's Capability of Infecting Different Grasses in Two Regions of Mexico.

The genus includes species that are phytopathogenic fungi, which infect different species of Poaceae, such as rice and sorghum. However, few isolates have been genetically characterized in North America. The current study addresses this lack of information by characterizing an additional 57 strains of three grasses (, and ) from two distant regions of Mexico.

Two-methods approach to follow up biomass by impedance spectroscopy: Bacillus thuringiensis fermentations as a study model.

Impedance spectroscopy is used for the characterization of electrochemical systems as well as for the monitoring of bioprocesses. However, the data obtained using this technique allow multiple interpretations, depending on the methodology implemented. Hence, it is necessary to establish a robust methodology to reliably follow-up biomass in fermentations.

Use of equivalent circuit analysis and Cole-Cole model in evaluation of bioreactor operating conditions for biomass monitoring by impedance spectroscopy.

The most important parameter in bioprocesses is biomass, where not only the quantity produced in a culture but also the behavior that is presented are important concerns. It is clear that conditions of operation in a bioreactor affect biomass production, but how operation conditions affect the measurement of biomass on-line is of special interest. We studied the effect of bioreactor operating condition variations on model parameters using impedance spectroscopy for biomass monitoring.

Flocculation and Expression of Genes of a Mezcal Strain with High Stress Tolerance.

Mezcal is a distillate produced by spontaneous fermentation of the must obtained from stalks of spp. plants that are cooked and pressed. Agave must contains a high amount of fructose and phenolic compounds, and fermentation usually occurs under stressful (and uncontrolled) environmental conditions.

Reactance and resistance: main properties to follow the cell differentiation process in Bacillus thuringiensis by dielectric spectroscopy in real time.

During growth, Bacillus thuringiensis presents three phases: exponential phase (EP), transition state (TS), and sporulation phase (SP). In order to form a dormant spore and to synthesize delta-endotoxins during SP, bacteria must undergo a cellular differentiation process initiated during the TS. Dielectric spectroscopy is a technique that can be utilized for continuous and in situ monitoring of the cellular state.

Genome distribution and validation of novel microsatellite markers of Fusarium verticillioides and their transferability to other Fusarium species.

Improved population studies in the fungus Fusarium verticillioides require the development of reliable microsatellite markers. Here we report a set of ten microsatellite loci that can be used for genetic diversity analyses in F. verticillioides, and are equally applicable to other fungi, especially those belonging to the Gibberella fujikuroi clade.

The effect of hexose ratios on metabolite production in Saccharomyces cerevisiae strains obtained from the spontaneous fermentation of mezcal.

Mezcal from Tamaulipas (México) is produced by spontaneous alcoholic fermentation using Agave spp. musts, which are rich in fructose. In this study eight Saccharomyces cerevisiae isolates obtained at the final stage of fermentation from a traditional mezcal winery were analysed in three semi-synthetic media.

Culture-independent analysis of lactic acid bacteria diversity associated with mezcal fermentation.

Mezcal is an alcoholic beverage obtained from the distillation of fermented juices of cooked Agave spp. plant stalks (agave must), and each region in Mexico with denomination of origin uses defined Agave species to prepare mezcal with unique organoleptic characteristics. During fermentation to produce mezcal in the state of Tamaulipas, not only alcohol-producing yeasts are involved, but also a lactic acid bacterial community that has not been characterized yet.

Morphometric evaluation of the specific growth rate of Aspergillus niger grown in agar plates at high glucose levels.

Development of surface grown cultures of Aspergillus niger no. 10 was studied at two experimental levels: (a) following the time course of the biomass density (X [=] mg cm(-2)) and fitting the data by the logistic expression, which yielded a macroscopic specific growth rate expressed as micro(obs) = (dX/Xdt)[1-(X/X(max))](-1); and (b) measuring morphometric parameters like the specific elongation rate (k) of the germ tubes and their diameters (D(h)), the colony rate of radial extension (u(r)), and the mean length of distal hyphae (L(av)) to estimate the specific growth rate with the following proposed expression: micro(calc) = u(r)ln2[L(av)ln(L(av)/D(h))](-1). Increases in the initial glucose concentration (10, 40, 70, 120, 200, and 300 g L(-1)) caused reductions in the specific growth rates, the elongation kinetics of the germ tubes, and the hyphal diameter, nevertheless, u(r) and X(max) presented parabolic behavior, showing their maxima in the interval of 90 to 120 g L(-1) of glucose.

Biocontrol potential and polyphasic characterization of novel native Trichoderma strains against Macrophomina phaseolina isolated from sorghum and common bean.

Native strains of Trichoderma isolated from sorghum and common bean crop soils were investigated to assess their biocontrol potential over the phytopathogenic fungus Macrophomina phaseolina, isolated from diseased plants. The Trichoderma strains were characterized with a polyphasic approach, which combined the analysis of their morphological characteristics, enzymatic activity, macro- and microculture test results, rDNA restriction patterns (AFLP), ITS1-5.8S-ITS2 rDNA sequences, and protein profiles.

Evaluation of chitosans and Pichia guillermondii as growth inhibitors of Penicillium digitatum.

Chitosans were obtained by room-temperature-homogeneous-deacetylation (RTHD) and freeze-pump-out-thaw-heterogeneous-deacetylation (FPT) from chitins purified from fermentations. Commercial chitosan was deacetylated by three-FPT-cycles. Chitosans and Pichia guillermondii were evaluated on the growth of Penicillium digitatum.

Development of advanced image analysis techniques for the in situ characterization of multiphase dispersions occurring in bioreactors.

Fermentation bioprocesses typically involve two liquid phases (i.e. water and organic compounds) and one gas phase (air), together with suspended solids (i.

Quantitative characterisation of the morphology of Trichoderma harzianum cultured in shake-flasks and containing tween 40.

Image analysis was used to measure the effect of Tween 40 on the morphology of Trichoderma harzianum. The percentage of pellets was maximal (93%) with Tween at 0.2 ml l(-1), whereas the maximal proportion of dispersed mycelia (40%) was with Tween at 1.

Oil and air dispersion in a simulated fermentation broth as a function of mycelial morphology.

The culture conditions of a multiphase fermentation involving morphologically complex mycelia were simulated in order to investigate the influence of mycelial morphology (Trichoderma harzianum) on castor oil and air dispersion. Measurements of oil drops and air bubbles were obtained using an image analysis system coupled to a mixing tank. Complex interactions of the phases involved could be clearly observed.