. Universidad Autonoma de Chihuahua. Av. Universidad S/N. Cd. Universitaria. Chihuahua, Apdo. Postal 669. c.p.31170, Mexico.