This paper addresses the design and evaluation of a robust observer for second order bioprocesses considering unknown bounded disturbance terms and uncertainty in the dynamics of the unknown and known states. The observer design and the stability analysis are based on dead-zone Lyapunov functions, and a detailed procedure is provided. The transient response bounds and the convergence region of the unknown observer error are determined in terms of the disturbance bounds, considering persistent but bounded disturbances in the dynamics of both the known and unknown observer errors. This is a significant contribution to closely related observer design studies, in which the transient response bounds are determined, but persistent and bounded disturbances are not considered in the dynamics of the known observer error. Other important contributions are: (i) the procedure for defining the observer parameters is significantly simpler than common observer designs, since a solution to the Ricatti equation, solution to LMI constraints, or the accomplishment of eigenvalue inequality conditions are not required; (ii) discontinuous signals are not used in the observer; and (iii) the effect of the gain sign associated with the unknown state in the dynamics of the known state is explicitly and clearly considered in the observer design and in the convergence study. In addition, the guidelines for selecting the observer parameters are provided. Numerical simulation confirms the stability analysis results: the observer errors converge within a short time, with a low estimation error, if observer-parameters are properly defined.

The inclusion of more sustainable alternatives such as bacterial inoculants is a viable option for the competitiveness of vegetable crops in tropical countries such as Colombia. The economic feasibility of a bacterial suspension of G. diazotrophicus applied to the carrot crop was determined. The native isolate G. diazotrophicus GIBI029 was evaluated and the strain ATCC 49037 was used as a control. The experiment was installed in a subdivided plot design, where the plot was the bacterium G. diazotrophicus (ATCC49037 and GIBI029. The subplot was the concentration of G. diazotrophicus (88×10 6 CFU/mL and 18×10 7 CFU/mL) and, in it, the levels of nitrogen and phosphorus (0% and 100% nitrogen and phosphorus) were assorted. The average weight of the carrot (g) and the yield by quality of the consuming organ (kg/ ha) were evaluated. Through the production cycle, fixed, variable, and total costs were calculated. Benefit / cost ratios higher than 1.46 and net income up to US$ 10,817/ha were achieved. It is possible to efficiently and economically use the native isolate G. diazotrophicus GIBI029 in the search for more sustainable and competitive cultural practices.

The natural biodiversity that is found in tropical areas offers countless biotechnological opportunities; especially if we take in account that many biomolecules from several microorganisms have supported for many years, different industrial applications in areas such as pharmacology, agro-industry, bioprocess, environmental technology, and bioconversion. In order to find new lignocellulolytic enzymes and evaluate bamboo fibers as substrate, Schizophyllum commune a fungus with broad distribution was isolated and grown during 15 days in liquid culture medium containing 1% lignocellulosic fibers from bamboo, banana stem, and sugarcane bagasse. The enzymatic activity of xylanase, mannanase, polygalacturonase, CMCase, FPase, and avicelase were evaluated. Sugarcane bagasse and banana stem showed to induce higher hollocellulase activity when compared with bamboo as the main carbon source. The physical mechanism that the fungus uses to degrade bamboo was observed not only in fibers naturally infected but also in healthy fibers that were treated and untreated with enzyme solution. SEM analysis showed the structural disruption and invasion of the vascular bundles, parenchyma cells, and parenchymatous tissues as a consequence of the presence of this fungus and the catalytic action of its enzymes into the plant tissue.

The small gold mining generates toxic substances discharges, being an environmental problem. The objective was to evaluate the removal of cyanide and heavy metals, in liquid effluents from the gold benefit, by adsorption with activated carbon and hydrogen peroxide. The residues were first treated with carbon to determine the adsorption efficiency with 20, 40, 60 g of carbon / L of solution at times of 4, 8, 12 hours. Then hydrogen peroxide (1.0, 1.5, 2.0 liters of peroxide / Kg CN in solution, was added over 4 hours). The response variables were concentrations of cyanide, lead, zinc, iron. The best treatment with carbon was 60 g of carbon / L of solution and 12 hours of contact and for the process with hydrogen peroxide: 2 liters of H2O2 / Kg of CN in solution, during 4 hours. A flow chart and tables for the implementation of the process were designed.

Use of biotechnological potential of native microorganisms as bio-inputs is having a great impact on agricultural systems. Plant Growth Promoting Rhizobacteria (PGPR), in addition to their beneficial effect on plant growth and on the availability of soil elements, also have an antagonistic effect against different pathogens. In this study, growth promotion mechanisms with emphasis on the antagonism of PGPR isolated from sugarcane and tomato crops were evaluated. Antagonism against Fusarium oxysporum f.sp lycopersici (Fol) was determined by dual tests, inhibition of germination and production of chitinases and endoglucanases. 52 isolates were evaluated and according to their results in dual tests 10 were selected for further analysis. Isolate GIBI127 showed the best percentage of Inhibition Germination (IG) of Fol (59.29%). Then, a selection index was calculated using results from gi, dual tests and growth promotion mechanisms to select five best isolates. Finally, these bacteria were evaluated for chitinases and endoglucanases production using Miller´s method. As a result, strain GIBI419 (Burkholderia cepacia) showed a higher production of these enzymes. Selected isolates have antagonistic potential along with plant growth promotion characteristics, which can be used for the development of microbial inoculants which allow the establishment of agricultural systems for tomato cultivation that are sustainable, efficient, and environmentally friendly.